3D printing silicone rubber ink containing high-dispersion and high-reinforcement white carbon black as well as preparation method and application of 3D printing silicone rubber ink

Abstract

The invention provides 3D printing silicone rubber ink containing high-dispersion and high-reinforcement white carbon black as well as a preparation method and application of the 3D printing silicone rubber ink. The 3D printing silicone rubber ink provided by the invention comprises the high-dispersion high-reinforcement white carbon black and the low-thickening white carbon black, and the combined use of the high-dispersion high-reinforcement white carbon black and the low-thickening white carbon black can enable the 3D printing silicone rubber ink to have thixotropy and self-supporting capability at the same time, and have the characteristic of being compatible with high-function filler; by applying the 3D printing silicone rubber ink, 3D printing silicone rubber with excellent mechanical properties can be obtained. The preparation method of the 3D printing silicone rubber ink is simple, the preparation cost is low, the mechanical property of the obtained 3D printing silicone rubber is excellent, mass production preparation of the 3D printing silicone rubber is facilitated, and the application requirements in the fields of thermal management elastomers, damping elastomers and the like are met.

Description

Technical Field

[0001] The present invention belongs to the technical field of new materials, and specifically provides a 3D printing silicone rubber ink comprising highly dispersed and highly reinforced white carbon black, and a preparation method and use thereof. Background Art

[0002] Silicone rubber has aroused extensive research attention in the fields of wearable devices, soft robots, biomedical devices, etc. Extrusion 3D printing is a revolutionary technology for the preparation of silicone rubber. Through computer-aided design for product manufacturing, 3D-printed silicone rubber is expected to have various complex structures to achieve customized production and obtain high-level performance. However, unlike traditional flat-plate vulcanization technology using mold molding, 3D printing technology suitable for heat-curing silicone rubber requires the use of a silicone rubber ink that is both thixotropic and self-supporting. That is, the silicone rubber ink is required to flow out stably only under the shear action of the printing needle, and has high shape fidelity after falling on the printing platform before thermal curing.

[0003] In this regard, the existing practice is to mix organic silicone thixotropic agents with liquid silicone rubber to improve the thixotropy of liquid silicone rubber to meet the requirements of specific applications such as mold-free packaging. However, organic silicone thixotropic agents are difficult to enhance the mechanical properties of silicone rubber. In this regard, the introduction of inorganic functional fillers is of great significance for the regulation of the rheological and mechanical properties of silicone rubber. At the same time, the functional level of silicone rubber is also highly dependent on the high filling of inorganic functional fillers.

[0004] However, high filling can easily lead to the problem of functional filler agglomeration, resulting in clogging of the printing needle and destroying the mechanical strength of silicone rubber. Existing research work attempts to use the backfilling method to circumvent the problem of functional filler agglomeration in the silicone rubber matrix, that is, first print with ink containing functional fillers, freeze-dry the printed structure, and then backfill the silicone rubber into the skeleton of the functional filler. However, this strategy severely limits the complexity and diversity of the printed structure, the production process is cumbersome, and energy consumption is increased. Therefore, how to design a 3D printing silicone rubber ink that has both printability and excellent mechanical properties and achieves compatibility with various functional fillers is a key issue facing the development of 3D printing silicone rubber towards multifunctionality. Summary of the invention

[0005] In order to improve the deficiencies of the prior art, the present invention provides a 3D printing silicone rubber ink including highly dispersed and highly reinforced white carbon black, and a preparation method and use thereof. The 3D printing silicone rubber ink provided by the present invention includes highly dispersed and highly reinforced white carbon black and low thickening white carbon black. The combined use of the highly dispersed and highly reinforced white carbon black and the low thickening white carbon black can make the 3D printing silicone rubber ink have both thixotropy and self-supporting ability, and has the characteristics of being compatible with high-quality functional 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, and the mechanical properties of the obtained 3D printing silicone rubber are excellent, which is conducive to the mass production of 3D printing silicone rubber and meets the application needs of thermal management elastomers, damping and shock absorbing elastomers and other fields.

