Oil-resistant and high-temperature-resistant two-component silicone rubber, preparation method and application

Abstract

The present invention relates to the technical field of adhesives, and particularly to an oil-resistant and high-temperature-resistant two-component silicone rubber, a preparation method and an application. The silicone rubber comprises component A and component B; component A comprises 92 to 110 parts by weight of modified polysiloxane, 4 to 12 parts by weight of toughening agent and 8 to 18 parts by weight of oil-resistant filler; component B comprises 10 to 40 parts by weight of dimethyl silicone oil, 10 to 20 parts by weight of crosslinking agent, 0.5 to 5 parts by weight of colorant and 1 to 8 parts by weight of thickening agent, and the mass ratio of component A to component B is (5 to 15):1. Compared with the prior art, the modification of polysiloxane in the present invention improves the bonding and thermal stability, resulting in the prepared silicone rubber having excellent oil resistance, high temperature resistance and good bonding performance, and being applicable to a variety of industrial application scenarios.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and particularly to an oil-resistant and high-temperature-resistant two-component silicone rubber, a preparation method and an application thereof. Background Art

[0002] Silicone rubber, also known as silicone building sealant, as the name implies, was originally developed to solve problems in the field of building sealing. The sealing principle of silicone sealant is to fill the tiny cracks and pores on the surface of the object to be sealed, so as to achieve the sealing effect. It has good adhesion and rheology, and can effectively contact the surface to be sealed during the filling process, filling cracks and pores. This filling effect can prevent the entry of external moisture, dust and other substances, thereby protecting the object to be sealed and extending its service life. Silicone rubber has many excellent properties and has now developed into an important sealing material.

[0003] Silicone sealants are usually divided into two types: one-component and two-component. For one-component silicone rubber, its curing depends on contacting moisture in the air to produce physical property changes; two-component means that the silicone rubber is divided into two groups, A and B. Neither group can form curing alone, but once the two groups of pastes are mixed, curing occurs. Two-component silicone sealant is a two-component, neutral-curing silicone sealant, specially designed for the secondary sealing of insulating glass, with high strength, high modulus, and high gloss. The curing speed can be adjusted, and the deep curing is fast, suitable for construction in factories. It is non-corrosive to building materials such as metals, coated glass, concrete, marble, granite, etc. When curing, it releases low molecular weight alcohols, without irritating or unpleasant odors. It also has excellent weather resistance, aging resistance, ultraviolet resistance, ozone resistance, and waterproof performance. After curing, it always maintains good elasticity and strength in the temperature range of -50°C to 150°C. Due to its excellent weather resistance, high and low temperature resistance, aging resistance and good adhesiveness, silicone sealant has become an indispensable sealing solution in many fields. Compared with one-component silicone sealant, two-component silicone sealant usually has a faster curing speed and higher strength, and is suitable for industrial fields that require rapid curing and high-strength bonding.

[0004] CN107043601A belongs to the technical field of sealants, and particularly relates to a high-strength two-component high-temperature resistant inorganic sealant. The sealant of this invention includes two parts, component A and component B; among them, by weight, component A is: inorganic oxide 60 - 80, curing agent 10 - 30, alkali metal oxide 1 - 10, and component B is: binder 80 - 100, additive 1 - 20; they are used after being mixed. The characteristics of the sealant of this invention are a wide service temperature range (0 - 1300 °C), excellent acid and alkali resistance and water resistance, good adhesion performance with materials such as metals, woods, and ceramics, and it is used in high-temperature resistant parts such as refractory materials, heating electrical appliances, and the assembly of flame-spraying parts and spark plugs of petrochemical equipment, and can be widely applied in fields such as aerospace, machinery, electronics, chemical industry, and high-tech.

[0005] CN105647462A discloses a condensation-type two-component silicone sealant and its preparation method, which is prepared from the following raw materials by weight: Component A: 100 parts of organopolysiloxane polymer, 60 - 150 parts of surface-treated calcium carbonate; Component B: 2 - 10 parts of organopolysiloxane polymer, 0.1 - 10 parts of inorganic filler, 2 - 10 parts of silane composite crosslinking agent, 2 - 6 parts of silane composite coupling agent, and 0.1 - 0.5 part of organotin catalyst. Compared with the existing condensation-type two-component silicone sealant, the product of this invention also has good physical and mechanical properties, and at the same time can maintain good adhesiveness for a long time under immersion conditions, and can be applied under immersion conditions or humid use environments after being completely cured.

