3D printing silicone rubber ink comprising highly dispersed and highly reinforcing white carbon black, and preparation method and use thereof

Abstract

The application provides a 3D printing silicone rubber ink containing highly dispersed and highly reinforcing white carbon black, a preparation method and application thereof. The 3D printing silicone rubber ink contains highly dispersed and highly reinforcing white carbon black and low thickening white carbon black. The combination of the highly dispersed and highly reinforcing white carbon black and the low thickening white carbon black can make the 3D printing silicone rubber ink have thixotropy and self-supporting ability at the same time, and have the characteristics of being compatible with high-function fillers. The application of the 3D printing silicone rubber ink can obtain 3D printing silicone rubber with excellent mechanical properties. The preparation method of the 3D printing silicone rubber ink is simple, the preparation cost is low, the obtained 3D printing silicone rubber has excellent mechanical properties, and the mass production of the 3D printing silicone rubber can be realized, so that the application requirements in multiple fields such as thermal management elastomers and damping and shock absorbing elastomers can be met.

Description

Technical Field

[0001] This invention belongs to the field of new materials technology, specifically providing a 3D printing silicone rubber ink comprising highly dispersed and highly reinforcing silica, its preparation method, and its uses. Background Technology

[0002] Silicone rubber has attracted widespread research attention in fields such as wearable devices, soft robots, and biomedical devices. Extrusion 3D printing is a revolutionary technology for preparing silicone rubber. Through computer-aided design and manufacturing, 3D-printed silicone rubber is expected to possess various complex structures, enabling customized production and achieving high-level performance. However, unlike traditional flat-plate vulcanization technology that utilizes molds, 3D printing technology suitable for thermosetting silicone rubber requires a silicone rubber ink that possesses both thixotropic and self-supporting capabilities. This means the ink must flow stably only under the shearing action of the printing needle and maintain high shape fidelity after landing on the printing platform before thermosetting.

[0003] Existing methods to address this issue involve mixing organosilicon thixotropic agents with liquid silicone rubber to enhance its thixotropy and meet the requirements of specific applications such as moldless encapsulation. However, organosilicon thixotropic agents are insufficient to significantly enhance the mechanical properties of silicone rubber. Therefore, the introduction of inorganic functional fillers is crucial for controlling the rheological and mechanical properties of silicone rubber. Furthermore, the functional level of silicone rubber is highly dependent on the high loading of inorganic functional fillers.

[0004] However, high filler content easily leads to the agglomeration of functional fillers, causing printing nozzle clogging and compromising the mechanical strength of silicone rubber. Existing research attempts to circumvent this agglomeration problem by using a backfill method. This involves printing with ink containing functional fillers, freeze-drying the printed structure, and then backfilling the silicone rubber onto the functional filler matrix. However, this strategy severely limits the complexity and diversity of printed structures, is cumbersome in the production process, and increases energy consumption. Therefore, designing a 3D printing silicone rubber ink that combines printability and excellent mechanical properties, while achieving compatibility with various functional fillers, is a key challenge for the multifunctional development of 3D printing silicone rubber. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a 3D printing silicone rubber ink comprising highly dispersed and highly reinforcing silica, its preparation method, and its applications. The 3D printing silicone rubber ink provided by this invention comprises highly dispersed and highly reinforcing silica and low-thickening silica. The combined use of these two silicas enables the 3D printing silicone rubber ink to simultaneously possess thixotropic and self-supporting capabilities, and also exhibits compatibility with high-quality functional fillers. Applying this 3D printing silicone rubber ink can yield 3D printing silicone rubber with excellent mechanical properties. The preparation method of this 3D printing silicone rubber ink is simple, has low preparation cost, and produces 3D printing silicone rubber with excellent mechanical properties, facilitating the mass production of 3D printing silicone rubber and meeting the application needs of various fields such as thermal management elastomers and damping elastomers.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A 3D printing silicone rubber ink, the 3D printing silicone rubber ink comprising highly dispersed and highly reinforcing silica and low-thickening silica;

[0008] The highly dispersed and highly reinforcing silica is selected from hydrophilic silica with hydroxyl groups on its surface; the primary particles of the highly dispersed and highly reinforcing silica are random fine gravel, and the primary particles constitute a branched secondary filler structure with a size of 0.2-1 μm.

[0009] The primary particles of the low-thickness silica have a particle size of 5-30 nm, and the primary particles form aggregates with a length of 60-500 nm. The aggregates have a flat structure with a thickness-to-length ratio of 1:8-1:20.

