A composite ink material, a preparation method and application thereof, and a method for preparing a heat-conducting part by ink direct writing 3D printing

Abstract

The application provides a composite ink material, a preparation method and application thereof, and a method for preparing a heat-conducting part by ink direct writing 3D printing. The composite ink material comprises a silicone rubber resin, a heat-conducting filler and a curing agent component. The composite ink material has excellent shear thinning rheological properties, good printing capability, good dispersibility, and the printed heat-conducting part has good heat conductivity and flexibility. In addition, the orientation degree of the heat-conducting particles in the composite material can be accurately controlled by regulating the printing speed, so as to control the heat-conducting performance of the obtained heat-conducting part.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of 3D printing of high polymers, and particularly relates to a composite ink material, a preparation method and application thereof, and a method for preparing a heat-conducting part by ink direct writing 3D printing. BACKGROUND

[0002] With the rapid increase of modern electronic power density, efficient heat dissipation has become an emerging demand for electronic devices including communication, information and energy storage technology, because the faster the microprocessor is cooled, the faster it can run, and thus the better the performance. Ultra-high-speed high-frequency devices generate a large amount of heat in a small local area, thereby generating hot spots with a work power more than ten times higher than the average, and although the work temperature in other areas is relatively low, the devices with low thermal conductivity can have performance deterioration or even failure. The heat-conductive composite material is a material capable of quickly transferring a large amount of heat, which can effectively protect and prolong the service life of electronic devices. The heat-conductive composite material mainly includes a heat-conductive matrix such as silicone rubber resin, epoxy resin, etc. The classification of heat-conductive fillers mainly includes three types: metals, inorganic particles and carbon materials. The limitation of the heat-conductive composite material at present lies in the preparation process. At present, the heat-conductive composite material is mostly manufactured by molding. In order to obtain high heat-conducting performance, a large amount of heat-conductive fillers need to be added, but high filling amount will bring about the loss of mechanical properties of the material. In order to obtain a heat-conductive composite material with excellent performance, it is necessary to obtain higher thermal conductivity under the condition of low filling amount.

[0003] In recent years, three-dimensional (3D) printing technology of various materials has attracted more and more attention because it has the potential to provide unique functions that cannot be achieved by traditional manufacturing methods, such as simplifying the manufacturing process, increasing the degree of design freedom, novel shape factors, reducing weight, and reducing prototype and manufacturing costs. Common 3D printing methods include extrusion printing (FDM, DIW, etc.), inkjet printing, and light curing printing. Among them, DIW is also called automatic grouting forming. The ink material is stored in a cartridge and connected with a nozzle and a 3-axis CNC platform. The ink is extruded by a screw or a pneumatic pressure control device and formed on the platform. The model can be built by CAD software and input into the printer to construct the pattern. The parameters and environment during printing will have a great influence on the formation of the material. Compared with other printing technologies, DIW technology has less requirement for the material, and only needs to meet the rheological properties required for printing. It is especially suitable for printing of thermosetting materials such as silicone rubber. However, the viscosity of the printing ink is difficult to control, and the ink support during printing also exists.

[0004] Based on the defects of the current printing ink, it is necessary to improve it. SUMMARY

[0005] In order to solve the problems in the above background art, the present application provides a composite ink material, a preparation method and application thereof, and a method for preparing a heat-conducting part by ink direct writing 3D printing.

[0006] In order to achieve the above-mentioned purpose, the present application is realized by the following technical measures.

[0007] In the first aspect, the present application provides a composite ink material, comprising the following components by weight: ≥600 parts of silicone rubber resin, ≤400 parts of heat-conducting filler, and ≤70 parts of curing agent.

[0008] The sum of the weight parts of the silicone rubber resin, the heat-conducting filler and the curing agent is 1000 parts.

[0009] Preferably, the silicone rubber resin comprises at least one of methyl silicone rubber, methyl vinyl silicone rubber, methyl phenyl vinyl silicone rubber and fluorosilicone rubber.

[0010] Preferably, the heat-conducting filler comprises at least one of boron nitride, magnesium oxide and aluminum oxide.

[0011] Preferably, the particle size of the heat-conducting filler is 1-10 μm.

[0012] Preferably, the composite ink material comprises the following components by weight: 600-680 parts of silicone rubber resin, 250-350 parts of heat-conducting filler, and 50-70 parts of curing agent.

[0013] The sum of the weight parts of the silicone rubber resin, the heat-conducting filler and the curing agent is 1000 parts.

[0014] In the second aspect, the present application further provides a preparation method of the composite ink material, comprising the following steps:

[0015] The heat-conducting filler is added to the silicone rubber resin to obtain a silicone rubber mixture;

[0016] The curing agent is added to the silicone rubber mixture, and after mixing, ultrasonic and centrifugal deaeration are performed to obtain the composite ink material.

[0017] Preferably, the centrifugal rate is 1000-6000 r / min, and the centrifugal time is 5-30 min.

[0018] Preferably, the ultrasonic time is 5-30 min.

[0019] In the third aspect, the present application further provides an application of the composite ink material or the composite ink material prepared by the preparation method in ink direct writing 3D printing for preparing a heat-conducting part.

[0020] In a fourth aspect, the present application further provides a method for preparing a heat-conducting part by inkjet 3D printing, comprising the following steps:

[0021] The composite ink material or the composite ink material prepared by the preparation method is loaded into a needle cylinder of an inkjet 3D printing device;

[0022] The printing process parameters are set, and the heat-conducting part is printed.

[0023] Preferably, the printing process parameters are as follows: the printing extrusion pressure is 0.5-3 MPa, the diameter of the printing needle is 0.7-1.2 mm, and the printing speed is 1-3 mm / s.

