Two-component thermocuring organic silicon adhesive and application thereof

Abstract

The invention belongs to the technical field of adhesives, and particularly discloses a bi-component thermocuring organic silicon adhesive and application thereof. The organic silicon adhesive comprises a benzotriazole derivative as shown in a formula (I) in the specification. According to the organic silicon adhesive disclosed by the invention, the benzotriazole derivative with a specific structure is introduced, so that the prepared organic silicon adhesive has excellent storage stability and low compression set, and a blooming phenomenon is avoided after the organic silicon adhesive is cured. In addition, after the organic silicon adhesive is sealed and stored at room temperature for a long time, the vulcanization rate and the compression permanent deformation performance are not attenuated and bloomed, and the organic silicon adhesive has excellent storage stability.

Description

Technical Field

[0001] This invention belongs to the field of adhesive technology, and specifically relates to a two-component thermosetting silicone adhesive and its applications. Background Technology

[0002] Automotive electronics is an industry that demands high reliability, mass production with automation, and rapid product iteration. For various housing seals involved, CIPG (Cured in Place Gasket) thermosetting silicone adhesives are a superior choice compared to traditional sealing rings. CIPG perfectly meets the needs of the automotive industry's development through greater design freedom, production efficiency, and sealing reliability, and has become the mainstream technology for housing seals. However, with the rapid development of automotive electrification and continuous material iteration, more and more engineering plastic housings are replacing traditional metal housings. The temperature resistance of engineering plastics and the rapid pace of automated production dictate that the thermosetting silicone adhesives used for CIPG must achieve good adhesion to engineering plastics within a temperature range below 120°C and a time of less than 60 minutes, while maintaining low compression set and meeting various high reliability and lifespan requirements.

[0003] US5104919A proposes using benzotriazole to improve the compression set properties of silicone rubber, but it does not consider the problem of decreased platinum catalyst activity caused by benzotriazole. CN115667408A proposes using a combination of alkynyl alcohol and tetramethyltetravinylcyclotetrasiloxane to achieve a stable curing rate while solving the problem of decreased platinum catalyst activity caused by benzotriazole derivatives as inhibitors. Although it mentions the storage verification of accelerated aging at 80°C for three days after the addition of benzotriazole derivatives, it does not mention the change in curing rate after long-term storage with the addition of benzotriazole derivatives, or the impact of this change on compression set properties, nor does it mention the problem of blooming caused by benzotriazole derivatives in cured silicone rubber. US5936054A uses benzotriazole-5-carboxylate to address compatibility issues encountered when adding benzotriazole or triazole-based substances to addition-cure silicone rubber. It mentions the contribution of benzotriazole derivatives to compression set and considers issues such as poor localized curing and appearance caused by dispersion and compatibility problems with benzotriazole derivatives. However, it does not mention the change in curing rate after long-term storage with added benzotriazole derivatives, or the impact of this change on compression set performance, nor does it address the issue of blooming caused by benzotriazole derivatives in cured silicone rubber. CN113272387A uses benzotriazole derivatives containing a silicon structure to obtain a self-adhesive silicone rubber composition with rapid curing and low compression set. However, it still does not mention the change in curing rate after long-term storage with added benzotriazole derivatives, or the impact of this change on compression set performance, nor does it address the issue of blooming caused by benzotriazole derivatives in cured silicone rubber. Summary of the Invention

[0004] In order to overcome at least one of the technical problems existing in the prior art, one of the objectives of the present invention is to provide an organosilicon adhesive.

[0005] The second objective of this invention is to provide the application of the above-mentioned silicone adhesive in the field of electronic product packaging.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A first aspect of the present invention provides an organosilicon adhesive comprising a benzotriazole derivative of formula (I);

[0007] Each R1 is independently selected from H and C. 1~5 Alkyl groups; R2 is selected from H and C. 1~15 Alkyl groups; n≥1, and n is an integer; m≥1, and m is an integer.

[0008] In some embodiments of the present invention, each R1 is independently selected from H, -CH3, -CH2CH3, -CH2CH2CH3, -CH(CH3)2, -CH2CH2CH2CH3, -CH2CH2CH(CH3)2, -CH2CH(CH3)2, -CH2CH2CH2CH2CH3.

