Photothermal dual-curing long-acting sealing silicone rubber, preparation method and application thereof

Abstract

The application belongs to the technical field of new energy battery sealant manufacturing, and discloses a light-heat dual-curing long-acting sealing silicone rubber, a preparation method and application thereof, the preparation method comprises the following steps: S1: preparing raw materials according to the mass fraction ratio, including platinum gold catalyst slow-release microcapsules; S2: preparing a silicone rubber base material; S3: preparing a long-acting sealing silicone rubber, under the action of a polymerization inhibitor, two types of molecular groups participate in UV curing and thermal curing respectively. The application also discloses the light-heat dual-curing long-acting sealing silicone rubber prepared by the method and application thereof in new energy battery manufacturing. The application prepares platinum gold catalyst slow-release microcapsules for passively releasing a catalyst to initiate a thermal curing reaction, adopts two-step curing in sequence, so that the structural adhesive layer respectively meets the performance requirements of a structural sealing stage and a disaster tolerance stage, and can overcome the defects of long curing time and no disaster tolerance performance of the existing sealant, and can be widely applied in the manufacturing of hydrogen fuel cells or lithium batteries.

Description

Technical Field

[0001] This invention belongs to the field of new energy battery sealant manufacturing technology, specifically relating to a staged photothermal dual-curing long-lasting sealing silicone rubber, its preparation method, and its application. Background Technology

[0002] In the sealing field of new energy batteries such as hydrogen fuel cells and ternary lithium batteries, sealant materials are exposed to various complex operating environments inside the battery, such as acidic media solutions, humid gases, coolants, and cycling temperatures, which seriously affect their service life. In the event of thermal runaway, the sealant material often fails rapidly and does not have a disaster recovery effect. The design, preparation, and performance characterization of high-performance sealing materials for new energy batteries are extremely important. To meet the normal operation of new energy batteries, the sealing gasket (sealant layer) must meet the following performance requirements: 1. Appropriate compressibility and excellent mechanical stability; 2. Thermal, chemical, and electrochemical stability, able to adapt to the complex and changing environmental conditions and operating conditions inside the battery for a long time; 3. Excellent electrical insulation, which should have good electrical insulation performance to prevent battery short circuits; 4. Low gas permeability, which should be able to prevent gas leakage inside the battery or the intrusion of external gases and moisture; 5. Good economic benefits and ease of processing, with low manufacturing costs and simple and rapid processing technology being crucial.

[0003] Existing sealing materials for new energy batteries mainly use silicone rubber and polyolefin sealants. Silicone rubber suffers from poor airtightness, high permeability, slow curing speed, and long processing cycles. Polyolefin sealants, on the other hand, have a large shrinkage rate and strong water absorption, leading to a decline in their performance in the high-temperature and humid environment inside new energy batteries. This affects their long-term performance and durability, making it impossible to guarantee stable and reliable high performance under different operating conditions. Furthermore, existing new energy battery sealants cannot simultaneously support UV curing and thermal curing. For example, CN116463082A discloses a UV-curable sealant for fuel cell bipolar plates and its preparation method, which only supports UV curing, and the UV curing time requires more than 20 seconds, and does not support thermal curing. On the other hand, sealants that support thermal curing cannot simultaneously support UV curing, nor can they support phased UV curing and thermal curing, and they lack passive protection and disaster recovery capabilities, failing to better meet the diverse and complex requirements of new energy batteries. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this paper provides a staged photothermal dual-curing long-lasting sealing silicone rubber, its preparation method, and its application. Through synergistic improvements to raw materials, preparation processes, and application methods, aromatic amine polymerization inhibitors and two types of molecular groups with significantly different polymerization rates are introduced. A unique passive-release catalyst-initiated platinum catalyst slow-release microcapsules are designed to enable the obtained sealing structure adhesive layer to cure in two steps, respectively meeting the performance requirements of the structural sealing stage and the disaster recovery stage. This can meet the comprehensive needs of new energy batteries, such as complex and variable operating conditions, durability, and safety, thereby improving the service life and disaster recovery capability of new energy batteries.

[0005] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0006] A method for preparing a photothermal dual-curing long-lasting sealing silicone rubber includes the following steps:

[0007] S1: Prepare raw materials according to the following mass ratio.

[0008] Acrylic modified polysiloxane 50~80

[0009] Vinyl polysiloxane 20~50

[0010] Hydrogen-containing silicone oil 8~15

[0011] Fumed silica 20~30

[0012] Catalyst sustained-release microcapsules 0.3~0.5

[0013] Initiator 1.5~3

[0014] Tackifier 1~2

[0015] Aromatic amine polymerization inhibitor 0.15~0.25

[0016] Among them, the platinum catalyst sustained-release microcapsules are spherical particles with an average particle size of 4~6μm, and the capsule shell formed by PP resin completely covers the platinum catalyst. The melting temperature of the capsule shell is not less than 150℃.

[0017] S2: Preparation of silicone rubber base material

[0018] Acrylic-modified polysiloxane and vinyl polysiloxane were added sequentially to a kneader, and fumed silica was added in batches. The mixture was kneaded at room temperature for 1 hour, then vacuumed at 150°C and kneaded for another 3 hours. The mixture was then cooled to room temperature to obtain the silicone rubber base material.

[0019] S3: Preparation of long-lasting sealing silicone rubber

[0020] Hydrogen-containing silicone oil, single-component platinum catalyst slow-release microcapsules, initiator, tackifier, and aromatic amine polymerization inhibitor are added sequentially to the silicone rubber base material. After stirring and mixing evenly, a long-lasting sealing silicone rubber is obtained. Among them, two types of molecular groups with different polymerization rates, acrylate and vinyl siloxane chains, participate in the first step of UV curing (mainly the double bonds of acrylate groups participate in the free radical polymerization reaction of UV curing) and the second step of heat curing (vinyl siloxane chains participate in the catalytic hydrosilylation reaction). After step-by-step curing, structural adhesive layers with different properties are obtained.

[0021] A photothermal dual-curing long-lasting sealing silicone rubber is prepared by the aforementioned method. Under the action of an aromatic amine polymerization inhibitor, two types of molecular groups with significantly different polymerization rates participate in the curing reaction in two steps. The first step is a UV curing reaction in which the acrylate molecular groups with high polymerization rate participate. The second step is a thermosetting hydrosilylation reaction in which the vinylsiloxane molecular groups with low polymerization rate participate together with the platinum catalyst passively released by the platinum catalyst slow-release microcapsules when the temperature reaches above 150°C.