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

[0007] A 3D printing silicone rubber ink, the 3D printing silicone rubber ink comprising highly dispersed and highly reinforced white carbon black and low thickening white carbon black;

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

[0009] The particle size of the primary particles of the low thickening white carbon black is 5-30nm, the primary particles form aggregates, the length of the aggregates is 60-500nm, the aggregates are flat structures, and the thickness and length ratio of the flat structures is 1:8-1:20.

[0010] Beneficial effects of the present invention:

[0011] (1) The present invention starts from the regulation of the physical and chemical properties of functional fillers, and introduces highly dispersed and highly reinforced white carbon black into the silicone rubber matrix. Due to the high dispersion characteristics of the highly dispersed and highly reinforced white carbon black, the 3D printing silicone rubber ink can be given thixotropy by adding a very small mass fraction of the highly dispersed and highly reinforced white carbon black to the 3D printing silicone rubber ink. At the same time, the introduced low-thickening white carbon black can provide the 3D printing silicone rubber ink with self-supporting ability. The present invention also regulates the rheological properties of the 3D printing silicone rubber ink by controlling the filler component, thereby achieving the printability of the thermosetting silicone rubber in the extrusion 3D printing process, and providing a feasible solution for the component design of the 3D printing silicone rubber ink.

[0012] (2) The 3D printing silicone rubber ink provided by the present invention, which includes highly dispersed, highly reinforced white carbon black and low thickening white carbon black, not only has thixotropy and the ability to fix the printed structure, but also can achieve the loading of high-quality functional fillers, which is conducive to the efficient and batch preparation of multifunctional silicone rubber. The 3D printing silicone rubber prepared using the 3D printing silicone rubber ink can further achieve high elongation at break and high tensile strength on the basis of having high thermal conductivity, overcome the problem of poor mechanical strength of the silicone rubber matrix, and can meet the mechanical performance requirements of products in the fields of thermal management or damping and shock absorption.

[0013] (3) Compared with photocurable silicone rubber, the thermosetting silicone rubber of the present invention is not limited to photocurable polymers and fillers that are transparent to light sources in the selection of the composition of 3D printing silicone rubber ink. There is no need to introduce 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 and mechanical strength of silicone rubber elastomers. BRIEF DESCRIPTION OF THE DRAWINGS

[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 Example 2, Example 6, Comparative Example 1, Comparative Example 2, and Comparative Example 4 are shown.

[0016] Figure 3 A schematic diagram of the grid structure 3D printed silicone rubber printed in Example 5 is shown. DETAILED DESCRIPTION

[0017] <3D printing silicone rubber ink>

[0018] As mentioned above, the present invention provides a 3D printing silicone rubber ink, wherein the 3D printing silicone rubber ink comprises highly dispersed and highly reinforced white carbon black and low thickening white carbon black;

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

[0020] The particle size of the primary particles of the low thickening white carbon black is 5-30nm, the primary particles form aggregates, the length of the aggregates is 60-500nm, the aggregates are flat structures, and the thickness and length ratio of the flat structures is 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 mass:

[0023] 1-10 parts by weight of highly dispersed and highly reinforced white carbon black;

[0024] 15-60 parts by weight of low thickening white carbon black;

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

[0026] Curing agent 0.1-10 parts by mass

[0027] According to an embodiment of the present invention, the 3D printing silicone rubber ink includes 1 mass parts, 2 mass parts, 3 mass parts, 4 mass parts, 5 mass parts, 6 mass parts, 7 mass parts, 8 mass parts, 9 mass parts or 10 mass parts of highly dispersed and highly reinforced white carbon black.

[0028] According to an embodiment of the present invention, the 3D printing silicone rubber ink includes 15 parts by mass, 20 parts by mass, 25 parts by mass, 30 parts by mass, 35 parts by mass, 40 parts by mass, 45 parts by mass, 50 parts by mass, 55 parts by mass, and 60 parts by mass of low thickening white carbon black.

