Low temperature curable high strength benzoxazine silicone adhesive formulations and methods of use

Abstract

The present application relates to the low temperature curing high-strength benzoxazine type silicone adhesive formula and use method, the formula includes the benzoxazine group containing organic silicon compound and organic alkali compound, the mass ratio of benzoxazine group containing organic silicon compound, organic alkali compound is 100:0.1-20.The adhesive of the present application is based on the cooperation between the benzoxazine group containing organic silicon compound and the basic catalyst, can be cured at low temperature, realize the higher strength bonding.The benzoxazine type silicone adhesive formula provided by the present application can be directly used as adhesive, and the bonding strength is high;It can also be used as a basic formula, used as an adhesive after adding other fillers, to meet the different needs of various special occasions.

Description

Technical Field

[0001] This invention relates to a formulation and application method of a high-strength benzoxazine-type organosilicon adhesive that can be cured at medium and low temperatures, belonging to the field of organosilicon polymer synthesis and material preparation. Background Technology

[0002] Organosilicon materials were discovered and applied as early as the 1940s. Due to their chemical inertness and excellent properties such as water resistance, heat resistance, weather resistance, hydrophobicity, and electrical insulation, they have become an important polymer material in the national economy. The application fields of organosilicon polymers are also very wide, with recent research increasingly applying them to medicine, rehabilitation, and even tumor treatment. Since the main components of adhesives are mostly synthetic polymers, the chemical structure and aggregation state of polymer molecules strongly influence the adhesive strength. Because the excellent properties of organosilicon polymers can complement some of the advantages and disadvantages of organic polymers used in adhesives, organosilicon-modified adhesives have overcome many of the shortcomings of ordinary molecular structure adhesives, and therefore have been widely used in bonding metals, plastics, rubber, and glass.

[0003] Organosilicon adhesives can be categorized by raw material source into adhesives based on silicone resin and adhesives based on silicone rubber. The former is primarily used for bonding metals and heat-resistant non-metallic materials, while the latter is mainly used for bonding heat-resistant rubber, rubber to metal, and other non-metallic materials. The performance of silicone resins varies depending on the number of functional groups, substituents, degree of polymerization, degree of branching, and degree of crosslinking. However, pure silicone resin suffers from low mechanical strength, which can only be improved through copolymerization with polyester, epoxy, or phenolic resins. Silicone rubber can be classified by its curing method into high-temperature vulcanizing silicone rubber and room-temperature vulcanizing silicone rubber. High-temperature vulcanizing silicone rubber adhesives have low bonding strength and require complex processing equipment, significantly limiting their application. Conversely, room-temperature vulcanizing silicone rubber has seen rapid development since its emergence. Besides possessing excellent properties such as oxidation resistance, resistance to alternating high and low temperatures, cold resistance, ozone resistance, and excellent electrical insulation, its greatest advantage is its ease of use.

[0004] Benzoxazine compounds are a class of heterocyclic intermediates, generally prepared by the condensation reaction of phenolic compounds, primary amine compounds, and formaldehyde. Under heating or with a catalyst, benzoxazine undergoes ring-opening polymerization to generate a nitrogen-containing network structure similar to phenolic resins. Therefore, this new type of resin is also called ring-opening polymerized phenolic resin, which led to the application of benzoxazine in adhesives. Due to its low volume shrinkage during curing, high mechanical strength, high glass transition temperature, high char residue, chemical resistance to acids and alkalis, low absorption rate, and flexible molecular designability, polybenzoxazine has become the fastest-growing thermosetting resin. The curing process of benzoxazine resin is carried out through the ring-opening reaction of the oxazine ring. Compared to the release of small molecule byproducts during the polymerization process of traditional phenolic resins, polybenzoxazine does not release small molecule byproducts during ring-opening polymerization, thus endowing it with excellent processing properties.