[0024] The present application has the following beneficial effects compared with the prior art:

[0025] 1. The composite ink material of the present application comprises a silicone rubber resin, a heat-conducting filler and a curing agent component, and has excellent shear thinning rheological properties, good printing ability, good dispersibility, and the printed heat-conducting part has good thermal conductivity and flexibility; in addition, the orientation degree of the heat-conducting particles in the composite material can be accurately controlled by adjusting the printing speed, thereby controlling the thermal conductivity of the obtained heat-conducting part;

[0026] 2. The composite ink material prepared by the present application is used for inkjet printing, and the obtained product is a composite material with low filling amount, high thermal conductivity and high elasticity, which is difficult to be prepared by other printing methods, and has good tensile strength, thereby expanding the selection range of the excellent performance of the heat-conducting composite material of 3D printing;

[0027] 3. The composite ink material prepared by the present application has moderate viscosity and good support, so it is suitable for inkjet printing processing, thereby widening the preparation way of the composite material ink and expanding the forming method of the silicone rubber-based composite material; the composite material ink prepared by the present application can control the thermal conductivity in different directions by controlling the printing speed and mode; the preparation method of the composite ink material of the present application has mature process conditions, simple preparation process, low manufacturing cost, and is suitable for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0029] Figure 1 SEM image of the heat-conducting part sample obtained in application example 1;

[0030] Figure 2 A schematic diagram for preparing a heat conducting member by 3D printing of the present application;

[0031] Figure 3 A graph of thermal conductivity of the heat conducting member sample obtained in Application Examples 1 to 4;

[0032] Figure 4 A graph of thermal conductivity of the heat conducting member sample obtained in Application Examples 2, 5 to 6;

[0033] Figure 5 A graph of thermal gravimetric test of the heat conducting member sample obtained in Application Examples 2, 5 to 6;

[0034] Figure 6 A graph of elongation at break of the heat conducting member sample obtained in Application Examples 1 to 3;

[0035] Figure 7 A graph of tensile stress of the heat conducting member sample obtained in Application Examples 1 to 3;

[0036] Figure 8 A graph of viscosity of the composite ink material obtained in Examples 1 to 3 as a function of shear rate;

[0037] Figure 9 A graph of storage modulus and loss modulus of the composite ink material obtained in Examples 1 to 3 as a function of oscillation strain. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0039] It is to be understood that the order of steps or description of steps in the embodiments does not imply that the order of such steps must be followed in practice. Further, in the following description of various embodiments of the application, terminology will be used in a descriptive sense only and should not be construed as being restrictive. Various embodiments of the present application can exist in a variety of forms; therefore, understand that the present application should not be limited to the particular forms described below. Additionally, as used in this description, the term "include" means "including, but not limited to". Various embodiments of the present application can exist in a range of forms; it should be understood that the description in a range form is merely for the convenience and brevity, and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single values within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single values within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. In addition, whenever a numerical range is indicated in this document, it means to include any cited number (fraction or integer) within the indicated range.

[0040] The present application provides a composite ink material, comprising the following components by weight: silicone rubber resin ≥ 600 parts, heat-conducting filler ≤ 400 parts, curing agent ≤ 70 parts;

[0041] The sum of the weight parts of the silicone rubber resin, the heat-conducting filler, and the curing agent is 1000 parts.

[0042] In some embodiments, the silicone rubber resin can be selected from any type or model of commercially available silicone rubber resin or prepared according to the prior art. For better illustration and to provide a preferred technical solution, the silicone rubber resin is selected from at least one of methyl silicone rubber, methyl vinyl silicone rubber, methyl phenyl vinyl silicone rubber, and fluorosilicone rubber.

[0043] In some embodiments, the heat-conducting filler is selected from heat-conducting fillers that can be used to prepare composite materials with silicone rubber resin according to the prior art, in particular, conventional processing fields such as mold forming and casting forming. For better illustration of the present application and to provide a preferred technical solution, the heat-conducting filler comprises at least one of boron nitride, magnesium oxide, and aluminum oxide. It should be noted that in order to better disperse the filler in the matrix, the heat-conducting filler should be selected as a powder, preferably a heat-conducting filler powder with a particle size of 1-10 μm.

[0044] In some embodiments, the composite ink material comprises the following components by weight: silicone rubber resin ≥ 600 parts, heat-conducting filler ≤ 400 parts, curing agent ≤ 60 parts;

[0045] The sum of the weight parts of the silicone rubber resin, the heat-conducting filler, and the curing agent is 1000 parts.

[0046] In some embodiments, the inventors found through comparative experiments that the composite ink material has the best rheological property when the amount of the heat-conducting filler is 300 parts, and the heat-conducting product obtained after 3D printing has good thermodynamic performance and good mechanical performance; when the amount of the filler is more than 400 parts, the printability of the ink material is greatly reduced, and the 3D printing of the heat-conducting product cannot be performed.

[0047] In some embodiments, the composite ink material comprises the following components by weight: 600-680 parts of silicone rubber resin, 250-350 parts of heat-conducting filler, and 50-70 parts of curing agent.

[0048] The sum of the weight parts of the silicone rubber resin, the heat-conducting filler, and the curing agent is 1000 parts.

[0049] Specifically, in some embodiments, preferably, the heat-conducting filler comprises 50 parts of magnesium oxide and 200-300 parts of boron nitride.

[0050] In some embodiments, the inventors found through comparative experiments that the ink obtained has the best printability when the amount of boron nitride is 25% wt and the amount of magnesium oxide is 5% wt.

[0051] Further, under the conditions of the composite ink material obtained above, preferably, a 0.7 mm needle is used for printing under a pressure of 1.5 MPa, and the printing speed can be adjusted (1-10 mm / s), and the heat-conducting part obtained has different vertical and in-plane thermal conductivities.

