Oil-resistant and high-temperature-resistant two-component silicone adhesive as well as preparation method and application thereof

Abstract

The invention relates to the technical field of adhesives, in particular to an oil-resistant and high-temperature-resistant two-component silicone adhesive as well as a preparation method and application thereof. The silicone adhesive comprises a component A and a component B, the component A is prepared from 92 to 110 parts by weight of modified polysiloxane, 4 to 12 parts by weight of a toughening agent and 8 to 18 parts by weight of oil-resistant filler; the component B comprises 10-40 parts by weight of dimethyl silicone oil, 10-20 parts by weight of a cross-linking agent, 0.5-5 parts by weight of a coloring agent and 1-8 parts by weight of a thickening agent, and the mass ratio of the component A to the component B is (5-15): 1. Compared with the prior art, the silicone adhesive disclosed by the invention has the advantages that the adhesion and thermal stability are improved by modifying polysiloxane, so that the prepared silicone adhesive has excellent oil resistance, high temperature resistance and good adhesion performance, and is suitable for various industrial application scenes.

Description

Technical Field

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

[0002] Silicone sealant, also known as organic silicon building sealant, is developed to solve the 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 sealed object to achieve the sealing effect. It has good adhesion and rheological properties, and can effectively contact the sealed surface during the filling process to fill the cracks and pores. This filling effect can prevent the entry of external moisture, dust and other substances, thereby protecting the sealed object and extending its service life. Silicone sealant 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. The curing of one-component silicone adhesive depends on the change of physical properties caused by contact with moisture in the air; two-component refers to the silicone adhesive divided into two groups, A and B. Either group alone cannot form a cure, but the two groups of glue will cure once mixed. Two-component silicone sealant is a two-component, neutral-curing silicone sealant designed for the second sealing of insulating glass. It has the characteristics of high strength, high modulus and high gloss. The curing speed is adjustable, the deep curing is fast, and it is suitable for construction in the factory. It is non-corrosive to building materials such as metal, coated glass, concrete, marble, and granite. Low-molecular alcohol substances are released during curing, without irritation or unpleasant odor. It also has excellent weather resistance, aging resistance, UV resistance, ozone resistance, and waterproof properties. After curing, it always maintains good elasticity and strength in the temperature range of -50℃ to 150℃. Silicone sealants have become an indispensable sealing solution in many fields due to their excellent weather resistance, high and low temperature resistance, aging resistance and good adhesion. Compared with single-component silicone sealants, two-component silicone sealants usually cure faster and have higher strength, and are suitable for industrial fields that require fast curing and high-strength bonding.

[0004] CN107043601A belongs to the technical field of sealants, and specifically relates to a high-strength two-component high-temperature resistant inorganic sealant. The sealant of the invention comprises two parts, component A and component B; wherein, by weight, component A is: 60-80 inorganic oxides, 10-30 curing agents, 1-10 alkali metal oxides, and component B is: 80-100 binders, 1-20 additives; the two are mixed and used. The characteristics of the sealant of the invention are that it has a wide operating temperature range (0-1300℃), excellent acid and alkali resistance and water resistance, and good bonding properties with materials such as metals, wood, and ceramics. It is used for high-temperature resistant parts such as refractory materials, heating appliances, and the assembly of flamethrower parts and ignition plugs of petrochemical equipment, and can be widely used in aerospace, machinery, electronics, chemical industry, high-tech and other fields.

[0005] CN105647462A discloses a condensation type two-component silicone sealant and a preparation method thereof, which is prepared from the following raw materials in parts by weight: component A: 100 parts of organic polysiloxane polymer, 60-150 parts of surface-treated calcium carbonate; component B: 2-10 parts of organic polysiloxane 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 parts of organic tin catalyst. Compared with the existing condensation type two-component silicone sealant, the product of the present invention also has good physical and mechanical properties, and can maintain good adhesion for a long time under water immersion conditions. After being fully cured, it can be used in water immersion conditions or humid use environments.

