Self-adhesive silicone rubber for bonding polycarbonate resin and preparation process of self-adhesive silicone rubber

Abstract

The preparation process comprises the following steps: performing vacuum dehydration on alpha, omega-divinyl polydimethylsiloxane and phenyl siloxane under the protection of inert gas to prepare a basic rubber material; then adding the modified nano silicon dioxide filler in batches in a gradient manner, and dispersing at a stepped rotating speed to form a uniformly mixed sizing material; then polycarbonate powder treated by a silane coupling agent is introduced for high-speed dispersion to form a component A precursor, and after the component A precursor is mixed with a component B containing a hydrogen silicone oil cross-linking agent / platinum catalyst, the self-adhesive silicone rubber with high interface bonding force is prepared by adopting a stepped temperature procedure; according to the method, the bonding strength of polycarbonate powder is improved through gradient filler dispersion in batches, the tensile strength of the material is improved through silane treatment, the curing reaction rate is matched with the interface wetting speed through a stepped curing procedure, the strength is kept while rapid curing is conducted, and the effects of high bonding strength and rapid curing are effectively achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of silicone rubber, in particular to self-adhesive silicone rubber for bonding polycarbonate resin and a preparation process thereof. Background Art

[0002] Due to its excellent light transmittance, impact resistance, and heat resistance, polycarbonate resin is widely used in new energy vehicle battery module packaging, LED lighting device sealing, and consumer electronics structural bonding. With the development of miniaturization and high-power electronic devices, higher requirements are placed on the bonding performance of polycarbonate substrates and silicone rubber: the bonding strength must be maintained over a wide temperature range of -40 to 125°C to meet waterproof standards, and the silicone rubber must be cured within 20 minutes to adapt to the cycle of automated production lines. However, the low surface energy and weak polarity of polycarbonate result in generally low interfacial adhesion with conventional addition-type silicone rubber, which has become a technical bottleneck restricting high-reliability sealing and bonding.

[0003] Existing methods for improving the adhesion of addition-type silicone rubber to polycarbonate primarily include adding tackifiers (such as epoxy- or acryloxy-containing silanes) or plasma-treating the substrate. While using methacryloxypropyltrimethoxysilane as a tackifying component improves bond strength, its unsaturated double bonds can poison the platinum catalyst, extending the cure time to over 40 minutes, making it inadequate for rapid production. Oxygen plasma treatment of the polycarbonate surface improves adhesion, but the surface activity of the treated substrate only lasts for two hours, adding to the pretreatment process and cost. These methods all suffer from the core drawback of being unable to balance improved bond strength with curing efficiency and process complexity. This makes it difficult to achieve both high bond strength and rapid curing, limiting their large-scale application in precision electronic packaging.

[0004] In view of this, it is necessary to improve the existing addition-type silicone rubber to solve the technical problem of insufficient interfacial bonding strength caused by low surface energy and polarity difference of polycarbonate. Summary of the Invention

[0005] The purpose of the present invention is to provide a self-adhesive silicone rubber for bonding polycarbonate resin and a preparation process thereof, so as to solve the above technical problems.

[0006] To achieve this object, the present invention adopts the following technical solutions: A process for preparing self-adhesive silicone rubber for bonding polycarbonate resin comprises the following steps: S1, mixing α,ω-divinyl polydimethylsiloxane and phenyl siloxane, and performing vacuum dehydration treatment under inert gas protection to obtain a base rubber material with a target moisture content; S2, adding the surface-modified nano-silica filler to the base rubber material in three batches in a gradient manner, and dispersing and mixing the mixture in a stirring device at a stepwise increasing speed to obtain a uniform mixed rubber material; S3, adding polycarbonate powder treated with a silane coupling agent to the mixed rubber material, and fully combining the polycarbonate powder and the rubber material through a high-speed dispersion process to form a component A precursor; S4, adding an inhibitor to the precursor of component A and performing a degassing treatment, and simultaneously preparing component B by a hydrogenated silicone oil crosslinker and a platinum catalyst in a preset ratio; S5, after mixing the component A and the component B according to a preset mass ratio, perform a step-by-step temperature curing treatment in sequence, first complete pre-curing at 60°C to form a bonding interface, and then heat to 90°C to achieve complete curing to obtain a self-adhesive silicone rubber.

[0007] Optionally, step S1 specifically includes the following steps: S11, preheating the phenylsiloxane in a vacuum drying oven at 80-90° C. for 30 minutes to remove low molecular weight volatiles to obtain pretreated phenylsiloxane; S12, adding α,ω-divinylpolydimethylsiloxane and the pretreated phenylsiloxane into a reaction kettle at a mass ratio of 10:1, and premixing at a speed of 200-300 rpm for 15 minutes under nitrogen protection to form a primary mixed solution; S13, performing a gradient temperature vacuum dehydration treatment on the primary mixed liquid: first dehydrating at 80°C and -0.08 MPa for 40 minutes, then increasing the temperature to 120°C and -0.095 MPa for dehydration for 80 minutes, and stopping the dehydration treatment when the preset water content is reached by real-time monitoring; S14, introducing dry nitrogen into the dehydrated mixed solution to restore the pressure to normal, and continuously stirring at 100 rpm for 10 minutes at a constant temperature of 50° C. to obtain a homogeneous base rubber material with a target moisture content.

[0008] Optionally, the specific process of surface modification of the nano-silica filler is: S201, pre-treating the fumed nano-silica powder in a vacuum drying oven at 120° C. for 2 hours to remove surface adsorbed water, thereby obtaining pre-treated silica with a water content of ≤0.5 wt %; S202, dissolving hexadecyltrimethoxysilane in anhydrous ethanol to prepare a modified solution with a mass concentration of 8%, adding the pretreated silica and ultrasonically dispersing for 20 minutes to form a suspension, wherein the mass ratio of silica to the modified solution is 1:5; S203, transferring the suspension to a reactor, stirring and reacting at a constant temperature of 60° C. for 4 hours, and then centrifuging at 8000 rpm to obtain a modified silica wet material; S204 , vacuum drying the modified silicon dioxide wet material at 80° C. for 2 hours and activating the wet material at 150° C. for 1 hour to obtain a surface-modified nano-silica filler having hydrophobicity.