[0009] In some embodiments of the present invention, R2 is selected from H and C. 1~5 Alkyl groups; in some embodiments of the present invention, R2 is selected from H, -CH3, -CH2CH3, -CH2CH2CH3, -CH(CH3)2, -CH2CH2CH2CH3, -CH2CH2CH(CH3)2, -CH2CH(CH3)2, -CH2CH2CH2CH2CH3.

[0010] In some embodiments of the present invention, n is an integer from 1 to 10; in some embodiments of the present invention, n is any value of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or a range formed by any two of them.

[0011] In some embodiments of the present invention, m is an integer from 1 to 10; in some embodiments of the present invention, m is any value of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or a range of values ​​formed by any two of them.

[0012] In some embodiments of the present invention, the structural formula of the benzotriazole derivative shown in formula (I) is:

[0013] In some embodiments of the present invention, the mass percentage of the benzotriazole derivative represented by formula (I) is 0.005-1% based on the total mass of the silicone adhesive; in some embodiments of the present invention, the mass percentage of the benzotriazole derivative represented by formula (I) is any one of 0.005%, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%, or a range formed by any two of these values, based on the total mass of the silicone adhesive.

[0014] In some embodiments of the present invention, the silicone adhesive comprises component A and component B; component A and / or component B contains a silicone rubber base material; at least one of component A and component B contains a silicone rubber base material.

[0015] In some embodiments of the present invention, the silicone rubber base material contains fumed silica treated with organosilicon compounds and vinyl-containing organopolysiloxanes; in some embodiments of the present invention, the mass ratio of fumed silica treated with organosilicon compounds to vinyl-containing organopolysiloxanes in the silicone rubber base material is 1:(1.5~2.5); in some embodiments of the present invention, the mass ratio of fumed silica treated with organosilicon compounds to vinyl-containing organopolysiloxanes in the silicone rubber base material is any value or a range formed by any two of 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2.0, 1:2.1, 1:2.2, 1:2.3, 1:2.4, and 1:2.5 in the silicone rubber base material.

[0016] In some embodiments of the present invention, the rubber base material also contains a solvent.

[0017] In some embodiments of the present invention, the solvent is water.

[0018] In some embodiments of the present invention, the mass ratio of the vinyl-containing organopolysiloxane to water is (40~50):1; in some embodiments of the present invention, the mass ratio of the vinyl-containing organopolysiloxane to water is any value of 40:1, 42:1, 44:1, 45:1, 46:1, 48:1, 50:1 or a range formed by any two of them.

[0019] In some embodiments of the present invention, component A further contains a caster platinum catalyst diluent, a silane coupling agent, tetramethyltetravinylcyclotetrasiloxane and / or tetramethyldivinylsiloxane.

[0020] In some embodiments of the present invention, based on the total mass of component A, component A comprises the following components by mass percentage: 50-90% vinyl-containing organopolysiloxane, 0.5-5% silane coupling agent, 0-35% silica treated with organosilicon compounds, 0.001-2% caster platinum catalyst dilution, and 0.01-1% tetramethyltetravinylcyclotetrasiloxane and / or tetramethyldivinylsiloxane.

[0021] In some embodiments of the present invention, the mass percentage of the vinyl-containing organopolysiloxane, based on the total mass of component A, is any one of 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or a range formed by any two of these values.

[0022] In some embodiments of the present invention, the silane coupling agent in component A is selected from at least one of epoxy silane coupling agents, methacryloxysilane coupling agents, and isocyanate-based silane coupling agents.

[0023] In some embodiments of the present invention, the silane coupling agent in component A is selected from at least one of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyltriethoxysilane, and γ-isocyanate-propyltrimethoxysilane.

[0024] In some embodiments of the present invention, the mass percentage of the silane coupling agent, based on the total mass of component A, is any one of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or a range formed by any two of these values.

[0025] In some embodiments of the present invention, the mass percentage of silica treated with organosilicon compounds, based on the total mass of component A, is any one of 0%, 0.1%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, or a range formed by any two of these values.

[0026] In some embodiments of the present invention, the casterplatin catalyst diluent contains a casterplatin catalyst and a vinyl-containing organopolysiloxane. The vinyl-containing organopolysiloxane is used as a diluent to dilute the casterplatin catalyst to prepare the casterplatin catalyst diluent. In some embodiments of the present invention, the casterplatin catalyst is a complex of chloroplatinic acid and an olefin.

[0027] In some embodiments of the present invention, the olefin is selected from at least one of vinyl polysiloxane, tetramethyldivinylsiloxane, and tetramethyltetravinylcyclotetrasiloxane.

