Liquid silicone rubber composition and automated dispensing process

Abstract

This invention provides a liquid silicone rubber composition comprising component A and component B in a mass ratio of 1:1. Component A contains a base composition consisting of 70-100 parts by mass of vinyl silicone oil, 20-40 parts by mass of fumed silica, 4-12 parts by mass of a structure control agent, 1-3 parts by mass of water, and 0.1-0.5 parts by mass of a catalyst. Component B contains 70-100 parts by mass of vinyl silicone oil, 20-40 parts by mass of fumed silica, 3-8 parts by mass of hydrogen-containing silicone oil, and a structure control agent. The liquid silicone rubber composition comprises 4-12 parts by weight, 1-3 parts by weight, and 0.01-0.05 parts by weight of inhibitor as a base component. Components A and B further contain 0.5%-5% by weight of a low-permeability modifier and 0.01%-1% by weight of polyether silicone oil or 0.5%-2% by weight of fumed silica, respectively, as a thixotropic agent. The low-permeability modifier is at least one of an aliphatic carbon chain silane coupling agent or an aliphatic carbon chain silicone oil additive. The thixotropic index of the liquid silicone rubber composition is 2-4. This liquid silicone rubber composition exhibits excellent performance and is conducive to the effective implementation of automated dispensing processes in the security field.

Description

Technical Field

[0001] This invention belongs to the field of silicone rubber materials, specifically relating to a liquid silicone rubber composition and an automated dispensing process. Background Technology

[0002] The traditional sealing process for security devices (such as cameras) involves the following steps: Step 1. Creating a mold based on the shape, size, and dimensions of the device to be sealed; Step 2. Manufacturing a sealing ring from polymer materials (such as solid rubber compounds, EPDM, and other synthetic rubbers) through molding and edge removal processes; Step 3. Manual assembly. This process is energy-intensive, has low automation, requires a large amount of manual labor, and the need for numerous molds is compounded by the fact that different products require sealing rings of varying shapes and sizes.

[0003] Currently developed and used automated dispensing processes have solved some of the aforementioned defects. However, automated dispensing processes used for automated sealing of security equipment still need to consider other special requirements caused by the characteristics of security equipment. Taking the cover sealing of a camera as an example, this product is used in security monitoring, and the cover is a glass panel. Under the requirements of high-precision monitoring, the following requirements need to be met: 1. Complete isolation between the inside and outside, requiring the sealing ring to fit perfectly to the part to be sealed, and the sealing ring must be free of defects inside and outside; 2. In addition to isolating external liquid contaminants, it is also necessary to prevent gaseous substances (such as water vapor) from entering the interior and causing the window to fog up; 3. The sealing ring itself has extremely low VOCs; 4. Low-temperature vulcanization is carried out during the integrated molding process of electronic equipment; 5. Support for quick disassembly and repair.

[0004] Therefore, to achieve automated sealing in the security field, the sealing material needs to meet the following conditions: a. For automated dispensing, the material needs to have good flowability and thixotropy. The flowability should meet the requirements of the extrusion dispensing process, and the thixotropy should ensure that the adhesive maintains good shape stability before vulcanization during construction; b. Regarding the aforementioned requirement 1, the sealing ring should be free of defects inside and out. During the dispensing process, the beginning and end interfaces of the adhesive should not result in obvious joints due to thixotropy, i.e., the adhesive should be able to fuse quickly and simultaneously possess thixotropy; c. Regarding the requirements in requirement 2... To isolate external gases (especially moisture), the sealing ring material must have a low gas permeability; d. For the extremely low VOCs required in requirement 3 and the low-temperature vulcanization required in requirement 4, the material must be able to achieve the low VOC requirement on its own without high-temperature baking; e. For the medium-low temperature vulcanization required in requirement 4, the material must be able to undergo a cross-linking reaction under medium-low temperature conditions (below 80°C); f. For the rapid disassembly and repair required in requirement 5, the sealing ring must be able to be stably fixed to the sealing part during the manufacturing process, but without forming an adhesive to the component, and the sealing ring must be removable.

[0005] To achieve automated sealing in the security field, the automated dispensing process must simultaneously meet the following conditions: a. To ensure the sealing ring has no external defects as required in Requirement 1, the amount of adhesive dispensed during extrusion cannot be uniform, especially at the joints. The amount of adhesive dispensed should be controlled in stages to avoid dimensional deformation caused by excessive adhesive at the joints; b. To ensure the sealing ring has no internal defects and dimensional stability as required in Requirement 1, an intelligent detection process must be integrated into the dispensing process to effectively identify internal defects (bubbles, gel points, etc.) and dimensions (aspect ratio, diameter, etc.).

[0006] CN112916322A discloses a dispensing and pressure-holding device for camera modules, including a worktable and a rotating feeding mechanism, a lens module feeding mechanism, a housing feeding mechanism, a dispensing mechanism, a curing mechanism, an airtightness testing mechanism, a secondary sealing mechanism, a pressing mechanism, and a discharging mechanism set on the worktable. This device can achieve good dispensing and sealing effects, stable product quality, and high assembly efficiency, replacing manual labor. However, this patent mainly solves the problems of unstable sealing effects and low efficiency caused by manual assembly; it does not control or detect internal or external defects of the sealant, only achieving an automated dispensing process.