[0006] Silicone glue is required for the encapsulation and bonding of electronic components. The sales volume of electronic components is large, and the improvement of electronic components puts forward higher requirements for the adhesives used therein. The silicone glue currently in use has problems such as low bonding strength, poor heat resistance, and poor quick-drying performance after use, which makes the chemical properties of the adhesive unstable, reduces the production efficiency of components, and is also prone to quality problems of devices due to unreliable bonding. Summary of the Invention

[0007] In view of the above-mentioned defects of the prior art, the technical problem to be solved by this invention is to provide an oil-resistant and high-temperature resistant two-component silicone glue, a preparation method, and an application.

[0008] Polysiloxane consists of a siloxane main chain and side chains. This special chemical structure endows it with many excellent properties, including thermal stability and chemical stability. However, due to the flexibility and non-polarity of the molecular chain, it may not form a strong adhesion with polar or rough surfaces, resulting in poor adhesiveness. Therefore, the present invention provides a modified polysiloxane. Epoxy resin is obtained by epoxidizing 1,4-dihydroxy-N-allyl phthalimide with an imide five-membered ring, and then reacting it with vinyl-terminated silicone oil to obtain the modified polysiloxane. Since the epoxy group has strong polarity, it can significantly improve the adhesion performance of polysiloxane. And under the action of a crosslinking agent, the epoxy group can also crosslink, thereby enhancing the strength and adhesion performance of the final product. The imide ring in the phthalimide group not only has high rigidity and stability but also has high thermal stability, so it is not easily broken or decomposed at high temperatures. And the benzene ring, as an aromatic ring, also has good rigidity and thermal stability. Therefore, the modified polysiloxane not only has better adhesiveness but also stronger high-temperature resistance. The present invention uses high-molecular-weight modified polysiloxane as the main component, which can maintain good adhesion strength and stability in a high-temperature environment. By adding fluorinated fillers such as polytetrafluoroethylene, it has excellent oil resistance and can be used in an environment where grease and chemicals exist without failure. By adding a toughening agent, the toughness and flexibility of the glue are improved, and its adhesion strength and impact resistance are enhanced. By using an amino silane as a crosslinking agent, the curing process is accelerated, and the production efficiency and use convenience are improved.

[0009] To achieve the above object, the present invention provides an oil-resistant and high-temperature-resistant two-component silicone glue, comprising component A and component B; component A comprises 92-110 parts by weight of modified polysiloxane, 4-12 parts by weight of a toughening agent, and 8-18 parts by weight of an oil-resistant filler; component B comprises 10-40 parts by weight of dimethyl silicone oil, 10-20 parts by weight of a crosslinking agent, 0.5-5 parts by weight of a colorant, and 1-8 parts by weight of a thickening agent; the mass ratio of component A to component B is (5-15):1.

[0010] The preparation method of the modified polysiloxane comprises the following steps:

[0011] X1. Mix 1,4-dihydroxy-N-allyl phthalimide, epichlorohydrin, and tetramethylammonium bromide evenly under an inert atmosphere, then heat to 90-110°C, stir for 1-2 h, then cool to 80-90°C, add sodium hydroxide and 4A molecular sieve in batches, continue to stir for 1-2 h, then filter to remove the molecular sieve, etc. After concentrating the filtrate, add toluene and water, extract, add alkali to the organic phase, stir, adjust the pH to neutral, and then separate, dry, and concentrate for the next step;

[0012] X2. Add the product of the previous step and the vinyl-terminated silicone oil into ethyl acetate, then add azobisisobutyronitrile, and stir at 75-85 °C for 2-6 h, and then concentrate to remove the solvent to obtain the modified polysiloxane.