[0005] However, this ring-opening self-polymerization reaction generally requires temperatures above 200℃, which is unsuitable for many bonding applications (especially high-end electronic components). Gu Yi et al. from Sichuan University studied the ring-opening polymerization reaction and regularity of benzoxazine under the action of active hydrogen compounds and catalysts in the case of thermal self-polymerization. Infrared spectroscopy revealed that with the addition of active hydrogen compounds, organic acids, and Lewis acids, the gelation time of benzoxazine was significantly shortened, the activation energy of the reaction decreased, and the initial curing temperature of bisphenol A benzoxazine decreased from 210℃ to 150℃, 132℃, and 130℃, respectively. However, they still could not achieve ring-opening curing at medium and low temperatures, and no specific formulation was provided. In particular, organic acids and Lewis acids can cause corrosion to the bonding site during use. For the bonding of stainless steel, corrosion not only causes corrosion of the bonding site but also causes devastating damage to the bonding interface.

[0006] Lomonaco et al. synthesized biomass benzoxazine using catechol and furanylamine as raw materials. Mechanistically, biomass benzoxazine shows promise for ring-opening polymerization at 120°C. However, they did not report any data related to adhesive strength, so it is unclear whether this type of substance can be used as an adhesive. The research group of Lu Zaijun at Shandong University introduced hydroxyl groups, such as catechol, into benzoxazine to attempt to lower its ring-opening polymerization temperature (a mechanism known as "autocatalysis"). DSC studies revealed that the polymerization temperature of one monomer decreased to 149°C, effectively improving adhesive strength, achieving a bonding strength of 2.61 MPa on steel plates. However, the presence of hydroxyl groups reduces the storage stability of benzoxazine adhesives, failing to meet end-customers' requirements for shelf life and performance reliability, and further improvements in adhesive strength are needed.

[0007] In summary, there are no reports, either domestically or internationally, of practical formulations and application methods for benzoxazine-type silicone adhesives that can be cured at medium and low temperatures and achieve high-strength bonding performance. Summary of the Invention

[0008] To address the shortcomings of existing benzoxazine-type silicone adhesives, particularly their high curing temperatures and difficulty in achieving high bond strength at lower curing temperatures, this invention provides a benzoxazine-type silicone adhesive formulation and its application method that can cure at medium to low temperatures. The inventors previously reported an adhesive based on an aminosiloxane and its preparation and application method in CN109054734A, which required a curing temperature as high as 200°C. During further research on this work, the inventors unexpectedly discovered that when this type of adhesive is blended with an organic alkali compound, strong bonding performance can be achieved at lower temperatures. Therefore, the adhesive of this invention is based on the combination of a benzoxazine-containing silicone compound and an alkaline catalyst, enabling curing at medium to low temperatures and achieving high-strength bonding. The benzoxazine-type silicone adhesive formulation provided by this invention can be used directly as an adhesive with high bond strength; it can also be used as a base formulation, with the addition of other fillers, to meet the different needs of various special applications.

[0009] The technical solution of the present invention is as follows:

[0010] A benzoxazine-type silicone adhesive formulation capable of curing at medium and low temperatures comprises a benzoxazine-containing silicone compound and an organic base compound, wherein the mass ratio of the benzoxazine-containing silicone compound to the organic base compound is 100:0.1-20, and the structure of the benzoxazine-containing silicone compound contains at least the structural unit shown in formula (I) and the structural unit shown in formula (II).

[0011]

[0012] Formula (I)

[0013]

[0014] Equation (II)

[0015] In formulas (I) and (II), R', R'' and R''' are various organic groups, including various aliphatic hydrocarbon groups, aromatic hydrocarbon groups and / or organosilicon groups; n is 1-100.

[0016] According to the present invention, in the above-mentioned organosilicon compounds containing benzoxazine groups, R' and R'' in formula (I) are various organic groups, including various aliphatic hydrocarbon groups, aromatic hydrocarbon groups and / or organosilicon groups, preferably methyl, phenyl, trifluoropropyl, ethyl; more preferably methyl and phenyl.

[0017] According to the present invention, in the above-mentioned organosilicon compounds containing benzoxazine groups, R``` in formula (II) is a variety of organic groups, including various aliphatic hydrocarbon groups, aromatic hydrocarbon groups and / or organosilicon groups, preferably hydroxyl groups, unsaturated double bonds, organosilicon groups and long-chain alkyl groups, and more preferably hydroxyl groups and organosilicon groups.

[0018] According to the present invention, the value of n in the above formula (I) is 1-100, preferably 1-50, and more preferably 2-30.