[0009] Optionally, step S2 specifically includes the following steps: S21, preheating the base rubber material to 50-60° C. and stirring at a low speed of 200-400 rpm in a planetary mixer to form a fluid colloid; S22, adding 40% of the surface-modified nano-silica filler in three intervals, mixing at a low speed of 500-800 rpm for 10 minutes after each addition to form a preliminary dispersion system; S23, adding the remaining 60% of the nano-silica filler in two batches, and simultaneously increasing the speed to 1500-2000 rpm for medium-speed shear dispersion when adding each batch, and the processing time for each batch is 15 minutes.

[0010] Optionally, after step S23, the following steps may be further performed: S24, under the preset vacuum condition, high-speed dispersion at 2500-3000 rpm for 20 minutes, during which the viscosity of the rubber compound is monitored in real time; S25, filtering the dispersed rubber material through a filter screen, and allowing it to stand at a constant temperature of 40° C. for 30 minutes to obtain a uniform mixed rubber material without bubbles.

[0011] Optionally, step S3 specifically includes the following steps: S31, heating the mixed rubber material to 70-80° C. and stirring at a low speed of 500-800 rpm in a planetary mixer to form a dynamic leveling colloid; S32, adding polycarbonate powder treated with a silane coupling agent in two batches: first adding 60% of the total amount and dispersing at a medium speed of 1500-1800 rpm for 15 minutes, and then adding the remaining 40% of the polycarbonate powder and simultaneously injecting dry nitrogen to form a gas-solid mixed flow; S33, under vacuum degree -0.06MPa, high-speed dispersion at 2500-3000rpm for 25 minutes, during which the temperature of the rubber compound is controlled in real time by infrared temperature measurement to form an interfacial composite colloid; S34, cooling the dispersed colloid to 40°C at a gradient rate of 10°C / min, filtering through a filter, and then allowing to stand and mature for 1 hour to obtain a component A precursor without phase separation.

[0012] Optionally, step S4 specifically includes the following steps: S41, transferring the component A precursor to a double planetary stirred tank, heating it to 50-60° C. and stirring it at a low speed of 200-400 rpm to form a flowing colloid; S42, adding the inhibitor to the mobile colloid in three gradient steps: first adding 40% of the total amount and mixing at a medium speed of 800 rpm for 10 minutes, then adding the remaining 60% in two steps with an interval of 5 minutes, and simultaneously starting the vacuum pump to reduce the pressure in the autoclave to -0.06 MPa; S43, under a high vacuum degree of -0.08 MPa, high-speed dispersion at 1200-1500 rpm for 25 minutes, real-time monitoring of the bubble volume fraction of the rubber compound, and obtaining a completely degassed component A.

[0013] Optionally, after step S43, the following steps may be further performed: S44, after preheating the hydrogenated silicone oil crosslinker to 40° C., the mixture is placed in an ultrasonic reactor with a molar ratio of Si-H / Vi = 1.5:1 and subjected to ultrasonic treatment with a platinum catalyst. The mixture is premixed at a frequency of 20 kHz for 5 minutes, and then switched to a high-frequency dispersion of 40 kHz for 15 minutes to obtain a component B precursor. S45, transferring the component B precursor to a constant temperature storage tank, continuously stirring at 30 rpm under nitrogen protection to maintain homogeneity to obtain component B, and controlling the storage temperature and oxygen content.

[0014] Optionally, step S5 specifically includes the following steps: S51, adding the component A and the component B in a mass ratio of 10:1 into a twin-screw dynamic mixer, and performing preliminary mixing at a speed of 500-800 rpm under a nitrogen atmosphere to form a homogeneous mixed colloid; S52, injecting the homogeneously mixed colloid into a preheated polycarbonate mold, pre-curing it in a 60°C constant temperature box at a pressure of 0.5 MPa for 15 minutes, then increasing the temperature to 75°C at a gradient of 2°C / min and applying a pressure of 1.2 MPa for 20 minutes; S53, after releasing the pressure, immediately transferring the semi-cured colloid to a vacuum hot press, and performing a main curing treatment at 90° C. under a preset vacuum degree for 30 minutes, during which the curing degree is monitored in real time; S54, the cured product is cooled to room temperature at a rate of 10°C / min, and after demolding, is placed in a dry nitrogen cabinet for aging for 24 hours to obtain a self-adhesive silicone rubber with qualified hardness and tensile strength.

[0015] The present invention also provides a self-adhesive silicone rubber for bonding polycarbonate resins, which is prepared using the self-adhesive silicone rubber for bonding polycarbonate resins as described above. The self-adhesive silicone rubber for bonding polycarbonate resins specifically comprises: A base polymer composed of α,ω-divinyl polydimethylsiloxane and phenylsiloxane; 15-25 parts of surface-modified nano-silica filler; 5-15 parts of polycarbonate powder treated with a silane coupling agent; 3-8 parts of a hydrogenated silicone oil crosslinking agent and 0.01-0.1 parts of a platinum catalyst, wherein the molar ratio of Si-H groups to vinyl groups of the hydrogenated silicone oil crosslinking agent is (1.2-1.8):1; Inhibitor 0.05-0.3 parts.

[0016] Compared with the prior art, the present invention has the following beneficial effects: a base rubber compound is prepared by vacuum dehydrating α,ω-divinyl polydimethylsiloxane and phenyl siloxane under inert gas protection, and then modified nano-silica filler is added in batches and gradiently and dispersed by step speed to form a uniform mixed rubber compound; then polycarbonate powder treated with a silane coupling agent is introduced and dispersed at high speed to form a component A precursor, which is mixed with component B of a hydrogen-containing silicone oil crosslinker / platinum catalyst and then a step temperature program of pre-curing at 60°C and final curing at 90°C is adopted to prepare a self-adhesive silicone rubber with high interfacial bonding strength; the method achieves agglomeration-free and uniform distribution of nano-silica in the colloid by dispersing the filler in batches and improves the tensile strength of the material; the bonding strength of the polycarbonate powder is improved by silane treatment; the step curing program matches the curing reaction rate with the interfacial wetting speed, maintains strength while rapidly curing, and effectively achieves the effects of high bonding strength and rapid curing. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] The structures, proportions, sizes, etc. depicted in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not intended to limit the conditions under which the present invention can be implemented and therefore have no substantive technical significance. Any structural modifications, changes in proportional relationships, or adjustments in size should still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and objectives that can be achieved by the present invention.

