A phase-change compressible silicone gasket based on additive manufacturing

Abstract

The present invention discloses a phase change compressible silicone gasket based on additive manufacturing. By mass, it includes 40-45 parts of methyl vinyl silicone rubber, 1.3-1.5 parts of crosslinking agent, 0.8-1.0 parts of chain extender, 15-20 parts of monofunctional vinyl, 0.05-0.1 parts of inhibitor, 30-35 parts of flame retardant, 3-5 parts of phase change microcapsules, 1-2 parts of colorant, and 0.03-0.05 parts of catalyst. The preparation method of the phase change compressible silicone gasket based on additive manufacturing adopts the method of screw extrusion + spraying layer by layer, including matrix premixing, functional filler dispersion, slurry preparation, material extrusion, deposition molding, and post-treatment. The phase change material of the present invention can dynamically change its size with temperature change; and a visual virtual drawing can be pre-generated, which is convenient for adjusting and optimizing parameters before production to meet customer requirements. The present invention adopts the method of screw extrusion + spraying layer by layer to produce the phase change silicone compression gasket, which can realize off-site production, and has no burrs, saves materials, and is environmentally friendly and simple.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a phase-change compressible silicone gasket based on additive manufacturing. Background Art

[0002] In consumer electronic display devices, silicone rubber gaskets are commonly used as limit blocks to buffer and protect between the plastic outer frame and the glass plate. Generally, silicone rubber materials such as Shin-Etsu silicone KE-951U are used as common solutions. With the change of environmental temperature and humidity, due to the inconsistent expansion coefficients of the glass plate and the plastic outer frame, dimensional changes are likely to occur in various scenarios. However, as a traditional silicone rubber solution, the silicone rubber itself is not sensitive to temperature-dependent dimensional changes and does not have variable dimensions. When either of them exceeds the upper limit of dimensional change, structural failure is likely to occur, that is, there is extrusion of the glass or plastic frame, or inappropriate retraction, which will cause damage or structural failure to the physical hardware of the assembled display device and ultimately affect the display effect of the terminal device.

[0003] Traditional silicone gaskets are usually formed by molding or injection molding, which have problems such as complex processes and low design freedom. Additive manufacturing (3D printing) technology provides the possibility of personalized customization for silicone products, but existing silicone materials are prone to problems such as poor fluidity and unstable curing speed during the printing process. In addition, conventional silicone gaskets have a single function and are difficult to meet the requirements of buffering, sealing, and thermal management at the same time. In addition, in the traditional production process of silicone gaskets, the mixed slurry is used, and the conventional mold opening method is used in the shaping stage. Due to the certain fluidity of the silicone polymer, local extrusion deformation and capillary phenomena are likely to occur during the demolding process, and the finally formed gasket has burrs, resulting in unqualified delivery quality. Each pattern requires a separate mold to be opened. If the size is not appropriate, the mold needs to be scrapped, which is a huge cost and resource waste for both the product and the mold.

[0004] Therefore, the present invention provides a phase-change compressible silicone gasket based on additive manufacturing. By using the phase-change compressible silicone gasket, the position of the limit block can be dynamically adjusted according to the temperature to meet the dimensional changes of the components, and it has the characteristics of compressibility / expansion with temperature that traditional silicone rubber itself does not have, and has great technical advantages. Obviously, it is of great significance to develop a silicone material with both compressibility, phase-change temperature regulation function and suitable for additive manufacturing. Summary of the Invention

[0005] The purpose of the present invention is to provide a phase-change compressible silicone gasket based on additive manufacturing to obtain a silicone material with both compressibility, phase-change temperature regulation function and suitable for additive manufacturing.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A phase-change compressible silicone gasket based on additive manufacturing, by mass, comprises 40-45 parts of methyl vinyl silicone rubber, 1.3-1.5 parts of cross-linking agent, 0.8-1.0 parts of chain extender, 15-20 parts of monofunctional vinyl, 0.05-0.1 parts of inhibitor, 30-35 parts of flame retardant, 3-5 parts of phase-change microcapsules, 1-2 parts of colorant, and 0.03-0.05 parts of catalyst.