[0019] According to the present invention, the above-mentioned organic base compound is an organic base compound that can be mixed with organosilicon compounds containing benzoxazine groups, including organic amine compounds, nitrogen-containing heterocyclic compounds, and more preferably compounds containing primary amino groups, secondary amino groups, tertiary amino groups, quaternary ammonium salt compounds, and pyridyl compounds, and even more preferably compounds containing primary amino groups, hexamethylenetetramine, and pyridine.

[0020] According to the present invention, the above-mentioned primary amino compounds include monoamino compounds, diamino compounds and polyamino compounds, with diamino compounds being more preferred, and ethylenediamine and 2-methylpentanediamine being more preferred.

[0021] According to the present invention, the mass ratio of the organosilicon compound containing benzoxazine group and the organic base compound is 100:0.1-20, more preferably 100:0.1-10, and even more preferably 100:1-10.

[0022] According to the present invention, preferably, the above-mentioned benzoxazine-type silicone adhesive formulation capable of curing at medium and low temperatures further comprises other components, preferably, the other components are various additives and auxiliaries that can improve the performance of benzoxazine-type silicone adhesives cured at medium and low temperatures; the additives are further preferably fumed silica, precipitated silica, carbon black, calcium carbonate, aluminum hydroxide and / or magnesium hydroxide, and various specially treated compounds thereof, more preferably silazane-treated silica;

[0023] Preferably, the additives are various additives that do not significantly reduce the performance of the adhesive after addition, including various functional and non-functional components, and more preferably spreading agents, wetting agents, thermo-oxidative stabilizers, flame retardants, conductive agents, foaming agents, deep curing agents, pigments and / or plasticizers; more preferably iron oxide red.

[0024] According to the present invention, the mass ratio of the organosilicon compound containing benzoxazine group, the organic base compound, and other components is 100:0.1-20:0-300, more preferably 100:0.1-10:0.5-100, and even more preferably 100:1-10:1-20.

[0025] According to the present invention, organosilicon compounds containing benzoxazine groups can be prepared with reference to CN109054734A.

[0026] According to the present invention, the method of using the above-mentioned low-temperature curing benzoxazine type silicone adhesive includes the following steps:

[0027] Organosilicon compounds and organic base compounds containing benzoxazine groups are packaged as components A and B, respectively. Before use, components A and B are mixed and used as a base formula, or other components with the desired function are added and compounded. The mixture is then placed at the adhesive interface and good adhesion is achieved through programmed heating.

[0028] According to the present invention, preferably, the programmed temperature rise is a gradual temperature rise process from an initial temperature to a final temperature, using a certain temperature difference as a gradient and passing through multiple "heating-isothermal" stages. Wherein, the temperature difference is a controllable temperature gradient permissible in the bonding application, including any temperature difference between 5°C and 100°C, preferably 20°C; in the "heating-isothermal" stages, the heating rate is any heating rate between 0.1°C / min and 20°C / min, preferably 10°C / min; in the "heating-isothermal" stages, the isothermal time is any time between 1 minute and 180 minutes, preferably any time between 30 minutes and 120 minutes, more preferably 60 minutes; the initial temperature is any temperature between room temperature and the final temperature, preferably 80°C; the final temperature is a temperature permissible in the bonding application that achieves the optimal bonding performance of the adhesive in this bonding application, including an optimal bonding temperature between 80°C and 120°C obtained through actual testing.

[0029] According to the present invention, a method for reducing the curing temperature of the above-mentioned benzoxazine-type silicone adhesive is also provided, wherein a benzoxazine-containing organosilicon compound and an organic base compound are mixed, and the mass ratio of the benzoxazine-containing organosilicon compound to the organic base compound is 100:0.1-20; wherein the organic base compound is an organic base compound that can be mixed with the benzoxazine-containing organosilicon compound, including organic amine compounds, nitrogen-containing heterocyclic compounds, and more preferably, compounds containing primary amine groups, compounds containing secondary amine groups, compounds containing tertiary amine groups, quaternary ammonium salt compounds, compounds containing pyridyl groups, and even more preferably, compounds containing primary amine groups, hexamethylenetetramine, and pyridine.

[0030] Unless otherwise described in this invention, all other aspects are based on existing technologies.