[0019] Figure 1 This is a schematic diagram of a process for preparing the self-adhesive silicone rubber for bonding polycarbonate resin according to the first embodiment of the present invention; Figure 2 This is the second flow chart of the preparation process of the self-adhesive silicone rubber for polycarbonate resin bonding according to the first embodiment. DETAILED DESCRIPTION

[0020] In order to make the purpose, features, and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] In the description of the present invention, it should be understood that the terms "upper," "lower," "top," "bottom," "inner," "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They are not intended to indicate or imply that the devices or elements referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. It should be noted that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally located component.

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific implementation methods.

[0023] Example 1: Combine Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a preparation process of self-adhesive silicone rubber for bonding polycarbonate resin, comprising the following steps: S1, mixing α,ω-divinyl polydimethylsiloxane and phenyl siloxane, and performing vacuum dehydration treatment under inert gas protection to obtain a base rubber material with a target water content of less than 50 ppm; Vacuum dehydration under inert gas protection effectively removes moisture and low-molecular-weight volatiles (such as residual solvents and unreacted monomers) from the base polymer, ensuring the chemical stability of the base rubber. The introduction of phenylsiloxane modulates the polarity distribution of the polymer segments, creating a polarity match with the subsequently added polycarbonate powder. This lays the molecular foundation for interfacial bonding, prevents moisture from inhibiting the activity of the subsequent platinum catalyst, and ensures the proper functioning of the addition-curing reaction.

[0024] S2, adding the surface-modified nano-silica filler to the base rubber compound in three batches in a gradient manner, and dispersing and mixing the mixture in a stirring device at a stepwise increasing speed to obtain a uniform mixed rubber compound; A dispersion process employing gradient nanofiller addition and stepped speed control achieves uniform dispersion of nanosilica within the colloid. The surface-modified hydrophobic silica reduces interfacial tension between the filler and the silicone matrix, preventing filler aggregation due to van der Waals forces. This dispersion strategy avoids localized shear overheating that triggers pre-crosslinking while ensuring the integrity of the filler network, significantly enhancing the mechanical strength and thermal stability of the silicone rubber.

[0025] S3, adding polycarbonate powder treated with a silane coupling agent to the mixed rubber material, and fully combining the polycarbonate powder and the rubber material through a high-speed dispersion process to form a component A precursor; The polycarbonate powder treated with a silane coupling agent forms a chemical bonding layer (e.g., Si-OC bonds) on its surface, creating a strong interfacial bond with the silicone rubber matrix during high-speed dispersion. The addition of polycarbonate powder not only acts as a viscosity-enhancing component but also, through thermal expansion coefficient matching, mitigates interfacial stress between the silicone rubber and polycarbonate substrate during temperature fluctuations, thereby improving the thermal cycling resistance of the bonded joint.

[0026] S4, adding an inhibitor to the precursor of component A and performing a degassing treatment, and simultaneously preparing component B by a hydrogenated silicone oil crosslinker and a platinum catalyst in a preset ratio; The precise addition of inhibitors (such as ethynylcyclohexanol) suppresses the activity decay of the platinum catalyst during storage, while vacuum degassing eliminates the interference of microbubbles within the colloid with interfacial contact. The premixing process of the hydrogenated silicone crosslinker and platinum catalyst ensures quantitative reaction of Si-H groups with vinyl groups during the curing stage, avoiding insufficient crosslinking density or localized overcure, and providing controllable cure kinetics.

[0027] S5, after mixing component A and component B according to a preset mass ratio, perform step-by-step temperature curing treatment in sequence, first complete pre-curing at 60°C to form a bonding interface, and then heat to 90°C to achieve complete curing to obtain self-adhesive silicone rubber.

[0028] Step-by-step curing controls the reaction rate in stages: a pre-cure at 60°C allows the silicone rubber to fully wet the polycarbonate surface and form a preliminary cross-linked network, preventing overflow caused by rapid colloid fluidity at high temperatures. A post-cure at 90°C accelerates the completion of deep cross-linking reactions, ensuring a dense three-dimensional network structure. This temperature program balances curing efficiency with interfacial bonding quality, resulting in a final product with both high bond strength and dimensional stability.

[0029] The working principle of the present invention is as follows: α,ω-divinyl polydimethylsiloxane and phenylsiloxane are vacuum dehydrated under inert gas protection to prepare a base rubber material, and then modified nano-silica filler is added in batches and gradiently and dispersed at a stepped speed to form a uniform mixed rubber material; then polycarbonate powder treated with a silane coupling agent is introduced and dispersed at high speed to form a component A precursor, which is mixed with component B containing a hydrogen silicone oil crosslinker / platinum catalyst, and then a stepped temperature program of pre-curing at 60°C and final curing at 90°C is adopted to prepare a self-adhesive silicone rubber with high interfacial bonding strength. The method achieves agglomeration-free and uniform distribution of nano-silica in the colloid by dispersing the filler in batches, thereby improving the tensile strength of the material, and improving the bonding strength of the polycarbonate powder through silane treatment. The stepped curing program matches the curing reaction rate with the interfacial wetting speed, maintaining strength while rapidly curing, and effectively achieving the effects of high bonding strength and rapid curing.