[0008] Preferably, the cross-linking agent is selected from one or more of polymethylhydrosiloxane (PMHS), HMS-991, dicumyl peroxide (DCP), 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

[0009] Preferably, the chain extender is selected from one or more of hydroxyl-terminated polydimethylsiloxane, α,ω-dihydroxypolydimethylsiloxane, tetramethyldivinyldisiloxane, vinyl silicone oil (vinyl content 0.1%-0.5%), γ-aminopropyltriethoxysilane (KH-550), N-phenyl-γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane (KH-560).

[0010] Preferably, the monofunctional vinyl is selected from one of vinyltrimethoxysilane (VTMS), vinyltriethoxysilane (VTES), vinylmethyldimethoxysilane (VMDMS), vinyldimethylmethoxysilane (VDMMS), γ-methacryloxypropyltrimethoxysilane (KH-570).

[0011] Preferably, the inhibitor is selected from one or more of ethynylcyclohexanol (ECH), methylbutynol (MBY), dimethylethynylcarbinol (DMA), vinylcyclohexene oxide (VCHO), diethyl maleate, dibutyltin dilaurate.

[0012] Preferably, the flame retardant is selected from one of aluminum hydroxide (ATH), magnesium hydroxide (MH), nano-silica, layered double hydroxide (LDH), carbon nanotube (CNT).

[0013] Preferably, the catalyst is selected from one of platinum-divinyltetramethyldisiloxane complex, RhCl(PPh3)3.

[0014] Preferably, the phase-change microcapsules are paraffin-based core-shell microcapsules, and the paraffin-based core-shell microcapsules are composed of an inner core and an outer shell. The inner core is selected from one of n-octadecane, n-eicosane, paraffin wax, and the outer shell is selected from one of melamine-formaldehyde resin (MF), silica, polymethyl methacrylate (PMMA).

[0015] Preferably, the colorant is selected from one of titanium dioxide (TiO2), iron oxide red, and iron oxide black, and the particle size of the colorant is 0.5 - 5 μm.

[0016] This application also claims to protect a preparation method of the above-mentioned phase change compressible silicone gasket based on additive manufacturing, which includes the following steps:

[0017] S1. Matrix premixing: Add methyl vinyl silicone rubber, monofunctional vinyl, and chain extender into a blender, and control the stirring speed at 300 rpm - 500 rpm and stir for 30 - 45 minutes under the conditions of 55 - 65 °C and a vacuum degree of -0.095 MPa to obtain a matrix premixed system;

[0018] S2. Functional filler dispersion: Then, add a flame retardant and phase change microcapsules to the matrix premixed system in sequence, and use a three-roll mill for dispersion to obtain a dispersed system; add a colorant to the dispersed system and treat it with an ultrasonic disperser at 500 W and 20 kHz for 15 - 18 minutes to obtain a mixture;

[0019] S3. Slurry preparation: Cool the mixture to below 40 °C; then add an inhibitor and stir for 5 - 8 minutes; slowly dropwise add a crosslinking agent and stir for 15 - 20 minutes; finally, add a catalyst and stir for 5 - 8 minutes to obtain a final slurry. Transfer the slurry to a vacuum planetary mixer and defoam for 30 minutes at -0.1 MPa and 25 °C, and control the viscosity to be 5000 - 8000 mPa·s;

[0020] S4. Material extrusion: Feed the slurry into the screw extrusion nozzle of the printer. After it completely becomes liquid in the nozzle, the nozzle moves to extrude the liquid slurry; the nozzle diameter is 0.1 - 0.4 mm; precisely control the moving speed and extrusion amount of the nozzle to ensure the accuracy and thickness of each layer;

[0021] S5. Deposition molding: The extruded material quickly cools and solidifies in mid-air, and then deposits on the workbench. After each layer of deposition is completed, the workbench will rise by 1 - 50 microns to facilitate the deposition of the next layer on a new plane. Repeat this process until the entire three-dimensional model is completed; the printing layer thickness is 0.02 mm - 20 mm, and the printing speed is 5 mm / s - 100 mm / s;

[0022] S6. Post-treatment: After printing is completed, perform post-treatment operations on the model. The post-treatment operations include removing the support structure, coating the surface, and coloring to obtain a phase change compressible silicone gasket. To improve the appearance and mechanical properties of the model and add other functionalities.