[0022] An application of a photothermal dual-curing long-lasting sealing silicone rubber involves using it as a structural sealant in the manufacture of hydrogen fuel cells or lithium batteries to seal the structural surfaces of the hydrogen fuel cells or lithium batteries. Through a two-step curing process, the structural adhesive layer successively achieves different performance requirements in the structural sealing stage and the disaster recovery stage, including the following steps:

[0023] A1: Photothermal dual-curing long-lasting sealing silicone rubber is coated onto the sealing structure surface of hydrogen fuel cells or lithium batteries. UV is used to cure the structural adhesive layer in the first step to form a structural adhesive layer and make its performance meet the requirements of the structural sealing stage.

[0024] A2: Bond another sealing structure surface to the structural adhesive layer to form a layered sealant structure for the battery;

[0025] A3: When the temperature of any sealed surface rises above 150°C, the shell of the platinum catalyst slow-release microcapsule melts due to heat, rapidly releasing the platinum catalyst inside the microcapsule. This catalyst undergoes a thermosetting reaction with the vinylsiloxane molecular groups, causing the sealing adhesive layer to be thermosetting. This rapidly increases the mechanical properties, heat resistance, and flame retardant properties of the sealing adhesive layer, enabling it to meet the performance requirements of the disaster recovery stage. In combination with other safety measures, this enhances the overall disaster recovery performance of the battery system, delays thermal runaway, and improves the overall safety of the battery system.

[0026] The staged photothermal dual-curing long-lasting sealing silicone rubber, its preparation method, and its application provided by this invention have at least the following beneficial effects:

[0027] 1. This invention, through synergistic improvement of the raw materials, preparation process, and application of sealing silicone rubber (hereinafter referred to as sealant), introduces two types of molecular groups with significantly different activities under UV conditions, including aromatic amine polymerization inhibitors. It designs a unique platinum catalyst slow-release microcapsule that initiates a thermosetting reaction by passively releasing the catalyst. The microcapsule undergoes photothermal dual curing in two independent stages, resulting in a sealed structural adhesive layer that cures in two steps, respectively meeting the performance requirements of the structural sealing stage and the disaster recovery stage. This invention can meet the comprehensive needs of new energy batteries, such as complex and variable operating conditions, durability, and safety, thereby improving the service life and disaster recovery capability of new energy batteries.

[0028] 2. This invention introduces a polymerization inhibitor, which forms two types of molecular groups with significantly different polymerization rates (UV curing activity), supporting UV curing and passive thermal curing above 150°C, respectively. The polymerization inhibitor significantly reduces the activity of vinylsiloxane under UV conditions, thus ensuring that the two types of molecular groups with different polymerization rates mainly participate in only one stage of the curing reaction, resulting in structural adhesive layers with different performance advantages. The sealing structural adhesive layer formed after the first stage of UV curing in the factory (mainly acrylate molecular groups) can fully meet the battery's bonding and sealing requirements. After the first step of UV curing, the proportion of acrylate segments reaches its peak, at which point the sealing structural adhesive layer has the best air-permeability and water-vapor-proof performance. However, if thermal curing continues to fully cure the structural adhesive layer, the increased polysiloxane segments after thermal curing will lead to an increase in the mechanical strength and flame retardancy of the structural adhesive layer, while reducing its air-permeability and water-vapor-proof performance, which is detrimental to the normal operation of the battery. Under the action of aromatic amine polymerization inhibitors, the activity of vinylsiloxane molecular groups in UV curing reaction is very low. Compared with acrylate molecular groups, the reactivity of vinylsiloxane molecular groups is very low, less than 0.01. Therefore, in UV curing reactions with a short duration of less than 10 seconds and in which acrylate molecular groups have not fully reacted, most of the vinylsiloxane molecular groups do not participate in the UV curing reaction.

[0029] 3. This invention prepares catalyst-releasing microcapsules with specific shapes, structures, sizes, and rupture temperatures, encapsulating the catalyst within the capsules to prevent contact with other components. The capsule shell ruptures only when the battery system temperature reaches 150°C, passively and rapidly releasing the catalyst to initiate a thermosetting reaction (photothermal dual curing). When the temperature is below 150°C, the microcapsule maintains its shape, does not affect the UV curing reaction, does not release the catalyst, and does not trigger a thermosetting reaction, thus maintaining the structural adhesive layer's high air-permeability and water-vapor resistance after one-step curing. The catalyst is passively released only when the battery system temperature rises to 150°C or above, under hazardous conditions, triggering a thermosetting reaction. This rapidly improves the structural adhesive layer's high-temperature resistance, mechanical strength, and flame-retardant properties, enhancing its disaster recovery performance. Combined with other safety measures, this improves the overall safety of the battery system.

[0030] 4. This invention designs and prepares highly stable catalyst sustained-release microcapsules, and uses PP resin with high softening point and high melting temperature to encapsulate the platinum catalyst, so that the catalyst is completely isolated from other active components. The resulting sealed silicone rubber product can be stored at room temperature (below 25°C) for more than 6 months without performance degradation, making it suitable for long-term storage and transportation, and overcoming the short shelf life of existing similar products.

[0031] 5. This invention uses the specially prepared photothermal dual-curing long-lasting sealing silicone rubber with special properties as a structural sealant in the manufacture of hydrogen fuel cells or lithium batteries to seal the structural surfaces of hydrogen fuel cells or lithium batteries. Through two-stage curing, the structural adhesive layer successively meets the performance requirements of the structural sealing stage and the disaster recovery stage. It can meet the long-term operating performance requirements under normal working conditions and the rapid disaster recovery performance requirements under crisis conditions, thus breaking through the limitations of existing similar products.