[0010] The beneficial effects of this invention are:

[0011] (1) Starting from the regulation of the physicochemical properties of functional fillers, this invention introduces highly dispersed and highly reinforcing silica into the silicone rubber matrix. Due to the high dispersion characteristics of highly dispersed and highly reinforcing silica, adding a very small amount of highly dispersed and highly reinforcing silica to the 3D printing silicone rubber ink can impart thixotropic properties to the 3D printing silicone rubber ink. At the same time, the introduced low-thickening silica can provide self-supporting ability to the 3D printing silicone rubber ink. This invention also regulates the rheological properties of 3D printing silicone rubber ink by controlling the filler composition, realizing the printability of thermosetting silicone rubber in the extrusion 3D printing process, and providing a feasible solution for the composition design of 3D printing silicone rubber ink.

[0012] (2) The 3D printing silicone rubber ink provided by this invention, comprising highly dispersed and highly reinforcing silica and low-thickening silica, not only possesses thixotropic properties and the ability to shape printed structures, but also enables the loading of high-quality functional fillers, which is beneficial for the efficient and mass production of multifunctional silicone rubber. 3D printing silicone rubber prepared using the aforementioned ink can achieve high elongation at break and high tensile strength on the basis of high thermal conductivity, overcoming the problem of poor mechanical strength of the silicone rubber matrix and meeting the mechanical performance requirements of products in thermal management or damping applications.

[0013] (3) Compared with photocurable silicone rubber, the thermocurable silicone rubber of the present invention is not limited to the selection of photocurable polymers and fillers that are transparent to light sources in the selection of 3D printing silicone rubber ink. It does not require the introduction of photoinitiators that may cause a decrease in the mechanical properties of silicone rubber and have potential biotoxicity. It has high material adaptability and is conducive to achieving the simultaneous improvement of the multifunctionality of silicone rubber elastomer and mechanical strength. Attached Figure Description

[0014] Figure 1 The shear viscosity curves of the 3D printing silicone rubber inks of Example 2, Comparative Example 1, Comparative Example 2 and Comparative Example 3 are shown.

[0015] Figure 2 The shear modulus curves of the 3D printing silicone rubber inks of Examples 2, 6, 1, 2 and 4 are shown.

[0016] Figure 3 A schematic diagram of the 3D-printed silicone rubber with a mesh structure obtained in Example 5 is shown. Detailed Implementation

[0017] <3D Printing Silicone Rubber Ink>

[0018] As mentioned above, the present invention provides a 3D printing silicone rubber ink, the 3D printing silicone rubber ink comprising highly dispersed and highly reinforcing silica and low-thickening silica;

[0019] The highly dispersed and highly reinforcing silica is selected from hydrophilic silica with hydroxyl groups on its surface; the primary particles of the highly dispersed and highly reinforcing silica are random fine gravel, and the primary particles constitute a branched secondary filler structure with a size of 0.2-1 μm.

[0020] The primary particles of the low-thickness silica have a particle size of 5-30 nm, and the primary particles form aggregates with a length of 60-500 nm. The aggregates have a flat structure with a thickness-to-length ratio of 1:8-1:20.

[0021] According to an embodiment of the present invention, the 3D printing silicone rubber ink further includes liquid silicone rubber and a curing agent.

[0022] According to an embodiment of the present invention, the 3D printing silicone rubber ink comprises the following components in parts by weight:

[0023] 1-10 parts by weight of highly dispersed and highly reinforcing silica;

[0024] 15-60 parts by weight of low-thickening silica;

[0025] 100 parts by weight of liquid silicone rubber;

[0026] Hardener 0.1-10 parts by weight.

[0027] According to an embodiment of the present invention, the 3D printing silicone rubber ink comprises 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, or 10 parts by weight of highly dispersed and highly reinforcing silica.

[0028] According to an embodiment of the present invention, the 3D printing silicone rubber ink comprises 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 50 parts by weight, 55 parts by weight, and 60 parts by weight of low-thickening silica.

[0029] According to an embodiment of the present invention, the 3D printing silicone rubber ink includes 0.1 parts by weight, 0.2 parts by weight, 0.5 parts by weight, 0.8 parts by weight, 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, or 10 parts by weight of curing agent.

[0030] According to an embodiment of the present invention, the 3D printing silicone rubber ink further includes functional fillers.

[0031] According to an embodiment of the present invention, the 3D printing silicone rubber ink comprises the following components in parts by weight:

[0032] 1-10 parts by weight of highly dispersed and highly reinforcing silica;

[0033] 15-60 parts by weight of low-thickening silica;

[0034] Functional filler: 0-500 parts by weight; preferably 20-500 parts by weight;

[0035] 100 parts by weight of liquid silicone rubber;

[0036] Hardener 0.1-10 parts by weight.

[0037] According to an embodiment of the present invention, the 3D printing silicone rubber ink comprises 1 part by weight, 5 parts by weight, 10 parts by weight, 20 parts by weight, 50 parts by weight, 80 parts by weight, 100 parts by weight, 120 parts by weight, 150 parts by weight, 180 parts by weight, 200 parts by weight, 300 parts by weight, 400 parts by weight, and 500 parts by weight of functional filler.