[0028] In some embodiments of the present invention, the olefin is a vinyl-terminated polysiloxane with a room temperature viscosity of 5000 mPa·s.

[0029] In some embodiments of the present invention, the caster platinum catalyst diluent contains 0.2 to 0.4% platinum atoms by mass.

[0030] In some embodiments of the present invention, the mass percentage of the caster platinum catalyst diluent, based on the total mass of component A, is any value or a range formed by any two of the following: 0.001%, 0.01%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%.

[0031] In some embodiments of the present invention, the mass percentage of tetramethyltetravinylcyclotetrasiloxane, based on the total mass of component A, is any one of 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%, or a range formed by any two of these values.

[0032] In some embodiments of the present invention, the mass percentage of tetramethyldivinylsiloxane, based on the total mass of component A, is any one of 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%, or a range formed by any two of these values.

[0033] In some embodiments of the present invention, the components A and / or B further contain additives.

[0034] In some embodiments of the present invention, the additive is selected from at least one of colorants, mildew inhibitors, antibacterial agents, physiologically active additives, conductive additives, and heat-resistant agents.

[0035] In some embodiments of the present invention, the colorant is selected from at least one of pigments, dyes, and fluorescent whitening agents.

[0036] In some embodiments of the present invention, the physiologically active additive is selected from marine organism repellents.

[0037] In some embodiments of the present invention, the conductive additive is selected from at least one of conductive graphite and metal powder.

[0038] In some embodiments of the present invention, the heat-resistant agent includes cerium oxide.

[0039] In some embodiments of the present invention, component B further contains an organohydrogen polysiloxane, a benzotriazole derivative represented by formula (I), a silane coupling agent, and a compound containing an alkynyl group.

[0040] In some embodiments of the present invention, the B component comprises, by mass percentage, the following components: 50-90% vinyl-containing organopolysiloxane, 0.1-10% organohydrogen polysiloxane, 0.01-1% benzotriazole derivative represented by formula (I), 0.001-0.5% alkynyl compound, 0-35% organosilicon compound-treated fumed silica, and 0.5-5% silane coupling agent.

[0041] In some embodiments of the present invention, the mass percentage of the vinyl-containing organopolysiloxane, based on the total mass of component B, is any one of 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or a range formed by any two of these values.

[0042] In some embodiments of the present invention, the mass percentage of the organohydrogen polysiloxane, based on the total mass of component B, is any one of 0.1%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or a range formed by any two of these values.

[0043] In some embodiments of the present invention, the mass percentage of the benzotriazole derivative represented by formula (I), based on the total mass of component B, is any one of 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1%, or a range formed by any two of these values.

[0044] In some embodiments of the present invention, the alkynyl-containing compound includes an alkynol compound and / or a compound obtained by modifying the hydroxyl group of the alkynol compound with a silane or siloxane. In some embodiments of the present invention, the alkynyl-containing compound includes at least one of ethynylcyclohexanol and methylbutynol.

[0045] In some embodiments of the present invention, the mass percentage of the compound containing the alkynyl group, based on the total mass of component B, is any one of 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, or a range formed by any two of these values.

[0046] In some embodiments of the present invention, the mass percentage of fumed silica treated with organosilicon compounds, based on the total mass of component B, is any one of 0%, 0.1%, 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, or a range formed by any two of these values.

[0047] In some embodiments of the present invention, the silane coupling agent in component B is selected from at least one of epoxy silane coupling agents, methacryloxysilane coupling agents, and isocyanate-based silane coupling agents.

[0048] In some embodiments of the present invention, the silane coupling agent in component B is selected from at least one of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyltriethoxysilane, and γ-isocyanate-propyltrimethoxysilane.

[0049] In some embodiments of the present invention, the mass percentage of the silane coupling agent, based on the total mass of component B, is any one of 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or a range formed by any two of these values.

[0050] In some embodiments of the present invention, the volume ratio of component A to component B is 1:(0.8~1.2); in some embodiments of the present invention, the volume ratio of component A to component B is any value of 1:0.8, 1:0.9, 1:1.0, 1:1.1, 1:1.2 or a range formed by any two of them.

[0051] In some embodiments of the present invention, the organosilicon compound-treated silica includes at least one of hexamethyldisilazane and tetramethyldivinyldisilazane.

[0052] In some embodiments of the present invention, the silica treated with the organosilicon compound is selected from at least one of fumed silica and precipitated silica.