[0006] Silicone adhesive is required for the packaging and bonding of electronic components. The sales volume of electronic components is large, and the improvement of electronic components has put forward higher requirements on the adhesives used therein. The silicone adhesive currently used has problems such as low bonding strength, poor temperature resistance, and poor quick-drying performance after use. This 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 in the prior art, the technical problem to be solved by the present invention is to provide an oil-resistant and high-temperature resistant two-component silicone adhesive, a preparation method and an application thereof.

[0008] Polysiloxane is composed of a siloxane main chain and a side chain. This special chemical structure gives it 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 strong adhesion with polar or rough surfaces, resulting in poor adhesion. Therefore, the present invention provides a modified polysiloxane, which is obtained by epoxidizing 1,4-dihydroxy-N-allylphthalimide having an imide five-membered ring to obtain an epoxy resin, and then reacting with a double-terminal vinyl silicone oil to obtain a modified polysiloxane. Since the epoxy group has a strong polarity, the adhesion of the polysiloxane can be significantly improved, and the epoxy group can also be cross-linked under the action of a cross-linking agent, thereby improving the strength and adhesion of the final product. The imide ring in the phthalimide group not only has a high degree of rigidity and stability, but also has a high thermal stability, so it is not easy to break or decompose at high temperatures, and the benzene ring as an aromatic ring also has good rigidity and thermal stability, so the modified polysiloxane not only has better adhesion, but also has stronger high temperature resistance. The present invention adopts high molecular weight modified polysiloxane as the main component, which can maintain good bonding 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 oils and chemicals exist without failure. By adding a toughening agent, the toughness and flexibility of the glue are improved, and its bonding strength and impact resistance are enhanced. By using aminosilane as a cross-linking agent, the curing process is accelerated, and the production efficiency and convenience of use are improved.

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

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

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

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

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

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

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

[0016] Furthermore, the dual-terminated vinyl silicone oil can be replaced by isocyanate-terminated silicone oil or methacryloxy-terminated silicone oil.

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

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

[0019] Furthermore, the cross-linking agent is aminopropyltriethoxysilane.

[0020] Furthermore, the colorant is one of titanium dioxide, carbon black and iron black.

[0021] Furthermore, the thickener is one or both of aluminum hydroxide and nano silicon.

[0022] A method for preparing an oil-resistant and high-temperature-resistant two-component silicone adhesive comprises the following steps:

[0023] S1, pre-drying the modified polysiloxane to remove its moisture;

[0024] S2, dry-mixing the modified polysiloxane, the toughening agent and the oil-resistant filler according to a proportion to obtain component A;

[0025] S3, mixing dimethyl silicone oil, a crosslinking agent, a colorant, and a thickener to obtain component B;

[0026] S4, degassing components A and B and packaging them separately;

[0027] S5. Component A and component B are uniformly mixed in a mass ratio of 5 to 15:1 before use.

[0028] The present invention also provides an oil-resistant and high-temperature-resistant two-component silicone adhesive for use in packaging and bonding of electronic components and in automobiles and buildings.

[0029] Beneficial effects of the present invention:

[0030] The present invention adopts high molecular weight modified polysiloxane as the main component, which can maintain good bonding 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 oils and chemicals exist without failure. By adding a toughening agent, the toughness and flexibility of the glue are improved, and its bonding strength and impact resistance are enhanced. By using aminosilane as a cross-linking agent, the curing process is accelerated, and the production efficiency and convenience of use are improved. DETAILED DESCRIPTION

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

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

[0033] 2-Allylbenzene-1,4-diol, CAS No.: 5721-21-1.

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

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

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

[0037] Preparation method of terminal isocyanate silicone oil: terminal hydrogen silicone oil and methallyl alcohol are mixed in a molar ratio of 1:2, and then chloroplatinic acid solution is added for catalysis, and the mixture is reacted at 85°C for 4 hours and then post-treated to obtain hydroxyalkyl polysiloxane. Hydroxyalkyl polysiloxane is used as a raw material and diphenylmethane diisocyanate is used as a functional modifier in a molar ratio of 1:2.4. Dibutyltin dilaurate is added for catalytic reaction at 75°C for 3 hours to obtain an isocyanate-terminated polysiloxane prepolymer. The system temperature is lowered to 50°C, and caprolactam is weighed and added thereto in a molar ratio of isocyanate-terminated polysiloxane prepolymer: caprolactam = 1:2.4. Stirring is continued for 3 hours and then the temperature is cooled to room temperature to obtain the obtained product.