[0052] Generally, the composite ink material of the present application can also add other antioxidants, flame retardants, anti-aging agents, and other processing aids known in the prior art, and other functional fillers such as carbon-based fillers, conductive fillers polyaniline, etc. can also be added according to the actual technical purpose or processing conditions, etc. The amount of the above-mentioned other functional fillers can be determined by those skilled in the art with reference to the prior art. However, the premise is that these processing aids and fillers do not adversely affect the realization of the purpose of the present application and the achievement of the excellent effects of the present application.

[0053] Based on the same inventive concept, the present application also provides a preparation method of the above-mentioned composite ink material, comprising the following steps:

[0054] S1, adding the heat-conducting filler to the silicone rubber resin to obtain a silicone rubber mixture;

[0055] S2, adding the curing agent to the silicone rubber mixture, and after mixing, performing ultrasonic and centrifugal defoaming to obtain the composite ink material.

[0056] In some embodiments, the sufficient mixing in step S1 is to make the thermally conductive filler fully dispersed in the silicone rubber matrix, prevent the thermally conductive filler from gathering, and thus affect the thermodynamic performance of the final thermally conductive part. Those skilled in the art can select a suitable mixing stirring process in the prior art according to the actual process conditions and the weight of the raw materials to be mixed. In order to better illustrate the present application, and provide a reference for the technical solution, the sufficient mixing can be mixed by a four-fluorine stirring paddle at a speed of 200-300 r / min for 1-5 h.

[0057] In some embodiments, the defoaming treatment in step S2 is to eliminate the influence of air bubbles in the mixed liquid. In order to better illustrate the present application, and provide a reference for the technical solution, the solidifying agent is added to the silicone rubber mixed liquid, and after mixing, the barrel is placed in the ultrasonic instrument, the ultrasonic time is 5-30 min, the ultrasonic temperature is controlled at 10-50℃, and after the ultrasonic ends, the barrel is placed in the centrifuge and the centrifugal speed is set to 1000-6000 r / min, and the time is 5-30 min.

[0058] In some embodiments, when the addition amount of the silicone rubber is 5-10 g and the addition amount of the thermally conductive filler is 3-5 g, the shear rate is 1-1000 s -1 , and the viscosity is 1-300 Pa·s, which meets the needs of ink direct writing printing and has printability.

[0059] In some embodiments, the viscosity of the composite ink material prepared by the present application is 100-3000 Pa·s, and the storage modulus and loss modulus are 10 2 -10 5 Pa.

[0060] It should be noted that the viscosity defined in the technical solution of the present application is the viscosity of the silicone rubber resin matrix / thermally conductive filler system to meet the printability, which is obtained through a large number of explorations and experiments. Those skilled in the art should know that in order to meet the printability of the ink direct writing printing, the viscosity coefficient standard of the ink material should be changed according to the specific ink material used, and the viscosity is not the only standard for measuring whether the ink material has printability.

[0061] Based on the same inventive concept, the present application also provides an application of the above-mentioned composite ink material or the composite ink material prepared by the above-mentioned preparation method in the preparation of a thermally conductive part by ink direct writing 3D printing.

[0062] The main inventive point of the present application is that the heat-conducting filler realizes high thermal conductivity under the condition of a lower filling amount, and the addition of the heat-conducting filler meets the required ink supporting property of the silicone resin matrix as an ink material, and the silicone resin is selected as the matrix, and the silicone resin still has good flexibility when part of the heat-conducting filler is added. After the de-bubbling treatment, the ink material has the characteristics of good printing capability, good dispersibility and strong supporting force, and when the ink material is applied to ink direct writing printing, the printed heat-conducting part has good flexibility and heat-conducting capability.

[0063] It is worth noting that the above-mentioned inventive characteristics of the present application are only applicable to ink direct writing printing, and other 3D printing processes cannot be applied to the present application. For example, when the heat-conducting filler is 30wt%, the selective laser sintering 3D printing technology cannot produce good bonding behavior due to the high content of the filler, and the present application technology does not have the above-mentioned defects.

[0064] The composite ink material of the present application has excellent shear thinning rheological properties, good printing capability, good dispersibility, and the printed heat-conducting part has good heat-conducting rate and flexibility. In addition, the orientation degree of the heat-conducting particles in the composite material can be accurately controlled by adjusting the printing speed, and then the heat-conducting performance of the obtained heat-conducting part is controlled.

[0065] Based on the same inventive concept, the present application also provides a method for preparing a heat-conducting part by ink direct writing 3D printing, which comprises the following steps:

[0066] S1, the composite ink material is loaded into the needle cylinder of the ink direct writing 3D printing equipment;

[0067] S2, the printing process parameters are set, and a heat-conducting part is printed.

[0068] In some embodiments, the composite ink material prepared according to the technical scheme of the present application can generally use the same process parameters as the existing ink direct writing printing silicone rubber-based composite material in the prior art. In order to better illustrate the application, the present application provides a specific way for reference. The composite ink material prepared by the technical scheme of the present application is used for ink direct writing, wherein the printing process parameters are as follows: the printing extrusion pressure is 0.5-3Mpa, the diameter of the printing needle is 0.7-1.2mm, and the printing speed is 1-10mm / s.

[0069] In some embodiments, a heating device is added on the printing substrate during the printing process, which can quickly form after the composite ink material is extruded, prevent the ink from collapsing, and the obtained heat-conducting part sample has good shape retention.

[0070] The present application has the following beneficial effects:

[0071] 1. The composite ink material prepared by the application is used for ink direct writing printing, and the obtained product is a composite material with low filling amount, high thermal conductivity and high elasticity, which is difficult to be prepared by other printing methods, and has good tensile strength, thereby expanding the selection range of the excellent performance of the thermal conductive composite material of 3D printing;

[0072] 2. The composite ink material prepared by the application has moderate viscosity and good support, so that it is suitable for ink direct writing printing processing, thereby widening the preparation way of the composite material ink and expanding the forming method of the silicone rubber-based composite material;

[0073] 3. The composite material ink prepared by the application can control the thermal conductivity in different directions by controlling the printing speed and mode;

[0074] 4. The preparation method of the application has mature process conditions, simple preparation process, low manufacturing cost and is suitable for large-scale production.