[0038] Highly Dispersible and Highly Reinforcing Silica

[0039] According to an embodiment of the present invention, the highly dispersed and highly reinforcing silica can regulate the thixotropic properties of 3D printing silicone rubber ink, thereby achieving mechanical reinforcement of 3D printing silicone rubber.

[0040] According to an embodiment of the present invention, the hydroxyl groups on the surface of the highly dispersed and highly reinforcing silica can interact with the Si-O chains in silicone rubber through hydrogen bonding, resulting in increased viscosity of the 3D printing silicone rubber ink in a static state. Under shearing, weak intermolecular interactions such as hydrogen bonds are disrupted, leading to decreased viscosity of the 3D printing silicone rubber ink and improved thixotropy. The primary particles of the highly dispersed and highly reinforcing silica are random fine gravel-like particles, forming a branched secondary filler structure with a size of 0.2-1 μm. This indicates that the highly dispersed and highly reinforcing silica has a highly dispersed characteristic. Due to the high dispersion characteristic of the highly dispersed and highly reinforcing silica, the thixotropy of the 3D printing silicone rubber ink can be further improved, especially for controlling the thixotropy of the 3D printing silicone rubber ink at a lower filler content.

[0041] According to an embodiment of the present invention, the highly dispersed and highly reinforcing silica has a branched secondary filler structure; the branched secondary filler structure is composed of primary particles, which have a random, fine, gravel-like structure.

[0042] According to an embodiment of the present invention, the particle size of the primary particles is 5-15 nm, for example, 5 nm, 10 nm or 15 nm.

[0043] According to an embodiment of the present invention, the size of the branched secondary packing structure is 0.2-1 μm, for example, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm or 1 μm.

[0044] According to an embodiment of the present invention, the specific surface area of ​​the highly dispersed and highly reinforcing silica is 340-420 m². 2 / g, for example, 340m 2 / g, 350m 2 / g、360m 2 / g、370m 2 / g、380m2 / g、390m 2 / g、400m 2 / g、410m 2 / g or 420m 2 / g.

[0045] According to an embodiment of the present invention, the average particle size of the highly dispersed and highly reinforcing silica is 0.2-1 μm, for example, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm or 1 μm.

[0046] According to an embodiment of the present invention, the preparation method of the highly dispersed and highly reinforcing silica includes the following steps:

[0047] i) Hydrophilic silica is prepared by burning chlorosilane with hydrogen and air.

[0048] ii) The hydrophilic silica prepared in step i) is mixed with sodium silicate and / or silicate ester, and then dispersed and graded to prepare the highly dispersed and highly reinforcing silica.

[0049] In a preferred embodiment of the present invention, in step i), the chlorosilane is selected from chlorosilanes known in the art, and by way of example, the chlorosilane is selected from monomethyltrichlorosilane or silicon tetrachloride.

[0050] In a preferred embodiment of the present invention, in step i), the hydrophilic silica is fumed silica known in the art.

[0051] In a preferred embodiment of the present invention, in step ii), the mass ratio of the hydrophilic silica to sodium silicate and / or silicate ester is 100:0.5-5, for example, 100:0.5, 100:1, 100:2, 100:3, 100:4 or 100:5.

[0052] In a preferred embodiment of the present invention, in step ii), the sodium silicate and / or silicate ester are introduced into the reaction system as surface modifiers, which can effectively increase the hydroxyl content on the surface of hydrophilic silica and reduce the size of the branched secondary filler structure, thereby improving the dispersion performance of hydrophilic silica and obtaining highly dispersed and highly reinforced silica.

[0053] In a preferred embodiment of the invention, in step ii), the dispersion is performed in a dispersion apparatus known in the art.

[0054] In a preferred embodiment of the present invention, in step ii), the frequency of dispersion is 20-50Hz, for example, 20Hz, 30Hz, 40Hz or 50Hz.

[0055] In a preferred embodiment of the present invention, in step ii), the grading is performed in a grading device known in the art.

[0056] In a preferred embodiment of the present invention, in step ii), the frequency of the gradation is 40-80Hz, for example, 40Hz, 50Hz, 60Hz, 70Hz or 80Hz.

[0057] Low-thickness silica

[0058] According to an embodiment of the present invention, the primary particles of the low-thickness silica have a particle size of 5-30 nm, the primary particles form aggregates, the length of the aggregates is 60-500 nm, the aggregates have a flat structure, and the thickness-to-length ratio of the flat structure is 1:8-1:20. Research has found that the low-thickness silica has a flat structure, which endows it with good low-thickness properties. When the low-thickness silica with the above structural characteristics is used in 3D printing silicone rubber ink, because the low-thickness silica can be uniformly dispersed in the silicone rubber matrix, through a relatively high filler content, it can form crosslinking points in the silicone rubber matrix, increasing the entanglement of silicone rubber molecular chains and the interaction between filler and matrix, improving the silicone rubber compound's ability to resist its own gravity and surface tension, thereby giving the 3D printing silicone rubber ink stronger self-supporting ability and enhancing the mechanical properties of 3D printing silicone rubber.