[0038] The preparation method of terminal methacryloyloxy silicone oil is as follows: hydroxyethyl methacrylate and sodium ethoxide are mixed and stirred for 1 hour for activation, γ-methacryloxypropyltrimethoxysilane is heated to 115°C and then the activated hydroxyethyl methacrylate is mixed therewith, the molar ratio of hydroxyethyl methacrylate, sodium ethoxide and γ-methacryloxypropyltrimethoxysilane is 2:0.1:1, the reaction is carried out for 3 hours and then cooled to room temperature, and then extracted, dried and concentrated to obtain an acrylate silicon monomer, hydroxyl-terminated polysiloxane is mixed with sodium ethoxide for activation, and then an equal volume of toluene is added for dilution, and the hydroxyl-terminated polysiloxane is mixed with the acrylate silicon monomer at 115°C, the molar ratio of hydroxyl-terminated polysiloxane to sodium ethoxide and acrylate silicon monomer is 1:0.1:1, the reaction is carried out for 3 hours and then the solvent is removed by concentration, and then the mixture is extracted, dried and concentrated to obtain the obtained product. The invention provides a creamy high temperature resistant two-component silicone adhesive, comprising modified polysiloxane, a toughening agent and an oil-resistant filler, dimethyl silicone oil, a cross-linking agent, a colorant and a thickener, wherein the modified polysiloxane is used as a base polymer to provide the main properties of the adhesive, such as high temperature resistance, chemical corrosion resistance and electrical insulation. The modified polysiloxane introduces functional groups through a specific chemical reaction, enhances the reactivity with the curing agent, and improves the high temperature resistance, bonding and other properties of the adhesive. Toughening agents such as dibutyl phthalate are used to improve the flexibility and impact resistance of the adhesive and improve its mechanical properties. Oil-resistant fillers such as polytetrafluoroethylene (PTFE) provide 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 helps to improve the flexibility of the adhesive. Cross-linking agents such as aminopropyltriethoxysilane promote the curing process of the adhesive and enhance its mechanical strength and temperature resistance. Colorants such as titanium dioxide or carbon black, iron black, are used to adjust the color of the adhesive, provide aesthetic effects or shading effects, and titanium dioxide also has the function of improving weather resistance and stability. Thickeners such as aluminum hydroxide or nano-silicon are used to adjust the viscosity and rheology of the adhesive, improve construction performance, and may provide a certain degree of thermal stability. These components work together to make the oil-resistant and high-temperature resistant two-component silicone adhesive have excellent oil resistance, high temperature resistance, chemical corrosion resistance and good bonding properties, suitable for a variety of industrial application scenarios.

[0039] Example 1

[0040] A method for preparing an oil-resistant and high-temperature-resistant two-component silicone adhesive comprises the following steps, measured in parts by weight:

[0041] S1, pre-drying the modified polysiloxane to remove its moisture;

[0042] S2, dry-mixing 110 parts of modified polysiloxane, 12 parts of dibutyl phthalate and 16 parts of polytetrafluoroethylene to obtain component A;

[0043] S3, 30 parts of dimethyl silicone oil, 20 parts of aminopropyl triethoxysilane, 5 parts of titanium dioxide, and 6 parts of aluminum hydroxide were mixed to obtain component B;

[0044] S4, degassing components A and B and packaging them separately;

[0045] S5, component A and component B were evenly mixed in a ratio of 10:1 before use.

[0046] The preparation method of the modified polysiloxane comprises 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 and stir evenly, then heat to 100°C, stir for 2 hours and then cool to 85°C, add 2 mol of sodium hydroxide and 4A molecular sieves in batches, the amount of 4A molecular sieves added is 50 wt% of 1,4-dihydroxy-N-allylphthalimide, continue stirring for 2 hours and filter to remove the molecular sieves, etc., concentrate the filtrate and add toluene and water, add 3 wt% sodium hydroxide aqueous solution to the organic phase after extraction, stir at 85°C for 1 hour, add disodium hydrogen phosphate and water, separate until the pH is neutral, 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-terminal vinyl silicone oil into ethyl acetate which is 10 times the volume of the double-terminal vinyl silicone oil, and then add 0.03 mol of azobisisobutyronitrile. Stir at 80°C for 4 hours and then concentrate to remove the solvent to obtain modified polysiloxane.