[0032] 6. The sealing silicone rubber preparation method and application provided by this invention are simple in process and have a short UV curing time. They can be widely applied to the CIPG (cured in place gasket) process in the production of new energy batteries. This process involves applying sealant to the sealing surface, allowing it to cure, and then assembling it to achieve single-sided bonding. Conventional silicone rubber curing time is more than 20 minutes, while the first step of UV curing in this invention can be completed within 10 seconds, and the second step of thermal curing is initiated automatically according to the battery temperature, without occupying production time. Since the curing speed of the sealant determines the assembly efficiency of the battery, this invention achieves UV and thermal dual curing of the sealant by modifying the acrylic with organosilicon and encapsulating the catalyst. Only UV curing is required in the factory assembly stage, which greatly shortens the assembly processing time, improves the assembly efficiency, and reduces production costs. Detailed Implementation

[0033] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0034] Basic Implementation

[0035] The method for preparing photothermal dual-curing long-lasting sealing silicone rubber provided in this embodiment includes the following steps:

[0036] S1: Prepare raw materials according to the following mass ratio.

[0037] Acrylic modified polysiloxane 50~80

[0038] Vinyl polysiloxane 20~50

[0039] Hydrogen-containing silicone oil 8~15

[0040] Fumed silica 20~30

[0041] Catalyst sustained-release microcapsules 0.3~0.5

[0042] Initiator 1.5~3

[0043] Tackifier 1~2

[0044] Aromatic amine polymerization inhibitor 0.15~0.25

[0045] Among them, the platinum catalyst sustained-release microcapsules are spherical particles with an average particle size of 4~6μm, and the capsule shell formed by PP resin completely covers the platinum catalyst. The melting temperature of the capsule shell is not less than 150℃.

[0046] The step S1-1, which involves preparing the platinum catalyst sustained-release microcapsules, includes:

[0047] S1-1-1: Add platinum catalyst and PP resin (melting point greater than 150℃, such as K9927) to D80 solvent oil at a mass ratio of 1.5~2:1, heat to 60~70℃, stir to dissolve, control the stirring speed at 300~500rpm, and the time is 2~3h; by controlling the ratio of platinum catalyst and PP resin and the stirring speed, the thickness of the capsule shell obtained is 2~3μm.

[0048] S1-1-2: Then the mixture is added dropwise to the polyacryl alcohol aqueous solution. After the addition is complete, the mixture is stirred at room temperature, with the stirring speed controlled at 500-600 rpm for 6-8 hours, to obtain spheres with an average particle size of 4-6 μm.

[0049] The particle size, overall shape, and surface roughness of the capsules are mainly controlled through this step S1-1-2. The faster the stirring speed, the finer the particle size, the longer the reaction time, the closer the overall shape is to a sphere, and the smoother the surface morphology.

[0050] S1-1-3: Remove the solvent by vacuum distillation to obtain spherical single-component platinum catalyst sustained-release microcapsules with a capsule wall thickness of 2~3μm and an average particle size of 4~6μm; the platinum catalyst sustained-release microcapsules remain stable and do not release the catalyst below 150℃; when the temperature reaches 150℃ and above, the capsule shell melts and can rapidly release the catalyst activity to participate in the thermosetting reaction.

[0051] If the particle size of the prepared catalyst-releasing microcapsules is too large, the number of microcapsules in the structural adhesive layer system will be too small, making it difficult to maintain morphological integrity during operation and causing them to be easily crushed by the system, affecting the stability of the structural adhesive layer. Conversely, if the particle size of the microcapsules is too small, the number of microcapsules will be too large, the shell thickness will be too thin, and the morphological integrity of the microcapsules will also be difficult to maintain. They may also release activity at normal temperatures, similarly affecting the stability of the capsule catalyst. The shell material selected for the microcapsules is PP resin with a melting point of 150℃ and above. PP resin has stable physical and chemical properties and can maintain good chemical and physical inertness when mixed with polysiloxanes at room temperature. When heated to a temperature above the softening point of PP resin (approximately 145℃), the shell of the microcapsule softens. At a temperature of 150℃ and above, the shell melts, rapidly releasing the internal catalyst and initiating the second-step thermosetting reaction.

[0052] The catalyst sustained-release microcapsules prepared in the embodiments of the present invention are spherical with a particle size of 4~6μm, a shell thickness of 2~3μm, and a rough outer surface. The particle size and shell thickness are moderate, the morphology is regular, and the stability at room temperature is good. When heated to above 150℃, they can quickly release the active catalyst and initiate a secondary thermosetting reaction, thereby greatly improving the overall disaster resistance performance of the structural adhesive layer material.

[0053] The PP resin used in this embodiment is a PP resin with a melting point greater than 150°C, including homopolymer PP (PP-H) or copolymer PP (PP-R). Specific models can be selected such as K9927, EP300M, etc. Of course, other PP resin products with a melting point greater than 150°C can also be used.

[0054] The platinum catalyst mentioned is a Karstedt platinum catalyst.

[0055] The step S1-2, which involves the preliminary preparation of acrylic acid-modified polysiloxane, includes:

[0056] S1-2-1: Take 1000 parts by weight of octamethylcyclotetrasiloxane, 2-5 parts by weight of tetramethyldivinyldisiloxane, and 200-350 parts by weight of hydroxy acrylate, and add them to the reaction vessel.

[0057] S1-2-2: While stirring, heat to 90~110℃ at a stirring speed of 700~800 rpm; then add 1~3 parts by weight of tetramethylammonium hydroxide and continue stirring at 500~600 rpm for 5 hours of polymerization reaction; after polymerization reaction, compared with the siloxane chain structure of silicone, the carboxylic acid structure of acrylic acid modified polysiloxane has a shorter intermolecular distance and a smaller free volume, which can provide higher gas leak-proof performance and lower moisture permeability.

[0058] S1-2-3: Then, the catalyst and small molecules are removed at 150~170℃ and 0.1MPa negative pressure to obtain acrylic acid modified polysiloxane; after the polymerization reaction, acrylate groups are introduced. The carbon-carbon molecular chains have a shorter intermolecular distance and a smaller free volume, which has two functions: first, it can provide higher gas leak-proof performance and lower moisture permeability; second, it supports UV curing.

[0059] S2: Preparation of silicone rubber base material

[0060] Acrylic-modified polysiloxane and vinyl polysiloxane were added sequentially to a kneader, and fumed silica was added in batches. The mixture was kneaded at room temperature for 1 hour, then vacuumed at 150°C and kneaded for another 3 hours. The mixture was then cooled to room temperature to obtain the silicone rubber base material.