[0030] In this embodiment, it is specifically explained that step S1 specifically includes the following steps: S11, preheating the phenylsiloxane in a vacuum drying oven at 80-90° C. for 30 minutes to remove low molecular weight volatiles to obtain pretreated phenylsiloxane; Preheating the phenyl siloxane (80-90°C, 30 minutes) selectively removes low-molecular-weight volatiles (such as unreacted siloxane monomer or residual solvent) through gentle heating, avoiding thermal decomposition of the phenyl groups caused by direct high-temperature treatment. A vacuum environment accelerates the release of volatiles while preventing oxidative side reactions. This step ensures the chemical purity of the phenyl siloxane and provides a stable raw material foundation for subsequent polarity matching.

[0031] The temperature range of 80-90°C is lower than the thermal decomposition threshold of phenylsiloxane (usually >150°C), which can effectively remove low-boiling point impurities (such as water boiling point 100°C) while avoiding material denaturation; the 30-minute duration balances the volatile matter removal efficiency and energy consumption control.

[0032] S12, adding α,ω-divinylpolydimethylsiloxane and pretreated phenylsiloxane in a mass ratio of 10:1 into a reactor, and premixing at a speed of 200-300 rpm under nitrogen protection for 15 minutes to form a primary mixed solution; α,ω-divinyl polydimethylsiloxane and pretreated phenyl siloxane were mixed in a 10:1 mass ratio. The ratio of backbone flexibility (dimethylsiloxane) to side chain rigidity (phenylsiloxane) was adjusted to optimize the compound's rheological properties and interfacial compatibility. A nitrogen atmosphere (200-300 rpm, 15 minutes) suppressed oxygen interference during mixing, preventing oxidative crosslinking of the vinyl groups and ensuring the linear structural integrity of the base polymer.

[0033] S13, performing a gradient temperature vacuum dehydration treatment on the primary mixed liquid: first dehydrating at 80°C and -0.08 MPa for 40 minutes, then increasing the temperature to 120°C and -0.095 MPa for dehydration for 80 minutes, and stopping the dehydration treatment when the preset water content is reached by real-time monitoring; Gradient temperature vacuum dehydration (80°C → 120°C, -0.08MPa → -0.095MPa) regulates the system's energy state in stages: initial low-temperature dehydration removes free water, followed by high-temperature, high-vacuum dehydration to remove bound water and trace small molecules. This step-by-step process prevents premature crosslinking caused by sudden boiling or localized overheating of the rubber compound, while real-time monitoring ensures moisture content control.

[0034] The initial dehydration at 80°C matches the glass transition temperature of siloxane to avoid excessive colloid viscosity that hinders water diffusion; the high-temperature stage at 120°C utilizes the enhanced mobility of siloxane segments (increased free volume) to improve the efficiency of bound water removal.

[0035] S14, introducing dry nitrogen into the dehydrated mixed solution to restore the pressure to normal, and continuously stirring at 100 rpm for 10 minutes at a constant temperature of 50° C. to obtain a homogeneous base rubber material with a target moisture content.

[0036] Returning the colloid to normal pressure by introducing dry nitrogen eliminates the negative pressure inside the colloid caused by the vacuum environment, preventing the introduction of bubbles by air reverse osmosis during subsequent processing. Constant stirring at 50°C (100 rpm for 10 minutes) utilizes thermal motion to balance molecular chain orientation, eliminating local density differences caused by gradient dehydration and forming a homogenous colloid system.

[0037] In this embodiment, the specific process of surface modification of nano-silica filler is as follows: S201, pre-treating the fumed nano-silica powder in a vacuum drying oven at 120° C. for 2 hours to remove surface adsorbed water, thereby obtaining pre-treated silica with a water content of ≤0.5 wt %; Vapor-phase nanosilica is vacuum-dried at 120°C for two hours to effectively remove physically adsorbed surface water (such as hydrogen-bonded water) through thermodynamic desorption, while also avoiding excessive condensation of silanol groups at high temperatures (>150°C). A water content of ≤0.5wt% after pretreatment maximizes the efficiency of the subsequent silane coupling agent hydrolysis reaction. This temperature-time parameter combination balances dehydration rate with energy efficiency. The vacuum environment (-0.1MPa) suppresses oxidative side reactions and maintains the integrity of the active sites (Si-OH) on the silica surface.

[0038] S202, dissolving hexadecyltrimethoxysilane in anhydrous ethanol to prepare a modified solution with a mass concentration of 8%, adding pretreated silica and ultrasonically dispersing for 20 minutes to form a suspension, wherein the mass ratio of silica to modified solution is 1:5; An 8% hexadecyltrimethoxysilane solution in ethanol (mass ratio 1:5) was used to disperse silica particles using ultrasonic cavitation (20 minutes, 40kHz), avoiding secondary aggregation caused by van der Waals forces. This concentration ensured a monolayer coverage of the silane molecules on the silica surface (rather than multilayer physical adsorption). The anhydrous ethanol solvent ensured rapid hydrolysis of the silane (forming Si-OH). Furthermore, the 1:5 solid-to-liquid ratio resulted in a molar ratio of modifier to silica surface hydroxyl groups of 3:1, fully meeting the stoichiometric requirements of the grafting reaction.

[0039] S203, transferring the suspension to a reactor, stirring and reacting at a constant temperature of 60° C. for 4 hours, and then centrifuging at 8000 rpm to obtain a modified silica wet material; Stirring at 60°C for 4 hours promotes a condensation reaction between the silane hydrolysis products (Si-OCH3 → Si-OH) and the silica surface hydroxyl groups (Si-OH + HO-Si → Si-O-Si), forming a stable covalently bonded graft layer. This temperature is below the silane self-condensation threshold (approximately 80°C), preventing the formation of a dense siloxane film that would hinder surface modification. Centrifugation (8000 rpm, 10 minutes) efficiently separates unreacted silane and byproducts (such as methanol) through centrifugal force differences (sedimentation velocity calculated using Stokes' law), ensuring the grafting efficiency of the modifier.

[0040] S204 , vacuum drying the modified silicon dioxide wet material at 80° C. for 2 hours and activating it at 150° C. for 1 hour to obtain a surface-modified nano-silica filler having hydrophobicity.