[0007] CN110783600A discloses a dispensing process for a sealing adhesive line in a hydrogen fuel cell. The dispensing trajectory can be arbitrarily changed according to the needs of the electrode plates, the operation is simple, and it is suitable for mass production. The cured adhesive bonds to the electrode plates as a single unit, enabling rapid stacking and assembly, and improving stacking efficiency. CN114784314A relates to a method for sealing bipolar plates in a fuel cell, a fuel cell, and a vehicle. The bipolar plate has a sealing groove, and the bottom of the sealing groove is coated with a primer. This solves the problems of high surface roughness of bipolar plates and low adhesion after dispensing and curing in the prior art. By forming an adhesive layer between the bipolar plate and the sealant, the process is simple, easy to operate, and requires low precision of automated equipment, making it suitable for mass production. The adhesive application significantly improves adhesion and meets the requirement that the dispensing sealant will not be damaged during subsequent stack disassembly and rework, reducing costs and minimizing equipment, labor, and time. Both of the above patents focus on automating the process to replace manual assembly, solving problems related to production efficiency and stability. However, they do not address the sealing performance issues caused by defects inside or outside the sealing ring in the security monitoring field.

[0008] Condensation-type silicone sealants, such as CN102627942A, release small molecules during the curing process, and the organotin / titanium-catalyzed curing reaction is slow, which makes them unable to meet the requirements of high efficiency and low VOC.

[0009] CN115386333A discloses a low compression set, one-component thermosetting silicone sealant that has a long shelf life at room temperature, cures rapidly at high temperatures, and has excellent adhesion to substrates. It mainly addresses the problem of unstable sealant performance and adhesion to substrates caused by uneven mixing of two-component adhesives. However, it does not solve the requirements for defect-free sealing rings, low volatility, and low moisture permeability for security monitoring equipment.

[0010] CN113265105B discloses a bipolar plate sealing material for fuel cells, its preparation method, and its application. This fuel cell bipolar plate sealing material has low gas permeability, low water vapor permeability, excellent resistance to strong acids, and high volume resistivity. It is easy to process, low in cost, and can be applied to hydrogen fuel cells. The patent explicitly points out that liquid silicone has poor acid resistance and gas permeability, making it unsuitable for fuel cell sealing where high water vapor permeability resistance is required. The main components of this invention are ethylene-propylene rubber or ethylene-propylene-non-conjugated diene rubber, liquid ethylene-propylene rubber or liquid ethylene-propylene-non-conjugated diene rubber, and it is not an organosilicon system.

[0011] CN105419723B relates to a crosslinkable, single-component, thermally conductive, dispenseable adhesive that solves the creep problem of existing dispenseable thermally conductive materials.

[0012] JP2022183745A provides an adhesive composition capable of forming an adhesive layer with excellent water vapor permeation barrier and bubble suppression properties, the main components of which are olefin polymers and hygroscopic fillers.

[0013] CN112778913B provides a UV-curable adhesive, its preparation method, and its application. The UV-curable adhesive uses a specific proportion of alicyclic and non-alicyclic epoxy resins as the matrix, combining the advantages of both, and adds specific proportions of cationic polymerization initiators and free radical polymerization initiators, ultimately obtaining a UV-curable adhesive with short curing time, excellent water vapor barrier properties, and superior mechanical properties. However, this invention was tested according to the boiling water resistance test method in GB 5237.4-2008 "Aluminum Alloy Building Profiles Part 4 Powder Coated Profiles," and did not examine the resistance to water vapor penetration.

[0014] Therefore, there is a need to provide new liquid silicone rubber materials and automated dispensing processes suitable for automated sealing in the security field. Summary of the Invention

[0015] To fill the gap in the prior art, the present invention provides a liquid silicone rubber composition suitable for automated sealing in the security field.

[0016] The basic concept of the technical solution of this invention is as follows:

[0017] A liquid silicone rubber composition comprising component A and component B in a mass ratio of 1:1, characterized in that component A comprises a base component consisting of 70-100 parts by mass of vinyl silicone oil, 20-40 parts by mass of fumed silica, 4-12 parts by mass of a structure control agent, 1-3 parts by mass of water, and 0.1-0.5 parts by mass of a catalyst.

[0018] Component B comprises a basic component consisting of 70-100 parts by weight of vinyl silicone oil, 20-40 parts by weight of fumed silica, 3-8 parts by weight of hydrogen-containing silicone oil, 4-12 parts by weight of structure control agent, 1-3 parts by weight of water, and 0.01-0.05 parts by weight of inhibitor.

[0019] Component A and component B further comprise 0.5% to 5% by mass of a low moisture permeability modifier and 0.01% to 1% polyether silicone oil or 0.5% to 2% fumed silica as a thixotropic agent, respectively; the low moisture permeability modifier is at least one of an aliphatic carbon chain silane coupling agent and an aliphatic carbon chain silicone oil additive.

[0020] The thixotropic index of the liquid silicone rubber composition is 2 to 4.

[0021] As one embodiment, the thixotropic index of the liquid silicone rubber composition is 2.5 to 3.5.

[0022] As one embodiment, the amount of polyether silicone oil added accounts for 0.01% to 0.5% of the total mass of the base components.