[0023] Due to the application of the above technical solutions, the present invention has the following beneficial effects compared with the prior art:

[0024] 1. The present invention adds a phase change material with a special formula design, which can dynamically change its size with temperature changes, sensitively follow the size changes of components, and has multiple functions such as heat conduction, very good elasticity and thermal stability; a thermoplastic elastomer that can ensure the initial thickness and elasticity under high and low temperature cycles; no oil leakage and very low small molecule volatilization.

[0025] 2. The additive manufacturing of the present invention can pre-generate a visual virtual drawing, which is convenient for adjusting and optimizing parameters before production to meet customer needs. Once a traditional mold is opened, it cannot be modified, and it can also be transmitted to other terminals for off-site production.

[0026] 3. The quality and appearance of the materials produced by the additive manufacturing of the present invention are controllable. The phase change silica gel compression gasket is produced by screw extrusion + spraying layer by layer, which can achieve off-site production, without burrs, save materials, do not require additional cleaning, is environmentally friendly and simple, greatly saves production costs, and can also be extended to the production of other polymer materials.

[0027] 4. The present invention can achieve phase change compressibility, intelligently and dynamically change its size, and has a unique compression ratio curve of the silica gel gasket. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, some of the drawings below are embodiments of the present invention. For those of ordinary skill in the art, without creative work, other drawings can be obtained based on these drawings.

[0029] Figure 1 is a schematic diagram of screw extrusion + spraying layer by layer in Embodiment 1 of the present invention;

[0030] Figure 2 is a compression ratio curve graph of the phase change compressible silica gel gasket in Embodiment 1 of the present invention;

[0031] Among them, 1 - screw, 2 - nozzle, 3 - slurry. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] In order to have a clearer understanding of the technical features, objectives and effects of the present invention, the specific implementation methods will be described in detail below.

[0033] The following describes the present invention in further detail with reference to the embodiments, but the present invention is not limited to the following embodiments. The implementation conditions adopted in the embodiments can be further adjusted according to different requirements of specific uses. The implementation conditions not specified are the conventional conditions in this industry. The technical features involved in each implementation manner of the present invention can be combined with each other as long as they do not conflict with each other.

[0034] Example 1

[0035] See the appendix Figure 1 and the appendix Figure 2 In this example, a phase change compressible silicone gasket based on additive manufacturing is provided. By mass, it includes 42 parts of methyl vinyl silicone rubber, 1.4 parts of crosslinking agent, 0.9 part of chain extender, 18 parts of monofunctional vinyl, 0.08 part of inhibitor, 32 parts of flame retardant, 4 parts of phase change microcapsules, 2 parts of colorant, and 0.04 part of catalyst;

[0036] The crosslinking agent is polymethylhydrosiloxane (PMHS);

[0037] The chain extender is hydroxyl-terminated polydimethylsiloxane;

[0038] The monofunctional vinyl is vinyltrimethoxysilane (VTMS);

[0039] The inhibitor is ethynylcyclohexanol (ECH);

[0040] The flame retardant is aluminum hydroxide (ATH);

[0041] The catalyst is platinum-divinyltetramethyldisiloxane complex;

[0042] The phase change microcapsules are paraffin-based core-shell microcapsules. The paraffin-based core-shell microcapsules are composed of an inner core and an outer shell. The inner core is selected as paraffin, and the outer shell is silica. The phase change microcapsules are paraffin@SiO2 phase change microcapsules;

[0043] The colorant is iron oxide red, and the particle size of the colorant is 0.5 - 5 μm;

[0044] The preparation method of the above phase change compressible silicone gasket based on additive manufacturing includes the following steps:

[0045] S1. Matrix premixing: Add methyl vinyl silicone rubber, monofunctional vinyl, and chain extender into a blender, and control the stirring speed at 400 rpm and stir for 40 minutes at 60 °C and a vacuum degree of -0.095 MPa to obtain a matrix premixed system;

[0046] S2. Functional filler dispersion: Then, add the flame retardant and phase change microcapsules to the matrix premixed system in sequence, and use a three-roll mill for dispersion to obtain a dispersed system; add the colorant to the dispersed system, and treat it with an ultrasonic disperser at 500 W and 20 kHz for 18 minutes to obtain a mixture;