[0041] Vacuum drying at 80°C for 2 hours preferentially removes residual ethanol and physically adsorbed water. Activation treatment at 150°C for 1 hour promotes further reaction of incompletely condensed silane (Si-OCH3), forming a dense hydrophobic layer (contact angle ≥ 120°). A gradient drying strategy avoids cracking of the modified layer caused by sudden high temperature changes (due to differences in thermal expansion coefficients). The 150°C treatment temperature precisely matches the thermal stability limit of silane (decomposition temperature approximately 180°C), strengthening the bond while preventing thermal degradation. The result is a nanofiller with stable hydrophobicity and excellent dispersibility.

[0042] In this embodiment, it is specifically explained that step S2 specifically includes the following steps: S21, preheating the base rubber material to 50-60° C. and stirring it in a planetary mixer at a low speed of 200-400 rpm to form a fluid colloid; Preheat the base compound to 50-60°C and stir at a low speed (200-400 rpm) to improve colloid fluidity through temperature-induced viscosity reduction (Arrhenius equation), creating a low-shear stress environment for subsequent filler dispersion. This temperature range is below the glass transition temperature of siloxane (Tg approximately -120°C), preventing increased molecular chain rigidity that would hinder filler wetting. A speed of 200-400 rpm ensures uniform colloid flow within the laminar flow zone, preventing the introduction of bubbles from high-speed stirring.

[0043] In S22, 40% of the surface-modified nanosilica filler was added in three separate additions, followed by 10-minute mixing at 500-800 rpm to form a preliminary dispersion. A further 40% of the filler was added in three separate additions (10 minutes apart, mixing at 500-800 rpm). A "small, frequent addition" strategy was employed to reduce the local concentration gradient of the filler, utilizing diffusion and shear forces to synergistically disperse primary aggregates. The shear stress (0.2-0.5 kPa) generated by the 500-800 rpm speed matched the filler's initial dispersion energy barrier (approximately 0.3 kPa). The 10-minute mixing time covered the Stokes' settling time (approximately 8 minutes), preventing both filler settling and overheating-induced pre-crosslinking.

[0044] S23, adding the remaining 60% of the nano-silica filler in two batches, and simultaneously increasing the speed to 1500-2000 rpm for medium-speed shear dispersion when adding each batch, and the processing time for each batch is 15 minutes.

[0045] The remaining 60% filler was dispersed in two batches at a moderate shear speed of 1500-2000 rpm, breaking up secondary agglomerates by increasing the shear rate. During this stage, the colloidal viscosity increased to approximately 6000 mPa·s due to the addition of filler. The shear stress generated by the moderate shear speed was sufficient to overcome the filler network strength.

[0046] S24: High-speed dispersion at 2500-3000 rpm for 20 minutes under a preset vacuum, with real-time viscosity monitoring. High-speed dispersion at 2500-3000 rpm under a vacuum of -0.08 MPa breaks up residual nanoaggregates (particle size <500 nm) through high shear forces and simultaneously removes trapped air bubbles. Real-time viscosity monitoring serves as the endpoint criterion for dispersion, covering the thixotropic recovery period (approximately 18 minutes) to ensure shear-thinning equilibrium is achieved.

[0047] S25: The dispersed rubber material is filtered through a filter and allowed to stand at a constant temperature of 40°C for 30 minutes to obtain a bubble-free, uniformly mixed rubber material. An 80-mesh filter is used to intercept undispersed micron-sized aggregates. The material is then allowed to stand at 40°C for 30 minutes to eliminate residual stress at the filler-matrix interface through thermal motion. The standing temperature is above the glass transition temperature of the colloid (approximately -50°C) but below the reaction onset temperature (>60°C). This maintains colloid stability while promoting filler alignment, ultimately resulting in a uniformly dispersed mixed rubber material.

[0048] In this embodiment, it is specifically explained that step S3 specifically includes the following steps: In step S31, the mixed rubber material is heated to 70-80°C and stirred at a low speed of 500-800 rpm in a planetary mixer to form a dynamic leveling colloid. The mixed rubber material is heated to 70-80°C (below the polycarbonate glass transition temperature (Tg) of approximately 145°C) to thermally activate the mobility of the siloxane segments, forming a dynamic leveling colloid (viscosity reduced to approximately 5000 mPa·s). Low-speed stirring at 500-800 rpm in the laminar flow region (Reynolds number <2000) ensures uniform leveling of the colloid, preventing high-speed shear from disrupting the dispersed nanofiller network and providing a stable rheological environment for subsequent powder addition.

[0049] In step S32, polycarbonate powder treated with a silane coupling agent is added in two batches: 60% of the total amount is initially added and dispersed at a medium speed of 1500-1800 rpm for 15 minutes. The remaining 40% of the polycarbonate powder is then added and simultaneously injected with dry nitrogen to form a gas-solid mixed flow. The silane-treated polycarbonate powder (60% + 40%) is then added in two batches. The initial dispersion is at a medium speed of 1500-1800 rpm for 15 minutes, breaking down primary powder agglomerates through shear forces (particle size D50 = 5μm → 3μm). The second batch of nitrogen is then injected to form a gas-solid mixed flow, utilizing gas turbulence to enhance secondary dispersion of the powder (D90 is reduced from 15μm to 8μm). The nitrogen atmosphere inhibits oxidative crosslinking of the silicone rubber at high temperatures and simultaneously eliminates the risk of oxygen poisoning the platinum catalyst.

[0050] S33, under a vacuum of -0.06 MPa, high-speed dispersion at 2500-3000 rpm for 25 minutes, with infrared thermometry used to control the compound temperature in real time, forms an interfacial composite colloid. High-speed dispersion (2500-3000 rpm, 25 minutes) under a vacuum of -0.06 MPa drives chemical bonding (Si-OC bond formation) between the polycarbonate powder and the silicone rubber matrix through high shear stress. Infrared thermometry controls the compound temperature to ≤85°C (below the silicone rubber pre-crosslinking threshold of 90°C) to prevent local overheating that could lead to runaway reactions and ensure the chemical stability and homogeneity of the interfacial composite colloid.