[0053] The organosilicon compound-treated silica in this invention is precipitated silica and / or fumed silica that has undergone surface hydrophobication treatment with hexamethyldisilazane and / or tetramethyldivinyldisilazane.

[0054] In some embodiments of the present invention, the specific surface area of ​​the silica treated with the organosilicon compound is ≥50 m². 2 / g; In some embodiments of the present invention, the specific surface area of ​​the silica treated with the organosilicon compound is ≥200m². 2 / g.

[0055] In some embodiments of the present invention, the vinyl-containing organopolysiloxane is an organopolysiloxane having at least two vinyl groups bonded to silicon atoms; in some embodiments of the present invention, the vinyl-containing organopolysiloxane is a linear organopolysiloxane, or may be a branched chain or network structure organopolysiloxane partially having a T-structure or Q-structure. The vinyl groups can be located at the ends of chain segments, in the middle of chain segments, or both. In some embodiments of the present invention, the vinyl-containing organopolysiloxane is a dimethylvinylsiloxane-terminated dimethylpolysiloxane.

[0056] In some embodiments of the present invention, the viscosity of the vinyl-containing organopolysiloxane measured at 25°C is 100~100000 mPa·s; in some embodiments of the present invention, the viscosity of the vinyl-containing organopolysiloxane measured at 25°C is 500~60000 mPa·s.

[0057] All viscosity data in this invention are measured at 25°C using a rheometer, according to the method described in ISO 3219.

[0058] In some embodiments of the present invention, the organohydrogen polysiloxane is an organohydrogen polysiloxane having at least two hydrogen atoms bonded to silicon atoms; in some embodiments of the present invention, the organohydrogen polysiloxane is a linear organohydrogen polysiloxane, or may partially have a branched chain or network structure with T-structures or Q-structures. The hydrogen groups can be located at the ends of chain segments, in the middle of chain segments, or both; in some embodiments of the present invention, the organohydrogen polysiloxane has a hydrogen content of 0.9%.

[0059] In some embodiments of the present invention, the viscosity of the organohydrogen polysiloxane measured at 25°C is 1–1000 mPa·s; in some embodiments of the present invention, the viscosity of the organohydrogen polysiloxane measured at 25°C is 10–100 mPa·s.

[0060] In some embodiments of the present invention, the organohydrogen polysiloxane contains 0.05% to 1.5% hydrogen atoms by mass; in some embodiments of the present invention, the mass percentage of hydrogen atoms in the organohydrogen polysiloxane is any value or a range formed by any two of 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, and 1.5%.

[0061] In some embodiments of the present invention, the organohydrogen polysiloxane contains 0.1% to 1.2% hydrogen atoms by mass.

[0062] The silicone rubber base material is prepared by mixing raw materials including organosilicon compounds, silicon dioxide, and vinyl-containing organopolysiloxanes and reacting them at a high temperature.

[0063] In some embodiments of the present invention, the mass ratio of the organosilicon compound to the silicon dioxide is 1:(4~6).

[0064] In some embodiments of the present invention, the organosilicon compound is a mixture of hexamethyldisilazane and tetramethyldivinyldisilazane in a mass ratio of (4~6):1.

[0065] The silicone rubber base material contains fumed silica treated with organosilicon compounds and vinyl-containing organopolysiloxanes; The second aspect of the present invention provides the application of the silicone adhesive described in the first aspect of the present invention in the field of electronic product packaging.

[0066] The beneficial effects of this invention are as follows: By introducing benzotriazole derivatives with specific structures, the silicone adhesive of this invention exhibits excellent storage stability, low compression set, and no blooming phenomenon after curing (i.e., no benzotriazole derivative precipitation on the surface). Furthermore, after prolonged sealed storage at room temperature, the silicone adhesive of this invention does not show any decrease in vulcanization rate or compression set performance, nor does it exhibit blooming, demonstrating excellent storage stability.

[0067] Furthermore, the silicone adhesive of this invention can be cured at a low temperature (below 120°C) and for a short time (less than 40 minutes), and the cured silicone rubber has low compression set and will not bloom during long-term storage. Attached Figure Description

[0068] Figure 1 The compound of formula (1) in Example 1 1 H-NMR spectrum.