[0047] S3. Slurry Preparation: Cool the mixture to below 40°C; then add an inhibitor and stir for 6 minutes; slowly drip in a crosslinking agent and stir for 18 minutes; finally add a catalyst and stir for 8 minutes to obtain the final slurry. Transfer the slurry to a vacuum planetary mixer and degas it at -0.1 MPa and 25°C for 30 minutes, controlling the viscosity to be 5500 - 5800 mPa·s;

[0048] S4. Material Extrusion: Feed the slurry (3) into the extrusion nozzle of the screw (1) of the printer. After it completely becomes liquid in the nozzle, the nozzle moves to extrude the liquid slurry; the diameter of the nozzle (2) is 0.3 mm; precisely control the moving speed and extrusion amount of the nozzle to ensure the precision and thickness of each layer;

[0049] S5. Deposition Molding: The extruded material rapidly cools and solidifies in mid-air and then deposits on the workbench. After each layer of deposition is completed, the workbench rises by 15 microns to enable the next layer of deposition on a new plane. Repeat this process until the entire three-dimensional model is completed; the printing layer thickness is 2 mm and the printing speed is 20 mm / s;

[0050] S6. Post-treatment: After printing is completed, perform post-treatment operations on the model. The post-treatment operations include removing the support structure, coating the surface, and coloring to obtain a phase-change compressible silicone gasket;

[0051] The compression ratio curve graph of the phase-change compressible silicone gasket prepared in this embodiment is shown in the appendix Figure 2 and shows the change curves at 30°C, 40°C, 50°C, and 60°C respectively.

[0052] Example 2

[0053] This embodiment provides a phase-change compressible silicone gasket based on additive manufacturing. By mass, it includes 45 parts of methyl vinyl silicone rubber, 1.3 parts of crosslinking agent, 1.0 part of chain extender, 15 parts of monofunctional vinyl, 0.06 part of inhibitor, 30 parts of flame retardant, 5 parts of phase-change microcapsules, 2 parts of colorant, and 0.04 part of catalyst;

[0054] The crosslinking agent is polymethylhydrosiloxane (PMHS);

[0055] The chain extender is hydroxyl-terminated polydimethylsiloxane;

[0056] The monofunctional vinyl is vinyltrimethoxysilane (VTMS);

[0057] The inhibitor is ethynylcyclohexanol (ECH);

[0058] The flame retardant is aluminum hydroxide (ATH);

[0059] The catalyst is a platinum-divinyltetramethyldisiloxane complex;

[0060] The phase change microcapsules are paraffin-based core-shell microcapsules, which are composed of a core and a shell. The core is selected as paraffin, and the shell is silica. The phase change microcapsules are paraffin@SiO2 phase change microcapsules;

[0061] The colorant is iron oxide red, and the particle size of the colorant is 0.5 - 5 μm;

[0062] The preparation method of the above-mentioned phase change compressible silicone gasket based on additive manufacturing includes the following steps:

[0063] S1. Matrix premixing: Add methyl vinyl silicone rubber, monofunctional vinyl, and chain extender into a blender, and control the stirring speed at 400 rpm and stir for 40 minutes at 60°C and a vacuum degree of -0.095 MPa to obtain a matrix premixed system;

[0064] S2. Functional filler dispersion: Then sequentially add a flame retardant and phase change microcapsules to the matrix premixed system, and disperse them using a three-roll mill to obtain a dispersed system; add a colorant to the dispersed system, and treat it with an ultrasonic disperser at 500 W and 20 kHz for 18 minutes to obtain a mixture;

[0065] S3. Slurry preparation: Cool the mixture to below 40°C; then add an inhibitor and stir for 6 minutes; slowly dropwise add a crosslinking agent and stir for 18 minutes; finally add a catalyst and stir for 8 minutes to obtain a final slurry. Transfer the slurry to a vacuum planetary mixer, and defoam it at -0.1 MPa and 25°C for 30 minutes, and control the viscosity to be 5500 - 5800 mPa·s;

[0066] S4. Material extrusion: Feed the slurry into the screw extrusion nozzle of the printer. After it completely becomes liquid in the nozzle, the nozzle moves to extrude the liquid slurry; the nozzle diameter is 0.3 mm; precisely control the moving speed and extrusion amount of the nozzle to ensure the accuracy and thickness of each layer;

[0067] S5. Deposition molding: The extruded material quickly cools and solidifies in mid-air, and then deposits on the workbench. After each layer of deposition is completed, the workbench rises 15 microns to deposit the next layer on a new plane. Repeat this process until the entire three-dimensional model is completed; the printing layer thickness is 2 mm, and the printing speed is 20 mm / s;

[0068] S6. Post-treatment: After printing, perform post-treatment operations on the model. The post-treatment operations include removing the support structure, coating the surface, and coloring to obtain a phase change compressible silicone gasket.