[0049] Example 2

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

[0051] Example 3

[0052] The method is substantially the same as Example 1, except that the amount of polytetrafluoroethylene is 12 parts.

[0053] Example 4

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

[0055] Example 5

[0056] It is basically the same as Example 1, the only difference being that the dual-terminated vinyl silicone oil is replaced by terminal isocyanate silicone oil.

[0057] Example 6

[0058] It is basically the same as Example 1, the only difference being that the dual-terminated vinyl silicone oil is replaced by terminal isocyanate silicone oil.

[0059] Comparative Example 1

[0060] A method for preparing an oil-resistant and high-temperature-resistant two-component silicone adhesive comprises the following steps, measured in parts by weight:

[0061] S1, pre-drying the modified polysiloxane to remove its moisture;

[0062] S2, dry-mixing 110 parts of double-terminated vinyl silicone oil, 12 parts of dibutyl phthalate and 16 parts of polytetrafluoroethylene to obtain component A;

[0063] S3, 30 parts of dimethyl silicone oil, 20 parts of aminopropyl triethoxysilane, 5 parts of titanium dioxide, and 6 parts of aluminum hydroxide were mixed to obtain component B;

[0064] S4, degassing components A and B and packaging them separately;

[0065] S5, component A and component B were evenly mixed in a ratio of 10:1 before use.

[0066] Comparative Example 2

[0067] A method for preparing an oil-resistant and high-temperature-resistant two-component silicone adhesive comprises the following steps, measured in parts by weight:

[0068] S1, pre-drying the modified polysiloxane to remove its moisture;

[0069] S2, dry-mixing 110 parts of modified polysiloxane, 12 parts of dibutyl phthalate and 16 parts of polytetrafluoroethylene to obtain component A;

[0070] S3, 30 parts of dimethyl silicone oil, 20 parts of aminopropyl triethoxysilane, 5 parts of titanium dioxide, and 6 parts of aluminum hydroxide were mixed to obtain component B;

[0071] S4, degassing components A and B and packaging them separately;

[0072] S5, component A and component B were evenly mixed 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, stir evenly, heat to 100°C, stir for 2 hours, cool to 85°C, add 2 mol of sodium hydroxide and 4A molecular sieves in batches, the amount of 4A molecular sieves added is 50 wt% of 1,4-dihydroxy-N-allylphthalimide, continue stirring for 2 hours, filter, remove the molecular sieves, etc., concentrate the filtrate, add toluene and water, add 3 wt% sodium hydroxide aqueous solution of the same volume as the organic phase after extraction, stir at 85°C for 1 hour, add 0.1 mol / L disodium hydrogen phosphate buffer to adjust to neutral pH, separate the organic phase, dry it and concentrate it for the next step;

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

[0076] Comparative Example 3

[0077] A method for preparing an oil-resistant and high-temperature-resistant two-component silicone adhesive comprises the following steps, measured in parts by weight:

[0078] S1, pre-drying the modified polysiloxane to remove its moisture;

[0079] S2, dry-mixing 110 parts of modified polysiloxane, 12 parts of dibutyl phthalate and 16 parts of polytetrafluoroethylene to obtain component A;

[0080] S3, 30 parts of dimethyl silicone oil, 20 parts of aminopropyl triethoxysilane, 5 parts of titanium dioxide, and 6 parts of aluminum hydroxide were mixed to obtain component B;

[0081] S4, degassing components A and B and packaging them separately;

[0082] S5, component A and component B were evenly mixed in a ratio of 10:1 before use.