[0023] As one approach, fumed silica used as a thixotropic agent is added after the base colloid is obtained by kneading vinyl silicone oil, a structure control agent, aliphatic carbon chain silane coupling agent, and fumed silica in the base components.

[0024] As one option, the aliphatic carbon chain silane coupling agent may be selected from octyltrimethoxysilane, n-dodecyltriethoxysilane, hexadecyltriethoxysilane, octadecyltriethoxysilane, propyltrimethoxysilane, dodecyltrimethoxysilane, diisopropyldiethoxysilane, 1,10-bis(trimethoxysilyl)octane, 11-(trimethylsiloxy)undecyltriethoxysilane, n-decyltrimethoxysilane, triethoxy-(2,4,4-trimethylpentyl)silane, n-hexyltriethoxysilane, or isobutyltrimethoxysilane.

[0025] The present invention further provides an automated dispensing process, which includes the steps of placing a workpiece, automatic dispensing, 3D inspection, transferring to the drying tunnel, adhesive curing and 3D inspection in sequence. It uses the liquid silicone rubber composition according to any one of the above contents as the raw material for automatic dispensing, and adds color paste to component A or component B before use.

[0026] During automatic dispensing, the total amount of adhesive at the beginning and end overlaps should be the same as that in the middle section. The dispensing rate should be controlled as follows:

[0027] Phase 1: The rubber extrusion rate is variable. The initial extrusion rate is 0. The total time for this phase is t1. The acceleration of the rubber extrusion rate is a. The extrusion rate at a certain moment t is V1.

[0028] Phase 2: The rubber compound extrusion rate is constant, and the extrusion speed is V2;

[0029] Where V2 = a*t1; V1 = a*t, 0 ≤ t ≤ t1

[0030] V2*t1=n*a*t1 2 0.95 <n<1.05。

[0031] As one possible approach, the method of using component A is as follows:

[0032] Step 1: Add the structure control agent, water, and some vinyl silicone oil to the kneader and knead at room temperature;

[0033] Step 2: Add the silica from the base components to the kneader in batches and knead at room temperature;

[0034] Step 3: Heat the kneader to 160℃, evacuate to <-0.09Mpa, and cool to room temperature after kneading to obtain the base adhesive;

[0035] Step 4: Add the catalyst, thixotropic agent and remaining vinyl silicone oil into a kneader, knead at room temperature, and discharge for later use;

[0036] When the low moisture permeability modifier is an aliphatic carbon chain silane coupling agent, it is added in step 1; when the low moisture permeability modifier is an aliphatic carbon chain silicone oil additive, it is added in step 4.

[0037] As one possible approach, the method of using component B is as follows:

[0038] Step 1: Add the structure control agent, water, and some vinyl silicone oil to the kneader and knead at room temperature;

[0039] Step 2: Add the silica from the base components to the kneader in batches and knead at room temperature;

[0040] Step 3: Heat the kneader to 160℃, evacuate to <-0.09Mpa, and cool to room temperature after kneading to obtain the base adhesive;

[0041] Step 4: Add the hydrogen-containing silicone oil, inhibitor, thixotropic agent, color paste and remaining vinyl silicone oil into a kneader, knead at room temperature, and discharge for later use;

[0042] When the low moisture permeability modifier is an aliphatic carbon chain silane coupling agent, it is added in step 1; when the low moisture permeability modifier is an aliphatic carbon chain silicone oil additive, it is added in step 4.

[0043] The present invention also protects a security device, wherein the sealing component of the security device is formed by an automated dispensing process according to any one of the above descriptions.

[0044] Compared with the prior art, the present invention has the following advantages:

[0045] 1. The liquid silicone rubber composition of the present invention facilitates automated dispensing processes suitable for the security field. By introducing the structure of petroleum-based polymer materials (such as silane coupling agents and long-chain alkyl silicone oils) into the silicone rubber, the moisture permeability of the liquid silicone rubber composition is reduced by long-chain alkyl and aromatic groups, achieving performance comparable to solid compound rubber. This mainly involves two approaches: First, during the base rubber kneading process, long-chain alkyl silanes are used to treat silica and graft onto the surface of silica; second, long-chain alkyl modified silicone oil, aromatic modified silicone oil, or polyether silicone oil (synthesized by hydrosilylation) is added to the liquid silicone rubber formulation, thereby introducing long-chain alkyl and aromatic groups into the crosslinking structure and reducing moisture permeability.

[0046] 2. The automated dispensing process of this invention can replace the traditional manual assembly of sealing rings, achieving automation and intelligence. In addition to meeting conventional sealing requirements, it can also meet the stringent requirements of the security monitoring field for sealing rings, such as high reliability, low VOC, and low gas permeability. Ultimately, through automated dispensing in a medium and low temperature environment, a reliable sealing ring with no internal or external defects and performance comparable to that of a molded sealing ring is obtained, which can be applied to security monitoring.

[0047] 3. Furthermore, the liquid silicone rubber composition of the present invention has a suitable range of thixotropic index, which allows the rubber compound to fuse quickly at the interface under gravity while ensuring a certain degree of thixotropy. At the same time, combined with an automatic dispensing process, the dispensing amount is controlled by the program at the first and last dispensing points to ensure that the amount of rubber at the first and last overlap is the same as that in the middle part, thus solving the problem of abnormal overlap at the first and last points.