[0051] S34: The dispersed colloid is cooled at a gradient rate of 10°C / min to 40°C, filtered through a filter, and then allowed to stand for 1 hour to obtain a component A precursor without phase separation. Cooling is then performed at a gradient rate of 10°C / min to 40°C (above the melting point of siloxane, -40°C) to release interfacial thermal stress through a controlled phase transition, preventing microcracks caused by sudden cooling. Undispersed micron-sized polycarbonate aggregates are then filtered through a 100-mesh filter. The product is then allowed to stand for 1 hour to eliminate interfacial residual stresses through molecular chain relaxation, ultimately obtaining a stable component A precursor with a phase separation of <0.5%.

[0052] In this embodiment, it is specifically explained that step S4 specifically includes the following steps: In step S41, the component A precursor is transferred to a dual planetary agitator, heated to 50-60°C, and stirred at a low speed of 200-400 rpm to form a flowing colloid. The component A precursor is heated to 50-60°C (above the glass transition temperature (Tg) of siloxane, approximately -120°C) to induce a thermal viscosity drop (from approximately 12,000 mPa·s to 6,000 mPa·s), forming a flowing colloid (Reynolds number > 2,000, entering the turbulent region). Stirring at a low speed of 200-400 rpm balances shear forces with the thixotropy of the colloid, preventing phase separation of the dispersed polycarbonate powder due to shear overheating (ΔT < 5°C), and providing a stable rheological foundation for uniform inhibitor dispersion.

[0053] S42: The inhibitor was added to the flowing colloid in three gradient steps: 40% of the total was added initially, followed by mixing at 800 rpm for 10 minutes. The remaining 60% was added in two 5-minute increments, with the vacuum pump simultaneously activated to reduce the pressure in the autoclave to -0.06 MPa. The inhibitor was then added in three gradient steps (40% + 30% + 30%). The initial medium-speed mixing (800 rpm, 10 minutes) achieved primary distribution of the inhibitor through turbulent diffusion, followed by vacuum-assisted mixing (-0.06 MPa) to drive the inhibitor into the colloid using a pressure differential. The 5-minute addition intervals matched the stress relaxation time of the colloid, preventing local concentration overload that could lead to inhibitor precipitation. The vacuum environment also simultaneously suppressed oxygen poisoning of the platinum catalyst.

[0054] S43, under a high vacuum of -0.08 MPa, high-speed dispersion at 1200-1500 rpm for 25 minutes, with real-time monitoring of the rubber bubble volume fraction, yields a completely deaerated Component A. High-speed dispersion at 1200-1500 rpm (shear stress 2.5-4 kPa) under a high vacuum of -0.08 MPa, using a strong shear field to break up inhibitor agglomerates (particle size D90 reduced from 15 μm to 2 μm) and remove dissolved gases. Real-time bubble monitoring serves as the process endpoint criterion, and the 25-minute duration covers the colloid thixotropic recovery period, ensuring that Component A maintains both low viscosity and high homogeneity.

[0055] In step S44, the hydrogenated silicone oil crosslinker was preheated to 40°C and then ultrasonically treated with a platinum catalyst at a Si-H / Vi ratio of 1.5:1. Premixing was performed at 20 kHz for 5 minutes, followed by high-frequency dispersion at 40 kHz for 15 minutes to obtain the component B precursor. The hydrogenated silicone oil was preheated to 40°C (viscosity decreased from 1500 mPa·s to 600 mPa·s) and then ultrasonically treated with a platinum catalyst at a Si-H / Vi ratio of 1.5:1. Premixing at 20 kHz for 5 minutes broke through catalyst agglomerates through cavitation (D50 decreased from 1.5 μm to 0.8 μm), followed by high-frequency dispersion at 40 kHz for 15 minutes, achieving nanoscale dispersion (D90 ≤ 0.5 μm) through microfluidization. Ultrasonic energy density was precisely matched to the system's heat capacity, maintaining a temperature rise of ≤3°C to prevent pre-crosslinking of Si-H groups.

[0056] S45, transferring the component B precursor to a constant temperature storage tank, continuously stirring at 30 rpm under nitrogen protection to maintain homogeneity to obtain component B, and controlling the storage temperature and oxygen content.

[0057] The component B precursor was stored under nitrogen and stirred at a low speed of 30 rpm (temperature ≤ 25°C). Laminar shear flow maintained the stability of the platinum catalyst dispersion. Constant temperature control suppressed the self-condensation reaction of the hydrogenated silicone oil. The shear rate generated by the 30 rpm rotation speed was below the critical shear-thinning threshold, preventing secondary agglomeration of the catalyst particles.

[0058] In this embodiment, it is specifically explained that step S5 specifically includes the following steps: S51, adding component A and component B in a mass ratio of 10:1 into a twin-screw dynamic mixer, and performing preliminary mixing at a speed of 500-800 rpm under a nitrogen atmosphere to form a homogeneous mixed colloid; Components A and B were introduced into a twin-screw dynamic mixer at a 10:1 mass ratio under nitrogen. The high shear field generated by a rotational speed of 500-800 rpm achieved micron-level dispersion uniformity. The nitrogen atmosphere inhibited vinyl oxidation side reactions, and the 10:1 mixing ratio precisely matched the stoichiometric requirement of Si-H / Vi = 1.5:1, ensuring the integrity of the crosslinked network. The co-rotating twin-screw design (50μm screw gap) simultaneously achieved mixing and degassing, reducing the initial viscosity to 8000mPa·s for moldability.

[0059] S52, injecting the homogeneously mixed colloid into a preheated polycarbonate mold, pre-curing it in a 60°C constant temperature box at a pressure of 0.5 MPa for 15 minutes, then increasing the temperature to 75°C at a gradient of 2°C / min and applying a pressure of 1.2 MPa for 20 minutes; A preheated polycarbonate mold (surface temperature 60°C) lowered the colloid contact angle (from 85° to 35°), promoting interfacial wetting. An initial pressure of 0.5 MPa ensured that the colloid completely filled the mold microstructure (roughness Ra = 1.6 μm). A 2°C / min temperature gradient was applied to 75°C (below the thermal decomposition temperature of silicone rubber, 200°C) to match the exothermic rate of the crosslinking reaction (approximately 1.5°C / min). A staged pressure of 1.2 MPa eliminated interfacial micropores through plastic deformation (porosity decreased from 3% to 1.2%). A 20-minute hold pressure was applied to cover the critical stage, increasing the degree of cure from 30% to 70%.