[0061] S2-1: First, add acrylic-modified polysiloxane and vinyl polysiloxane to the kneader in sequence;

[0062] S2-2: Add fumed silica in batches and knead at room temperature for 1 hour;

[0063] S2-3: Then, vacuum knead at 150℃ for 3 hours, cool to room temperature, and obtain silicone rubber base material.

[0064] S3: Preparation of long-lasting sealing silicone rubber

[0065] Hydrogen-containing silicone oil, single-component platinum catalyst slow-release microcapsules, initiator, tackifier, and aromatic amine polymerization inhibitor are added sequentially to the silicone rubber base material. After stirring and mixing evenly, a long-lasting sealing silicone rubber is obtained. Among them, two types of molecular groups with different polymerization rates, acrylate and vinylsiloxane, participate in the first step of UV curing (the double bonds of the acrylate groups with high polymerization rate undergo free radical polymerization until the reaction is complete) and the second step of heat curing (vinylsiloxane with low polymerization rate participates in a catalytic hydrosilylation reaction). After step-by-step curing, structural adhesive layers with different properties are obtained. In the two-stage curing of the sealant coating prepared from long-lasting silicone rubber, a portion of the high-reactivity groups (acrylates) only participate in the first stage of UV curing (factory assembly stage) and are completely consumed after the first UV curing reaction. The other portion of low-reactivity groups (vinylsiloxanes) are protected by the polymerization inhibitor. At this time, the vinylsiloxane groups have very low activity in the UV curing reaction. Compared with the acrylate groups, the reactivity of the vinylsiloxane groups is very low, less than 0.01. Therefore, in the short first UV curing reaction of less than 10 seconds, when the acrylate groups have not fully reacted, most of the vinylsiloxane groups do not participate in the UV curing reaction. This portion of vinylsiloxane groups and the platinum catalyst in the sustained-release microcapsules only participate in the second stage of heating curing at a temperature above 150°C (passively triggered after leaving the factory).

[0066] S3-1: Add hydrogen-containing silicone oil, platinum catalyst slow-release microcapsules, initiator, tackifier, and aromatic amine polymerization inhibitor to the silicone rubber base material in the following proportions; wherein the aromatic amine polymerization inhibitor is diphenylamine or N-nitrosodiphenylamine.

[0067] S3-2: Mix at room temperature in a mixer to obtain long-lasting sealing silicone rubber (referred to as sealant).

[0068] A photothermal dual-curing long-lasting sealing silicone rubber is prepared by the aforementioned method, wherein two types of molecular groups with significantly different polymerization rates participate in the curing reaction in two steps. The first step is mainly a UV curing reaction in which acrylate molecular groups participate; the second step is mainly a thermosetting hydrosilylation reaction in which vinylsiloxane molecular groups participate together with platinum catalyst passively released by platinum catalyst slow-release microcapsules when the temperature reaches above 150°C.

[0069] More specifically, due to the action of aromatic amine polymerization inhibitors, during the first step of UV curing, one type of molecular group with a high polymerization rate (acrylate) participates in the UV curing process, while another type of molecular group with a low polymerization rate (vinylsiloxane) and the platinum catalyst mostly do not participate in the reaction. The specific principle is that, due to the protection of the aromatic amine polymerization inhibitor, the activity of the vinylsiloxane group is very low under UV curing conditions. Compared with the acrylate group, the polymerization rate of the vinylsiloxane group is very low, less than 0.01. Within a limited UV curing time (e.g., within 10 seconds) and with acrylate... In the presence of ester groups, most vinylsiloxane groups do not participate in the UV curing reaction. After UV curing, the proportion of acrylate segments in the structural adhesive layer reaches its peak, giving the structural adhesive layer the best air-permeability and water-vapor resistance. Most of the other type of vinylsiloxane molecular groups undergo thermosetting together with the platinum catalyst passively released after the shell of the platinum catalyst sustained-release microcapsule melts when the temperature reaches above 150°C. During the thermosetting process, the mechanical strength, heat resistance and flame retardancy of the structural adhesive layer can be rapidly increased through addition reactions.

[0070] After the first step of UV curing, the resulting sealing adhesive layer can fully meet the bonding and sealing requirements of the battery. After the first step of UV curing, the proportion of acrylate segments reaches its peak. At this time, the sealing adhesive layer achieves the best air-permeability and water-vaporization resistance. If it is fully cured at the beginning (continued to complete thermal curing), the polysiloxane segments added after hydrosilylation curing will cause the air-permeability and water-vaporization resistance of the sealing adhesive layer to decrease.

[0071] When the battery reaches its thermal runaway limit temperature of 150°C, the cohesive strength and adhesive strength of the sealing structure adhesive layer can rapidly increase by 30% to 50%. At the same time, the released platinum catalyst also increases the flame retardant effect of the sealing adhesive layer, raising the flame retardant rating from V1 to V0. The temperature resistance of the sealing structure adhesive layer increases from 160°C to over 220°C. The long-lasting sealing silicone rubber provided in this embodiment can simultaneously support photothermal dual curing (UV and thermal curing). The second step of thermal curing is passive curing only when the battery system temperature reaches 150°C, in order to improve the overall safety of the battery system. Under normal operating conditions of the battery system (system temperature below 120°C), no reaction occurs, and it is in a quiescent state, which is a safety redundancy design.

[0072] The aromatic amine polymerization inhibitors selected in this embodiment of the invention are specifically diphenylamine or N-nitrosodiphenylamine. Their polymerization inhibition effect is relatively weak; under UV conditions, they only inhibit the polymerization of vinyl siloxanes, but have no inhibitory effect on acrylates. Due to the polymerization inhibition effect of the aromatic amine inhibitors, during the photocuring process, most of the vinyl siloxane groups can be protected and prevent free radical polymerization, while the free radical polymerization reaction of acrylate groups remains unaffected. Therefore, most of the vinyl siloxane groups can participate in the second-stage thermosetting reaction.

[0073] This embodiment introduces acrylic-modified silicone, enabling the sealant to support both UV and thermal curing. Furthermore, the sealant can be UV cured within 10 seconds, greatly shortening the processing time and improving the battery assembly efficiency.