[0075] The following further illustrates the composite ink material, the preparation method and application thereof and the method for preparing the thermal conductive part by ink direct writing 3D printing of the application with specific examples. This part further illustrates the content of the application in combination with specific examples, but should not be understood as limiting the application. If not particularly stated, the technical means adopted in the examples is the conventional means familiar to those skilled in the art. Unless particularly stated, the reagents, methods and equipment adopted in the application are the conventional reagents, methods and equipment in the art.

[0076] The following examples mainly illustrate the raw materials and reagents

[0077] The polydimethylsilicone rubber (PDMS) and the curing agent are both SLYGARD 184 (PDMS is a two-component kit product composed of a liquid component, including a PDMS base and a curing agent), the density is 1.04 g / cm 3 , the specific heat capacity is 1.363 j / g·K, and it is produced by the United States Dow corning company;

[0078] Boron nitride (BN): the density is 2.29 g / cm 3 , the specific heat capacity is 0.794 j / g·K, the particle size is 5-10 μm, the structure is hexagonal sheet layer, and it is produced by the Mcrline company;

[0079] Magnesium oxide (MgO): the density is 3.58 g / cm -3 , the specific heat capacity is 0.92 j / g·K, the particle size is 1-5 μm, the structure is spherical, and it is produced by the Bengbu Kexing Nanometer Technology Company.

[0080] Testing and characterization

[0081] Scanning electron microscope analysis

[0082] The sample morphology of the heat conducting member was observed by a scanning electron microscope (SIGMA500, Beijing Optics Technology Co., Ltd.); the sample of the heat conducting member was quenched in liquid nitrogen, and the observation surface was vacuum gold sprayed.

[0083] Thermal conductivity test

[0084] The thermal diffusivity a (unit: mm / s) of the heat conducting member was tested by a laser flash method thermal conductivity tester. The thermal conductivity λ (W / m·K) was calculated from the following formula: 2

[0085] λ = a·p·C p

[0086] In the formula, the thermal diffusivity a of the silicone rubber composite ink material was measured by a laser thermal conductivity tester, the test temperature was 25°C, and the density p of the silicone rubber composite ink material was calculated according to the formula:

[0087] p = f1p1 + f2p2

[0088] In the formula, f1 and f2 represent the volume fractions of the matrix (i.e. the cured silicone rubber resin) and the heat conducting filler respectively, and p1 and p2 represent the densities of the matrix and the heat conducting filler respectively. The specific heat capacity C (unit: J / g·K) of the composite material was calculated according to the formula: p

[0089] C p = ω1C p1 + ω2C p2

[0090] In the formula, ω1 and ω2 represent the mass fractions of the matrix (i.e. the cured silicone rubber resin) and the heat conducting filler respectively, and C p1 and C p1 represent the specific heat capacities of the matrix and the heat conducting filler respectively.

[0091] The in-plane thermal conductivity was tested by cutting the printed 20×20×1.5mm heat conducting product into 10×10×1mm sheet-shaped samples. The vertical thermal conductivity was tested by cutting the printed 10×15×12mm heat conducting product into 10×10×1mm sheet-shaped samples. All samples were sprayed with a graphite coating before testing, dried, and then placed in the corresponding fixture for testing. Before testing, the graphite coating must be sprayed, dried, and then placed in the corresponding fixture for testing.

[0092] Mechanical property test

[0093] The mechanical properties of the heat conducting member were tested by an INSTRON68TM-10 tensile machine, and the tensile properties at break were tested at a tensile rate of 500mm / min. ​​

[0094] Thermogravimetric test

[0095] The thermogravimetric test of the heat conducting member was performed by using a thermogravimetric analyzer (CLY01-TGA1, Wuhan Hui Neng Zhi Technology Co., Ltd.). The sample was dried and placed in an alumina crucible for testing. The sample mass was about 5 mg, the test temperature range was 30-800℃, the test rate was 10℃ / min, and the test atmosphere was nitrogen.

[0096] The rheological test in the experiment was performed by using a strain-controlled rotary rheometer (DH-2), and a clamp with a diameter of 15 mm was selected for the rheological test of the ink. The rheological characterization of the composite ink material was performed under flow mode (Flow) and oscillation mode (Oscillation), respectively. Under the flow mode, the apparent viscosity of the ink was characterized in the shear rate range of 10 -3 -1000s -1 Under the oscillation mode, the oscillation strain was changed in the range of 0.001-10% under the condition of a fixed frequency of 1HZ, and the linear viscoelastic region of the ink in this range and the variation law of the storage modulus and the loss modulus were characterized.

[0097] Example 1

[0098] The present embodiment provides a composite ink material, which comprises the following components by weight:

[0099] 650 parts of silicone rubber resin, 300 parts of heat-conducting filler, and 50 parts of curing agent;

[0100] The silicone rubber resin is polydimethylsilicone rubber.

[0101] The heat-conducting filler comprises magnesium oxide and boron nitride, wherein the magnesium oxide is 50 parts, and the boron nitride is 250 parts.

[0102] The present embodiment further provides a preparation method of the composite ink material, which comprises the following steps:

[0103] S1, the heat-conducting filler is added to the silicone rubber resin and mixed at a speed of 300 r / min for 3 h to obtain a silicone rubber mixed solution;

[0104] S2, the curing agent is added to the silicone rubber mixed solution, and after mixing, ultrasonic and centrifugal defoaming are performed to obtain the composite ink material;

[0105] The ultrasonic time is 10 min, and the ultrasonic temperature is controlled at 25℃; the centrifugal speed is 3000 r / min, and the centrifugal time is 5 min.

[0106] The composite ink material prepared in Example 1 has a shear rate of 100 s -1At this time, the viscosity is 1000 Pa·s.