[0059] According to an embodiment of the present invention, the specific surface area of ​​the low-thickening silica is 110-300 m². 2 / g, for example, 110m 2 / g、120m 2 / g, 150m 2 / g、160m 2 / g、180m 2 / g、200m 2 / g、220m 2 / g、240m 2 / g、250m 2 / g、260m 2 / g、280m 2 / g or 300m 2 / g.

[0060] According to an embodiment of the present invention, the carbon content of the low-thickening silica is 1.5-3.5 wt%, for example, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, or 3.5 wt%.

[0061] According to an embodiment of the present invention, the particle size of the primary particles of the low-thickness silica is 5nm, 10nm, 15nm, 20nm, 25nm or 30nm.

[0062] According to an embodiment of the present invention, the length of the aggregate is 60nm, 70nm, 80nm, 90nm, 100nm, 120nm, 150nm, 180nm, 200nm, 250nm, 280nm, 300nm, 330nm, 350nm, 380nm, 400nm, 450nm, 480nm, or 500nm.

[0063] According to an embodiment of the present invention, the thickness to length ratio of the flat structure is 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19 or 1:20.

[0064] According to an embodiment of the present invention, the low-thickening silica is a hydrophobic silica modified with methyl functional groups.

[0065] According to an embodiment of the present invention, the preparation method of the low-thickening silica can refer to the method disclosed in Chinese patent document CN113105758A.

[0066] Liquid silicone rubber

[0067] According to an embodiment of the present invention, the liquid silicone rubber can be prepared by methods known in the art or obtained through commercial purchase.

[0068] According to an embodiment of the present invention, the viscosity of the liquid silicone rubber is 0.5-10 Pa·s, for example, 0.5 Pa·s, 1 Pa·s, 2 Pa·s, 3 Pa·s, 4 Pa·s, 5 Pa·s, 6 Pa·s, 7 Pa·s, 8 Pa·s, 9 Pa·s or 10 Pa·s.

[0069] <Curing agent>

[0070] According to an embodiment of the present invention, the curing agent is selected from one or more of platinum catalysts, organotin catalysts, or titanate catalysts.

[0071] <Functional packing>

[0072] According to an embodiment of the present invention, the functional filler is selected from one or more of alumina, aluminum nitride, and boron nitride.

[0073] According to an embodiment of the present invention, the functional filler is a spherical functional filler.

[0074] According to embodiments of the present invention, the average particle size of the functional filler is 5-200 μm, for example, 5 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm or 200 μm.

[0075] <Preparation Method of 3D Printing Silicone Rubber Ink>

[0076] The present invention also provides a method for preparing the above-mentioned 3D printing silicone rubber ink, the method comprising the following steps:

[0077] Highly dispersed and highly reinforcing silica, low-thickening silica, liquid silicone rubber, curing agent, and optionally functional fillers are mixed and degassed to obtain 3D printing silicone rubber ink.

[0078] According to an embodiment of the present invention, the mixing is carried out under stirring conditions, with a stirring speed of 1000-2000 rpm and a stirring time of 10-30 min.

[0079] According to an embodiment of the present invention, the degassing is centrifugal degassing, the centrifugal degassing speed is 1000-3000 rpm, and the centrifugal degassing time is 5-30 min.

[0080] <Applications of 3D Printing Silicone Rubber Ink>

[0081] The present invention also provides the use of the above-mentioned 3D printing silicone rubber ink in the field of 3D printing silicone rubber.

[0082] <3D Printing Silicone Rubber>

[0083] The present invention also provides a 3D printing silicone rubber, which is prepared by the above-mentioned 3D printing silicone rubber ink.

[0084] According to an embodiment of the present invention, the 3D printing silicone rubber is prepared by 3D printing using the above-mentioned 3D printing silicone rubber ink.

[0085] According to an embodiment of the present invention, the 3D printing is extrusion 3D printing.

[0086] According to an embodiment of the present invention, the parameters of the 3D printing include: extrusion pressure 0.1-0.5MPa, printing speed 5-20mm / min, initial platform spacing 0.2-0.6mm, printing layer height 0.2-0.6mm, and printing linewidth 0.2-1.0mm.

[0087] The present invention also provides a 3D printing silicone rubber, wherein the raw materials for preparing the 3D printing silicone rubber include the above-mentioned 3D printing silicone rubber ink.

[0088] <Preparation Method of 3D Printed Silicone Rubber>

[0089] This invention also provides a method for preparing 3D printed silicone rubber, the method comprising the following steps:

[0090] (a) Set the printing parameters and extrude the 3D printing silicone rubber ink into a predetermined structure to obtain a three-dimensional silicone rubber preform.