[0048] 4. Furthermore, the automated dispensing process of the present invention ensures the semi-transparent appearance of the liquid adhesive, with different colors for components A and B, and only one of them is added with color paste, so that the adhesive remains transparent and the transmittance in the ultraviolet band and visible light meets the index requirements (index control: transmittance in the ultraviolet band 200-405nm <60%, visible light transmittance >10%). Combined with an intelligent detection scheme, it realizes the detection of internal and external defects and improves the reliability of sealing.

[0049] 5. Furthermore, fumed silica is specifically used to ensure transparency, and the selection of a liquid silicone rubber formulation and process that does not require secondary vulcanization can ensure low VOC requirements. The viscosity of vinyl silicone oil is controlled at 10,000-300,000 mPa.s.

[0050] The liquid silicone rubber composition of the present invention is highly susceptible to static electricity and has a certain degree of adsorption, which solves the problem that the sealing ring of the flip cover of security equipment is easy to fall off during disassembly or maintenance, making disassembly and assembly more convenient.

[0051] 6. Furthermore, the automated dispensing process and liquid silicone rubber composition formulation of the present invention, in combination, achieve the following effects:

[0052] It solves the problem that factories need different molds to produce sealing rings of different shapes, reduces the number of molds, and thus overcomes the problems of large amount of sealing ring materials and high management costs, achieving material standardization and replacing tens of thousands of sealing ring materials with one type of glue;

[0053] The problem of high defect rate in manual assembly of sealing rings has been solved. By adopting automatic dispensing and machine vision recognition, problems such as using the wrong sealing ring or assembly errors can be better avoided, thus improving the yield rate of the sealing ring assembly process.

[0054] The use of liquid silicone composition effectively improves the utilization rate of raw materials, achieves low carbon emissions, and overcomes the problems of time-consuming and material-intensive molding of traditional sealing rings. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of the overlapping parts of the first and last parts of the automated dispensing process of this invention.

[0056] Figure 2 yes Figure 1 The diagram illustrates the control of glue dispensing speed at the overlapping joints. Detailed Implementation

[0057] Thixotropic index refers to the slope of the relationship between viscosity and shear rate during a shear test of a rubber compound. It is generally selected as the viscosity ratio when the shear rate is 1 and 10.

[0058] Specifically, the structural formula of the vinyl-terminated silicone oil used in the following cases is as follows:

[0059]

[0060] The structural formula of the side-chain hydrogen-containing silicone oil used in the following cases is as follows:

[0061]

[0062] The values ​​of m and n in the above structural formula are not limited. In this field, the viscosity of silicone oil is conventionally used to represent the molecular weight.

[0063] In the following cases, unless the dosage of a particular component is specifically specified, the dosage of components A and B shall be used in accordance with the formula amounts in the table.

[0064] As an example, the following examples of the present invention provide implementation details of applying the liquid silicone rubber composition of the present invention to an automated dispensing process, but do not limit the use of the liquid silicone rubber composition to the automated dispensing process only.

[0065] In the following cases 1-6, the vinyl silicone oil selected is an end-vinyl silicone oil with a viscosity of 20000 cs and a vinyl content of 0.2% wt;

[0066] The selected silica has a specific surface area of ​​200 m². 2 / g of fumed silica;

[0067] The hydrogen-containing silicone oil is selected from side-chain hydrogen-containing silicone oils with a viscosity of 50 cs and a hydrogen content of 0.5% wt.

[0068] The structure control agents are selected from hexamethyldisilazane and divinyltetramethyldisilazane, wherein the mass ratio of hexamethyldisilazane to divinyltetramethyldisilazane is 30:1;

[0069] The inhibitor is selected as 1-ethynyl-1-cyclohexanol;

[0070] The catalyst used is a platinum catalyst.

[0071] Example 1

[0072] The automated dispensing process uses component A and component B in a 1:1 mass ratio.

[0073] Furthermore, to optimize the automated detection of internal and external defects, color pastes were further employed. This allows for online automatic detection of internal and external defects in sealed components formed during the automated dispensing process, eliminating the need for manual inspection and significantly improving efficiency. Specifically, the following raw materials were used:

[0074]

[0075] Instructions for use of component A:

[0076] Step 1: Add the structure control agent, water, octyltrimethoxysilane and a portion of vinyl silicone oil (70 parts) into a kneader and knead for 10 minutes at room temperature;

[0077] Step 2: Add the silica from the base ingredients into the kneader in 3 batches and knead for 30 minutes at room temperature;

[0078] Step 3: Heat the kneader to 160℃, evacuate to <-0.09Mpa, knead for 3 hours, and cool to room temperature to obtain the base adhesive;

[0079] Step 4: Add the catalyst, polyether silicone oil and the remaining vinyl silicone oil (20 parts) into a kneader and knead at room temperature for 1 hour. Discharge and set aside for later use.