[0074] An application of a photothermal dual-curing long-lasting sealing silicone rubber is disclosed. This silicone rubber is used as a structural sealant in the manufacture of hydrogen fuel cells or lithium batteries to seal the structural surfaces of these batteries. The process involves two curing steps to achieve different performance requirements for the structural sealant layer during the structural sealing and disaster recovery stages. The steps include the following:

[0075] A1: Photothermal dual-curing long-lasting sealing silicone rubber is coated onto the sealing structure surface of hydrogen fuel cells or lithium batteries. UV is used to cure the structural adhesive layer in the first step to form a structural adhesive layer and make its performance meet the requirements of the structural sealing stage.

[0076] A2: Bond another sealing structure surface to the structural adhesive layer to form a layered sealant structure for the battery;

[0077] A3: When the temperature of any sealed surface rises above 150°C, the shell of the platinum catalyst slow-release microcapsule melts due to heat, rapidly releasing the liquid platinum catalyst inside the microcapsule. This catalyst reacts with the vinylsiloxane molecular groups to form a thermosetting reaction, causing the sealing adhesive layer to be thermally cured. This rapidly increases the mechanical properties, heat resistance, and flame retardant properties of the sealing adhesive layer, enabling it to meet the performance requirements of the disaster recovery stage. In combination with other safety measures, this enhances the overall disaster recovery performance of the battery system, delays thermal runaway, and improves the safety of the battery system.

[0078] The following describes the process in detail with reference to several specific embodiments.

[0079] Example 1

[0080] The photothermal dual-curing long-lasting sealing silicone rubber (hereinafter referred to as sealant), its preparation method, and its application provided in this embodiment are specific selections based on the aforementioned basic embodiment. The difference between this embodiment and the basic embodiment lies in the specific preparation method of the photothermal dual-curing long-lasting sealing silicone rubber:

[0081] First, mix 60 parts acrylic acid-modified polysiloxane and 40 parts 50000mm 2 / s Vinyl polysiloxane is added to a kneader, followed by 20 parts of fumed silica in batches. The mixture is kneaded at room temperature for 1 hour, then vacuum kneaded at 150°C for 3 hours. After cooling to room temperature, a base compound is obtained. Then, 12 parts of 1.0% hydrogen-containing silicone oil, 0.4 parts of single-component platinum catalyst, 2 parts of 1-hydroxycyclohexylphenyl ketone (photoinitiator), 1.5 parts of γ-glycidyl etheroxypropyltrimethoxysilane (tackifier), and 0.15 parts of diphenylamine are added and mixed at room temperature in a mixer to obtain a photothermal dual-curing long-lasting sealing silicone rubber.

[0082] The step S1-1, which involves preparing the platinum catalyst sustained-release microcapsules, is as follows:

[0083] Karstedt platinum catalyst and PP resin K9927 were added to D80 solvent oil at a mass ratio of 1:1. The mixture was heated to 60-70°C and stirred to dissolve, obtaining a solution. This solution was then added dropwise to an aqueous polyacrylamide solution. After the addition was complete, the mixture was stirred at room temperature for 8 hours. The solvent was removed by vacuum distillation, yielding platinum catalyst sustained-release microcapsules (microcapsule-encapsulated catalyst). The mass ratio of the solution to the aqueous polyacrylamide solution was 2:1. The PP resin K9927 used in this embodiment has a melting point of approximately 160°C. This melting point ensures that the prepared platinum catalyst sustained-release microcapsules will not melt during subsequent processing, assembly, and normal operation, maintaining the integrity of the microcapsule structure and isolating the catalyst from other components.

[0084] In this embodiment, the thickness of the capsule wall is 2-3 μm by controlling the ratio of platinum catalyst and PP resin. The stirring speed and reaction time affect the particle size and surface morphology of the capsules. By controlling the stirring speed at 500-600 rpm and the reaction time at 6-8 h, spherical microcapsules with an average particle size of 4-6 μm can be obtained. If the particle size of the prepared microcapsules is too large, they are easily damaged by pressure during subsequent assembly and use, making it difficult to maintain the integrity of the microcapsule morphology and affecting its stability. Conversely, if the particle size of the microcapsules is too small, the capsule wall thickness is too thin, which also makes them prone to rupture, similarly affecting the integrity of the microcapsule shape. The wall material selected for the microcapsules is high-melting-point PP resin. PP resin has stable physical and chemical properties and maintains good chemical and physical inertness when mixed with polysiloxanes at room temperature. The activity of the microcapsules is rapidly released only when the temperature reaches above the melting point of the PP resin, which is 160°C. The final spherical microcapsules prepared in this embodiment have a particle size of 4~6μm and a thickness of 2~3μm. The particle size is moderate, the morphology is regular, and the stability at room temperature is good. They can quickly release their activity to participate in the reaction only when heated to above 160℃, while they can always maintain their morphology when heated below 160℃.

[0085] The aforementioned application of photothermal dual-curing long-lasting sealing silicone rubber involves using it as a structural sealant in the manufacture of hydrogen fuel cells (normal operating temperature between 60℃ and 120℃) or lithium batteries (normal operating temperature of ternary lithium battery systems is -20℃ to 60℃). It seals the structural surfaces of the hydrogen fuel cells or lithium batteries through two curing steps, achieving different performance requirements for the structural sealant layer in the structural sealing and disaster recovery stages, respectively. The steps include:

[0086] A1: Photothermal dual-curing long-lasting sealing silicone rubber is coated onto the sealing structure surface of hydrogen fuel cells or lithium batteries. UV light source is used to irradiate for 8 seconds to cure the structural adhesive layer in the first step, forming a structural adhesive layer and making its performance meet the requirements of the structural sealing stage (high sealing performance).

[0087] A2: Bond another sealing structure surface to the structural adhesive layer to form a layered sealant structure for the battery;

[0088] A3: When the temperature of any sealed surface of the battery system rises above 150°C, the shell of the platinum catalyst slow-release microcapsule melts due to heat, rapidly releasing the liquid platinum catalyst inside the microcapsule. This catalyst undergoes a thermosetting reaction with the vinylsiloxane molecular groups, causing the sealing adhesive layer to be thermosetting. This rapidly increases the mechanical properties, heat resistance, and flame retardant properties of the sealing adhesive layer, enabling it to meet the performance requirements (high safety) of the disaster recovery stage. In combination with other safety measures, this enhances the overall disaster recovery performance of the battery system, delays thermal runaway, and improves the overall safety of the battery system.