[0069] Figure 2 For the compound of formula (2) in Comparative Example 1 1 H-NMR spectrum. Detailed Implementation

[0070] The following examples provide a more detailed description of the specific implementation of the present invention, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described below are methods that can be implemented or understood by those skilled in the art by referring to existing technology. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0071] In the following examples and comparative examples, the viscosity was measured at 25°C using a rheometer according to the test method described in ISO 3219. Example 1 This example provides a method for preparing a two-component thermosetting silicone adhesive, specifically including the following steps: 1300g of dimethylvinylsiloxane-terminated dimethylpolysiloxane (A1) with a viscosity of 5000mPa·s was mixed with 600g of dimethylvinylsiloxane with a viscosity of 300mPa·s. 2 Fumed silica (Cl) with a BET specific surface area of ​​ / g (purchased from Wacker HDK T30), 100g hexamethyldisilazane, 20g tetramethyldivinyldisilazane, and 30g water were kneaded at room temperature for 2 hours to obtain a mixture. The mixture was then heated to 170°C. During the heating process, when the temperature reached 150°C, a vacuum was turned on, and the mixture was kneaded under vacuum for 2 hours. Then, 100g of Al was added for dilution, and the mixture was cooled to obtain a silicone rubber base material.

[0072] Add 284g of dimethylvinylsiloxane-terminated dimethylpolysiloxane (A1), 10g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 2g of tetramethyltetravinylcyclotetrasiloxane (E-2), and 4g of caster platinum catalyst dilution C (commercially available, platinum content 3000ppm) to 700g of silicone rubber base material to obtain a mixture; disperse the mixture in a high-speed disperser for 30min to obtain adhesive component A.

[0073] Add 249.8g of dimethylvinylsiloxane-terminated dimethylpolysiloxane (A1), 20g of 3-(2,3-epoxypropoxy)propyltrimethoxysilane, 0.2g of ethynylcyclohexanol E-1, 20g of organohydrogen polysiloxane B1 with a hydrogen content of 0.9% to 700g of silicone rubber base material to obtain adhesive component B.

[0074] The structural formula of the benzotriazole derivative of formula (1) is as follows:

[0075] Adhesive component A and adhesive component B were packaged in a 400mL two-component tube with a volume ratio of 1:1 and sealed at room temperature to obtain the two-component thermosetting silicone adhesive in this example.

[0076] The compound of formula (1) in this example can be synthesized by the following method: Add 54.8g of hydroxyvinyl silicone oil to a three-necked flask, stir and evacuate, control the oil temperature at 105℃, raise the material temperature to 100℃ and start timing for 2 hours, then cool down to below 60℃, purge with dry nitrogen to release the vacuum, then add 87.2g of methanol and 0.1g of tetrabutyl titanate, maintain the methanol reflux temperature, add 32.4g of compound (3) dropwise while stirring, control the dropwise addition time within 30min, then set the oil temperature to 95℃, condense and recover methanol, start timing after the material temperature reaches 90℃, continue the reaction for 30min, then turn on the vacuum, degas and boil at low temperature for 30min, then cool down to room temperature, turn off the vacuum, release the pressure with nitrogen, and obtain the benzotriazole derivative shown in formula (1). 1 H-NMR spectrum (solvent CDCl3, 400MHz) as shown Figure 1 As shown.

[0077] Hydroxyvinyl silicone oil can be synthesized by the manufacturer or commercially available products, such as 207V-1 from Zhejiang Zhenghe Silicon Materials, SK-VOH-10 from Shenzhen Tianqi New Materials, or DA30 from Anbiya.

[0078] Comparative Example 1 The difference between the preparation method of the two-component thermosetting silicone adhesive in this example and that in Example 1 is that an equal amount of the benzotriazole derivative shown in formula (2) is used instead of the benzotriazole derivative shown in formula (1) in Example 1.

[0079] The structural formula of the benzotriazole derivative shown in formula (2) is as follows:

[0080] The benzotriazole derivative shown in formula (2) can be synthesized using the compound of formula (3) and hydroxyl silicone oil as reactants, following the synthesis steps of the compound of formula (1). 1 H-NMR spectrum (solvent CDCl3, 400MHz) as shown Figure 2 As shown, hydroxyl silicone oil can be synthesized at home or commercially available products, such as Ambiar's OH30.