[0080] Instructions for use of component B:

[0081] Step 1: Add the structure control agent, water, octyltrimethoxysilane, and a portion of vinyl silicone oil (70 parts) into a kneader and knead for 10 minutes at room temperature;

[0082] Step 2: Add 30 parts of silica to the kneader in 3 batches and knead for 30 minutes at room temperature;

[0083] Step 3: Heat the kneader to 160℃, evacuate to <-0.09Mpa, knead for 3 hours, and cool to room temperature to obtain the base adhesive;

[0084] Step 4: Put the hydrogen-containing silicone oil, inhibitor, polyether silicone oil, color paste (Carrel B866-4) and the remaining vinyl silicone oil (20 parts) into a kneader and knead at room temperature for 1 hour. Discharge and set aside for use.

[0085] The two materials to be used are packaged into a 1:1 tubing or into containers A and B. They are then mixed and extruded in a 1:1 ratio using a static mixer under pressure for dispensing.

[0086] As an example, the automated dispensing equipment and automated testing integration device are model BV100-T.

[0087] The dispensing process can use conventional existing technologies, and includes the following steps in sequence: placing the workpiece → automatic dispensing → 3D inspection → transfer to the drying tunnel → adhesive curing → 3D inspection. After passing the inspection, the workpiece will proceed to the subsequent assembly process.

[0088] like Figure 1-2 As shown, during the automatic dispensing process, the total amount of adhesive at the beginning and end overlaps is controlled to be the same as that in the middle section, and the dispensing speed is controlled in the following way:

[0089] Phase 1: The rubber extrusion rate is variable. The initial extrusion rate is 0. The total time of this phase is t1. The acceleration of the rubber extrusion rate is a. Let the extrusion rate at time t be V1.

[0090] Phase Two: The rubber compound extrusion rate is constant, and the extrusion speed is V2.

[0091] The parameters satisfy the following relationship:

[0092] Extrusion speed: V2 = a * t1; V1 = a * t (0 ≤ t ≤ t1)

[0093] Extrusion amount: V2*t1=n*a*t1 2 (0.95 <n<1.05)。

[0094] Example 2

[0095] The difference from Example 1 is that the following raw material formula is used, while everything else remains the same as in Example 1.

[0096]

[0097] Example 3

[0098] The difference from Example 1 is that the following raw material formulation is used, and the methods of using components A and B are different.

[0099]

[0100] Instructions for use of component A:

[0101] Step 1: Add the structure control agent, water, octyltrimethoxysilane and a portion of vinyl silicone oil (70 parts) to a kneader and knead for 10 minutes at room temperature;

[0102] Step 2: Add the silica from the base ingredients into the kneader in 3 batches and knead for 30 minutes at room temperature;

[0103] Step 3: Heat the kneader to 160℃, evacuate to <-0.09Mpa, knead for 3 hours, and cool to room temperature to obtain the base adhesive;

[0104] Step 4: Add the catalyst, fumed silica (0.5% of the base composition) used as a thixotropic agent, alkyl aromatic modified silicone oil OFX0203, color paste (Kaller B866-4), and the remaining vinyl silicone oil into a kneader and knead at room temperature for 1 hour. Discharge and set aside for later use.

[0105] Instructions for use of component B:

[0106] Step 1: Add the structure control agent, water, octyltrimethoxysilane and a portion of vinyl silicone oil (70 parts) into a kneader and knead for 10 minutes at room temperature;

[0107] Step 2: Add 30 parts of silica from the base ingredients into the kneader in 3 batches and knead for 30 minutes at room temperature;

[0108] Step 3: Heat the kneader to 160℃, evacuate to <-0.09Mpa, knead for 3 hours, and cool to room temperature to obtain the base adhesive;

[0109] Step 4: Add the hydrogen-containing silicone oil, inhibitor, fumed silica (0.5% of the base composition) used as a thixotropic agent, alkyl aromatic modified silicone oil OFX0203, color paste (Kaller B866-4), and the remaining vinyl silicone oil into a kneader and knead at room temperature for 1 hour. Discharge and set aside for later use.

[0110] Example 4

[0111] The difference from Example 1 lies in the use of the following raw material formulation and the different methods of using components A and B.

[0112]

[0113] Instructions for use of component A:

[0114] Step 1: Add the structure control agent, water and a portion of vinyl silicone oil (70 parts) into a kneader and knead for 10 minutes at room temperature;

[0115] Step 2: Add the silica from the base ingredients into the kneader in 3 batches and knead for 30 minutes at room temperature;

[0116] Step 3: Heat the kneader to 160℃, evacuate to <-0.09Mpa, knead for 3 hours, and cool to room temperature to obtain the base adhesive;

[0117] Step 4: Add the catalyst, fumed silica (2% of the base composition), alkyl aromatic modified silicone oil OFX0203, and the remaining vinyl silicone oil (20 parts) into a kneader and knead at room temperature for 1 hour. Discharge and set aside for later use.

[0118] Instructions for use of component B:

[0119] Step 1: Add the structure control agent, water and a portion of vinyl silicone oil (70 parts) into a kneader and knead for 10 minutes at room temperature;

[0120] Step 2: Add the silica from the base ingredients into the kneader in 3 batches and knead for 30 minutes at room temperature;

[0121] Step 3: Heat the kneader to 160℃, evacuate to <-0.09Mpa, knead for 3 hours, and cool to room temperature to obtain the base adhesive;

[0122] Step 4: Add the hydrogen-containing silicone oil, inhibitor, fumed silica (2% of the base components), alkyl aromatic modified silicone oil OFX0203, color paste (Carrel B866-4), and the remaining vinyl silicone oil (20 parts) into a kneader and knead at room temperature for 1 hour. Discharge and set aside for use.