[0013] Further, the molar ratio of 1,4-dihydroxy-N-allylphthalimide, epichlorohydrin, tetramethylammonium bromide, and sodium hydroxide is 1:8-12:0.05-0.07:1-3.

[0014] Further, the molar ratio of the product of the previous step, the vinyl-terminated silicone oil, and azobisisobutyronitrile is 1-3:1:0.01-0.05.

[0015] Further, the addition amount of the 4A molecular sieve is 50-60 wt% of 1,4-dihydroxy-N-allylphthalimide.

[0016] Furthermore, the vinyl-terminated silicone oil can be replaced with an isocyanate-terminated silicone oil or a methacryloxy-terminated silicone oil.

[0017] Further, the toughening agent is dibutyl phthalate.

[0018] Further, the oil-resistant filler is a fluorinated filler, specifically polytetrafluoroethylene.

[0019] Further, the crosslinking agent is aminopropyltriethoxysilane.

[0020] Further, the coloring agent is titanium dioxide or one of carbon black and iron black.

[0021] Further, the thickening agent is one or both of aluminum hydroxide and nano-silicon.

[0022] A preparation method of an oil-resistant and high-temperature-resistant two-component silicone rubber, comprising the following steps:

[0023] S1. Pre-dry the modified polysiloxane to remove its moisture;

[0024] S2. Dry-mix the modified polysiloxane, the toughening agent, and the oil-resistant filler according to the ratio to obtain component A;

[0025] S3. Mix dimethyl silicone oil, the crosslinking agent, the coloring agent, and the thickening agent evenly to obtain component B;

[0026] S4. Degas components A and B and package them separately;

[0027] S5. Uniformly mix components A and B at a mass ratio of 5-15:1 before use.

[0028] The present invention also provides an oil-resistant and high-temperature-resistant two-component silicone rubber for the encapsulation and bonding of electronic components and its applications in the automotive and construction fields.

[0029] Advantages of the present invention:

[0030] The present invention uses high-molecular-weight modified polysiloxane as the main component, which can maintain good bonding strength and stability in high-temperature environments. By adding fluorinated fillers such as polytetrafluoroethylene, it has excellent oil resistance and can be used in environments where grease and chemical substances exist without failure. By adding toughening agents, the toughness and flexibility of the glue are improved, enhancing its bonding strength and impact resistance. By using amino silane as a crosslinking agent, the curing process is accelerated, improving production efficiency and ease of use. Specific embodiments

[0031] Polytetrafluoroethylene, PTFE-1700, 3M, USA.

[0032] 1,4-Dihydroxy-N-allylphthalimide, 1,4-dihydroxy-N-allylphthalimide, CAS No.: 174713-29-2.

[0033] 2-Prop-2-enylbenzene-1,4-diol, 2-prop-2-enylbenzene-1,4-diol, CAS No.: 5721-21-1.

[0034] (3R,4R)-3,4-Dihydroxy-1-prop-2-enylpyrrolidine-2,5-dione, (3R,4R)-3,4-dihydroxy-1-prop-2-enylpyrrolidine-2,5-dione, CAS No.: 1026400-17-8.

[0035] Bifunctional vinyl silicone oil, 5000 cs, model: JP-01V-5000, Shenzhen Jipeng Silicon Fluoride Materials.

[0036] Dimethyl silicone oil, model: PMX-200, Dow Corning.

[0037] Preparation method of terminal isocyanate group silicone oil: Terminal hydrogen silicone oil and methallyl alcohol are mixed in a molar ratio of 1:2, then a chloroplatinic acid solution is added for catalysis, and the reaction is carried out at 85°C for 4 h, and after post-treatment, a hydroxyalkyl polysiloxane is obtained. Using the hydroxyalkyl polysiloxane as the raw material and diphenylmethane diisocyanate as the functional modifier, the molar ratio of the two is 1:2.4, and dibutyltin dilaurate is added at 75°C for catalytic reaction for 3 h to obtain an isocyanate group-terminated polysiloxane prepolymer. The temperature of the system is lowered to 50°C, and caprolactam is weighed and added according to the molar ratio of isocyanate group-terminated polysiloxane prepolymer:caprolactam = 1:2.4, and stirring is continued for 3 h and then cooled to room temperature to obtain the product.