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

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

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

[0032] 1-10 parts by weight of highly dispersed and highly reinforced white carbon black;

[0033] 15-60 parts by weight of low thickening white carbon black;

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

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

[0036] Curing agent 0.1-10 parts by mass

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

[0038] <Highly dispersed and highly reinforced white carbon black>

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

[0040] According to an embodiment of the present invention, the hydroxyl groups on the surface of the highly dispersed and highly reinforced silica can interact with the Si-O chains in the silicone rubber by hydrogen bonding, so that the viscosity of the 3D printed silicone rubber ink increases in a static state, and the weak intermolecular interactions such as hydrogen bonds are destroyed under shearing, so that the viscosity of the 3D printed silicone rubber ink decreases, and the thixotropy of the 3D printed silicone rubber ink is improved. The primary particles of the highly dispersed and highly reinforced silica are irregular and fine gravel-like, and the primary particles constitute a branched secondary filler structure, and the size of the branched secondary filler structure is 0.2-1μm; it means that the highly dispersed and highly reinforced silica has the characteristics of high dispersion. Due to the high dispersion characteristics of the highly dispersed and highly reinforced silica, the thixotropy of the 3D printed silicone rubber ink can be further improved, especially it is conducive to the regulation of the thixotropy of the 3D printed silicone rubber ink at a lower filling number.

[0041] According to an embodiment of the present invention, the highly dispersed and highly reinforced silica has a branched secondary filler structure; the branched secondary filler structure is composed of primary particles, and the primary particles 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 filler 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 reinforced white carbon black is 340-420 m 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 reinforced white carbon black 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 method for preparing highly dispersed and highly reinforced white carbon black comprises the following steps:

[0047] i) using chlorosilane as a raw material, introducing hydrogen and air for combustion, and preparing hydrophilic white carbon black;

[0048] ii) The hydrophilic white carbon black prepared in step i) is mixed with sodium silicate and / or silicate, and dispersed and classified to prepare the highly dispersed and highly reinforced white carbon black.

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

[0050] In a preferred embodiment of the present invention, in step i), the hydrophilic white carbon black 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 white carbon black to the sodium silicate and / or silicate 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 is introduced into the reaction system as a surface regulating agent, which can effectively increase the hydroxyl content on the surface of the hydrophilic silica, while reducing the size of the branched secondary filler structure, thereby improving the dispersion performance of the hydrophilic silica, thereby obtaining highly dispersed and highly reinforced silica.

[0053] In a preferred embodiment of the present invention, in step ii), the dispersion is carried out in a dispersion device known in the art.

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

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

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

[0057] <Low Thickening Silica>

[0058] According to an embodiment of the present invention, the particle size of the primary particles of the low-thickening silica is 5-30nm, the primary particles form aggregates, the length of the aggregates is 60-500nm, the aggregates are flat structures, and the thickness and length ratio of the flat structure is 1:8-1:20; the study found that the low-thickening silica has a flat structure, which gives it good low-thickening properties. When the low-thickening silica with the above structural characteristics is used in 3D printing silicone rubber ink, since the low-thickening silica can be evenly dispersed in the silicone rubber matrix, through a relatively high filling number, it can form cross-linking points in the silicone rubber matrix, increase the entanglement of the silicone rubber molecular chains and the interaction between the filler and the matrix, and improve the ability of the silicone rubber compound to resist its own gravity and surface tension, thereby giving the 3D printing silicone rubber ink a stronger self-supporting ability and reinforcing the mechanical properties of the 3D printing silicone rubber.

[0059] According to an embodiment of the present invention, the specific surface area of ​​the low thickening white carbon black is 110-300m 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 white carbon black 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 thickening silica is 5 nm, 10 nm, 15 nm, 20 nm, 25 nm or 30 nm.

[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 and 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 a methyl functional group.