[0123] Example 5

[0124] The difference from Example 1 is the use of the following raw material formulation and the method of using components A and B; otherwise, it remains the same as Example 1.

[0125]

[0126] Instructions for use of component A:

[0127] Step 1: Add the structure control agent, water, octyltrimethoxysilane and a portion of vinyl silicone oil (70 parts) into a kneader and knead for 10 minutes at room temperature;

[0128] Step 2: Add the silica from the base ingredients into the kneader in 3 batches and knead for 30 minutes at room temperature;

[0129] Step 3: Heat the kneader to 160℃, evacuate to <-0.09Mpa, knead for 3 hours, and cool to room temperature to obtain the base adhesive;

[0130] Step 4: Add the catalyst and the remaining vinyl silicone oil (15 parts) into a kneader and knead at room temperature for 1 hour. Discharge and set aside for later use.

[0131] Instructions for use of component B:

[0132] Step 1: Add the structure control agent, water, octyltrimethoxysilane and a portion of vinyl silicone oil (70 parts) into a kneader and knead for 10 minutes at room temperature;

[0133] Step 2: Add the silica from the base ingredients into the kneader in 3 batches and knead for 30 minutes at room temperature;

[0134] Step 3: Heat the kneader to 160℃, evacuate to <-0.09Mpa, knead for 3 hours, and cool to room temperature to obtain the base adhesive;

[0135] Step 4: Add the hydrogen-containing silicone oil, 0.02 parts of inhibitor, color paste (Carrel B866-4), and the remaining vinyl silicone oil (15 parts) into a kneader and knead at room temperature for 1 hour. Discharge and set aside for use.

[0136] Example 6

[0137] The difference from Example 1 is the use of the following raw material formulation and the method of using components A and B; otherwise, it remains the same as Example 1.

[0138]

[0139] Instructions for use of component A:

[0140] Step 1: Add the structure control agent, water, n-hexyltriethoxysilane and 70 parts of vinyl silicone oil to a kneader and knead for 10 minutes at room temperature;

[0141] Step 2: Add the silica from the base ingredients into the kneader in 3 batches and knead for 30 minutes at room temperature;

[0142] Step 3: Heat the kneader to 160℃, evacuate to <-0.09Mpa, knead for 3 hours, and cool to room temperature to obtain the base adhesive;

[0143] Step 4: Add the catalyst and the remaining vinyl silicone oil (20 parts) into a kneader and knead at room temperature for 1 hour. Discharge and set aside.

[0144] Instructions for use of component B:

[0145] Step 1: Put 8 parts of the structure control agent, 1.8 parts of water, all of the n-hexyltriethoxysilane and part of the vinyl silicone oil (70 parts) into a kneader and knead for 10 minutes at room temperature.

[0146] Step 2: Add the silica from the base ingredients into the kneader in 3 batches and knead for 30 minutes at room temperature;

[0147] Step 3: Heat the kneader to 160℃, evacuate to <-0.09Mpa, knead for 3 hours, and cool to room temperature to obtain the base adhesive;

[0148] Step 4: Add the hydrogen-containing silicone oil, 0.02 parts of inhibitor, color paste (Carrel B866-4), and the remaining vinyl silicone oil (20 parts) into a kneader and knead at room temperature for 1 hour. Discharge and set aside for use.

[0149] Example 7

[0150] The difference from Example 1 is that the vinyl silicone oil selected is an end-vinyl silicone oil with a viscosity of 10000 cs and a vinyl content of 0.38% wt; the silica selected has a specific surface area of ​​300 m². 2 / g of fumed silica; the hydrogen-containing silicone oil selected is a side-chain hydrogen-containing silicone oil with a viscosity of 20cs and a hydrogen content of 0.8%wt; the following raw material formulation and the usage methods of components A and B are used, and other aspects are consistent with Example 1.

[0151]

[0152] Instructions for use of component A:

[0153] Step 1: Add the structure control agent, water, octyltrimethoxysilane and vinyl silicone oil (70 parts) into a kneader and knead for 10 minutes at room temperature;

[0154] Step 2: Add the silica from the base ingredients into the kneader in 3 batches and knead for 30 minutes at room temperature;

[0155] Step 3: Heat the kneader to 160℃, evacuate to <-0.09Mpa, knead for 3 hours, and cool to room temperature to obtain the base adhesive;

[0156] Step 4: Add 0.4 parts of catalyst and the remaining vinyl silicone oil (10 parts) into a kneader and knead at room temperature for 1 hour. Discharge and set aside for later use.

[0157] Instructions for use of component B:

[0158] Step 1: Add 12 parts of structure control agent, 3 parts of water, octyltrimethoxysilane and 70 parts of vinyl silicone oil to a kneader and knead for 10 minutes at room temperature.