[0107] Application Example 1

[0108] The application example provides a method for preparing a heat-conducting piece by inkjet 3D printing, comprising the following steps:

[0109] S1, the composite ink material prepared in Example 1 is loaded into the needle cylinder of the inkjet 3D printing equipment;

[0110] S2, setting the printing process parameters, and printing to obtain a heat-conducting piece;

[0111] The printing process parameters are: the printing extrusion pressure is 1.5 Mpa, the diameter of the printing needle is 0.7 mm, and the printing speed is 2 mm / s.

[0112] According to the method in the above application example 1, a cuboid-shaped heat-conducting piece with a length, width and height of 20 mm, 20 mm and 1.5 mm, a heat-conducting piece with a length, width and height of 10 mm, 15 mm and 12 mm, and a cuboid-shaped heat-conducting piece with a length, width and height of 40 mm, 40 mm and 1 mm are respectively printed.

[0113] Test results show that the thermal conductivity of the prepared cuboid-shaped heat-conducting piece with a length, width and height of 20 mm, 20 mm and 1.5 mm and the heat-conducting piece with a length, width and height of 10 mm, 15 mm and 12 mm is as shown in the following table. Figure 3

[0114] Test results show that the elongation at break and tensile strength of the prepared cuboid-shaped heat-conducting piece with a length, width and height of 40 mm, 40 mm and 1 mm are as shown in the following table and Figure 6 Figure 7

[0115] Application Example 2

[0116] The application example provides a method for preparing a heat-conducting piece by inkjet 3D printing, comprising the following steps:

[0117] S1, the composite ink material prepared in Example 1 is loaded into the needle cylinder of the inkjet 3D printing equipment;

[0118] S2, setting the printing process parameters, and printing to obtain a heat-conducting piece;

[0119] The printing process parameters are: the printing extrusion pressure is 1.5 Mpa, the diameter of the printing needle is 0.7 mm, and the printing speed is 2.5 mm / s.

[0120] ​​​According to the method in the above application example 1, a cuboid-shaped heat conducting piece with a length, width and height of 20 mm, 20 mm and 1.5 mm, a heat conducting piece with a length, width and height of 10 mm, 15 mm and 12 mm, and a cuboid-shaped heat conducting piece with a length, width and height of 40 mm, 40 mm and 1 mm are printed respectively.

[0121] It is tested that the thermal conductivities of the prepared cuboid-shaped heat conducting piece with a length, width and height of 20 mm, 20 mm and 1.5 mm and the heat conducting piece with a length, width and height of 10 mm, 15 mm and 12 mm are as shown in the following table. Figure 3

[0122] It is tested that the elongation at break and tensile strength of the prepared cuboid-shaped heat conducting piece with a length, width and height of 40 mm, 40 mm and 1 mm at a stretching rate of 500 mm / min are as shown in the following table. Figure 6 Figure 7

[0123] Application Example 3

[0124] The application example provides a method for preparing a heat conducting piece by ink direct writing 3D printing, which comprises the following steps:

[0125] S1, the composite ink material prepared in example 1 is loaded into the needle cylinder of the ink direct writing 3D printing equipment;

[0126] S2, the printing process parameters are set, and a heat conducting piece is printed;

[0127] The printing process parameters are as follows: the printing extrusion pressure is 1.5 Mpa, the diameter of the printing needle is 0.7 mm, and the printing speed is 3 mm / s.

[0128] According to the method in the above application example 1, a cuboid-shaped heat conducting piece with a length, width and height of 20 mm, 20 mm and 1.5 mm, a heat conducting piece with a length, width and height of 10 mm, 15 mm and 12 mm, and a cuboid-shaped heat conducting piece with a length, width and height of 40 mm, 40 mm and 1 mm are printed respectively.

[0129] It is tested that the thermal conductivities of the prepared cuboid-shaped heat conducting piece with a length, width and height of 20 mm, 20 mm and 1.5 mm and the heat conducting piece with a length, width and height of 10 mm, 15 mm and 12 mm are as shown in the following table. Figure 3

[0130] It is tested that the elongation at break and tensile strength of the prepared cuboid-shaped heat conducting piece with a length, width and height of 40 mm, 40 mm and 1 mm at a stretching rate of 500 mm / min are as shown in the following table. Figure 6 Figure 7 ​​​​​as shown.

[0131] Application Example 4

[0132] The application example provides a method for preparing a heat-conducting piece by inkjet 3D printing, comprising the following steps:

[0133] S1, the composite ink material prepared in Example 1 is loaded into the needle cylinder of the inkjet 3D printing equipment;

[0134] S2, setting the printing process parameters, and printing a heat-conducting piece;

[0135] The printing process parameters are: the printing extrusion pressure is 1.5 MPa, the diameter of the printing needle is 0.7 mm, and the printing speed is 1.5 mm / s.

[0136] According to the method in the above application example 1, a rectangular parallelepiped heat-conducting piece with a length, width and height of 20 mm, 20 mm and 1.5 mm, a heat-conducting piece with a length, width and height of 10 mm, 15 mm and 12 mm, and a rectangular parallelepiped heat-conducting piece with a length, width and height of 40 mm, 40 mm and 1 mm are respectively printed.

[0137] The thermal conductivity of the rectangular parallelepiped heat-conducting piece with a length, width and height of 20 mm, 20 mm and 1.5 mm and the heat-conducting piece with a length, width and height of 10 mm, 15 mm and 12 mm prepared is tested as shown in the following table. Figure 3 as shown.

[0138] The elongation at break and tensile strength of the rectangular parallelepiped heat-conducting piece with a length, width and height of 40 mm, 40 mm and 1 mm prepared are tested under the condition of a tensile rate of 500 mm / min as shown in the following table. Figure 6 , Figure 7 as shown.