[0065] According to an embodiment of the present invention, the preparation method of the low-thickening white carbon black 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 a method known in the art, or can be purchased through commercial channels.

[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 a platinum catalyst, an organic tin catalyst or a titanate catalyst.

[0071] <Functional filler>

[0072] According to an embodiment of the present invention, the functional filler is selected from one or more of aluminum oxide, 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 an embodiment of the present invention, the average particle size of the functional filler is 5-200μm, for example, 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm or 200μm.

[0075] <Method for preparing 3D printing silicone rubber ink>

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

[0077] Highly dispersed and highly reinforced white carbon black, low thickening white carbon black, liquid silicone rubber, a curing agent, and optionally adding or not adding a functional filler 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, the stirring speed is 1000-2000 rpm, and the stirring time is 10-30 min.

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

[0080] <Application of 3D printing silicone rubber ink>

[0081] The present invention also provides the use of the above 3D printing silicone rubber ink, which is used in the field of 3D printing silicone rubber.

[0082] <3D printing silicone rubber>

[0083] The present invention also provides a 3D printing silicone rubber, wherein the 3D printing silicone rubber 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 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 0.1-0.5 MPa, printing speed 5-20 mm / min, initial platform spacing 0.2-0.6 mm, printing layer height 0.2-0.6 mm, and printing line width 0.2-1.0 mm.

[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] <Method for preparing 3D printing silicone rubber>

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

[0090] (a) setting printing parameters, extruding 3D printing the 3D printing silicone rubber ink according to a predetermined structure, and obtaining a three-dimensional structure silicone rubber preform;

[0091] (b) heat treating the three-dimensional structured silicone rubber preform of step (a) to obtain 3D printed silicone rubber.

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

[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 printing silicone rubber is silicone rubber with enhanced mechanical properties.

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

[0096] The present invention also provides the use of the above 3D printed silicone rubber, which is used in the field of thermal management or damping and shock absorption.

[0097] The present invention will be described in further detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations 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 included in the scope that the present invention is intended to protect.

[0098] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the reagents, materials, etc. used in the following examples, unless otherwise specified, can be obtained from commercial channels.

[0099] In the following examples and comparative examples, the component contents of the 3D printing silicone rubber ink, if not otherwise specified, represent parts by mass.

[0100] The low thickening white carbon black used in the following examples and comparative examples was prepared by the following method:

[0101] 1) Preparation of precursor solution

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

[0103] 2) Structural flattening modification

[0104] The tap density of 1kg is 55g / L and the specific surface area is 205m 2 / g of fumed silica powder, adding it into a rotary vacuum reactor;

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

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

[0107] The first stage heating temperature is 80°C, the reaction time is 3 hours, the second stage heating temperature is 110°C, the reaction time is 2 hours, and the third stage heating temperature is 180°C, the reaction time is 5 hours.

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

[0109] The low-thickening white carbon black 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 reinforced white carbon black used in the following examples and comparative examples was prepared by the following method:

[0111] 1) Silicon tetrachloride was used as raw material, hydrogen and air were introduced for combustion, and a specific surface area of ​​400m 2 / g of hydrophilic silica;

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

[0113] Example 1

[0114] After mixing 2 parts of highly dispersed and highly reinforced silica, 30 parts of low thickening silica, 100 parts of liquid silicone rubber (viscosity 5.2 Pa·s) and 10 parts of platinum catalyst, centrifugal degassing was performed at a speed of 2000 rpm for 5 minutes to obtain 3D printing silicone rubber ink, which has both thixotropy and setting ability.

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

[0116] Example 2

[0117] 3 parts of highly dispersed and highly reinforced white carbon black, 21 parts of low thickening white carbon black, 100 parts of liquid silicone rubber (viscosity 5.2 Pa·s) and 10 parts of platinum catalyst were mixed and centrifuged for degassing at a speed of 2000 rpm for 5 min to obtain 3D printing silicone rubber ink, such as Figure 1 and Figure 2 As shown, the 3D printing silicone rubber ink has both thixotropy and setting ability.