[0091] (b) The three-dimensional silicone rubber preform from step (a) is heat-treated to obtain 3D printed silicone rubber.

[0092] According to an embodiment of the present invention, in step (a), the printing parameters include: extrusion pressure 0.1-0.5MPa, printing speed 5-20mm / min, initial platform spacing 0.2-0.6mm, printing layer height 0.2-0.6mm, and printing line width 0.2-1.0mm.

[0093] According to an embodiment of the present invention, in step (b), the temperature of the heat treatment is 100-150°C and the time of the heat treatment is 60-180 minutes.

[0094] According to an embodiment of the present invention, in step (b), the 3D printed silicone rubber is a silicone rubber with enhanced mechanical properties.

[0095] <Applications of 3D Printed Silicone Rubber>

[0096] The present invention also provides applications of the above-mentioned 3D printed silicone rubber in the fields of thermal management or damping and vibration reduction.

[0097] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0098] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0099] Unless otherwise specified, the component content in the 3D printing silicone rubber ink in the following examples and comparative examples refers to parts by weight.

[0100] The low-thickening silica used in the following examples and comparative examples was prepared by the following method:

[0101] 1) Preparation of precursor solution

[0102] The silicon precursor tetraethyl orthosilicate and tetramethyldivinyldisilazane were added to ethanol to prepare a solution with a tetraethyl orthosilicate concentration of 0.5 wt% and a tetramethyldivinyldisilazane concentration of 5 wt%. The solution was stirred for 20 minutes to allow the silicon precursor to dissolve fully in the solvent.

[0103] 2) Structural flattening modification

[0104] The tap density of 1 kg is 55 g / L, and the specific surface area is 205 m². 2 / g of fumed silica powder was added to a rotary vacuum reactor;

[0105] Take 12L of the precursor solution obtained in step 1) and spray it evenly onto the above fumed silica powder to fully wet the powder;

[0106] Turn on the rotary vacuum reactor, start the rotation, turn on the vacuum pump, and turn on the heating;

[0107] The first stage of heating is at 80℃ and the reaction lasts for 3 hours. The second stage of heating is at 110℃ and the reaction lasts for 2 hours. The third stage of heating is at 180℃ and the reaction lasts for 5 hours.

[0108] The rotation speed is 8 rpm and the vacuum degree is 10. 4 Pa.

[0109] The low-thickness silica has an aggregate size of 80 nm, a flat structure, and a thickness-to-length ratio of 1:16.

[0110] The highly dispersed and highly reinforcing silica used in the following examples and comparative examples was prepared by the following method:

[0111] 1) Using silicon tetrachloride as a raw material, hydrogen and air are introduced for combustion to prepare a product with a specific surface area of ​​400 m². 2 / g of hydrophilic silica;

[0112] 2) The prepared hydrophilic silica and sodium silicate are mixed at a mass ratio of 100:1. The mixture is then placed in a dispersion device for dispersion treatment (dispersion frequency of 30Hz), and then classified in a classification device (classification frequency of 50Hz) to obtain highly dispersed and highly reinforcing silica with a particle size of 0.2-1μm.

[0113] Example 1

[0114] Two parts of highly dispersed and reinforcing silica, 30 parts of low-thickening silica, 100 parts of liquid silicone rubber (viscosity 5.2 Pa·s) and 10 parts of platinum catalyst were mixed and centrifuged at 2000 rpm for 5 min to obtain 3D printing silicone rubber ink. This 3D printing silicone rubber ink has both thixotropic and shaping capabilities.

[0115] The printing parameters were set, including an extrusion pressure of 0.40 MPa, a printing speed of 10 mm / min, an initial platform spacing of 0.3 mm, a layer height of 0.3 mm, and a linewidth of 0.4 mm. The 3D printing silicone rubber ink was extruded and 3D printed according to a predetermined structure to obtain a three-dimensional silicone rubber preform. The three-dimensional silicone rubber preform was then heat-treated at 150°C for 30 minutes to obtain 3D printed silicone rubber with a specific structure, exhibiting high structural precision and excellent tensile properties.

[0116] Example 2

[0117] Three parts of highly dispersed and reinforcing silica, 21 parts of low-thickening silica, 100 parts of liquid silicone rubber (viscosity 5.2 Pa·s), and 10 parts of platinum catalyst were mixed and then centrifuged at 2000 rpm for 5 minutes to obtain 3D printing silicone rubber ink. Figure 1 and Figure 2 As shown, this 3D printing silicone rubber ink combines thixotropy and shaping ability.