[0069] Example 3

[0070] This embodiment provides a phase change compressible silicone gasket based on additive manufacturing. By mass, it includes 40 parts of methyl vinyl silicone rubber, 1.5 parts of crosslinking agent, 0.8 part of chain extender, 20 parts of monofunctional vinyl, 0.08 part of inhibitor, 35 parts of flame retardant, 3 parts of phase change microcapsules, 2 parts of colorant, and 0.04 part of catalyst;

[0071] The crosslinking agent is polymethylhydrosiloxane (PMHS);

[0072] The chain extender is hydroxyl-terminated polydimethylsiloxane;

[0073] The monofunctional vinyl is vinyltrimethoxysilane (VTMS);

[0074] The inhibitor is ethynylcyclohexanol (ECH);

[0075] The flame retardant is aluminum hydroxide (ATH);

[0076] The catalyst is platinum-divinyltetramethyldisiloxane complex;

[0077] The phase change microcapsules are paraffin-based core-shell microcapsules. The paraffin-based core-shell microcapsules are composed of an inner core and an outer shell. The inner core is selected as paraffin, and the outer shell is silica. The phase change microcapsules are paraffin@SiO2 phase change microcapsules;

[0078] The colorant is iron oxide red, and the particle size of the colorant is 0.5 - 5 μm;

[0079] The preparation method of the above-mentioned phase change compressible silicone gasket based on additive manufacturing includes the following steps:

[0080] S1. Matrix premixing: Add methyl vinyl silicone rubber, monofunctional vinyl, and chain extender into a blender, and control the stirring speed at 400 rpm and stir for 40 minutes at 60°C and a vacuum degree of -0.095 MPa to obtain a matrix premixed system;

[0081] S2. Functional filler dispersion: Then, sequentially add the flame retardant and phase change microcapsules to the matrix premixed system, and use a three-roll mill to disperse to obtain a dispersed system; add the colorant to the dispersed system, and treat it with an ultrasonic disperser at 500 W and 20 kHz for 18 minutes to obtain a mixture;

[0082] S3. Slurry preparation: Cool the mixture to below 40°C; then add the inhibitor and stir for 6 minutes; slowly dropwise add the crosslinking agent and stir for 18 minutes; finally, add the catalyst and stir for 8 minutes to obtain the final slurry. Transfer the slurry to a vacuum planetary blender and defoam for 30 minutes at -0.1 MPa and 25°C, and control the viscosity to be 5500 - 5800 mPa·s;

[0083] S4, Material Extrusion: Feed the slurry into the screw extrusion nozzle of the printer. After it completely becomes liquid inside the nozzle, the nozzle moves to extrude the liquid slurry; the nozzle diameter is 0.3 mm; precisely control the moving speed and extrusion amount of the nozzle to ensure the precision and thickness of each layer;

[0084] S5, Deposition Molding: The extruded material rapidly cools and solidifies in mid-air and then deposits on the workbench. After each layer of deposition is completed, the workbench rises by 15 microns to enable the next layer of deposition on a new plane. Repeat this process until the entire three-dimensional model is completed; the printing layer thickness is 2 mm, and the printing speed is 20 mm / s;

[0085] S6, Post-treatment: After printing is completed, perform post-treatment operations on the model. The post-treatment operations include removing the support structure, coating the surface, and coloring to obtain a phase-change compressible silicone gasket.