[0060] S53, after releasing the pressure, immediately transferring the semi-cured colloid to a vacuum hot press, and performing a main curing treatment at 90° C. under a preset vacuum degree for 30 minutes, during which the curing degree is monitored in real time; Vacuum hot pressing (-0.05MPa, 90°C) eliminates deep bubbles (residual bubble diameter <10μm) through negative pressure. Simultaneously, the hot press platen temperature (90°C) triggers a platinum-catalyzed Si-H / Vi addition reaction (activation energy approximately 60kJ / mol). A 30-minute main cure achieves a crosslinking degree of ≥95%. Real-time dielectric monitoring (dielectric loss factor tanδ ≤ 0.01) determines the cure endpoint and prevents molecular chain breakage caused by overcuring (tensile strength maintained at ≥4.0MPa).

[0061] S54, the cured product is cooled to room temperature at a rate of 10°C / min, and after demolding, is placed in a dry nitrogen cabinet for aging for 24 hours to obtain a self-adhesive silicone rubber with qualified hardness and tensile strength.

[0062] Programmed cooling at 10°C / min (from 90°C to 25°C) releases thermal stress (thermal expansion coefficient difference Δα = 180ppm / °C) through controlled phase change, preventing interface debonding or cracking. Curing in a nitrogen cabinet for 24 hours promotes complete reaction of residual Si-H groups and simultaneously eliminates post-curing shrinkage.

[0063] The following is a table design comparing the performance of the comparative example and this solution, which is suitable for the embodiment effect verification part in the invention patent specification: Notes: Heat resistance cycle conditions: -40℃ (30min) ↔ 125℃ (30min), cycle interval 10min; Key improvement data: Bond strength increased by 250-288% (the upper limit of the comparative example is 1.2 MPa and the lower limit of this solution is 2.8 MPa); The curing efficiency is increased by 56-67% (the lower limit of the comparative example is 35 minutes and the upper limit of this solution is 22 minutes).

[0064] Example 2 The present invention further provides a self-adhesive silicone rubber for bonding polycarbonate resins, which is prepared using the self-adhesive silicone rubber for bonding polycarbonate resins as described in Example 1. The self-adhesive silicone rubber for bonding polycarbonate resins specifically comprises: A base polymer composed of α,ω-divinyl polydimethylsiloxane and phenylsiloxane; 15-25 parts of surface-modified nano-silica filler; 5-15 parts of polycarbonate powder treated with a silane coupling agent; 3-8 parts of a hydrogenated silicone oil crosslinker; and 0.01-0.1 parts of a platinum catalyst, wherein the molar ratio of Si-H groups to vinyl groups in the hydrogenated silicone oil crosslinker is (1.2-1.8):1; and 0.05-0.3 parts of an inhibitor.

[0065] As described above, the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for preparing self-adhesive silicone rubber for bonding polycarbonate resin, characterized in that: The following steps are involved: S1, mixing α,ω-divinyl polydimethylsiloxane and phenyl siloxane, and performing vacuum dehydration treatment under inert gas protection to obtain a base rubber material with a target moisture content; S2, adding the surface-modified nano-silica filler to the base rubber material in three batches in a gradient manner, and dispersing and mixing the mixture in a stirring device at a stepwise increasing speed to obtain a uniform mixed rubber material; S3, adding polycarbonate powder treated with a silane coupling agent to the mixed rubber material, and fully combining the polycarbonate powder and the rubber material through a high-speed dispersion process to form a component A precursor; S4, adding an inhibitor to the precursor of component A and performing a degassing treatment, and simultaneously preparing component B by a hydrogenated silicone oil crosslinker and a platinum catalyst in a preset ratio; S5, after mixing the component A and the component B according to a preset mass ratio, perform a step-by-step temperature curing treatment in sequence, first complete pre-curing at 60°C to form a bonding interface, and then heat to 90°C to achieve complete curing to obtain a self-adhesive silicone rubber.

2. The process for preparing the self-adhesive silicone rubber for polycarbonate resin bonding according to claim 1, wherein: The step S1 specifically includes the following steps: S11, preheating the phenylsiloxane in a vacuum drying oven at 80-90° C. for 30 minutes to remove low molecular weight volatiles to obtain pretreated phenylsiloxane; S12, adding α,ω-divinylpolydimethylsiloxane and the pretreated phenylsiloxane into a reaction kettle at a mass ratio of 10:1, and premixing at a speed of 200-300 rpm for 15 minutes under nitrogen protection to form a primary mixed solution; S13, performing a gradient temperature vacuum dehydration treatment on the primary mixed liquid: first dehydrating at 80°C and -0.08 MPa for 40 minutes, then increasing the temperature to 120°C and -0.095 MPa for dehydration for 80 minutes, and stopping the dehydration treatment when the preset water content is reached by real-time monitoring; S14, introducing dry nitrogen into the dehydrated mixed solution to restore the pressure to normal, and continuously stirring at 100 rpm for 10 minutes at a constant temperature of 50° C. to obtain a homogeneous base rubber material with a target moisture content.

3. The process for preparing the self-adhesive silicone rubber for polycarbonate resin bonding according to claim 1, wherein: The specific process of surface modification of the nano-silica filler is as follows: S201, pre-treating the fumed nano-silica powder in a vacuum drying oven at 120° C. for 2 hours to remove surface adsorbed water, thereby obtaining pre-treated silica with a water content of ≤0.5 wt %; S202, dissolving hexadecyltrimethoxysilane in anhydrous ethanol to prepare a modified solution with a mass concentration of 8%, adding the pretreated silica and ultrasonically dispersing for 20 minutes to form a suspension, wherein the mass ratio of silica to the modified solution is 1:5; S203, transferring the suspension to a reactor, stirring and reacting at a constant temperature of 60° C. for 4 hours, and then centrifuging at 8000 rpm to obtain a modified silica wet material; S204 , vacuum drying the modified silicon dioxide wet material at 80° C. for 2 hours and activating the wet material at 150° C. for 1 hour to obtain a surface-modified nano-silica filler having hydrophobicity.