[0118] The printing parameters were set, including an extrusion pressure of 0.37 MPa, a printing speed of 10 mm / min, an initial platform spacing of 0.4 mm, a layer height of 0.4 mm, and a linewidth of 0.5 mm. The 3D printing silicone rubber ink was extruded and 3D printed according to a predetermined structure to obtain a three-dimensional silicone rubber preform. The three-dimensional silicone rubber preform was then heat-treated at 150°C for 30 minutes to obtain 3D printed silicone rubber with a specific structure, exhibiting high structural precision and excellent tensile properties.

[0119] Example 3

[0120] Five parts of highly dispersed and reinforcing silica, 35 parts of low-thickening silica, 100 parts of liquid silicone rubber (viscosity 2.5 Pa·s) and 0.2 parts of platinum catalyst were mixed and centrifuged at 2000 rpm for 10 min to obtain 3D printing silicone rubber ink. This 3D printing silicone rubber ink has both thixotropic and shaping capabilities.

[0121] The printing parameters were set as follows: extrusion pressure 0.42 MPa, printing speed 5 mm / min, initial platform spacing 0.5 mm, layer height 0.5 mm, and linewidth 0.8 mm. The 3D printing silicone rubber ink was extruded and 3D printed according to the predetermined structure to obtain a three-dimensional silicone rubber preform. The three-dimensional silicone rubber preform was then heat-treated at 100°C for 120 minutes to obtain 3D printed silicone rubber, which exhibited high structural precision and excellent tensile properties.

[0122] Example 4

[0123] Three parts of highly dispersed and reinforcing silica, 45 parts of low-thickening silica, 100 parts of liquid silicone rubber (viscosity 2.5 Pa·s) and 0.2 parts of platinum catalyst were mixed and centrifuged at 2000 rpm for 10 min to obtain 3D printing silicone rubber ink. This 3D printing silicone rubber ink has both thixotropic and shaping capabilities.

[0124] The printing parameters were set as follows: extrusion pressure 0.47 MPa, printing speed 5 mm / min, initial platform spacing 0.5 mm, layer height 0.5 mm, and linewidth 0.8 mm. The 3D printing silicone rubber ink was extruded and 3D printed according to the predetermined structure to obtain a three-dimensional silicone rubber preform. The three-dimensional silicone rubber preform was then heat-treated at 100°C for 120 minutes to obtain 3D printed silicone rubber, which exhibited high structural precision and excellent tensile properties.

[0125] Example 5

[0126] Two parts of highly dispersed and reinforcing silica, 18 parts of low-thickening silica, 100 parts of liquid silicone rubber (viscosity 5.2 Pa·s), 10 parts of platinum catalyst, and 300 parts of spherical alumina thermally conductive filler with an average particle size of 120 μm were mixed and centrifuged at 2000 rpm for 20 min to obtain 3D printing silicone rubber ink. This 3D printing silicone rubber ink has both thixotropic and shaping capabilities.

[0127] The printing parameters were set, including an extrusion pressure of 0.44 MPa, a printing speed of 5 mm / min, an initial platform spacing of 0.5 mm, a layer height of 0.5 mm, and a linewidth of 0.8 mm. The 3D printing silicone rubber ink was extruded and 3D printed according to the predetermined structure to obtain a three-dimensional silicone rubber preform. The three-dimensional silicone rubber preform was then heat-treated at 150°C for 30 minutes to obtain the 3D printed silicone rubber.

[0128] Figure 3 This diagram illustrates the structure of the 3D-printed silicone rubber with a mesh structure obtained in Example 5. Figure 3As can be seen, the 3D-printed silicone rubber exhibits excellent mesh structure precision. This indicates that the resulting 3D-printed silicone rubber possesses high structural precision, excellent thermal conductivity, and excellent tensile properties.

[0129] Example 6

[0130] Two parts of highly dispersed and reinforcing silica, 30 parts of low-thickening silica, 100 parts of liquid silicone rubber (viscosity 5.2 Pa·s), 10 parts of platinum catalyst, 180 parts of spherical aluminum nitride with an average particle size of 120 μm, 90 parts of spherical aluminum nitride with an average particle size of 80 μm, and 30 parts of spherical aluminum nitride with an average particle size of 20 μm were mixed and centrifuged at 2000 rpm for 20 min to obtain 3D printing silicone rubber ink. Figure 2 As shown, this 3D printing silicone rubber ink combines thixotropy and shaping ability.

[0131] The printing parameters were set as follows: extrusion pressure 0.50 MPa, printing speed 5 mm / min, initial platform spacing 0.5 mm, layer height 0.5 mm, and linewidth 0.8 mm. The 3D printing silicone rubber ink was extruded and 3D printed according to the predetermined structure to obtain a three-dimensional silicone rubber preform. The three-dimensional silicone rubber preform was then heat-treated at 150°C for 30 minutes to obtain 3D printed silicone rubber. The resulting 3D printed silicone rubber exhibits high structural precision, excellent thermal conductivity, and excellent tensile properties.