[0083] The preparation method of the modified polysiloxane comprises 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, stir evenly, heat to 100°C, stir for 2 hours, cool to 85°C, add 2 mol of sodium hydroxide and 4A molecular sieves in batches, the amount of 4A molecular sieves added is 50 wt% of 1,4-dihydroxy-N-allylphthalimide, continue stirring for 2 hours, filter, remove the molecular sieves, etc., concentrate the filtrate, add toluene and water, add 3 wt% sodium hydroxide aqueous solution of the same volume as the organic phase after extraction, stir at 85°C for 1-2 hours, add 0.1 mol / L disodium hydrogen phosphate buffer to adjust to a neutral pH, separate the organic phase, dry it and concentrate it for the next step;

[0085] X2. Add 2 mol of the product from the previous step and 1 mol of double-terminal vinyl silicone oil into ethyl acetate which is 10 times the volume of the double-terminal vinyl silicone oil, and then add 0.03 mol of azobisisobutyronitrile. Stir at 80°C for 4 hours and then concentrate to remove the solvent to obtain modified polysiloxane.

[0086] Test Example 1

[0087] The mechanical properties and oil and water resistance of the silicone adhesive prepared in the embodiment and the control example were tested. The mechanical properties include tensile bonding strength and hardness. The test method of tensile bonding was tested with reference to "GB / T13477.8-2017 Test Methods for Building Sealing Materials Part 8: Determination of Tensile Adhesion"; the two-component silicone adhesive was mixed according to the formula and coated on a pre-treated aluminum plate to form a 12mm×12mm tensile specimen. After curing at room temperature for 72 hours, a tensile test was performed, and the maximum tensile force and elongation at the time of specimen fracture were recorded. The hardness of the cured silicone adhesive was measured using a Shore durometer. The oil and water resistance test was to immerse each group of samples in different types of mineral oil and water, and set the immersion time (72 hours); after taking out the samples, the change in mass before and after immersion was calculated. The specific results are shown in Table 1.

[0088] Table 1 Mechanical properties test results of two-component silicone adhesive

[0089]

[0090]

[0091] It can be seen from Table 1 that the silicone adhesive prepared by the present invention has good mechanical properties and oil resistance and water resistance. From the comparison between the embodiments, it can be seen that when the amount of polyvinyl fluoride filler added is different, it will not only affect the mechanical properties, but also the oil resistance and water resistance. Compared with the comparative example 1, the double-terminal vinyl silicone oil is modified in Example 1, and 1,4-dihydroxy-N-allylphthalimide having an imide five-membered ring is epoxidized to obtain an epoxy resin, which is then reacted with the double-terminal vinyl silicone oil to obtain a modified polysiloxane. The imide ring and the benzene ring in 1,4-dihydroxy-N-allylphthalimide have high rigidity and stability. Therefore, the mechanical properties of the silicone adhesive in Example 1 are better, while the double-terminal vinyl silicone oil is not modified in the comparative example 1, and the polysiloxane It is composed of a siloxane main chain and side chains. This special chemical structure gives it 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 strong adhesion with polar or rough surfaces, resulting in poor adhesion, so the tensile bonding strength, shear strength and other performances are poor. Compared with Example 1 and Control Examples 2 to 3, different substances are used to modify the double-terminal vinyl silicone oil. 2-Allylbenzene-1,4-diol is used in the control example, and (3R, 4R)-3,4-dihydroxy-1-prop-2-enylpyrrolidine-2,5-dione is used in Control Example 3. Compared with Example 1, they do not have an imide ring and a benzene ring, respectively. This may be because the modified polysiloxanes do not have rigid rings as in Example 1, so the mechanical properties are not as good as those in Example 1. In Example 1, 1,4-dihydroxy-N-allylphthalimide with an imide five-membered ring is epoxidized to obtain an epoxy resin, which is then reacted with a double-terminal vinyl silicone oil to obtain a modified polysiloxane. Since the epoxy group has a strong polarity, the bonding properties of the polysiloxane can be significantly improved, and the epoxy group can also be cross-linked under the action of a cross-linking agent, thereby improving the mechanical and bonding strength of the final product. Compared with Example 1, Example 5 has better mechanical properties, which may be due to the fact that the isocyanate group in the terminal isocyanate silicone oil in Example 5 can react with active hydrogen-containing compounds (such as hydroxyl groups and amino groups) to form urea bonds or carbamate bonds, so that a cross-linked network can be further constructed, thereby improving the mechanical properties of the material.