[0159] Step 2: Add the silica from the base ingredients into the kneader in 3 batches and knead for 30 minutes at room temperature;

[0160] Step 3: Heat the kneader to 160℃, evacuate to <-0.09Mpa, knead for 3 hours, and cool to room temperature to obtain the base adhesive;

[0161] Step 4: Add the hydrogen-containing silicone oil, inhibitor, color paste (Carrel B866-4), and the remaining vinyl silicone oil (10 parts) into a kneader and knead at room temperature for 1 hour. Discharge and set aside for use.

[0162] Example 8

[0163] The difference from Example 1 is that the vinyl silicone oil used is a vinyl-terminated silicone oil with a viscosity of 10000 cs and a vinyl content of 0.38% wt; the silica used is a silica with a specific surface area of ​​200 m². 2 / g of fumed silica; the following raw material formulation and the usage methods of components A and B are used, otherwise consistent with Example 1.

[0164]

[0165] Instructions for use of component A:

[0166] Step 1: Add the structure control agent, water, octyltrimethoxysilane and a portion of vinyl silicone oil (70 parts) into a kneader and knead for 10 minutes at room temperature;

[0167] Step 2: Add the basic component, silica, into the kneader in 3 batches and knead for 30 minutes at room temperature;

[0168] Step 3: Heat the kneader to 160℃, evacuate to <-0.09Mpa, knead for 3 hours, and cool to room temperature to obtain the base adhesive;

[0169] Step 4: Add the catalyst and the remaining vinyl silicone oil (30 parts) into the kneader and knead at room temperature for 1 hour. Discharge and set aside for later use.

[0170] Instructions for use of component B:

[0171] Step 1: Add the structure control agent, water, octyltrimethoxysilane and a portion of vinyl silicone oil (70 parts) into a kneader and knead for 10 minutes at room temperature;

[0172] Step 2: Add the silica from the base ingredients into the kneader in 3 batches and knead for 30 minutes at room temperature;

[0173] Step 3: Heat the kneader to 160℃, evacuate to <-0.09Mpa, knead for 3 hours, and cool to room temperature to obtain the base adhesive;

[0174] Step 4: Put the hydrogen-containing silicone oil, inhibitor, color paste (Carrel B866-4), and the remaining vinyl silicone oil (30 parts) into a kneader and knead at room temperature for 1 hour. Discharge and set aside for use.

[0175] Comparative Example 1

[0176] The difference from Example 1 is the absence of octyltrimethoxysilane and polyether silicone oil, while everything else remains the same.

[0177]

[0178] Comparative Example 2

[0179]

[0180] Comparative Example 3

[0181]

[0182] Comparative Example 4

[0183] The amount of adhesive at the overlap during automatic dispensing does not satisfy the relationship listed in this invention, specifically V2*t1=0.9*a*t1 2 .

[0184]

[0185] During the automatic dispensing process, the amount of adhesive at the beginning and end overlaps is greater than that in the middle section, resulting in sealing defects.

[0186] Comparative Example 5

[0187]

[0188] Comparative Example 6

[0189] During the automatic dispensing process, the amount of adhesive at the overlap between the beginning and end does not satisfy the relationship listed in this invention, specifically V2*t1=1.1*a*t1 2 Everything else remains the same.

[0190]

[0191] During the automatic dispensing process, the amount of adhesive at the beginning and end of the dispensing process does not meet the listed relationship, that is, the amount of adhesive at the beginning and end of the overlap is less than that in the middle section, resulting in a sealing defect at the beginning and end of the overlap.

[0192] Example of effect

[0193] The performance indicators of the sealing components obtained by the automated dispensing process of Examples 1-8 and Comparative Examples 1-6 were tested, as well as their effects when applied to a camera.

[0194] Moisture transmittance was tested according to GB / T21529-2008 (electrolysis method, 38℃, 90%RH). Thixotropic index was tested using an Anton Paar MCR 302 rheometer, and the ratio of viscosity at rotation speeds of 1 and 10 was used. Visible light transmittance was tested using a WGT-S transmittance meter and a UV2600 UV-Vis spectrophotometer.

[0195] The effect when applied to a camera was observed by assembling a DH-SD-49D412U-HN camera and then placing it in a natural outdoor working environment for a year to check for fogging in the viewing window.

[0196] The test results are detailed in Table 1 - Performance Indicators and Table 2 - Application Evaluation. In the tables, "1" is an abbreviation for Example 1, "1" is an abbreviation for Comparative Example 1, and so on.

[0197] Table 1 Performance Indicators

[0198]

[0199] Table 2 Application Evaluation

[0200]

[0201] The following conclusions can be drawn from the above test results:

[0202] In Comparative Example 1, no moisture permeability and thixotropic modification were performed on the rubber compound. The resulting rubber compound had a significantly higher moisture permeability, a lower thixotropic index, and excessive fluidity, making it unable to form a good seal.

[0203] The excessive amount of pigment added in Comparative Example 2 resulted in excessively low visible light transmittance and ultraviolet light transmittance, making it impossible to detect internal and external defects and leading to a high scrap rate in the automatic dispensing process. At the same time, the excessively high thixotropic index prevented the joints from fusing, resulting in abnormal joints and sealing defects.

[0204] Comparative Example 3, without the addition of colorant, resulted in high ultraviolet light transmittance and insufficient reflection, making it impossible to automatically detect internal and external defects. Consequently, it could not achieve automated detection, could not identify defective seals, and had a low defect detection rate. This prevented the realization of the automated dispensing process concept and led to the overall automated dispensing process being deemed unqualified.