[0038] Preparation method of terminal methacryloxy silicone oil: Mix hydroxyethyl methacrylate and sodium ethoxide and stir for 1 h for activation. Heat γ-methacryloxypropyltrimethoxysilane to 115 °C, and then mix it with the activated hydroxyethyl methacrylate. The molar ratio of hydroxyethyl methacrylate, sodium ethoxide, and γ-methacryloxypropyltrimethoxysilane is 2:0.1:1. After reacting for 3 h, cool to room temperature, and then carry out extraction, drying, and concentration to obtain acrylate silicone monomer. Mix the hydroxyl-terminated polysiloxane with sodium ethoxide for activation, then add an equal volume of toluene for dilution, and mix with the acrylate silicone monomer at 115 °C. The molar ratio of the hydroxyl-terminated polysiloxane, sodium ethoxide, and acrylate silicone monomer is 1:0.1:1. After reacting for 3 h, concentrate to remove the solvent, and then carry out extraction, drying, and concentration to obtain the product. The present invention provides a high-temperature-resistant two-component silicone rubber for cream, which includes modified polysiloxane, toughening agent, oil-resistant filler, dimethyl silicone oil, cross-linking agent, coloring agent, and thickening agent. Among them, the modified polysiloxane serves as the base polymer, providing the main properties of the adhesive, such as high temperature resistance, chemical corrosion resistance, and electrical insulation. The modified polysiloxane introduces functional groups through specific chemical reactions, enhancing the reactivity with the curing agent and improving the high-temperature resistance, adhesion, and other properties of the adhesive. The toughening agent, such as dibutyl phthalate, is used to improve the flexibility and impact resistance of the adhesive and improve its mechanical properties. The oil-resistant filler, such as polytetrafluoroethylene (PTFE), provides excellent oil resistance and chemical stability, while enhancing the wear resistance and chemical corrosion resistance of the adhesive. Dimethyl silicone oil reduces the viscosity of the adhesive, improves its fluidity and workability, and at the same time helps to improve the flexibility of the adhesive. The cross-linking agent, such as aminopropyltriethoxysilane, promotes the curing process of the adhesive, enhancing its mechanical strength and temperature resistance. The coloring agent, such as titanium dioxide or carbon black, iron black, is used to adjust the color of the adhesive, providing an aesthetic or light-shielding effect. At the same time, titanium dioxide also has the function of improving weather resistance and stability. The thickening agent, such as aluminum hydroxide or nano-silicon, is used to adjust the viscosity and rheology of the adhesive, improve the workability, and at the same time may provide certain thermal stability. These components work together to make the oil-resistant and high-temperature-resistant two-component silicone rubber have excellent oil resistance, high temperature resistance, chemical corrosion resistance, and good adhesion performance, and is suitable for a variety of industrial application scenarios.

[0039] Example 1

[0040] A preparation method of an oil-resistant and high-temperature-resistant two-component silicone rubber includes the following steps, in parts by weight:

[0041] S1. Pre-dry the modified polysiloxane to remove its moisture;

[0042] S2. Dry-mix 110 parts of the modified polysiloxane, 12 parts of dibutyl phthalate, and 16 parts of polytetrafluoroethylene to obtain component A;

[0043] S3. Mix 30 parts of dimethyl silicone oil, 20 parts of aminopropyltriethoxysilane, 5 parts of titanium dioxide, and 6 parts of aluminum hydroxide evenly to obtain Component B;

[0044] S4. Degas Components A and B and package them separately;

[0045] S5. Uniformly mix Components A and B in a ratio of 10:1 before use.