[0092] Test Example 2

[0093] The silicone adhesives prepared in the examples and control examples were tested for high temperature resistance. The thermal weight loss temperatures of different samples were tested using a thermal analyzer. The specific results are shown in Table 2.

[0094] Table 2 Test results of high temperature resistance of two-component silicone adhesive

[0095] Experimental protocol Thermal weight loss temperature / ℃ Example 1 350.4 Example 2 345.3 Example 3 346.7 Example 4 342.6 Example 5 355.3 Example 6 357.2 Comparative Example 1 268.7 Comparative Example 2 300.2 Comparative Example 3 310.4

[0096] Thermogravimetric temperature refers to the temperature at which the mass of a sample decreases by a certain percentage (usually 5%) during heating in thermogravimetric analysis. This temperature is the temperature at which the thermal decomposition or thermal weight loss of the sample begins, so it can be used to evaluate the thermal stability of the sample. Thermogravimetric temperature is of great significance to 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 thermogravimetric temperature, the stability of materials during actual use can be evaluated, appropriate use conditions can be selected, material performance can be improved, and service life can be extended. As can be seen from Table 2, the thermal weight loss temperature of the silicone adhesive prepared in Example 1 is the highest, which indicates that the thermal stability of the silicone adhesive prepared therefrom is the best. Compared with Control Example 1, Control Example 1 does not modify the double-terminal vinyl silicone oil, while in Example 1, 1,4-dihydroxy-N-allylphthalimide having an imide five-membered ring is epoxidized to obtain an epoxy resin, which is then reacted with the double-terminal vinyl silicone oil to obtain a modified polysiloxane. The imide ring and benzene ring in 1,4-dihydroxy-N-allylphthalimide are both highly rigid and stable, so the thermal weight loss temperature is significantly increased compared with Control Example 1. Compared with Control Examples 2 and 3, the modified polysiloxane in Example 1 has more rigid rings, so the thermal stability is slightly better than that of Control Examples 2 and 3. The thermal weight loss temperatures of Examples 5 to 6 are all higher than those of Example 1. This may be because the isocyanate group in the isocyanate-terminated silicone oil in Example 5 can react with active hydrogen-containing compounds (such as hydroxyl groups and amino groups) to form urea bonds or carbamate bonds, thereby further constructing a cross-linked network, making it difficult for the bonds to break at high temperatures. The methacryloxy functional group in the methacryloxy-terminated silicone oil in Example 6 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 are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

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

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

3. The oil-resistant and high-temperature-resistant two-component silicone adhesive according to claim 1, characterized in that: The molar ratio of the product of the previous step to the double-terminal vinyl silicone oil and azobisisobutyronitrile is 1-3:1:0.01-0.

05.

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

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

6. The oil-resistant and high-temperature-resistant two-component silicone adhesive according to claim 1, characterized in that: The oil-resistant filler is a fluorinated filler, specifically polytetrafluoroethylene.

7. The oil-resistant and high-temperature-resistant two-component silicone adhesive according to claim 1, characterized in that: The crosslinking agent is aminopropyltriethoxysilane.

8. The oil-resistant and high-temperature-resistant two-component silicone adhesive according to claim 1, characterized in that: The colorant is one of titanium dioxide, carbon black and iron black; the thickener is one or both of aluminum hydroxide and nano silicon.

9. The method for preparing the oil-resistant and high-temperature-resistant two-component silicone adhesive according to any one of claims 1 to 8, characterized in that: The steps include: S1, pre-drying the modified polysiloxane to remove its moisture; S2, dry-mixing the modified polysiloxane, the toughening agent and the oil-resistant filler according to a proportion to obtain component A; S3, mixing dimethyl silicone oil, a crosslinking agent, a colorant, and a thickener to obtain component B; S4, degassing components A and B and packaging them separately; S5. Component A and component B are uniformly mixed in a mass ratio of 5 to 15:1 before use.

10. Use of the oil-resistant and high-temperature-resistant two-component silicone adhesive according to any one of claims 1 to 9 in the packaging and bonding of electronic components and in automobiles and buildings.

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