[0205] In Comparative Examples 4 and 6, the glue dispensing control at the beginning and end overlaps in the automatic dispensing process does not meet the listed relationship. The amount of glue at the beginning and end is different from that in the middle section, resulting in defects at the beginning and end overlaps.

[0206] Comparative Example 5 did not modify the moisture transmittance of the rubber compound, and the resulting rubber compound had a significantly higher moisture transmittance, which would cause the camera window to fog up during outdoor testing.

Claims

1. A liquid silicone rubber composition comprising component A and component B in a mass ratio of 1:1, characterized in that, Used for manufacturing sealing components for security equipment; Component A comprises a basic composition consisting of 70-100 parts by weight of vinyl silicone oil, 20-40 parts by weight of fumed silica, 4-12 parts by weight of structure control agent, 1-3 parts by weight of water, and 0.1-0.5 parts by weight of catalyst. Component B comprises a basic component consisting of 70-100 parts by weight of vinyl silicone oil, 20-40 parts by weight of fumed silica, 3-8 parts by weight of hydrogen-containing silicone oil, 4-12 parts by weight of structure control agent, 1-3 parts by weight of water, and 0.01-0.05 parts by weight of inhibitor. Component A and Component B further comprise 0.5% to 5% by mass of a low moisture permeability modifier and 0.01% to 1% polyether silicone oil or 0.5% to 2% fumed silica as a thixotropic agent, respectively; the low moisture permeability modifier is at least one of an aliphatic carbon chain silane coupling agent and an aliphatic carbon chain silicone oil additive. The thixotropic index of the liquid silicone rubber composition is 2 to 4; Fumed silica used as a thixotropic additive is added after the base glue is obtained by kneading vinyl silicone oil, structure control agent, aliphatic carbon chain silane coupling agent and fumed silica in the base components. The aliphatic carbon chain silane coupling agent may be selected from octyltrimethoxysilane, n-dodecyltriethoxysilane, hexadecyltriethoxysilane, octadecyltriethoxysilane, propyltrimethoxysilane, dodecyltrimethoxysilane, diisopropyldiethoxysilane, 1,10-bis(trimethoxysilyl)octane, 11-(trimethylsiloxy)undecyltriethoxysilane, n-decyltrimethoxysilane, triethoxy-(2,4,4-trimethylpentyl)silane, n-hexyltriethoxysilane, or isobutyltrimethoxysilane.

2. The liquid silicone rubber composition according to claim 1, characterized in that, The thixotropic index of the liquid silicone rubber composition is 2.5 to 3.

5.

3. The liquid silicone rubber composition according to claim 1, characterized in that, The amount of polyether silicone oil added accounts for 0.01% to 0.5% of the total mass of the base components.

4. An automated dispensing process, comprising the steps of placing a workpiece, automatic dispensing, 3D inspection, transferring to an oven tunnel, adhesive curing, and 3D inspection, characterized in that, The liquid silicone rubber composition according to any one of claims 1-3 is used as the raw material for automatic dispensing, and is used after adding color paste to component A or component B; During automatic dispensing, the total amount of adhesive at the beginning and end overlaps should be the same as that in the middle section. The dispensing rate should be controlled as follows: Phase 1: The rubber extrusion rate is variable. The initial extrusion rate is 0. The total time for this phase is t1. The acceleration of the rubber extrusion rate is a. The extrusion rate at a certain moment t is V1. Phase 2: The rubber compound extrusion rate is constant, and the extrusion speed is V2; V2 = a * t 1； V1 = a * t, 0 ≤ t ≤ t1, V2*t1=n*a*t1 2 0.95 <n<1.05 ; The method of using component A is as follows: Step 1: Add the structure control agent, water, and some vinyl silicone oil to the kneader and knead at room temperature; Step 2: Add the silica from the base components to the kneader in batches and knead at room temperature; Step 3: Heat the kneader to 160℃, evacuate to <-0.09Mpa, and cool to room temperature after kneading to obtain the base adhesive; Step 4: Add the catalyst, thixotropic agent and remaining vinyl silicone oil into a kneader, knead at room temperature, and discharge for later use; When the low moisture permeability modifier is an aliphatic carbon chain silane coupling agent, it is added in step 1; when the low moisture permeability modifier is an aliphatic carbon chain silicone oil additive, it is added in step 4. Instructions for using component B: Step 1: Add the structure control agent, water, and some vinyl silicone oil to the kneader and knead at room temperature; Step 2: Add the silica from the base components to the kneader in batches and knead at room temperature; Step 3: Heat the kneader to 160℃, evacuate to <-0.09Mpa, and cool to room temperature after kneading to obtain the base adhesive; Step 4: Add the hydrogen-containing silicone oil, inhibitor, thixotropic agent, color paste and remaining vinyl silicone oil into a kneader, knead at room temperature, and discharge for later use; When the low moisture permeability modifier is an aliphatic carbon chain silane coupling agent, it is added in step 1; when the low moisture permeability modifier is an aliphatic carbon chain silicone oil additive, it is added in step 4.

5. A security device, characterized in that, The sealing components of the security equipment are formed using the automated dispensing process described in claim 4.

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