[0139] Example 2

[0140] The application example provides a composite ink material, comprising the following components by weight:

[0141] The silicon rubber resin is 680 parts, the heat-conducting filler is 250 parts, and the curing agent is 70 parts.

[0142] The silicon rubber resin is polydimethylsilicone rubber.

[0143] The heat-conducting filler comprises magnesium oxide and boron nitride, wherein the magnesium oxide is 50 parts, and the boron nitride is 200 parts.

[0144] The application example also provides a preparation method of the above-mentioned composite ink material, comprising the following steps:

[0145] S1, the heat conductive filler is added to the silicone rubber resin and mixed at a speed of 300 r / min for 3 h to obtain a silicone rubber mixed solution;

[0146] S2, a curing agent is added to the silicone rubber mixed solution, and after mixing, ultrasonic and centrifugal deaeration are performed to obtain a composite ink material;

[0147] The ultrasonic time is 10 min, the ultrasonic temperature is controlled at 25°C, the centrifugal speed is 3000 r / min, and the centrifugal time is 5 min.

[0148] The composite ink material prepared in Example 2 has a viscosity of 200 Pa·s at room temperature and a shear rate of 100 s -1 .

[0149] Application Example 5

[0150] The application example provides a method for preparing a heat conducting part by ink direct writing 3D printing, which comprises the following steps:

[0151] S1, the composite ink material prepared in Example 2 is loaded into a needle cylinder of an ink direct writing 3D printing device;

[0152] S2, printing process parameters are set, and a heat conducting part is printed;

[0153] The printing process parameters are: the printing extrusion pressure is 1 Mpa, the diameter of the printing needle is 0.7 mm, and the printing speed is 2 mm / s.

[0154] According to the method in the above application example 1, a rectangular cuboid heat conducting part with a length, width and height of 20 mm, 20 mm and 1.5 mm, and a heat conducting part with a length, width and height of 10 mm, 15 mm and 12 mm are respectively printed.

[0155] It is tested that the thermal conductivities of the rectangular cuboid heat conducting part with a length, width and height of 20 mm, 20 mm and 1.5 mm, and the heat conducting part with a length, width and height of 10 mm, 15 mm and 12 mm prepared are as shown in the table. Figure 4

[0156] Example 3

[0157] The example provides a composite ink material, which comprises the following components by weight:

[0158] 600 parts of silicone rubber resin, 350 parts of heat conductive filler, and 50 parts of curing agent;

[0159] The silicone rubber resin is polydimethylsilicone rubber.

[0160] The heat conductive filler comprises magnesium oxide and boron nitride, wherein the magnesium oxide is 50 parts, and the boron nitride is 300 parts.​

[0161] The embodiment also provides a preparation method of the composite ink material, comprising the following steps:

[0162] S1, adding the heat-conducting filler into the silicone rubber resin and mixing at a speed of 300 r / min for 3 h to obtain a silicone rubber mixed solution;

[0163] S2, adding the curing agent into the silicone rubber mixed solution, and after mixing, performing defoaming by ultrasonic and centrifugation to obtain the composite ink material;

[0164] The ultrasonic time is 10 min, and the ultrasonic temperature is controlled at 25 ℃; the centrifugal speed is 3000 r / min, and the centrifugal time is 5 min.

[0165] The composite ink material prepared in the embodiment 1 has a viscosity of 2500 Pa·s at room temperature and a shear rate of 100 s -1 .

[0166] Application Example 6

[0167] The application example provides a method for preparing a heat-conducting part by ink direct writing 3D printing, comprising the following steps:

[0168] S1, loading the composite ink material prepared in the embodiment 3 into a needle cylinder of an ink direct writing 3D printing device;

[0169] S2, setting printing process parameters to print a heat-conducting part;

[0170] The printing process parameters are as follows: the printing extrusion pressure is 2 Mpa, the diameter of the printing needle is 0.7 mm, and the printing speed is 2 mm / s.

[0171] According to the method in the application example 1, a cuboid-shaped heat-conducting part with a length, a width and a height of 20 mm, 20 mm and 1.5 mm, respectively, and a heat-conducting part with a length, a width and a height of 10 mm, 15 mm and 12 mm, respectively, are printed.

[0172] It is tested that the thermal conductivities of the prepared cuboid-shaped heat-conducting part with a length, a width and a height of 20 mm, 20 mm and 1.5 mm, respectively, and the heat-conducting part with a length, a width and a height of 10 mm, 15 mm and 12 mm, respectively, are as shown in the following table. Figure 4

[0173] Embodiment 4

[0174] The embodiment provides a composite ink material, comprising the following components by weight:

[0175] 650 parts of silicone rubber resin, 300 parts of heat-conducting filler and 50 parts of curing agent;

[0176] ​The silicon rubber resin is methyl vinyl silicone rubber.

[0177] The heat-conducting filler includes aluminum oxide and boron nitride, wherein the aluminum oxide is 50 parts, and the boron nitride is 300 parts.

[0178] The embodiment also provides a preparation method of the composite ink material, including the following steps:

[0179] S1, the heat-conducting filler is added to the silicon rubber resin and mixed at a speed of 300 r / min for 3 h to obtain a silicon rubber mixed solution;

[0180] S2, the curing agent is added to the silicon rubber mixed solution, and after mixing, ultrasonic and centrifugal are performed to remove bubbles to obtain the composite ink material;

[0181] The ultrasonic time is 5 min, and the ultrasonic temperature is controlled at 25 DEG C; the centrifugal speed is 2000 r / min, and the centrifugal time is 10 min.

[0182] Application Example 7

[0183] The application example provides a method for preparing a heat-conducting part by ink direct writing 3D printing, including the following steps:

[0184] S1, the composite ink material prepared in the embodiment 4 is loaded into a needle cylinder of an ink direct writing 3D printing device;

[0185] S2, printing process parameters are set, and a heat-conducting part is printed;

[0186] The printing process parameters are as follows: the printing extrusion pressure is 2 Mpa, the diameter of the printing needle is 0.5 mm, and the printing speed is 2 mm / s.