[0046] The preparation method of the modified polysiloxane includes the following steps:

[0047] X1. Mix 1 mol of 1,4-dihydroxy-N-allylphthalimide, 10 mol of epichlorohydrin, and 0.06 mol of tetramethylammonium bromide evenly, then heat to 100 °C, stir for 2 h, cool to 85 °C, add 2 mol of sodium hydroxide and 4A molecular sieve in batches. The addition amount of 4A molecular sieve is 50 wt% of 1,4-dihydroxy-N-allylphthalimide. Continue to stir for 2 h and then filter to remove the molecular sieve, etc. After concentrating the filtrate, add toluene and water. After extraction, add 3 wt% sodium hydroxide aqueous solution to the organic phase, stir at 85 °C for 1 h, then add disodium hydrogen phosphate and water until the pH is neutral, separate and dry to remove water, and concentrate the organic phase for the next step;

[0048] X2. Add 2 mol of the product from the previous step and 1 mol of double-end vinyl silicone oil to ethyl acetate with a volume 10 times that of the double-end vinyl silicone oil, then add 0.03 mol of azobisisobutyronitrile, stir at 80 °C for 4 h, and concentrate to remove the solvent to obtain the modified polysiloxane.

[0049] Example 2

[0050] It is basically the same as Example 1, and the only difference is that the polytetrafluoroethylene is 8 parts.

[0051] Example 3

[0052] It is basically the same as Example 1, and the only difference is that the polytetrafluoroethylene is 12 parts.

[0053] Example 4

[0054] It is basically the same as Example 1, and the only difference is that the polytetrafluoroethylene is 18 parts.

[0055] Example 5

[0056] It is basically the same as Example 1, and the only difference is that the double-end vinyl silicone oil is replaced with terminal isocyanate group silicone oil.

[0057] Example 6

[0058] It is basically the same as Example 1, and the only difference is that the double-end vinyl silicone oil is replaced with terminal isocyanate group silicone oil.

[0059] Control Example 1

[0060] A method for preparing an oil-resistant and high-temperature-resistant two-component silicone rubber, comprising the following steps, by weight:

[0061] S1. Pre-dry the modified polysiloxane to remove its moisture;

[0062] S2. Dry-mix 110 parts of vinyl-terminated silicone oil, 12 parts of dibutyl phthalate, and 16 parts of polytetrafluoroethylene to obtain Component A;

[0063] S3. Mix 30 parts of dimethyl silicone oil, 20 parts of aminopropyltriethoxysilane, 5 parts of titanium dioxide, and 6 parts of aluminum hydroxide evenly to obtain Component B;

[0064] S4. Degas Components A and B and package them separately;

[0065] S5. Uniformly mix Components A and B in a ratio of 10:1 before use.

[0066] Control Example 2

[0067] A method for preparing an oil-resistant and high-temperature-resistant two-component silicone rubber, comprising the following steps, by weight:

[0068] S1. Pre-dry the modified polysiloxane to remove its moisture;

[0069] S2. Dry-mix 110 parts of modified polysiloxane, 12 parts of dibutyl phthalate, and 16 parts of polytetrafluoroethylene to obtain Component A;

[0070] S3. Mix 30 parts of dimethyl silicone oil, 20 parts of aminopropyltriethoxysilane, 5 parts of titanium dioxide, and 6 parts of aluminum hydroxide evenly to obtain Component B;

[0071] S4. Degas Components A and B and package them separately;

[0072] S5. Uniformly mix Components A and B in a ratio of 10:1 before use.

[0073] The preparation method of the modified polysiloxane comprises the following steps:

[0074] X1. Mix 1 mol of 2 - allylbenzene - 1,4 - diol, 10 mol of epichlorohydrin, and 0.06 mol of tetramethylammonium bromide evenly, then heat up to 100 °C. After stirring for 2 h, cool down to 85 °C. Add 2 mol of sodium hydroxide and 4A molecular sieve in batches. The addition amount of 4A molecular sieve is 50 wt% of 1,4 - dihydroxy - N - allylphthalimide. Continue to stir for 2 h and then filter to remove the molecular sieve, etc. Concentrate the filtrate, add toluene and water. After extraction, add an equal - volume 3 wt% aqueous sodium hydroxide solution to the organic phase. Stir at 85 °C for 1 h, then add 0.1 mol / L disodium hydrogen phosphate buffer solution to adjust to pH neutral, and then separate to obtain the organic phase. Dry it and concentrate for the next step;

[0075] X2. Add 2 mol of the product from the previous step and 1 mol of double - ended vinyl silicone oil into ethyl acetate with a volume 10 times that of the double - ended vinyl silicone oil. Then add 0.03 mol of azobisisobutyronitrile. Stir at 80 °C for 4 h and then concentrate to remove the solvent to obtain the modified polysiloxane.