[0118] The printing parameters are 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 printing layer height of 0.4 mm, and a printing line width of 0.5 mm. The 3D printed silicone rubber ink is extruded 3D printed according to a predetermined structure to obtain a three-dimensional structure silicone rubber preform. The three-dimensional structure silicone rubber preform is heat treated at 150°C for 30 minutes to obtain a 3D printed silicone rubber with a specific structure, and the obtained 3D printed silicone rubber has high structural accuracy and excellent tensile properties.

[0119] Example 3

[0120] After mixing 5 parts of highly dispersed and highly reinforced 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, centrifugal degassing was performed at a speed of 2000 rpm for 10 minutes to obtain 3D printing silicone rubber ink, which has both thixotropy and setting ability.

[0121] The printing parameters are set, including an extrusion pressure of 0.42 MPa, a printing speed of 5 mm / min, an initial platform spacing of 0.5 mm, a printing layer height of 0.5 mm, and a printing line width of 0.8 mm. The 3D printed silicone rubber ink is extruded 3D printed according to a predetermined structure to obtain a three-dimensional structure silicone rubber preform. The three-dimensional structure silicone rubber preform is heat treated at 100°C for 120 minutes to obtain a 3D printed silicone rubber, and the obtained 3D printed silicone rubber has high structural accuracy and excellent tensile properties.

[0122] Example 4

[0123] After mixing 3 parts of highly dispersed and highly reinforced 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, centrifugal degassing was performed at a speed of 2000 rpm for 10 minutes to obtain 3D printing silicone rubber ink, which has both thixotropy and setting ability.

[0124] The printing parameters are set, including an extrusion pressure of 0.47 MPa, a printing speed of 5 mm / min, an initial platform spacing of 0.5 mm, a printing layer height of 0.5 mm, and a printing line width of 0.8 mm. The 3D printed silicone rubber ink is extruded 3D printed according to a predetermined structure to obtain a three-dimensional structure silicone rubber preform. The three-dimensional structure silicone rubber preform is heat treated at 100°C for 120 minutes to obtain a 3D printed silicone rubber, and the obtained 3D printed silicone rubber has high structural accuracy and excellent tensile properties.

[0125] Example 5

[0126] 2 parts of highly dispersed and highly reinforced 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 thermal conductive filler with an average particle size of 120 μm were mixed and centrifuged for degassing at a speed of 2000 rpm for 20 minutes to obtain 3D printing silicone rubber ink, which has both thixotropy and setting ability.

[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 printing layer height of 0.5 mm, and a printing line width of 0.8 mm. The 3D printed silicone rubber ink was extruded and 3D printed according to a predetermined structure to obtain a three-dimensional structure silicone rubber preform. The three-dimensional structure silicone rubber preform was heat treated at 150° C. for 30 minutes to obtain a 3D printed silicone rubber.

[0128] Figure 3 The schematic diagram of the structure of the 3D printed silicone rubber with a grid structure obtained by printing in Example 5 is shown. Figure 3It can be seen that the mesh structure accuracy of 3D printed silicone rubber is good, which means that the obtained 3D printed silicone rubber has high structural accuracy, excellent thermal conductivity and excellent tensile properties.

[0129] Example 6

[0130] 2 parts of highly dispersed and highly reinforced white carbon black, 30 parts of low thickening white carbon black, 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 for degassing at a speed of 2000 rpm for 20 min to obtain 3D printing silicone rubber ink, such as Figure 2 As shown, the 3D printing silicone rubber ink has both thixotropy and setting ability.

[0131] The printing parameters are set, including an extrusion pressure of 0.50 MPa, a printing speed of 5 mm / min, an initial platform spacing of 0.5 mm, a printing layer height of 0.5 mm, and a printing line width of 0.8 mm. The 3D printed silicone rubber ink is extruded 3D printed according to a predetermined structure to obtain a three-dimensional structure silicone rubber preform. The three-dimensional structure silicone rubber preform is heat treated at 150° C. for 30 minutes to obtain a 3D printed silicone rubber, and the obtained 3D printed silicone rubber has high structural accuracy, excellent thermal conductivity, and excellent tensile properties.