[0086] Comparative Example 1

[0087] This comparative example provides a silicone gasket which, by mass, includes 42 parts of methyl vinyl silicone rubber, 1.4 parts of cross-linking agent, 0.9 part of chain extender, 18 parts of monofunctional vinyl, 0.08 part of inhibitor, 32 parts of flame retardant, 0 part of phase-change microcapsule, 2 parts of colorant, and 0.04 part of catalyst;

[0088] The cross-linking agent is polymethylhydrosiloxane (PMHS);

[0089] The chain extender is hydroxyl-terminated polydimethylsiloxane;

[0090] The monofunctional vinyl is vinyltrimethoxysilane (VTMS);

[0091] The inhibitor is ethynylcyclohexanol (ECH);

[0092] The flame retardant is aluminum hydroxide (ATH);

[0093] The catalyst is platinum-divinyltetramethyldisiloxane complex;

[0094] The colorant is iron oxide red, and the particle size of the colorant is 0.5 - 5 μm;

[0095] The preparation method of the above-mentioned phase-change compressible silicone gasket based on additive manufacturing includes the following steps:

[0096] S1, Matrix Premixing: Add methyl vinyl silicone rubber, monofunctional vinyl, and chain extender into a blender and control the stirring speed at 400 rpm and stir for 40 minutes under the conditions of 60 °C and a vacuum degree of -0.095 MPa to obtain a matrix premixed system;

[0097] S2. Functional filler dispersion: Then, a flame retardant is successively added to the matrix premixed system, and dispersion is carried out using a three-roll mill to obtain a dispersion system; a colorant is added to the dispersion system, and it is treated with an ultrasonic disperser at 500 W and 20 kHz for 18 minutes to obtain a mixture;

[0098] S3. Slurry preparation: The mixture is cooled to below 40 °C; then an inhibitor is added thereto and stirred for 6 minutes; a crosslinking agent is slowly added dropwise and stirred for 18 minutes; finally, a catalyst is added and stirred for 8 minutes to obtain a final slurry. The slurry is transferred to a vacuum planetary mixer and degassed at -0.1 MPa and 25 °C for 30 minutes, and the viscosity is controlled to be 5500 - 5800 mPa·s;

[0099] S4. Material extrusion: The slurry is fed into the screw extrusion nozzle of the printer. After it completely becomes liquid in the nozzle, the nozzle moves to extrude the liquid slurry; the nozzle diameter is 0.3 mm; the moving speed and extrusion amount of the nozzle are precisely controlled to ensure the accuracy and thickness of each layer;

[0100] S5. Deposition molding: The extruded material rapidly cools and solidifies in mid-air, and then is deposited on the workbench. After each layer of deposition is completed, the workbench rises by 15 microns to facilitate the deposition of the next layer on a new plane. This process is repeated until the entire three-dimensional model is completed; the printing layer thickness is 2 mm, and the printing speed is 20 mm / s;

[0101] S6. Post-treatment: After printing is completed, post-treatment operations are performed on the model. The post-treatment operations include removing the support structure, coating the surface, and coloring to obtain a phase-change compressible silicone gasket.

[0102] Comparative Example 2

[0103] This comparative example provides a silicone gasket, which includes 42 parts by mass of methyl vinyl silicone rubber, 1.4 parts of crosslinking agent, 0 parts of chain extender, 18 parts of monofunctional vinyl, 0.08 parts of inhibitor, 32 parts of flame retardant, 4 parts of phase-change microcapsule, 2 parts of colorant, and 0.04 parts of catalyst;

[0104] The crosslinking agent is polymethylhydrosiloxane (PMHS);

[0105] The monofunctional vinyl is vinyltrimethoxysilane (VTMS);

[0106] The inhibitor is ethynylcyclohexanol (ECH);

[0107] The flame retardant is aluminum hydroxide (ATH);

[0108] The catalyst is platinum-divinyltetramethyldisiloxane complex;

[0109] The phase change microcapsules are paraffin-based core-shell microcapsules, which are composed of an inner core and an outer shell. The inner core is selected as paraffin, and the outer shell is silica. The phase change microcapsules are paraffin@SiO2 phase change microcapsules;

[0110] The colorant is iron oxide red, and the particle size of the colorant is 0.5 - 5 μm;

[0111] The preparation method of the above-mentioned phase change compressible silicone gasket based on additive manufacturing includes the following steps:

[0112] S1. Matrix premixing: Add methyl vinyl silicone rubber and monofunctional vinyl into a blender, and control the stirring speed at 400 rpm and stir for 40 minutes under the conditions of 60 °C and a vacuum degree of -0.095 MPa to obtain a matrix premixed system;

[0113] S2. Functional filler dispersion: Then, add a flame retardant and phase change microcapsules to the matrix premixed system in sequence, and use a three-roll mill for dispersion to obtain a dispersed system; add a colorant to the dispersed system, and treat it with an ultrasonic disperser at 500 W and 20 kHz for 18 minutes to obtain a mixture;

[0114] S3. Slurry preparation: Cool the mixture to below 40 °C; then add an inhibitor and stir for 6 minutes; slowly dropwise add a crosslinking agent and stir for 18 minutes; finally, add a catalyst and stir for 8 minutes to obtain a final slurry. Transfer the slurry to a vacuum planetary mixer, and defoam at -0.1 MPa and 25 °C for 30 minutes, and control the viscosity to be 5500 - 5800 mPa·s;

[0115] S4. Material extrusion: Feed the slurry into the screw extrusion nozzle of the printer. After it completely becomes liquid in the nozzle, the nozzle moves to extrude the liquid slurry; the nozzle diameter is 0.3 mm; precisely control the moving speed and extrusion amount of the nozzle to ensure the accuracy and thickness of each layer;

[0116] S5. Deposition molding: The extruded material quickly cools and solidifies in the air, and then deposits on the workbench. After each layer of deposition is completed, the workbench will rise by 15 microns to facilitate the deposition of the next layer on a new plane. Repeat this process until the entire three-dimensional model is completed; the printing layer thickness is 2 mm, and the printing speed is 20 mm / s;

[0117] S6. Post-treatment: After printing, perform post-treatment operations on the model. The post-treatment operations include removing the support structure, coating the surface, and coloring to obtain a phase change compressible silicone gasket.

[0118] Comparative Example 3

[0119] This comparative example provides a silicone gasket. The composition of the silicone gasket in this comparative example is the same as that in Example 1, and the traditional molding method is adopted in this comparative example.

[0120] Perform performance tests on the phase change compressible silicone gaskets prepared in Examples 1 - 3 and the silicone gaskets prepared in Comparative Examples 1 - 3. The test results are shown in Table 1.

[0121] Table 1

[0122]

[0123] It can be seen from Table 1 that comparing Example 1 with Comparative Example 1, it can be seen that adding 4 parts of microcapsules increases the hot spot delay time from 5 min to 18 min, and the phase change enthalpy value reaches 23 J / g; comparing Example 1 with Comparative Example 2, it can be seen that the lack of chain extender leads to an increase in permanent deformation to 15% and poor interfacial bonding strength; comparing Example 1 with Comparative Example 3, it can be seen that additive manufacturing has higher dimensional accuracy, but slightly lower surface finish; and additive manufacturing saves mold costs; in Example 2, when the addition amount of microcapsules is 5 parts, the phase change enthalpy value is optimal (25 J / g), but the cost is slightly higher.

[0124] In summary, the present invention adds a phase change material with a special formula design, which can dynamically change the size with the change of temperature, sensitively follow the size change of the component, has multiple functions such as heat conduction, very good elasticity and thermal stability; the thermoplastic elastomer can ensure the initial thickness and elasticity under high and low temperature cycles; there is no oil leakage and very low small molecule volatilization; the additive manufacturing of the present invention can pre - generate a visual virtual drawing, which is convenient for adjusting and optimizing parameters before production to meet customer requirements. Once the traditional mold is opened, it cannot be modified, and it can also be transmitted to other terminals for off - site production; the material quality and appearance of the additive manufacturing production of the present invention are controllable. By using the method of screw extrusion + spraying layer - by - layer printing to produce the phase change silicone compression gasket, off - site production can be realized, without burrs, saving materials, not requiring additional cleaning, being environmentally friendly and simple, greatly saving production costs, and can also be extended to the production of other polymer materials; the present invention can achieve phase change compressibility, intelligently and dynamically change the size, and has a unique silicone gasket compression ratio curve.