[0089] Example 2

[0090] The photothermal dual-curing long-lasting sealing silicone rubber, its preparation method, and its application provided in this embodiment are specific selections based on the aforementioned basic embodiment and embodiment 1. The difference between this embodiment and the basic embodiment and embodiment 1 lies in the specific preparation method of the photothermal dual-curing long-lasting sealing silicone rubber:

[0091] 50 parts of acrylic acid-modified polysiloxane and 50 parts of 50000mm 2 / s Vinyl polysiloxane is added to a kneader, and 25 parts of fumed silica are added in batches. The mixture is kneaded at room temperature for 1 hour, and then kneaded under vacuum at 150°C for 3 hours. After cooling to room temperature, a base compound is obtained. Then, 15 parts of 1.0% hydrogen-containing silicone oil, 0.5 parts of single-component platinum catalyst, 1.5 parts of 1-hydroxycyclohexylphenyl ketone, 1.5 parts of γ-glycidyl etheroxypropyltrimethoxysilane, and 0.2 parts of diphenylamine are added. The mixture is stirred at room temperature to obtain a photothermal dual-curing long-lasting sealing silicone rubber.

[0092] The PP resin used in this embodiment is a PP resin with a melting point greater than 160°C, specifically EP300M, whose melting point is approximately 160°C to 170°C.

[0093] The step S1-1, which involves preparing the platinum catalyst sustained-release microcapsules, is as follows:

[0094] Karstedt platinum catalyst and PP resin EP300M were added to D80 solvent oil in a 1:1 ratio, heated to 60-70℃, and stirred to dissolve to obtain a mixture. The mixture was then added dropwise to a polyacrylamide aqueous solution. After the addition was complete, the mixture was stirred at room temperature for 8 hours. The solvent was removed by vacuum distillation to obtain platinum catalyst sustained-release microcapsules (microcapsule-encapsulated catalyst). The mass ratio of the mixture to the polyacrylamide aqueous solution was 2:1.

[0095] The spherical microcapsules prepared by this invention have a particle size of 4~6μm and a shell thickness of 2~3μm. The particle size and shell thickness are moderate, the morphology is regular, and the stability at room temperature is good. When heated to above 160℃, they can quickly release the active catalyst and initiate the second step of thermosetting reaction.

[0096] Example 3

[0097] The photothermal dual-curing long-lasting sealing silicone rubber, its preparation method, and its application provided in this embodiment are specific selections based on the aforementioned basic embodiment and embodiment 1. The difference between this embodiment and the basic embodiment and embodiment 1 lies in the specific preparation method of the photothermal dual-curing long-lasting sealing silicone rubber:

[0098] 65 parts acrylic acid-modified polysiloxane and 35 parts 50000mm 2 / s Vinyl polysiloxane is added to a kneader, and 25 parts of fumed silica are added in batches. The mixture is kneaded at room temperature for 1 hour, and then kneaded under vacuum at 150°C for 3 hours. After cooling to room temperature, a base compound is obtained. Then, 11.5 parts of 1.0% hydrogen-containing silicone oil, 0.4 parts of single-component platinum catalyst, 2.5 parts of 1-hydroxycyclohexylphenyl ketone, 1 part of γ-glycidyl etheroxypropyltrimethoxysilane, and 0.25 parts of N-nitrosodiphenylamine are added. The mixture is stirred at room temperature to obtain a photothermal dual-curing long-lasting sealing silicone rubber.

[0099] The step S1-1, which involves preparing the platinum catalyst sustained-release microcapsules, is as follows:

[0100] Karstedt platinum catalyst and PP resin were added to D80 solvent oil at a mass ratio of 1.5:1. The mixture was heated to 60-70℃ and stirred to dissolve, and then added dropwise to a polyacrylamide aqueous solution. After the addition was complete, the mixture was stirred at room temperature for 8 hours. The solvent was removed by vacuum distillation to obtain platinum catalyst sustained-release microcapsules. The mass ratio of the mixture to the polyacrylamide aqueous solution was 2.3:1.

[0101] The PP resin used in this embodiment is LG SEETEC PP H1315, which has a melting point greater than 150°C. In other embodiments, homopolymer PP (PP-H) or copolymer PP (PP-R) can be selected, depending on the requirements of the battery thermal runaway safety trigger temperature.

[0102] Example 4

[0103] The photothermal dual-curing long-lasting sealing silicone rubber, its preparation method, and its application provided in this embodiment are specific selections based on the aforementioned basic embodiment and embodiment 1. The difference between this embodiment and the basic embodiment and embodiment 1 lies in the specific preparation method of the photothermal dual-curing long-lasting sealing silicone rubber:

[0104] 80 parts of acrylic acid-modified polysiloxane and 20 parts of 50000mm 2 / s Vinyl polysiloxane is added to a kneader, and 30 parts of fumed silica are added in batches. The mixture is kneaded at room temperature for 1 hour, and then kneaded under vacuum at 150°C for 3 hours. After cooling to room temperature, a base compound is obtained. Then, 8 parts of 1.0% hydrogen-containing silicone oil, 0.3 parts of single-component platinum catalyst, 3 parts of 1-hydroxycyclohexylphenyl ketone, 2 parts of γ-glycidyl etheroxypropyltrimethoxysilane, and 0.2 parts of N-nitrosodiphenylamine are added. The mixture is stirred at room temperature to obtain a photothermal dual-curing long-lasting sealing silicone rubber.

[0105] The PP resin used in this embodiment is RP340P resin, which has a melting point of around 160°C.

[0106] The step S1-1, which involves preparing the platinum catalyst sustained-release microcapsules, is as follows:

[0107] The Karstedt platinum catalyst and PP resin were added to D80 solvent oil at a ratio of 1.25:1. The mixture was heated to 60-70°C and stirred to dissolve, and then added dropwise to a polyacrylamide aqueous solution. After the addition was complete, the mixture was stirred at room temperature for 8 hours. The solvent was removed by vacuum distillation to obtain the platinum catalyst sustained-release microcapsules. The mass ratio of the mixture to the polyacrylamide aqueous solution was 2.2:1.