[0081] Comparative Example 2 The difference between the preparation method of the two-component thermosetting silicone adhesive in this example and that in Example 1 is that: in this example, an equal amount of dimethylvinylsiloxane-terminated dimethylpolysiloxane (A1) is used instead of the benzotriazole derivative shown in formula (1) in Example 1, that is, no benzotriazole derivative shown in formula (1) is added in this example, and the amount of A1 used in this example is increased by 10g compared with Example 1.

[0082] Comparative Example 3 The difference between the preparation method of the two-component thermosetting silicone adhesive in this example and that in Example 1 is that an equal amount of the benzotriazole derivative shown in formula (3) is used instead of the benzotriazole derivative shown in formula (1) in Example 1.

[0083] The structural formula of the benzotriazole derivative shown in formula (3) is as follows:

[0084] Comparative Example 4 The only difference between the preparation method of the two-component thermosetting silicone adhesive in this example and that in Example 1 is that an equal amount of benzotriazole-5-carboxylic acid ethyl ester is used instead of the benzotriazole derivative shown in formula (1) in Example 1.

[0085] Comparative Example 5 The only difference between the preparation method of the two-component thermosetting silicone adhesive in this example and Comparative Example 3 is that the amount of benzotriazole derivative shown in formula (3) in this example is adjusted to 5g, and in order to ensure that the total amount of component B remains unchanged, the amount of dimethylvinylsiloxane-terminated dimethylpolysiloxane (A1) is increased by 5g compared with Comparative Example 3.

[0086] Comparative Example 6 The only difference between the preparation method of the two-component thermosetting silicone adhesive in this example and Comparative Example 4 is that the amount of benzotriazole-5-carboxylic acid ethyl ester in this example is adjusted to 5g, and the amount of dimethylpolysiloxane (A1) end-capped with dimethylvinylsiloxane is increased by 5g compared with Comparative Example 4 to ensure that the total amount of component B remains unchanged.

[0087] Comparative Example 7 The only difference between the preparation method of the two-component thermosetting silicone adhesive in this example and Comparative Example 3 is that the amount of benzotriazole derivative shown in formula (3) in this example is adjusted to 2g, and the amount of A1 added is increased by 8g compared with Comparative Example 3 in order to ensure that the total amount of component B remains unchanged.

[0088] Comparative Example 8 The only difference between the preparation method of the two-component thermosetting silicone adhesive in this example and Comparative Example 4 is that the amount of benzotriazole-5-carboxylic acid ethyl ester in this example is adjusted to 2g, and the amount of A1 added is increased by 8g compared with Comparative Example 4 to ensure that the total amount of component B remains unchanged.

[0089] Performance testing: The vulcanization curves and compression set data of the two-component thermosetting silicone adhesives prepared in Example 1 and Comparative Examples 1-8 were tested respectively. The specific test methods are as follows: Following the initial (freshly prepared) and sealed storage period of 3 months, 400 mL of the sealed two-component thermosetting silicone adhesive was removed. Components A and B were statically mixed using a 400 mL two-component glue gun. The vulcanization curves of the mixture of components A and B were measured at 90°C for 30 min and at 110°C for 30 min, respectively. The TC10 (min) and TC90 (min) results of the vulcanization curves are recorded in Tables 1 and 2, respectively. TC10 refers to the time required from the start of the experiment until the torque reaches: minimum torque + (maximum torque - minimum torque) × 10%; TC90 refers to the time required from the start of the experiment until the torque reaches: minimum torque + (maximum torque - minimum torque) × 90%. The vulcanization rate test method involved in this invention refers to ISO 3414:2008. Curing was performed using a flat vulcanizing machine with curing processes of 90℃ for 30 min and 110℃ for 30 min, respectively. After curing, the compression set was tested according to the test methods described in ISO 815-1:2022. Then, according to the ISO 815 type B specimen requirements, specimens with a thickness of 6.3±0.3 mm and a diameter of 13.0±0.5 mm were prepared. The compression set was then tested after 25% compression at 125℃ for 72 h and after 150℃ for 72 h. The compression set after 25% compression at 125℃ and 72 h of heat aging was recorded as CSET1. The compression set after 25% compression at 150℃ and 72 h of heat aging was recorded as CSET2. The results of the compression set measurements are recorded in Tables 1 and 2, respectively.

[0090] Table 1. Vulcanization curves and compression set data after vulcanization at 90℃ for 30 min.

[0091] Table 2. Vulcanization curves and compression set data after vulcanization at 110℃ for 30 min.