[0187] According to the method in the application example 7, a heat-conducting part in the shape of a cuboid with a length of 20 mm, a width of 20 mm and a height of 1.5 mm is printed.

[0188] Embodiment 5

[0189] The embodiment provides a composite ink material, including the following components by weight:

[0190] The silicon rubber resin is 650 parts, the heat-conducting filler is 300 parts, and the curing agent is 50 parts.

[0191] The silicon rubber resin is fluorosilicone rubber.

[0192] The heat-conducting filler is aluminum oxide.

[0193] The embodiment also provides a preparation method of the composite ink material, including the following steps:

[0194] S1, the heat conductive filler is added to the silicone rubber resin and mixed at a speed of 300 r / min for 3 h to obtain a silicone rubber mixed solution;

[0195] S2, a curing agent is added to the silicone rubber mixed solution, and after mixing, ultrasonic and centrifugal are performed to remove bubbles to obtain a composite ink material;

[0196] The ultrasonic time is 5 min, the ultrasonic temperature is controlled at 25°C, the centrifugal speed is 3000 r / min, and the centrifugal time is 10 min.

[0197] Application Example 8

[0198] The application example provides a method for preparing a heat conducting part by ink direct writing 3D printing, which comprises the following steps:

[0199] S1, the composite ink material prepared in Example 5 is loaded into a needle cylinder of an ink direct writing 3D printing device;

[0200] S2, the printing process parameters are set, and a heat conducting part is printed;

[0201] The printing process parameters are: the printing extrusion pressure is 1 Mpa, the diameter of the printing needle is 0.9 mm, and the printing speed is 2 mm / s.

[0202] According to the method in the above application example 8, a cuboid heat conducting part with a length, width and height of 20 mm, 20 mm and 1.5 mm is printed.

[0203] Comparative Example 1

[0204] The comparative example provides a preparation method of pure silicone rubber, which comprises the following steps:

[0205] S1, 650 parts by weight of silicone rubber resin and 50 parts by weight of curing agent are mixed and then formed by flow casting, and then vacuum degassing to obtain pure silicone rubber;

[0206] The silicone rubber resin is polydimethylsilicone rubber.

[0207] Figure 1 The SEM diagram of the heat conducting part (specifically: a cuboid heat conducting part with a length, width and height of 20 mm, 20 mm and 1.5 mm) sample obtained in application example 1; wherein, Fig. a is an electron microscope diagram of the printed composite material line, from which it can be seen that boron nitride is oriented along the extrusion direction. Fig. b is an electron microscope diagram of the quenched and broken heat conducting product formed by printing, from which it can also be clearly seen that boron nitride is oriented in one direction. It is shown that the shear orientation of boron nitride in the extrusion process has a good effect.

[0208] Specifically, refer to Figure 2As shown, it displays a schematic diagram of the 3D printing preparation of the thermal conductive part according to the present invention. In this diagram, the composite ink material is loaded into the syringe 1 of the ink direct writing 3D printing equipment and printed to obtain the thermal conductive part 2. The thermal conductive part 2 is rectangular, where L represents the length of the thermal conductive part, W represents the width of the thermal conductive part, and H represents the height of the thermal conductive part. Figure 2 In this context, 'a' represents the direction parallel to the length on the upper surface, which is an in-plane direction. Figure 3 The 'a' in the middle represents the direction parallel to the width on the side, which is the vertical direction.

[0209] Figure 3 For the heat-conducting components obtained in Examples 1-4, specifically: the in-plane thermal conductivity of a cuboid heat-conducting component sample with length, width, and height of 20mm, 20mm, and 1.5mm respectively; and the vertical thermal conductivity of a cuboid heat-conducting component sample with length, width, and height of 15mm, 10mm, and 12mm respectively; wherein, Figure 2 The printing speed of 1.5 mm / s represents the thermally conductive part prepared in Example 4, 2 mm / s represents the thermally conductive part prepared in Example 1, 2.5 mm / s represents the thermally conductive part prepared in Example 2, and 3 mm / s represents the thermally conductive part prepared in Example 3. The sample with a printing speed of 0 mm / s was made by casting the composite ink material prepared in Example 1 and then vacuum debubbling it.

[0210] from Figure 3 As can be seen, when composite ink materials are extruded and printed at different speeds, the magnitude of the shear force applied to the composite ink materials will change depending on the extrusion speed. Figure 3 In the process, the faster the printing speed, the greater the shear force applied to boron nitride, the higher the orientation degree of boron nitride, and the higher its thermal conductivity along the printing direction (in-plane).

[0211] Figure 4 This is a thermal conductivity diagram of the thermal conductive components obtained using Examples 2, 5, and 6 (specifically, rectangular thermal conductive components with lengths of 20mm, widths of 20mm, and heights of 1.5mm, and rectangular thermal conductive component samples with lengths of 15mm, widths of 10mm, and heights of 12mm). Figure 4The 250 parts refer to the heat conducting member prepared in Application Example 5, the 300 parts refer to the heat conducting member prepared in Application Example 2, and the 350 parts refer to the heat conducting member prepared in Application Example 6. The filler addition amount of 0 parts refers to the pure silicone rubber prepared in Comparative Example 1. The vertical and in-plane refer to the vertical and in-plane thermal conductivities of the heat conducting member prepared in Application Example 5, Application Example 2, Application Example 6, and the pure silicone rubber prepared in Comparative Example 1, which are tested according to the above method. The 250 parts correspond to the unoriented, which refers to the thermal conductivity of the composite ink material prepared in Example 2 after being obtained by flow casting and vacuum degassing. The 300 parts correspond to the unoriented, which refers to the thermal conductivity of the composite ink material prepared in Example 1 after being obtained by flow casting and vacuum degassing. The 350 parts correspond to the unoriented, which refers to the thermal conductivity of the composite ink material prepared in Example 3 after being obtained by flow casting and vacuum degassing. The 0 parts correspond to the unoriented, which refers to the thermal conductivity of the sample obtained by mixing 650 parts by weight of silicone rubber resin (PDMS) and 50 parts by weight of curing agent according to the method of Comparative Example 1, then flow casting, and then vacuum degassing.