[0031] The principles and beneficial effects of this invention are as follows:

[0032] During further research and development of previous work, the inventors of this invention unexpectedly discovered that mixing benzoxazine-type silicone compounds with organic alkali compounds could achieve strong adhesion at 120°C (far lower than the original curing temperature of 200°C). Numerous studies have reported that acids and alkalis can promote the cross-linking and curing of benzoxazine. However, research revealed that while acids promote the cross-linking of benzoxazine groups, they also cause corrosion of metals. This corrosion often occurs at the interface between the adhesive and the metal, leading to a rapid decrease in bond strength. When using alkalis such as sodium hydroxide reported in the literature, at temperatures close to 200°C, sodium hydroxide breaks the silicon-oxygen-silicon bonds, also reducing the bond strength of the benzoxazine-type silicone adhesive. Therefore, alkaline compounds such as sodium hydroxide reported in the literature cannot be used for the curing and bonding of benzoxazine-type silicone adhesives. Through extensive experimentation, the inventors discovered that using an organic alkali compound as a catalyst while simultaneously lowering the curing temperature enables high-strength adhesion of benzoxazine-type silicone adhesives. Therefore, significant results were achieved.

[0033] Research has revealed that organic bases containing primary amine groups are more effective than those with similar structures containing secondary, tertiary, or nitrogen-containing heterocyclic groups. This is because organic bases containing primary amine groups can simultaneously catalyze the ring-opening curing of benzoxazine groups and bond to the curing system, becoming part of the cross-linking network. This characteristic is unattainable with inorganic bases (such as sodium hydroxide) and represents a new discovery made by the inventors through extensive experimentation. Further research showed that organic base compounds containing multiple amine groups are more effective than those containing only one amine group. This is because while organic base compounds containing only one amine group can participate in the curing and become part of the cross-linking network during the catalytic curing and cross-linking process of benzoxazine groups, their contribution to increasing the cross-linking density is not as significant as that of organic base compounds containing multiple amine groups. Further research into the performance of organic base compounds containing multiple amine groups revealed that organic base compounds containing two amine groups (such as trivinyltetramine) perform better than those containing multiple amine groups, and the molecular structure of organic base compounds containing two amine groups also affects the adhesive strength. The above-mentioned content has not been reported in relevant literature, but strong adhesion has been achieved in this invention.

[0034] The benzoxazine-containing siloxanes prepared in this invention can be used directly as adhesives. However, the performance of such adhesives is greatly affected by the siloxane portion, enabling bonding in specific applications. Combining these adhesives with various additives (including fillers and auxiliaries) can significantly improve their overall performance, thereby meeting the bonding requirements of various applications. Examples are provided below:

[0035] The use of various fillers, especially reinforcing fillers, can effectively improve the mechanical properties of such adhesives. Because the base polymer used in this invention contains both benzoxazine groups and silicon-oxygen bonds, it exhibits rapid absorption, good compatibility, and high reinforcing efficiency with various inorganic and organic polar fillers. To further improve the adhesive's performance at high temperatures, this invention further prefers fumed silica treated with phenyl compounds for reinforcement, thus slowing down degradation during high-temperature use.

[0036] Adding various additives to the formulations involved in this invention can further improve their performance and expand their applications. These additives include thermo-oxidative stabilizers, flame retardants, conductive agents, foaming agents, deep-curing agents, pigments, and plasticizers. Some additives can perform multiple functions; for example, iron oxide red can simultaneously act as a thermo-oxidative stabilizer, pigment, and reinforcing filler. Adding special polymers can improve the wetting properties of these adhesives at specific interfaces. Adding special coupling agents can improve the adhesion properties of these adhesives at specific interfaces. In summary, by changing the amount of additives and using multiple additives together, high-performance adhesives that meet the needs of various applications can be prepared, with broad application prospects and a promising market outlook. Attached Figure Description

[0037] Figure 1 The adhesive strength curves of the formulation without catalyst and the formulation with alkaline catalyst in Experiment Example 1.

[0038] Figure 2 The adhesive strength curves of the formulation without catalyst and the formulation with acidic catalyst in Experiment Example 2.