[0076] Comparative Example 3

[0077] A preparation method of an oil - resistant and high - temperature - resistant two - component silicone rubber, including the following steps, in parts by weight:

[0078] S1. Pre - dry the modified polysiloxane to remove its moisture;

[0079] S2. Dry - mix 110 parts of the modified polysiloxane, 12 parts of dibutyl phthalate, and 16 parts of polytetrafluoroethylene to obtain component A;

[0080] S3. Mix 30 parts of dimethyl silicone oil, 20 parts of aminopropyltriethoxysilane, 5 parts of titanium dioxide, and 6 parts of aluminum hydroxide evenly to obtain component B;

[0081] S4. Degas components A and B and package them separately;

[0082] S5. Uniformly mix components A and B in a ratio of 10:1 before use.

[0083] The preparation method of the said modified polysiloxane includes the following steps:

[0084] X1. Mix 1 mol of (3R,4R)-3,4-dihydroxy-1-prop-2-enylpyrrolidine-2,5-dione, 10 mol of epichlorohydrin, and 0.06 mol of tetramethylammonium bromide evenly, then heat the mixture to 100 °C. After stirring for 2 h, cool it to 85 °C. Add 2 mol of sodium hydroxide and 4A molecular sieve in batches. The addition amount of 4A molecular sieve is 50 wt% of 1,4-dihydroxy-N-allylphthalimide. Continue to stir for 2 h, then filter to remove the molecular sieve, etc. Concentrate the filtrate, add toluene and water. After extraction, add an equal volume of 3 wt% sodium hydroxide aqueous solution to the organic phase. Stir at 85 °C for 1 - 2 h, then add 0.1 mol / L disodium hydrogen phosphate buffer solution to adjust to pH neutral, and separate to obtain the organic phase. Dry it and concentrate for the next step;

[0085] X2. Add 2 mol of the product from the previous step and 1 mol of vinyl-terminated silicone oil to ethyl acetate with a volume 10 times that of the vinyl-terminated silicone oil. Then add 0.03 mol of azobisisobutyronitrile. Stir at 80 °C for 4 h, and then concentrate to remove the solvent to obtain the modified polysiloxane.

[0086] Test Example 1

[0087] Test the mechanical properties, oil resistance, and water resistance of the silicone adhesives prepared in the examples and control examples. The mechanical properties include tensile adhesion strength and hardness. The test method for tensile adhesion refers to "GB / T 13477.8 - 2017 Test Methods for Building Sealants - Part 8: Determination of Tensile Adhesion". Mix the two-component silicone adhesive according to the formula, coat it on a pre-treated aluminum plate to form a 12 mm × 12 mm tensile specimen, and conduct a tensile test after curing at room temperature for 72 h. Record the maximum tensile force and elongation at break of the specimen. Use a Shore hardness tester to measure the hardness of the cured silicone adhesive. The oil resistance and water resistance tests are to immerse each group of samples in different types of mineral oils and water, and set the immersion time (72 h); after taking out the samples, calculate the change in mass before and after immersion. The specific results are shown in Table 1.

[0088] Table 1 Test Results of the Mechanical Properties of Two-Component Silicone Adhesives

[0089]

[0090]