[0092] As shown in Tables 1 and 2, compared with Comparative Example 2 (which did not contain a benzotriazole derivative), the curing rate indices TC10 and TC90 of the silicone adhesive in Example 1 were less affected. Comparative Examples 3 and 5, which contained a benzotriazole derivative of formula (3), showed a smaller impact on TC10 compared to TC90, while the impact on TC90 was relatively larger. Comparative Examples 4, 6, and 8, which contained ethyl benzotriazole-5-carboxylate, all had significant effects on the curing rate indices TC10 and TC90 of the two-component thermosetting adhesive.

[0093] After 3 months of sealed storage at room temperature, Comparative Example 4, which contained ethyl benzotriazole-5-carboxylate, failed to form under both 90°C and 110°C curing conditions for 30 min. Comparative Example 3 showed a significant decrease in the curing rate of the benzotriazole derivative of formula (3). Comparative Example 5, by reducing the amount added, could appropriately weaken the influence of the benzotriazole derivative on the curing performance of the adhesive during storage, but its improvement on compression set performance did not meet expectations. The compression set test specimens prepared under 110°C curing conditions for 30 min showed some improvement in the compression set performance of Comparative Example 7 with the added amount, but after 3 months of storage, the compression set performance deteriorated to some extent. The compression set test specimens prepared under 90°C curing conditions for 30 min showed virtually no improvement in the compression set performance of Comparative Example 7 with the added amount.

[0094] The benzotriazole derivative added in Example 1, under the premise of ensuring the amount added, has no significant impact on the curing rate and storage stability of the adhesive. The compression set performance at 125℃ and 150℃ for 72h is significantly improved. After 3 months of storage, the compression set performance of the adhesive has basically not decreased.

[0095] Using a flat vulcanizing machine, a curing process of 110℃ for 30 minutes was used to prepare test pieces with dimensions of 100mm×100mm×2mm. The test pieces were placed in a transparent sealed box for 3 months. The appearance of the sealed silicone rubber test pieces was observed to confirm whether blooming occurred. The cases where no white substance was precipitated and there were no abnormalities were marked as ○, and the cases where white substance was precipitated and blooming occurred were marked as X. The samples were also roughly graded according to the amount of precipitation: a small amount of precipitation was X-1, a large amount of precipitation was X-3, and the middle was X-2. The specific test results are recorded in Table 3.

[0096] Table 3 Blending Data

[0097] As shown in Table 3, compared with Comparative Example 2, Example 1, which added a benzotriazole derivative with a special structure, did not exhibit blooming on the material surface either initially or after 3 months of sealed storage. This demonstrates that the present invention, by introducing a benzotriazole derivative and adjusting the formulation of the silicone adhesive, can solve the blooming problem present with conventional benzotriazole derivatives. In Comparative Examples 1, 3, and 5-8, the silicone adhesives showed white precipitates on the surface of the test pieces after 3 months of sealed storage at room temperature. In Comparative Example 4, blooming test data was not tested after 3 months of storage because it could not be molded.

[0098] The test method for lap shear strength was based on ISO 4587-2003. A 0.2 mm diameter copper wire was used to define the adhesive layer thickness, and the length of the bonding surface of the sample was 12.5 mm ± 0.25 mm. The silicone adhesives of Examples 1 and 1-2 were prepared according to the lap shear test method. The test materials used were aluminum substrate Al5052, aluminum substrate Al3003, PBT30%GF, and PA66, respectively. The prepared samples were cured in a pre-set 110℃ forced-air oven for 30 min, and then cooled at 25℃ for 2 h. The butt shear strength was then tested using an electronic universal testing machine at a tensile rate of 10 mm / min, and the data were recorded in Table 4.

[0099] Table 4 Butt Shear Strength

[0100] As shown in Table 4, compared with Comparative Example 2, the shear strength data of Example 1 and Comparative Example 1, which added benzotriazole derivatives, were better in tests using aluminum materials Al5052 commonly used for motor and electronic control housings and Al3003 commonly used for inverter housings. The shear strength data of engineering plastic PBT30%GF material decreased to a certain extent, but still met the shear strength requirements (1.7MPa) for most CIPG application scenarios. The shear strength of engineering plastic PA66, which has lower temperature resistance, was excellent, with a shear strength of over 3MPa, which was much higher than that of Comparative Example 2 without the addition of benzotriazole derivatives. This further indicates that the silicone adhesive in this invention has good bonding strength.