[0039] Figure 3 Figures showing the bond interface failure in Experiment Example 2: (a) Formulation without catalyst; (b) Formulation with acidic catalyst; (c) Formulation with organic amine. Detailed Implementation

[0040] The present invention will be further described below through specific embodiments, but is not limited thereto.

[0041] All raw materials used in the examples were either commercially available or synthesized according to the methods described in the references.

[0042] The molar ratio mentioned in the embodiments is the proportion of the amount of substance, and the proportion of parts is the mass ratio.

[0043] In Examples 1-3 of this invention, organosilicon compounds containing benzoxazine groups were prepared according to CN109054734A and used as component A.

[0044] Example 1

[0045] Aminopropyl vinyldiethoxysilane and p-hydroxybenzophenone were blended in a tetrahydrofuran solution at a molar ratio of 1:1.5, and the mixture was mechanically stirred at 40°C for 4 hours. The resulting product was purified to obtain an intermediate. Subsequently, the intermediate product was mixed with trioxymethylene and n-butylamine in toluene (molar ratio 1:10:4), and the mixture was mechanically stirred at 80°C for 6 hours. The resulting product was purified to obtain vinyldiethoxysilane containing benzoxazine groups, with a yield of 85%. This was used as component A in a benzoxazine-type silicone adhesive formulation that cures at medium to low temperatures.

[0046] Example 2

[0047] As described in Example 1, except that aminopropylvinyldiethoxysilane was replaced with 1,3-diaminopropyltetramethyldisiloxane, and p-hydroxybenzophenone was replaced with p-hydroxybenzaldehyde. The reaction temperature was changed to 70°C, and the intermediate product was obtained after purification. Subsequently, the intermediate product was mixed evenly with an aqueous formaldehyde solution (37wt%) and aniline in tetrahydrofuran (molar ratio 1:2:4), and the mixture was kept at 70°C and mechanically stirred for 5 hours to obtain tetramethyldisiloxane containing two benzoxazine functionalized groups, with a reaction yield of 100%. This was used as component A of a benzoxazine-type silicone adhesive formulation that is cured at medium and low temperatures.

[0048] Example 3

[0049] As described in Example 2, the difference is that 1,3-diaminopropyltetramethyldisiloxane was replaced with a polysiloxane containing an aminopropyl side chain (11% content) (number average molecular weight of 70,000), while all other parameters remained the same, resulting in a polysiloxane containing benzoxazine groups in the side chain, with a reaction yield of 70%. This was used as component A of a benzoxazine-type silicone adhesive formulation that is cured at medium and low temperatures.

[0050] Example 4

[0051] Ethanolamine was used as component B and mixed uniformly with the benzoxazine-containing organosilicon compound prepared in Example 2 at a mass ratio of 1:9. The mixture was then evenly applied to an iron plate and thermotreated under specific conditions (curing conditions: 80°C for 2 hours, 90°C for 2 hours, 100°C for 4 hours, 110°C for 2 hours, and 120°C for 2 hours). After curing, the mixture was left to stand for one day. Its adhesive properties were then measured using a tensile testing machine.

[0052] Example 5

[0053] As described in Example 4, the only difference is that ethanolamine is replaced with aniline as component B, while the other parameters and operations are the same.

[0054] Example 6

[0055] As described in Example 4, the difference is that ethanolamine is replaced with 2-methylpentanediamine as component B, and 2-methylpentanediamine is first dissolved in a small amount of acetone, and then mixed evenly with the benzoxazine-containing organosilicon compound. The acetone solvent is dried with cold air before application. All other parameters and operations are the same.

[0056] Example 7

[0057] As described in Example 6, the difference is that the mass ratio of 2-methylpentanediamine to the adhesive containing benzoxazine organosilicon compound is changed to 1:12, while the other parameters and operations are the same.

[0058] Example 8

[0059] As described in Example 4, the only difference is that ethanolamine is replaced with pyridine as component B, while the other parameters and operations are the same.

[0060] Example 9

[0061] As described in Example 6, the difference is that 2-methylpentanediamine is replaced with hexamethylenetetramine as component B, and acetone is replaced with ethanol as the solvent. All other parameters and operations are the same.

[0062] Example 10

[0063] As described in Example 4, the difference is that ethanolamine is replaced with ethylenediamine as component B, while the other parameters and operations are the same.