[0212] As can be seen from Figure 4 , for different mass fractions of heat conducting fillers, under the condition of the same printing speed, as the mass fraction of the heat conducting fillers increases, the thermal conductivity of the heat conducting member oriented along the printing direction (in-plane) is higher.

[0213] Figure 5 are the thermogravimetric test graphs of the heat conducting member samples obtained in Application Examples 2, 5, and 6 (specifically: rectangular cuboid heat conducting members with a length, width, and height of 20 mm, 20 mm, and 1.5 mm, respectively). Figure 5 The 250 parts refer to the heat conducting member prepared in Application Example 5, the 300 parts refer to the heat conducting member prepared in Application Example 2, and the 350 parts refer to the heat conducting member prepared in Application Example 6. The filler addition amount of 0 parts refers to the pure silicone rubber prepared in Comparative Example 1. The vertical and in-plane refer to the vertical and in-plane thermal conductivities of the heat conducting member prepared in Application Example 5, Application Example 2, Application Example 6, and the pure silicone rubber prepared in Comparative Example 1, which are tested according to the above method. The 250 parts correspond to the unoriented, which refers to the thermal conductivity of the composite ink material prepared in Example 2 after being obtained by flow casting and vacuum degassing. The 300 parts correspond to the unoriented, which refers to the thermal conductivity of the composite ink material prepared in Example 1 after being obtained by flow casting and vacuum degassing. The 350 parts correspond to the unoriented, which refers to the thermal conductivity of the composite ink material prepared in Example 3 after being obtained by flow casting and vacuum degassing. The 0 parts correspond to the unoriented, which refers to the thermal conductivity of the sample obtained by mixing 650 parts by weight of silicone rubber resin (PDMS) and 50 parts by weight of curing agent according to the method of Comparative Example 1, then flow casting, and then vacuum degassing.

[0214] As can be seen from Figure 5 , as the amount of heat conducting fillers increases, the remaining mass of the heat conducting member at 800°C also increases, and the thermal stability also improves.

[0215] Figure 6 and Figure 7 are the tensile test graphs of the heat conducting member samples obtained in Application Examples 1-3. Figures 6-7 In the table, 2 mm / s refers to the heat conducting member prepared in Application Example 1, 2.5 mm / s refers to the heat conducting member prepared in Application Example 2, 3 mm / s refers to the heat conducting member prepared in Application Example 3, and pure silicone rubber refers to the pure silicone rubber prepared in Comparative Example 1.

[0216] As can be seen from Figures 6-7As can be seen, the addition of thermally conductive filler will reduce the elongation at break and tensile strength of the material. However, as the printing speed increases, the orientation of the filler in the matrix increases, which hinders the propagation of cracks in the matrix. The higher the orientation, the more obvious the hindering effect, and the elongation at break and tensile strength of the material will increase.

[0217] Figures 8-9 These are rheological test diagrams of the composite ink materials obtained in Examples 1, 2, and 3. Specifically, Figure 8 The graph shows the viscosity of the composite ink material as a function of shear rate. Figure 9 The graph shows the changes in storage modulus and loss modulus of composite ink materials with oscillation strain.

[0218] Figures 8-9 In this context, 20% BN + 5% MgO represents the composite ink material prepared in Example 2, 25% BN + 5% MgO represents the composite ink material prepared in Example 1, and 30% BN + 5% MgO represents the composite ink material prepared in Example 3. Figure 8 The term "pure silicone rubber" refers to the pure silicone rubber prepared in Comparative Example 1.

[0219] from Figures 8-9 As can be seen, with the increase of thermally conductive filler, the viscosity and modulus of the ink material will increase; when the mass fraction of thermally conductive filler is greater than 300 parts, the storage modulus of the ink material is greater than the loss modulus, and the ink material is in a solid state. At this time, the ink material has sufficient rheological properties to meet the printing requirements.

[0220] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. 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 method of preparing a thermally conductive article by ink direct writing 3D printing, characterized in that, The method comprises the following steps: loading the composite ink material into a needle cylinder of an ink direct writing 3D printing device; setting printing process parameters to print a heat conducting part; the printing process parameters are: printing extrusion pressure is 1-2 Mpa, printing needle diameter is 0.7-1.2 mm, and printing speed is 2.5-3 mm / s; the composite ink material comprises the following components in parts by weight: 600-650 parts of silicone rubber resin, 300-350 parts of heat conducting filler, and 50-70 parts of curing agent; the sum of the parts by weight of the silicone rubber resin, the heat conducting filler and the curing agent is 1000 parts; the silicone rubber resin is polydimethylsilicone rubber; the heat conducting filler comprises 50 parts of magnesium oxide and 250-300 parts of boron nitride.

2. The method of claim 1, wherein the ink direct writing 3D printing is performed by using a thermal inkjet printer. The preparation method of the composite ink material comprises the following steps: adding the heat conducting filler to the silicone rubber resin to obtain a silicone rubber mixed solution; adding the curing agent to the silicone rubber mixed solution, and after mixing, performing ultrasonic and centrifugal defoaming to obtain the composite ink material.

3. The method of claim 2, wherein the ink direct write 3D printing of the thermally conductive article is performed by, The centrifugal rate is 1000-6000 r / min, and the centrifugal time is 5-30 min.

4. The method of claim 2, wherein the ink direct write 3D printing of the thermally conductive article is performed by a method comprising: The ultrasonic time is 5-30 min.

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