[0108] Comparative Example

[0109] The photothermal dual-curing long-lasting sealing silicone rubber and its preparation method provided in this embodiment are basically the same as those in Example 1. The difference is that an unencapsulated catalyst is directly used, which cannot support photothermal two-stage curing and can only be cured directly during factory assembly. It does not have disaster recovery characteristics and has a relatively short shelf life. The specific preparation method of this photothermal dual-curing long-lasting sealing silicone rubber is as follows:

[0110] 100 pieces of 50000mm 2 / s Vinyl polysiloxane is added to a kneader, and 25 parts of fumed silica are added in batches. The mixture is kneaded at room temperature for 1 hour, and then kneaded under vacuum at 150°C for 3 hours. After cooling to room temperature, a base compound is obtained. Then, 13.5 parts of 1.0% hydrogen-containing silicone oil, 0.4 parts of single-component liquid platinum catalyst (free state, not microencapsulated), 2 parts of 1-hydroxycyclohexylphenyl ketone, and 1.5 parts of γ-glycidyl etheroxypropyltrimethoxysilane are added. The mixture is stirred at room temperature to obtain a sealing silicone rubber.

[0111] The structural adhesive layers of the sealing silicone rubber prepared in the above embodiments after two-step curing were tested. The main physicochemical properties and index parameters obtained are shown in Table 1 (performance after UV curing in the first stage) and Table 2 (performance after heat curing in the second stage).

[0112] Table 1

[0113]

[0114] Table 2

[0115]

[0116] As shown in Tables 1 and 2, the above embodiments 1-4 of this invention, by preparing catalyst-releasing microcapsules with specific shapes, structures, sizes, and melting temperatures, isolate the catalyst from other components, allowing UV curing and thermal curing to proceed in stages. This results in two structural adhesive layers with different advantageous properties, meeting the requirements of battery system manufacturing, use, and safety. When the battery system reaches hazardous operating temperatures of 150°C and above, the capsule shell of the catalyst-releasing microcapsule passively melts, rapidly releasing the catalyst and triggering a second-stage thermal curing reaction. This rapidly increases the main disaster recovery performance of the structural adhesive layer, and, in conjunction with other measures, improves the overall safety of the battery system.

[0117] In the above embodiments, only the first stage of UV curing is required during factory assembly to maintain the high sealing performance of the structural adhesive layer, meeting the needs of battery manufacturing and normal operation. The second stage of passive thermal curing is used as a safety redundancy, with 150°C as the safety critical temperature. When this temperature is reached or exceeded, passive thermal curing is initiated. The thermal curing reaction rapidly enhances the disaster recovery performance of the structural adhesive layer, such as high temperature resistance, mechanical strength, and flame retardancy, while sacrificing some sealing performance (the air permeability of the thermally cured structural adhesive layer increases significantly) to delay catastrophic conditions such as thermal runaway and improve the overall safety of the battery system.

[0118] The above embodiments of the present invention, on the one hand, improve upon the shortcomings of ordinary silicone rubber in terms of high air permeability and inadequate sealing performance against highly permeable gases such as hydrogen, oxygen, and water vapor by introducing acrylic acid-modified polysiloxane. This significantly reduces the air permeability and moisture permeability of the structural adhesive layer after UV curing. Compared with the siloxane chain structure of silicone, the carboxylic acid structure of acrylic acid-modified polysiloxane has a shorter intermolecular distance and smaller free volume, which can provide higher gas leak-proof performance and lower moisture permeability. On the other hand, the specially formulated catalyst-release microcapsules passively initiate the thermosetting reaction, thereby improving the safety performance of the structural adhesive layer.

[0119] The photothermal dual-curing long-lasting sealing silicone rubber provided in the above embodiments of the present invention also provides a synergistic improvement for the situation where the construction process of hydrogen fuel cell sealant mainly adopts CIPG (cured in place gasket). The CIPG process involves applying the sealant to the sealing surface, allowing it to cure, and then assembling it to achieve single-sided bonding. Conventional silicone rubber curing time is over 20 minutes (compared to 20 seconds for the patented technology in the background using UV curing). Since the curing speed of the sealant determines the assembly efficiency of the battery module in the factory stage, this invention application, through two-stage curing, achieves simultaneous support for UV and thermal dual-curing modes for the sealant, and enables the sealant to complete curing within 10 seconds during the factory assembly stage, greatly shortening processing time, improving assembly efficiency, and reducing manufacturing costs.

[0120] The photothermal dual-curing long-lasting sealing silicone rubber samples prepared in the above embodiments of the present invention have been tested and applied to the assembly of ternary lithium-ion battery modules and hydrogen fuel cell modules, specifically for connecting and sealing the gap between the metal casings of two batteries. Actual testing shows that the prepared sealing structure adhesive layer can meet the high sealing and high disaster recovery performance requirements of new energy batteries.

[0121] The two-stage reaction method provided in the above embodiments of the present invention, in addition to introducing a small amount of polymerization inhibitor, can also implement this polymerization inhibition strategy under specific conditions. During the UV curing process, the polymerization activity of vinylsiloxanes can be reduced by reasonably adjusting the polymerization conditions. For example, adjusting the wavelength and intensity of the light source, using appropriate wavelengths and intensities of UV light, and adjusting the excitation efficiency of the photoinitiator can control the rate of free radical generation, thereby affecting the polymerization activity of vinylsiloxane molecular groups under UV conditions. Specific details will not be elaborated further.

[0122] It should be noted that the components, proportions, particle sizes and process parameters used in the above specific embodiments of the present invention are only examples. Other different implementation schemes obtained by making specific selections within the scope of the basic embodiments of the present invention can achieve the technical effects described in the present invention. Therefore, the present invention will not list them one by one.