[0091] As can be seen from Table 1, the silicone rubber prepared by the present invention has good mechanical properties, oil resistance and water resistance. From the comparison between the examples, it can be seen that when the addition amount of polyvinyl fluoride filler is different, it will not only affect the mechanical properties, but also affect the oil resistance and water resistance. Compared with Comparative Example 1, in Example 1, the bis-terminal vinyl silicone oil was modified. Epoxy resin was obtained by epoxidizing 1,4-dihydroxy-N-allyl phthalimide with an imide five-membered ring, and then reacted with bis-terminal vinyl silicone oil to obtain a modified polysiloxane. The imide ring and benzene ring in 1,4-dihydroxy-N-allyl phthalimide have high rigidity and stability. Therefore, the mechanical properties of the silicone rubber in Example 1 are better. In Comparative Example 1, the bis-terminal vinyl silicone oil was not modified. The polysiloxane is composed of a silicone oxygen main chain and side chains. This special chemical structure endows it with many excellent properties, including thermal stability and chemical stability. However, due to the flexibility and non-polarity of the molecular chain, it may not form a strong adhesion with polar or rough surfaces, resulting in poor adhesion. Therefore, the tensile adhesion strength, shear strength, etc. are relatively poor. Compared with Comparative Examples 2-3, in Example 1, different substances were used to modify the bis-terminal vinyl silicone oil. In Comparative Example 2, 2-allylbenzene-1,4-diol was used, and in Comparative Example 3, (3R,4R)-3,4-dihydroxy-1-prop-2-enylpyrrolidin-2,5-dione was used. Compared with Example 1, the imide ring and benzene ring were respectively absent. It may be because the modified polysiloxanes do not have a rigid ring like that in Example 1, so the mechanical properties are not as good as those in Example 1. In Example 1, epoxy resin was obtained by epoxidizing 1,4-dihydroxy-N-allyl phthalimide with an imide five-membered ring, and then reacted with bis-terminal vinyl silicone oil to obtain a modified polysiloxane. Since the epoxy group has strong polarity, it can significantly improve the adhesion performance of the polysiloxane. And under the action of the cross-linking agent, the epoxy group can also cross-link, thereby improving the mechanical and adhesion strength of the final product. Compared with Example 1, the mechanical properties of Example 5 are better. This may be because the isocyanate group in the terminal isocyanate group silicone oil in Example 5 can react with compounds containing active hydrogen (such as hydroxyl group, amino group) to form urea bonds or carbamate bonds. Therefore, it can further construct a cross-linking network, thereby improving the mechanical properties of the material.

[0092] Test Example 2

[0093] The silicone rubbers prepared in the examples and comparative examples were tested for high-temperature resistance. The thermogravimetric temperature of different specimens was tested using a thermal analyzer. The specific results are shown in Table 2.

[0094] Table 2 Test Results of High-Temperature Resistance Performance of Two-Component Silicone Rubber

[0095] Experimental Scheme Thermogravimetric Temperature / °C Example 1 350.4 Example 2 345.3 Example 3 346.7 Example 4 342.6 Example 5 355.3 Example 6 357.2 Control Example 1 268.7 Control Example 2 300.2 Control Example 3 310.4

[0096] The thermogravimetric temperature refers to the temperature at which, in thermogravimetric analysis, the mass of a sample decreases by a certain percentage (usually 5%) during heating. This temperature is the starting temperature of the thermal decomposition or thermogravimetric loss of the sample, and thus can be used to evaluate the thermal stability of the sample. The thermogravimetric temperature is of great significance for the performance and application of materials because it reflects the thermal stability of materials during actual use and has practical value for the design and development of materials. By measuring the thermogravimetric temperature, the stability of materials during actual use can be evaluated, appropriate usage conditions can be selected, the material performance can be improved, and the service life can be extended. As can be seen from Table 2, the thermogravimetric temperature of the silicone rubber prepared in Example 1 is the highest, indicating that the silicone rubber prepared therein has the best thermal stability. Compared with Comparative Example 1, in Comparative Example 1, the double-end vinyl silicone oil was not modified, while in Example 1, 1,4-dihydroxy-N-allyl phthalimide with an imide five-membered ring was epoxidized to obtain an epoxy resin, and then reacted with the double-end vinyl silicone oil to obtain a modified polysiloxane. The imide ring and benzene ring in 1,4-dihydroxy-N-allyl phthalimide have high rigidity and stability. Therefore, compared with Comparative Example 1, the thermogravimetric temperature is significantly increased. Compared with Comparative Examples 2 and 3, the modified polysiloxane in Example 1 has more rigid rings, so the thermal stability is slightly better than that of Comparative Examples 2 and 3. The thermogravimetric temperatures of Examples 5 to 6 are all higher than that of Example 1. This may be because the isocyanate group in the terminal isocyanate group silicone oil in Example 5 can react with compounds containing active hydrogen (such as hydroxyl groups and amino groups) to form urea bonds or urethane bonds, so that a crosslinked network can be further constructed, and thus the bonds are not easily broken at high temperatures. In Example 6, the methacryloxy functional group in the terminal methacryloxy silicone oil is not easily decomposed at high temperatures, thereby improving the thermal stability of the overall material, and thus the thermal decomposition temperature is higher.