[0132] Example 7

[0133] 7 parts of highly dispersed and highly reinforced 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 for degassing at a speed of 2000 rpm for 20 minutes to obtain 3D printing silicone rubber ink, which has both thixotropy and setting ability.

[0134] The printing parameters are set, including an extrusion pressure of 0.47 MPa, a printing speed of 5 mm / min, an initial platform spacing of 0.5 mm, a printing layer height of 0.5 mm, and a printing line width of 0.8 mm. The 3D printed silicone rubber ink is extruded 3D printed according to a predetermined structure to obtain a three-dimensional structure silicone rubber preform. The three-dimensional structure silicone rubber preform is heat treated at 100°C for 240 minutes to obtain a 3D printed silicone rubber, and the obtained 3D printed silicone rubber has high structural accuracy, excellent thermal conductivity, and excellent tensile properties.

[0135] Comparative Example 1

[0136] After mixing 3 parts of highly dispersed and highly reinforced white carbon black, 100 parts of liquid silicone rubber (viscosity 5.2 Pa·s) and 10 parts of platinum catalyst, centrifugal degassing was performed at a speed of 2000 rpm for 5 minutes to obtain silicone rubber ink.

[0137] like Figure 1 and Figure 2 As shown in the figure, although the silicone rubber ink has thixotropy (i.e., the shear viscosity decreases significantly with the increase of shear rate, showing 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 dotted line), and cannot be printed.

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

[0139] Comparative Example 2

[0140] 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 centrifuged for degassing at a speed of 1000 rpm for 5 minutes to obtain silicone rubber ink.

[0141] like Figure 1 and Figure 2 As shown, the silicone rubber ink lacks thixotropy (i.e., the shear viscosity does not change with the increase of shear rate and is always relatively gentle) and self-supporting ability, and cannot be printed.

[0142] The silicone rubber ink was heat treated in a mold at 100° C. for 120 minutes, and the tensile strength and elongation at break of the obtained silicone rubber were lower than those in Example 2, indicating that the addition of highly dispersed and highly reinforced silica is of great significance for the thixotropy of the silicone rubber ink and the mechanical properties of the 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 for degassing at a speed of 2000 rpm for 10 min to obtain silicone rubber ink.

[0145] like Figure 1 As shown, the silicone rubber ink has no thixotropy 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, and centrifuged for degassing at a speed of 2000 rpm for 20 minutes to obtain silicone rubber ink.

[0148] like Figure 2 As shown, the silicone rubber ink lacks the ability to set and cannot be printed.

[0149] The silicone rubber ink was heat-treated at 100° C. for 120 minutes in a mold. The silicone rubber obtained was very easy to break when demolded, had very poor mechanical properties, could not complete mechanical testing, and could not meet actual application requirements.

[0150] The 3D printing silicone rubber prepared in the above examples and comparative examples was subjected to performance tests. The thermal conductivity test standard was ASTM E-1461 Standard Test Method for Determining Thermal Diffusivity by 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 3D printing silicone rubber prepared in Examples and Comparative Examples

[0152] Can I print? <![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 above is an explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in 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 reinforced white carbon black and low thickening white carbon black; The highly dispersed and highly reinforced silica is selected from hydrophilic silica containing hydroxyl groups on the surface; the primary particles of the highly dispersed and highly reinforced silica are irregular fine gravel-like, the primary particles constitute a branched secondary filler structure, and the size of the branched secondary filler structure is 0.2-1 μm; The particle size of the primary particles of the low thickening white carbon black is 5-30nm, the primary particles form aggregates, the length of the aggregates is 60-500nm, the aggregates are flat structures, and the thickness and length ratio of the flat structures is 1:8-1:

20.