[0132] Example 7

[0133] Seven parts of highly dispersed and reinforcing silica, 15 parts of low-thickening silica, 100 parts of liquid silicone rubber (viscosity 2.5 Pas), 0.2 parts of platinum catalyst, 240 parts of spherical aluminum nitride with an average particle size of 120 μm, 120 parts of aluminum nitride with an average particle size of 80 μm, and 40 parts of aluminum nitride with an average particle size of 20 μm were mixed and centrifuged at 2000 rpm for 20 min to obtain 3D printing silicone rubber ink. This 3D printing silicone rubber ink has both thixotropic and shaping capabilities.

[0134] The printing parameters were set as follows: extrusion pressure 0.47 MPa, printing speed 5 mm / min, initial platform spacing 0.5 mm, layer height 0.5 mm, and linewidth 0.8 mm. The 3D printing silicone rubber ink was extruded and 3D printed according to the predetermined structure to obtain a three-dimensional silicone rubber preform. The three-dimensional silicone rubber preform was then heat-treated at 100°C for 240 minutes to obtain 3D printed silicone rubber. The resulting 3D printed silicone rubber exhibits high structural precision, excellent thermal conductivity, and excellent tensile properties.

[0135] Comparative Example 1

[0136] Three parts of highly dispersed and reinforced silica, 100 parts of liquid silicone rubber (viscosity 5.2 Pa·s) and 10 parts of platinum catalyst were mixed and then centrifuged at 2000 rpm for 5 min to obtain silicone rubber ink.

[0137] like Figure 1 and Figure 2 As shown, although the silicone rubber ink has thixotropic properties (i.e., the shear viscosity decreases significantly with increasing shear rate, exhibiting shear thinning behavior), it lacks shaping ability (i.e., the shear storage modulus G' corresponding to the solid line is always lower than the shear loss modulus G” corresponding to the dashed line), and therefore cannot be printed.

[0138] The silicone rubber ink was heat-treated in a mold at 100°C for 120 minutes. The tensile strength of the resulting silicone rubber was similar to that of Example 2, but the elongation at break was lower than that of Example 2. This indicates that the addition of low-thickness silica is of great significance for the self-supporting ability of silicone rubber ink and for further enhancing the mechanical properties of silicone rubber.

[0139] Comparative Example 2

[0140] 21 parts of low-thickness silica, 100 parts of liquid silicone rubber (viscosity 5.2 Pa·s) and 10 parts of platinum catalyst were mixed and then centrifuged at 1000 rpm for 5 min to obtain silicone rubber ink.

[0141] like Figure 1 and Figure 2 As shown, this silicone rubber ink lacks thixotropy (i.e., its shear viscosity does not change with the increase of shear rate and remains relatively flat) and self-supporting ability, making it unsuitable for printing.

[0142] The silicone rubber ink was heat-treated in a mold at 100°C for 120 minutes. The tensile strength and elongation at break of the resulting silicone rubber were lower than those in Example 2, indicating that the addition of highly dispersed and reinforcing silica is of great significance to the thixotropy of silicone rubber ink and the mechanical properties of silicone rubber.

[0143] Comparative Example 3

[0144] 100 parts of liquid silicone rubber (viscosity 5.2 Pa s) and 10 parts of platinum catalyst were mixed and centrifuged at 2000 rpm for 10 min to obtain silicone rubber ink.

[0145] like Figure 1 As shown, this silicone rubber ink has no thixotropic properties and cannot be printed.

[0146] Comparative Example 4

[0147] 100 parts of liquid silicone rubber (viscosity 2.5 Pa s) and 0.2 parts of platinum catalyst were mixed, and then mixed with 30 parts of spherical aluminum nitride with an average particle size of 5 μm, 90 parts of spherical aluminum nitride with an average particle size of 70 μm and 180 parts of spherical aluminum nitride with an average particle size of 120 μm. The mixture was centrifuged at 2000 rpm for 20 min to obtain silicone rubber ink.

[0148] like Figure 2 As shown, this silicone rubber ink lacks setting ability and cannot be printed.

[0149] The silicone rubber ink was heat-treated at 100°C for 120 minutes in a mold. The resulting silicone rubber was extremely prone to cracking upon demolding, had very poor mechanical properties, could not complete mechanical testing, and could not meet the requirements of practical applications.

[0150] The 3D printing silicone rubbers prepared in the above embodiments and comparative examples were subjected to performance tests. The thermal conductivity test standard was ASTM E-1461, the standard test method for determining thermal diffusivity using the flash method. The tensile strength test standard was GB / T528-2009, determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber.

[0151] Table 1. Performance test results of the 3D printing silicone rubber prepared in the examples and comparative examples.