[0064] Comparative Example 1

[0065] As described in Example 4, the difference is that no catalyst is added, and an adhesive containing benzoxazine organosilicon compounds is used directly to bond the iron sheets. All other parameters and operations are the same.

[0066] Comparative Example 2

[0067] As described in Example 4, the difference is that ethanolamine is replaced with solid sodium hydroxide, and acetone is replaced with ethanol. All other parameters and operations are the same.

[0068] Comparative Example 3

[0069] As described in Example 6, the only difference is that 2-methylpentanediamine is replaced with p-toluenesulfonic acid, while the other parameters and operations are the same.

[0070] Comparative Example 4

[0071] As described in Example 4, the only difference is that ethanolamine is replaced with phosphoric acid, while all other parameters and operations remain the same.

[0072] Comparative Example 5

[0073] As described in Example 4, the only difference is that ethanolamine is replaced with glacial acetic acid, while the other parameters and operations are the same.

[0074] Experimental Example 1

[0075] According to the national standard GB / T7124-2008, "Determination of Tensile Shear Strength of Adhesives (Rigid Material to Rigid Material)", the bonding strength of the iron plates in Examples 6, 7, and Comparative Example 1 was tested, and the results are as follows: Figure 1 As shown. By Figure 1 It is known that the present invention uses the organic base 2-methylpentanediamine for curing, which has good bonding strength at a relatively low curing temperature of 120℃, and the bonding strength after curing can reach 4.5MPa-6.5MPa.

[0076] Experimental Example 2

[0077] According to the standard "Determination of Tensile Shear Strength of Adhesives (Rigid Material to Rigid Material)" (National Standard: GB / T7124-2008), the bond strength of the adhesives to the iron plates in Comparative Examples 1 and 5 was tested, and the results are as follows. Figure 2 As shown. By Figure 2 It can be seen that when acetic acid is used for curing, the bonding strength is low at a curing temperature of 120℃, only 0.7MPa.

[0078] The bonding interface failure diagrams for the formulations without catalyst, with acidic catalyst, and with organic amine catalyst in Experimental Examples 1 and 2 are shown below. Figure 3 As shown. Among them: (a) formulation without catalyst; (b) formulation with acidic catalyst; (c) formulation with organic amine. From Figure 3 It is evident that the formulation of this invention with added organic amines exhibits better adhesive strength.

[0079] Experimental Example 3

[0080] According to the "Determination of Tensile Shear Strength of Adhesives (Rigid Material to Rigid Material)" (National Standard: GB / T7124-2008), the bonding strength of the iron plates in Examples 4, 6, 7 and Comparative Examples 1, 4, 5 was tested, and the test results are shown in Table 1.

[0081] Table 1 Test Results

[0082]

[0083] *Note: The adhesive strength data of the benzoxazine group-containing siloxane in CN109054734A after curing is 130℃.

[0084] **Note: The adhesive strength data of the benzoxazine group-containing siloxane in CN107955580A after curing is 200℃.

[0085] ***Note: The adhesive strength data of the benzoxazine group-containing siloxane in CN102936474A after curing is 200℃.

[0086] As shown in Table 1, the benzoxazine-type silicone adhesive prepared in this invention, which cures at medium and low temperatures, can achieve high-strength bonding at temperatures of 120°C and below. For example, after curing at 120°C, the bond strength can reach 4.5 MPa-6.5 MPa. This is 80°C lower than the curing temperature of 200°C in CN107955580A and CN102936474A, while the bond strength is further improved, demonstrating outstanding superiority. This adhesive formulation can not only be used as an adhesive on its own with high strength, but its performance is further improved when compounded with other fillers and additives. Combined with the aforementioned advantages of the preparation process of this invention, the inventiveness of this invention is further highlighted.