2. The 3D printing silicone rubber ink according to claim 1, wherein: The 3D printing silicone rubber ink also includes liquid silicone rubber and a curing agent. Preferably, the 3D printing silicone rubber ink comprises the following components in parts by mass: 1-10 parts by weight of highly dispersed and highly reinforced white carbon black; 15-60 parts by weight of low thickening white carbon black; 100 parts by mass of liquid silicone rubber; Curing agent 0.1-10 parts by mass 3. The 3D printing silicone rubber ink according to claim 1 or 2, wherein: The 3D printing silicone rubber ink also includes a functional filler. Preferably, the 3D printing silicone rubber ink comprises the following components in parts by mass: 1-10 parts by weight of highly dispersed and highly reinforced white carbon black; 15-60 parts by weight of low thickening white carbon black; Functional filler 0-500 parts by mass; 100 parts by mass of liquid silicone rubber; Curing agent 0.1-10 parts by mass 4. The 3D printing silicone rubber ink according to any one of claims 1 to 3, wherein: The highly dispersed and highly reinforced white carbon black has a branched secondary filler structure; the branched secondary filler structure is composed of primary particles, the primary particles have an irregular fine gravel structure, and the particle size of the primary particles is 5-15 nm. Preferably, the specific surface area of ​​the highly dispersed and highly reinforced white carbon black is 340-420 m 2 / g. Preferably, the specific surface area of ​​the low thickening white carbon black is 110-300m 2 / g. Preferably, the carbon content of the low thickening white carbon black is 1.5-3.5 wt %. Preferably, the viscosity of the liquid silicone rubber is 0.5-10 Pa·s. Preferably, the functional filler is selected from one or more of aluminum oxide, aluminum nitride and boron nitride. Preferably, the average particle size of the functional filler is 5-200 μm.

5. The method for preparing the 3D printing silicone rubber ink according to any one of claims 1 to 4, the method comprising the following steps: Highly dispersed and highly reinforced white carbon black, low thickening white carbon black, liquid silicone rubber, a curing agent, and optionally adding or not adding a functional filler are mixed and degassed to obtain 3D printing silicone rubber ink. Preferably, the mixing is carried out under stirring conditions, the stirring speed is 1000-2000 rpm, and the stirring time is 10-30 min; and / or, the deaeration is centrifugal deaeration, the speed of centrifugal deaeration is 1000-3000 rpm, and the time of centrifugal deaeration is 5-30 min.

6. A 3D printed silicone rubber, wherein: The 3D printing silicone rubber is prepared by the 3D printing silicone rubber ink according to any one of claims 1 to 4.

7. The 3D printing silicone rubber according to claim 6, wherein: The 3D printing silicone rubber is prepared by 3D printing the 3D printing silicone rubber ink according to any one of claims 1 to 4. Preferably, the 3D printing is extrusion 3D printing, and the parameters of the 3D printing include: extrusion pressure 0.1-0.5 MPa, printing speed 5-20 mm / min, initial platform spacing 0.2-0.6 mm, printing layer height 0.2-0.6 mm, and printing line width 0.2-1.0 mm.

8. A 3D printing silicone rubber, wherein the raw materials for preparing the 3D printing silicone rubber include the 3D printing silicone rubber ink according to any one of claims 1 to 4.

9. The method for preparing the 3D printing silicone rubber according to any one of claims 6 to 8, the method comprising the following steps: (a) setting printing parameters, extruding 3D printing the 3D printing silicone rubber ink according to a predetermined structure, and obtaining a three-dimensional structure silicone rubber preform; (b) heat treating the three-dimensional structured silicone rubber preform of step (a) to obtain 3D printed silicone rubber. Preferably, 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, printing line width 0.2-1.0mm. Preferably, in step (b), the temperature of the heat treatment is 100-150° C., and the time of the heat treatment is 60-180 minutes.

10. Use of the 3D printing silicone rubber according to any one of claims 6 to 8, which is used in the field of thermal management or damping and shock absorption.

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