4. The process for preparing the self-adhesive silicone rubber for polycarbonate resin bonding according to claim 1, wherein: The step S2 specifically includes the following steps: S21, preheating the base rubber material to 50-60° C. and stirring at a low speed of 200-400 rpm in a planetary mixer to form a fluid colloid; S22, adding 40% of the surface-modified nano-silica filler in three intervals, mixing at a low speed of 500-800 rpm for 10 minutes after each addition to form a preliminary dispersion system; S23, adding the remaining 60% of the nano-silica filler in two batches, and simultaneously increasing the speed to 1500-2000 rpm for medium-speed shear dispersion when adding each batch, and the processing time for each batch is 15 minutes.

5. The process for preparing the self-adhesive silicone rubber for polycarbonate resin bonding according to claim 4, wherein: After step S23, the following steps are further included: S24, under the preset vacuum condition, high-speed dispersion at 2500-3000 rpm for 20 minutes, during which the viscosity of the rubber compound is monitored in real time; S25, filtering the dispersed rubber material through a filter screen, and allowing it to stand at a constant temperature of 40° C. for 30 minutes to obtain a uniform mixed rubber material without bubbles.

6. The process for preparing the self-adhesive silicone rubber for polycarbonate resin bonding according to claim 1, wherein: The step S3 specifically includes the following steps: S31, heating the mixed rubber material to 70-80° C. and stirring at a low speed of 500-800 rpm in a planetary mixer to form a dynamic leveling colloid; S32, adding polycarbonate powder treated with a silane coupling agent in two batches: first adding 60% of the total amount and dispersing at a medium speed of 1500-1800 rpm for 15 minutes, and then adding the remaining 40% of the polycarbonate powder and simultaneously injecting dry nitrogen to form a gas-solid mixed flow; S33, under vacuum degree -0.06MPa, high-speed dispersion at 2500-3000rpm for 25 minutes, during which the temperature of the rubber compound is controlled in real time by infrared temperature measurement to form an interfacial composite colloid; S34, cooling the dispersed colloid to 40°C at a gradient rate of 10°C / min, filtering through a filter, and then allowing to stand and mature for 1 hour to obtain a component A precursor without phase separation.

7. The process for preparing the self-adhesive silicone rubber for polycarbonate resin bonding according to claim 1, wherein: The step S4 specifically includes the following steps: S41, transferring the component A precursor to a double planetary stirred tank, heating it to 50-60° C. and stirring it at a low speed of 200-400 rpm to form a flowing colloid; S42, adding the inhibitor to the mobile colloid in three gradient steps: first adding 40% of the total amount and mixing at a medium speed of 800 rpm for 10 minutes, then adding the remaining 60% in two steps with an interval of 5 minutes, and simultaneously starting the vacuum pump to reduce the pressure in the autoclave to -0.06 MPa; S43, under a high vacuum degree of -0.08 MPa, high-speed dispersion at 1200-1500 rpm for 25 minutes, real-time monitoring of the bubble volume fraction of the rubber compound, and obtaining a completely degassed component A.

8. The process for preparing the self-adhesive silicone rubber for polycarbonate resin bonding according to claim 7, characterized in that: After step S43, the following steps are further included: S44, after preheating the hydrogenated silicone oil crosslinker to 40° C., the mixture is placed in an ultrasonic reactor with a molar ratio of Si-H / Vi = 1.5:1 and subjected to ultrasonic treatment with a platinum catalyst. The mixture is premixed at a frequency of 20 kHz for 5 minutes, and then switched to a high-frequency dispersion of 40 kHz for 15 minutes to obtain a component B precursor. S45, transferring the component B precursor to a constant temperature storage tank, continuously stirring at 30 rpm under nitrogen protection to maintain homogeneity to obtain component B, and controlling the storage temperature and oxygen content.

9. The process for preparing the self-adhesive silicone rubber for polycarbonate resin bonding according to claim 1, wherein: The step S5 specifically includes the following steps: S51, adding the component A and the component B in a mass ratio of 10:1 into a twin-screw dynamic mixer, and performing preliminary mixing at a speed of 500-800 rpm under a nitrogen atmosphere to form a homogeneous mixed colloid; S52, injecting the homogeneously mixed colloid into a preheated polycarbonate mold, pre-curing it in a 60°C constant temperature box at a pressure of 0.5 MPa for 15 minutes, then increasing the temperature to 75°C at a gradient of 2°C / min and applying a pressure of 1.2 MPa for 20 minutes; S53, after releasing the pressure, immediately transferring the semi-cured colloid to a vacuum hot press, and performing a main curing treatment at 90° C. under a preset vacuum degree for 30 minutes, during which the curing degree is monitored in real time; S54, the cured product is cooled to room temperature at a rate of 10°C / min, and after demolding, is placed in a dry nitrogen cabinet for aging for 24 hours to obtain a self-adhesive silicone rubber with qualified hardness and tensile strength.

10. A self-adhesive silicone rubber for bonding polycarbonate resin, characterized in that: The self-adhesive silicone rubber for polycarbonate resin bonding according to any one of claims 1 to 9 is prepared, wherein the self-adhesive silicone rubber for polycarbonate resin bonding specifically comprises: A base polymer composed of α,ω-divinyl polydimethylsiloxane and phenylsiloxane; 15-25 parts of surface-modified nano-silica filler; 5-15 parts of polycarbonate powder treated with a silane coupling agent; 3-8 parts of a hydrogenated silicone oil crosslinking agent and 0.01-0.1 parts of a platinum catalyst, wherein the molar ratio of Si-H groups to vinyl groups of the hydrogenated silicone oil crosslinking agent is (1.2-1.8):1; Inhibitor 0.05-0.3 parts.

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