[0125] The above - described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A phase change compressible silicone gasket based on additive manufacturing, characterized in that, By mass fraction, it includes 40-45 parts of methyl vinyl silicone rubber, 1.3-1.5 parts of crosslinking agent, 0.8-1.0 parts of chain extender, 15-20 parts of monofunctional vinyl, 0.05-0.1 parts of inhibitor, 30-35 parts of flame retardant, 3-5 parts of phase change microcapsule, 1-2 parts of colorant, and 0.03-0.05 parts of catalyst; The monofunctional vinyl is selected from one of vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, vinyldimethylmethoxysilane, γ-methacryloxypropyltrimethoxysilane; The phase change microcapsule is a paraffin-based core-shell microcapsule, and the paraffin-based core-shell microcapsule is composed of an inner core and an outer shell. The inner core is selected from one of n-octadecane, n-eicosane, paraffin wax, and the outer shell is selected from one of melamine-formaldehyde resin, silicon dioxide, and polymethyl methacrylate; The preparation method of the phase change compressible silicone gasket based on additive manufacturing includes the following steps: S1. Matrix premixing: Add methyl vinyl silicone rubber, monofunctional vinyl, and chain extender into a blender, and control the stirring speed at 300 rpm - 500 rpm and stir for 30 - 45 minutes under the conditions of 55 - 65 °C and a vacuum degree of -0.095 MPa to obtain a matrix premixed system; S2. Functional filler dispersion: Then sequentially add the flame retardant and phase change microcapsule to the matrix premixed system, and use a three-roll mill for dispersion to obtain a dispersed system; add the colorant to the dispersed system, and treat it with an ultrasonic disperser at 500 W and 20 kHz for 15 - 18 minutes to obtain a mixture; S3. Slurry preparation: Cool the mixture to below 40 °C; then add the inhibitor and stir for 5 - 8 minutes; slowly dropwise add the crosslinking agent and stir for 15 - 20 minutes; finally add the catalyst and stir for 5 - 8 minutes to obtain the final slurry. Transfer the slurry to a vacuum planetary mixer and defoam for 30 minutes at -0.1 MPa and 25 °C, and control the viscosity at 5000 - 8000 mPa·s; S4. Material extrusion: Feed the slurry into the screw extrusion nozzle of the printer. After it completely becomes liquid in the nozzle, the nozzle moves to extrude the liquid slurry; the nozzle diameter is 0.1 - 0.4 mm; S5. Deposition molding: The extruded material quickly cools and solidifies in the air, and then deposits on the workbench. After each layer of deposition is completed, the workbench will rise by 1 - 50 microns to deposit the next layer on a new plane. Repeat this process until the entire three-dimensional model is completed; the printing layer thickness is 0.02 mm - 20 mm, and the printing speed is 5 mm / s - 100 mm / s; S6. Post-treatment: After printing, perform post-treatment operations on the model. The post-treatment operations include removing the support structure, coating the surface, and coloring to obtain the phase change compressible silicone gasket.

2. The phase change compressible silicone gasket based on additive manufacturing according to claim 1, characterized in that, The crosslinking agent is selected from one or more of polymethylhydrosiloxane, HMS-991, dicumyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

3. The phase change compressible silicone gasket based on additive manufacturing according to claim 1, wherein The chain extender is selected from one or more of hydroxy-terminated polydimethylsiloxane, α,ω-dihydroxy polydimethylsiloxane, tetramethyldivinyldisiloxane, vinyl silicone oil, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane.

4. The phase change compressible silicone gasket based on additive manufacturing according to claim 1, characterized in that, The inhibitor is selected from one or more of ethynylcyclohexanol, methylbutynol, dimethylethynylcarbinol, vinylcyclohexene oxide, diethyl maleate, dibutyltin dilaurate.

5. The phase change compressible silicone gasket based on additive manufacturing according to claim 1, wherein The flame retardant is selected from one of aluminum hydroxide, magnesium hydroxide, nano-silica, layered double hydroxide, carbon nanotubes.

6. The phase change compressible silicone gasket based on additive manufacturing according to claim 1, wherein The catalyst is selected from one of platinum-divinyltetramethyldisiloxane complex, RhCl(PPh3)3.

7. The phase change compressible silicone gasket based on additive manufacturing according to claim 1, wherein The colorant is selected from one of titanium dioxide, iron oxide red, iron oxide black, and the particle size of the colorant is 0.5 - 5 μm.

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