Claims

1. A benzoxazine-type silicone adhesive capable of curing at medium and low temperatures, characterized in that, The silicone adhesive comprises an organosilicon compound containing a benzoxazine group and an organic base compound, wherein the mass ratio of the organosilicon compound containing the benzoxazine group to the organic base compound is 100:0.1-20, and the organic base compound is ethylenediamine or 2-methylpentanediamine; The organosilicon compound containing the benzoxazine group was prepared by the following method: Aminopropyl vinyldiethoxysilane and p-hydroxybenzophenone were mixed in a tetrahydrofuran solution at a molar ratio of 1:1.5, and the mixture was stirred mechanically at 40°C for 4 hours. The intermediate product was then purified. Subsequently, the intermediate product was mixed with trioxymethylene and n-butylamine in toluene at a molar ratio of 1:10:4, and the mixture was stirred mechanically at 80°C for 6 hours. The resulting product was purified to obtain vinyldiethoxysilane containing benzoxazine groups. Alternatively, 1,3-diaminopropyltetramethyldisiloxane and p-hydroxybenzaldehyde are mixed in a tetrahydrofuran solution at a molar ratio of 1:1.5, and the mixture is stirred mechanically at 70°C for 4 hours. After purification, an intermediate product is obtained. Subsequently, the intermediate product is mixed with 37wt% formaldehyde aqueous solution and aniline in tetrahydrofuran at a molar ratio of 1:2:4, and the mixture is stirred mechanically at 70°C for 5 hours. After purification, a tetramethyldisiloxane containing two benzoxazinyl functionalized groups is obtained. Alternatively, a polysiloxane containing 11% aminopropyl side chains and with a number average molecular weight of 70,000 is mixed with p-hydroxybenzaldehyde in a tetrahydrofuran solution at a molar ratio of 1:1.5, and the mixture is kept at 70°C and mechanically stirred for 4 hours. After purification, an intermediate product is obtained. Subsequently, the intermediate product is mixed with 37wt% formaldehyde aqueous solution and aniline in tetrahydrofuran at a molar ratio of 1:2:4, and the mixture is kept at 70°C and mechanically stirred for 5 hours. After purification, a polysiloxane containing benzoxazine groups in the side chains is obtained.

2. The benzoxazine-type silicone adhesive capable of curing at medium and low temperatures according to claim 1, characterized in that, The silicone adhesive also contains other components, which are various additives and auxiliaries that can improve the performance of medium and low temperature curing benzoxazine-type silicone adhesives; the additives are fumed silica, precipitated silica, carbon black, calcium carbonate, aluminum hydroxide and / or magnesium hydroxide, and the auxiliaries are spreading agents, wetting agents, thermo-oxidative stabilizers, flame retardants, conductive agents, foaming agents, deep curing agents, pigments and / or plasticizers.

3. The benzoxazine-type silicone adhesive capable of curing at medium and low temperatures according to claim 2, characterized in that, The mass ratio of organosilicon compounds containing benzoxazine groups, organic base compounds, and other components is 100:0.1-10:0.5-100.

4. The method of using the medium-low temperature curing benzoxazine type silicone adhesive according to any one of claims 1-3, comprising the following steps: Organosilicon compounds and organic base compounds containing benzoxazine groups are packaged as components A and B, respectively. Before use, components A and B are mixed and used as a base formula, or other components with the desired function are added and compounded. The mixture is then placed at the adhesive interface and good adhesion is achieved through programmed heating.

5. The method of using the low-temperature curing benzoxazine-type silicone adhesive according to claim 4, characterized in that, The programmed temperature rise is a temperature rise process that gradually increases from the initial temperature to the final temperature through multiple "temperature rise-constant temperature" stages, with a certain temperature difference as the gradient. The temperature difference is a controllable temperature gradient permissible in the bonding application, including any temperature difference between 5°C and 100°C; in the "heating-isothermal" stage, the heating rate is any heating rate between 0.1°C / min and 20°C / min; in the "heating-isothermal" stage, the isothermal time is any time between 1 minute and 180 minutes; the initial temperature is any temperature between room temperature and the termination temperature; the termination temperature is a temperature permissible in the bonding application that achieves the optimal bonding performance of the adhesive in this bonding application, including bonding temperatures between 80°C and 120°C.

6. A method for reducing the curing temperature of a benzoxazine-type silicone adhesive, comprising using the benzoxazine-type silicone adhesive according to any one of claims 1-3, characterized in that, Mix organosilicon compounds containing benzoxazine groups and organic base compounds, wherein the mass ratio of organosilicon compounds containing benzoxazine groups to organic base compounds is 100:0.1-20.

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