[0101] In summary, the present invention provides a two-component thermosetting silicone adhesive with a benzotriazole derivative having a specific structure, as shown in Example 1. This adhesive can be rapidly cured at 110°C or 90°C for 30 minutes. The cured silicone rubber has excellent compression set properties. The silicone rubber does not exhibit blooming of benzotriazole derivative during long-term storage at room temperature, and has good storage stability and good vulcanization performance.

[0102] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. An organosilicon adhesive, characterized in that: Including benzotriazole derivatives as shown in formula (I); Each R1 is independently selected from H and C. 1~5 Alkyl groups; R2 is selected from H and C. 1~15 Alkyl groups; n≥1, and n is an integer; m≥1, and m is an integer.

2. The silicone adhesive according to claim 1, characterized in that: The mass percentage of the benzotriazole derivative represented by formula (I) is 0.005~1% based on the total mass of the silicone adhesive.

3. The silicone adhesive according to claim 1, characterized in that: The silicone adhesive comprises component A and component B; component A and / or component B contain a silicone rubber base material; The silicone rubber base material contains fumed silica treated with organosilicon compounds and vinyl-containing organopolysiloxanes; Component A also contains castal platinum catalyst diluent, silane coupling agent, tetramethyltetravinylcyclotetrasiloxane and / or tetramethyldivinylsiloxane. Component B also contains organohydrogen polysiloxane, benzotriazole derivatives represented by formula (I), silane coupling agents, and compounds containing alkynyl groups.

4. The silicone adhesive according to claim 3, characterized in that: Based on the total mass of component A, component A comprises the following components by mass percentage: 60-90% vinyl-containing organopolysiloxane, 0.5-5% silane coupling agent, 0-35% silica treated with organosilicon compounds, 0.001-2% caster platinum catalyst dilution, and 0.01-3% tetramethyltetravinylcyclotetrasiloxane and / or tetramethyldivinylsiloxane; And / or, based on the total mass of said component B, said component B comprises the following components in mass percentage: 50-90% vinyl-containing organopolysiloxane, 0.1-10% organohydrogen-containing polysiloxane, 0.01-1% benzotriazole derivative represented by formula (I), 0.001-0.5% alkynyl-containing compound, 0-35% organosilicon compound-treated fumed silica, and 0.5-5% silane coupling agent.

5. The silicone adhesive according to claim 3, characterized in that: The volume ratio of component A to component B is 1:(0.8~1.2).

6. The silicone adhesive according to claim 3 or 4, characterized in that: The silica treated with the organosilicon compound has at least one of the following characteristics: (a1) Organosilicon compounds include at least one of hexamethyldisilazane and tetramethyldivinyldisilazane; (a2) The silica is selected from at least one of fumed silica and precipitated silica; (a3) The specific surface area of ​​the silica treated with the organosilicon compound is ≥50 m². 2 / g.

7. The silicone adhesive according to claim 3 or 4, characterized in that: The vinyl-containing organopolysiloxane has at least one of the following characteristics: (b1) The vinyl-containing organopolysiloxane is an organopolysiloxane having at least two vinyl groups bonded to silicon atoms; (b2) The viscosity of the vinyl-containing organopolysiloxane measured at 25°C is 100~100000 mPa·s; And / or, the organohydrogen polysiloxane has at least one of the following characteristics: (c1) The organohydrogen polysiloxane is an organohydrogen polysiloxane having at least two hydrogen atoms bonded to silicon atoms; (c2) The viscosity of the organohydrogen polysiloxane measured at 25°C is 1–1000 mPa·s; (c3) The organohydrogen polysiloxane contains 0.05 to 1.5% hydrogen atoms by mass.

8. The silicone adhesive according to claim 3 or 4, characterized in that: The compounds containing an alkyne group include alkynol compounds and / or compounds obtained by modifying the alcohol hydroxyl groups in the alkynol compounds with silanes or siloxanes. And / or, the casterplatin catalyst diluent contains casterplatin catalyst and vinyl-containing organopolysiloxane; And / or, the caster platinum catalyst diluent contains 0.2-0.4% platinum atoms by mass.

9. The silicone adhesive according to claim 1, characterized in that: The silicone rubber base material is prepared by mixing raw materials including organosilicon compounds, silicon dioxide, and vinyl-containing organopolysiloxanes and reacting them at a high temperature.

10. The application of the silicone adhesive according to any one of claims 1 to 9 in the field of electronic product packaging.

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