[0097] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative labor. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field based on the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. A two-component silicone rubber resistant to oil and high temperature, characterized in that, It includes Component A and Component B; Component A includes 92 to 110 parts by weight of modified polysiloxane, 4 to 12 parts by weight of toughening agent, and 8 to 18 parts by weight of oil-resistant filler; Component B includes 10 to 40 parts by weight of dimethyl silicone oil, 10 to 20 parts by weight of crosslinking agent, 0.5 to 5 parts by weight of coloring agent, and 1 to 8 parts by weight of thickening agent, and the mass ratio of Component A to Component B is (5 to 15):1; The oil-resistant filler is polytetrafluoroethylene; The crosslinking agent is aminopropyltriethoxysilane; The preparation method of the modified polysiloxane includes the following steps: X1. Mix 1,4-dihydroxy-N-allylphthalimide, epichlorohydrin, and tetramethylammonium bromide evenly under an inert atmosphere, then heat to 90 to 110 °C, stir for 1 to 2 h, then cool to 80 to 90 °C, add sodium hydroxide and 4A molecular sieve in batches, continue to stir for 1 to 2 h, then filter to remove the molecular sieve, etc. After the filtrate is concentrated, add toluene and water, after extraction, add alkali to the organic phase and stir to adjust the pH to neutral, then separate, dry, and concentrate for the next step; X2. Add the product of the previous step and double-end vinyl silicone oil to ethyl acetate, then add azobisisobutyronitrile, stir at 75 to 85 °C for 2 to 6 h, and then concentrate to remove the solvent to obtain the modified polysiloxane.

2. The oil-resistant and high-temperature-resistant two-component silicone rubber according to claim 1, wherein The molar ratio of 1,4-dihydroxy-N-allylphthalimide, epichlorohydrin, tetramethylammonium bromide, and sodium hydroxide is 1:8 to 12:0.05 to 0.07:1 to 3.

3. The oil-resistant and high-temperature-resistant two-component silicone rubber according to claim 1, wherein The molar ratio of the product of the previous step, double-end vinyl silicone oil, and azobisisobutyronitrile is 1 to 3:1:0.01 to 0.

05.

4. The oil-resistant and high-temperature-resistant two-component silicone rubber according to claim 1, characterized in that, The addition amount of the 4A molecular sieve is 50 to 60 wt% of 1,4-dihydroxy-N-allylphthalimide.

5. The oil-resistant and high-temperature-resistant two-component silicone rubber according to claim 1, characterized in that, The toughening agent is dibutyl phthalate.

6. The oil-resistant and high-temperature-resistant two-component silicone rubber according to claim 1, wherein The coloring agent is titanium dioxide or one of carbon black and iron black; the thickening agent is one or two of aluminum hydroxide or nano-silicon.

7. The preparation method of the oil-resistant and high-temperature-resistant two-component silicone rubber according to any one of claims 1 to 6, characterized in that, It includes the following steps: S1. Pre-dry the modified polysiloxane to remove its moisture; S2. Dry-mix the modified polysiloxane, toughening agent, and oil-resistant filler according to the ratio to obtain Component A; S3. Mix dimethyl silicone oil, crosslinking agent, coloring agent, and thickening agent evenly to obtain Component B; S4. Degas Components A and B and package them separately; S5. Evenly mix Components A and B according to the mass ratio of 5 to 15:1 before use.

8. The application of the oil-resistant and high-temperature-resistant two-component silicone rubber according to any one of claims 1 to 6 in the encapsulation and bonding of electronic components and in automobiles and buildings.

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