[0152] Can it be printed? <![CDATA[Thermal conductivity (W m -1 K -1 )]]> Tensile strength (MPa) Elongation at break (%) Example 1 Printable - 7.4 104.7 Example 2 Printable - 6.6 82.3 Example 3 Printable - 3.0 193.6 Example 4 Printable - 4.2 172.1 Example 5 Printable 0.8 3.3 33.9 Example 6 Printable 1.9 3.8 19.7 Example 7 Printable 2.6 2.4 41.5 Comparative Example 1 Unable to print - 6.4 68.6 Comparative Example 2 Unable to print - 4.4 56.6 Comparative Example 3 Unable to print - - - Comparative Example 4 Unable to print - - -

[0153] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A 3D printing silicone rubber ink, wherein, The 3D printing silicone rubber ink includes highly dispersed and highly reinforcing silica, low-thickening silica, liquid silicone rubber, and a curing agent; The highly dispersed and highly reinforcing silica is selected from hydrophilic silica with hydroxyl groups on its surface; the primary particles of the highly dispersed and highly reinforcing silica are random fine gravel, the primary particles constitute a branched secondary filler structure, the size of the branched secondary filler structure is 0.2-1μm, and the particle size of the primary particles is 5-15nm. The primary particles of the low-thickening silica have a particle size of 5-30 nm, and the primary particles form aggregates with a length of 60-500 nm. The aggregates have a flat structure with a thickness-to-length ratio of 1:8-1:

20. The specific surface area of ​​the highly dispersed and highly reinforcing silica is 340-420 m². 2 / g; The specific surface area of ​​the low-thickening silica is 110-300 m². 2 / g; the carbon content of the low-thickening silica is 1.5-3.5wt%; The 3D printing silicone rubber ink comprises the following components in parts by weight: 1-10 parts by weight of highly dispersed and highly reinforcing silica; 15-60 parts by weight of low-thickening silica; 100 parts by weight of liquid silicone rubber; Hardener 0.1-10 parts by weight.

2. The 3D printing silicone rubber ink according to claim 1, wherein, The 3D printing silicone rubber ink also includes functional fillers.

3. The 3D printing silicone rubber ink according to claim 2, wherein, The 3D printing silicone rubber ink comprises the following components in parts by weight: 1-10 parts by weight of highly dispersed and highly reinforcing silica; 15-60 parts by weight of low-thickening silica; Functional fillers: 0-500 parts by weight; 100 parts by weight of liquid silicone rubber; Hardener 0.1-10 parts by weight.

4. The 3D printing silicone rubber ink according to claim 3, wherein, The viscosity of the liquid silicone rubber is 0.5-10 Pa·s; And / or, the functional filler is selected from one or more of alumina, aluminum nitride, and boron nitride; And / or, the average particle size of the functional filler is 5-200 μm.

5. A method for preparing 3D printing silicone rubber ink according to any one of claims 1-4, the method comprising the following steps: Highly dispersed and highly reinforcing silica, low-thickening silica, liquid silicone rubber, curing agent, and optionally functional fillers are mixed and degassed to obtain 3D printing silicone rubber ink.

6. The preparation method according to claim 5, wherein, The mixing is carried out under stirring conditions, with a stirring speed of 1000-2000 rpm and a stirring time of 10-30 min; and / or, the degassing is carried out by centrifugation, with a centrifugation speed of 1000-3000 rpm and a centrifugation time of 5-30 min.

7. A 3D-printed silicone rubber, wherein, The 3D printing silicone rubber is prepared using the 3D printing silicone rubber ink according to any one of claims 1-4.

8. The 3D printing silicone rubber according to claim 7, wherein, The 3D printing is extrusion 3D printing, and the parameters of the 3D printing include: extrusion pressure 0.1-0.5MPa, printing speed 5-20mm / min, initial platform spacing 0.2-0.6mm, printing layer height 0.2-0.6mm, and printing linewidth 0.2-1.0mm.

9. A 3D-printed silicone rubber, wherein, The raw materials for preparing the 3D printing silicone rubber include the 3D printing silicone rubber ink as described in any one of claims 1-4.

10. A method for preparing 3D printed silicone rubber according to any one of claims 7-9, the method comprising the following steps: (a) Set the printing parameters and extrude the 3D printing silicone rubber ink according to the predetermined structure to obtain a three-dimensional silicone rubber preform. (b) The three-dimensional silicone rubber preform from step (a) is heat-treated to obtain 3D printed silicone rubber.

11. The preparation method according to claim 10, wherein, In step (a), the printing parameters include: extrusion pressure 0.1-0.5MPa, printing speed 5-20mm / min, initial platform spacing 0.2-0.6mm, printing layer height 0.2-0.6mm, and printing line width 0.2-1.0mm.

12. The preparation method according to claim 10, wherein, In step (b), the heat treatment temperature is 100-150°C and the heat treatment time is 60-180 minutes.

13. Use of the 3D printed silicone rubber according to any one of claims 7-9, for use in thermal management or damping applications.

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