[0123] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the present invention. All equivalent changes made based on the components, proportions, and processes of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for preparing a photothermal dual-curing long-lasting sealing silicone rubber, characterized in that, It includes the following steps: S1: Prepare raw materials according to the following mass ratio. Acrylic modified polysiloxane 50~80 Vinyl polysiloxane 20~50 Hydrogen-containing silicone oil 8~15 Fumed silica 20~30 Catalyst sustained-release microcapsules 0.3~0.5 Initiator 1.5~3 Tackifier 1~2 Aromatic amine polymerization inhibitor 0.15~0.25 Among them, the catalyst sustained-release microcapsules are spherical particles with an average particle size of 4~6μm, whose capsule shells formed by PP resin completely encapsulate the platinum catalyst, and whose capsule shell melting temperature is not less than 150℃. S2: Preparation of silicone rubber base material Acrylic-modified polysiloxane and vinyl polysiloxane were added to a kneader in sequence, fumed silica was added in batches, kneaded at room temperature, then vacuumed at 150°C, kneaded again, and cooled to room temperature to obtain silicone rubber base material. S3: Preparation of long-lasting sealing silicone rubber Hydrogen-containing silicone oil, catalyst slow-release microcapsules, initiator, tackifier, and aromatic amine polymerization inhibitor are added sequentially to the silicone rubber base material. After stirring and mixing evenly, a long-lasting sealing silicone rubber is obtained. Under the action of the aromatic amine polymerization inhibitor, acrylate and vinylsiloxane, two types of molecular groups with different polymerization rates, participate in the first step of UV curing and the second step of heat curing, respectively. After step-by-step curing, structural adhesive layers with different properties are obtained.

2. The method for preparing the photothermal dual-curing long-lasting sealing silicone rubber according to claim 1, characterized in that, Its S1 also includes the following steps: S1-1: Preparation of catalyst sustained-release microcapsules S1-1-1: Add platinum catalyst and PP resin to D80 solvent oil at a mass ratio of (1.5~2):1, heat to 60~70℃, stir to dissolve, control the stirring speed at 300~500rpm, and the time is 2~3h. By controlling the ratio of platinum catalyst and PP resin and the stirring speed, the thickness of the capsule shell obtained is 2~3μm. S1-1-2: Then the mixture is added dropwise to the polyacryl alcohol aqueous solution. After the addition is complete, the mixture is stirred at room temperature. The stirring speed is controlled at 500-600 rpm for 6-8 hours to obtain spheres with an average particle size of 4-6 μm and a smooth outer surface. S1-1-3: Remove the solvent by vacuum distillation to obtain spherical single-component platinum catalyst sustained-release microcapsules with a capsule wall thickness of 2~3μm and an average particle size of 4~6μm.

3. The method for preparing the photothermal dual-curing long-lasting sealing silicone rubber according to claim 2, characterized in that, Specifically, S1-1 includes the following steps: The PP resin mentioned is a PP resin with a melting point greater than 150°C, including homopolymer PP or copolymer PP; The platinum catalyst mentioned is a Karstedt platinum catalyst.

4. The method for preparing the photothermal dual-curing long-lasting sealing silicone rubber according to claim 1, characterized in that, Its S1 also includes the following steps: S1-2: Preparation of acrylic acid-modified polysiloxane S1-2-1: Take 1000 parts by weight of octamethylcyclotetrasiloxane, 2-5 parts by weight of tetramethyldivinyldisiloxane, and 200-350 parts by weight of hydroxy acrylate, and add them to the reaction vessel. S1-2-2: While stirring, heat to 90~110℃, then add 1~3 parts by weight of tetramethylammonium hydroxide, continue stirring, and polymerize for 5 hours; S1-2-3: The catalyst and small molecules are removed at 150~170℃ and 0.1MPa negative pressure to obtain acrylic acid modified polysiloxane.

5. The method for preparing the photothermal dual-curing long-lasting sealing silicone rubber according to claim 1, characterized in that, Step S2 involves preparing the silicone rubber base material, including the following specific steps: S2-1: First, add acrylic-modified polysiloxane and vinyl polysiloxane to the kneader in sequence; S2-2: Add fumed silica in batches and knead at room temperature for 1 hour; S2-3: Vacuum at 150℃, knead for 3 hours, and then cool to room temperature to obtain silicone rubber base material.

6. The method for preparing the photothermal dual-curing long-lasting sealing silicone rubber according to claim 1, characterized in that, Step S3, preparing the long-lasting sealing silicone rubber, includes the following specific steps: S3-1: Add hydrogen-containing silicone oil, platinum catalyst slow-release microcapsules, initiator, tackifier, and aromatic amine polymerization inhibitor to the silicone rubber base material in the following proportions. S3-2: Mix evenly at room temperature in a mixer to obtain long-lasting sealing silicone rubber; The aromatic amine polymerization inhibitor is diphenylamine or N-nitrosodiphenylamine.

7. A photothermal dual-curing long-lasting sealing silicone rubber, characterized in that, It is prepared by the method described in any one of claims 1-6.

8. The photothermal dual-curing long-lasting sealing silicone rubber according to claim 7, characterized in that, Under the action of aromatic amine polymerization inhibitors, two types of molecular groups with significantly different polymerization rates participate in the curing reaction in two steps. The first step is the UV curing reaction in which acrylate molecular groups participate; the second step is the thermosetting hydrosilylation reaction in which vinylsiloxane molecular groups participate together with platinum catalyst passively released by platinum catalyst slow-release microcapsules when the temperature reaches above 150°C.

9. An application of a photothermal dual-curing long-lasting sealing silicone rubber, characterized in that, The photothermal dual-curing long-lasting sealing silicone rubber described in claim 7 or 8 is used as a structural sealant in the manufacture of hydrogen fuel cells or lithium batteries to seal the structural surfaces of hydrogen fuel cells or lithium batteries. After two-step curing, the structural adhesive layer successively meets the different performance requirements of the structural sealing stage and the disaster recovery stage.

10. The application of the photothermal dual-curing long-lasting sealing silicone rubber according to claim 9, characterized in that, It includes the following steps: A1: Photothermal dual-curing long-lasting sealing silicone rubber is coated on the sealing structure surface of hydrogen fuel cells or lithium batteries. UV is used to cure the structural adhesive layer in the first step. Under the action of aromatic amine polymerization inhibitor, the double bonds of the acrylate groups in it undergo free radical polymerization reaction to form a structural adhesive layer, and make its performance meet the requirements of the structural sealing stage. A2: Bond another sealing structure surface to the structural adhesive layer to form a layered sealant structure for the battery; A3: When the temperature of any sealed structural surface rises to above 150°C, the shell of the platinum catalyst slow-release microcapsule melts due to heat, rapidly releasing the platinum catalyst inside the microcapsule. This catalyst reacts with the vinylsiloxane molecular groups to undergo a thermosetting reaction, causing the sealing structure adhesive layer to be thermosetting. This rapidly increases the mechanical properties, heat resistance, and flame retardant properties of the sealing structure adhesive layer, enabling it to meet the performance requirements of the disaster recovery stage.

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