Silicon-free polyurethane heat-conducting gel and preparation method thereof

Abstract

The invention discloses a silicon-free polyurethane heat-conducting gel and a preparation method thereof. The silicon-free polyurethane heat-conducting gel comprises a first component and a second component, the first component is prepared from the following components in parts by weight: 0.5 to 2.5 parts of first polyether polyol, 3 to 4.5 parts of first polyester polyol, 0.4 to 0.6 part of a molecular sieve, 0.05 to 0.1 part of a catalyst, 0.3 to 0.5 part of an antioxidant, 0.3 to 0.5 part of a first wetting dispersant and 92 to 94 parts of heat-conducting filler; the second component is prepared from the following components in parts by weight: 1 to 2 parts of second polyether polyol, 0.5 to 1.5 parts of second polyester polyol, 3 to 5 parts of isocyanate, 0.1 to 0.2 part of water removal agent, 0.3 to 0.5 part of second wetting dispersant and 92 to 94 parts of heat conduction filler. The invention provides the silicone-free polyurethane heat-conducting gel which does not contain organosilicone, and the silicone-free polyurethane heat-conducting gel has heat conductivity, flexibility, high temperature resistance, aging resistance and environmental friendliness.

Description

Technical Field

[0001] The invention relates to the technical field of thermally conductive gels, and in particular to a high thermally conductive, high temperature resistant two-component silicon-free polyurethane thermally conductive gel and a preparation method thereof. Background Art

[0002] In modern electronic devices, in the fields of LED lighting, 5G communications, new energy vehicles, and aerospace, as electronic devices develop towards miniaturization, high power density, and lightweight, traditional heat dissipation materials and methods can no longer meet the heat dissipation needs, and there is an urgent need to develop new efficient and environmentally friendly thermal conductive materials. Polyurethane (PU) is a commonly used polymer material that is widely used in various fields due to its excellent mechanical properties and chemical stability. Among them, silicone-free polyurethane (SFPU) has received more and more attention because it does not contain silicone and has better environmental friendliness and biocompatibility. At the same time, silicone-free polyurethane also has good thermal conductivity, making it a strong candidate for thermal interface materials.

[0003] Existing thermal interface materials are mainly based on silicone thermal conductive gels, although they have excellent thermal conductivity and high temperature resistance. However, the silicone oil in the thermal conductive gel will seep out due to heat and extrusion of parts, which not only causes pollution to electronic equipment and components, but also may seriously cause equipment short circuits and affect the service life; on the other hand, the molding process of existing silicone thermal conductive gels requires high-temperature curing, and small molecules in the silicone resin system will volatilize, thereby polluting the environment and affecting human health. Therefore, silicone-free thermal conductive gels have become the direction of research and development. At present, there have been some reports on silicone-free polyurethane thermal conductive gels. These thermal conductive gels are usually prepared by mixing polyurethane prepolymers with other components, which may contain polyether polyols, catalysts, antioxidants, wetting dispersants, etc. However, the thermal conductivity, high temperature resistance, production process and cost of these existing silicone-free polyurethane thermal conductive gels still need to be improved.

[0004] Although the research and application of silicone-free polyurethane thermally conductive gels have made certain progress, there are still some problems that need to be solved. First, the thermal conductivity of existing silicone-free polyurethane thermally conductive gels is still somewhat different from that of silicone-based thermally conductive gels. Secondly, the high temperature resistance of silicone-free polyurethane thermally conductive gels also needs to be further improved to meet the needs of use in high temperature environments. In addition, the preparation method of existing silicone-free polyurethane thermally conductive gels is relatively complex and costly, which limits their large-scale application. Therefore, developing a silicone-free polyurethane thermally conductive gel with high thermal conductivity, good flexibility, high temperature resistance and aging resistance, and a simple preparation method and low cost is an important challenge facing current technology.

[0005] The present invention solves at least one of the above problems. Summary of the invention

[0006] The object of the present invention is to provide a silicone-free polyurethane thermally conductive gel and a preparation method thereof, so as to provide a silicone-free polyurethane thermally conductive gel that does not contain silicone and has thermal conductivity, flexibility, high temperature resistance and aging resistance, and environmental friendliness.

[0007] The purpose of the present invention is achieved by the following technical solutions:

[0008] In a first aspect of the present invention, there is provided a silicone-free polyurethane thermally conductive gel, comprising a first component and a second component;

[0009] The first component comprises, by weight: 0.5 to 2.5 parts of a first polyether polyol, 3 to 4.5 parts of a first polyester polyol, 0.4 to 0.6 parts of a molecular sieve, 0.05 to 0.1 parts of a catalyst, 0.3 to 0.5 parts of an antioxidant, 0.3 to 0.5 parts of a wetting and dispersing agent, and 92 to 94 parts of a thermally conductive filler;

[0010] The second component comprises, by weight: 1 to 2 parts of a second polyether polyol, 0.5 to 1.5 parts of a second polyester polyol, 3 to 5 parts of isocyanate, 0.1 to 0.2 parts of a dewatering agent, 0.3 to 0.5 parts of a wetting dispersant, and 92 to 94 parts of a thermally conductive filler.

[0011] In some possible implementations, the volume ratio of the first component to the second component is 4:1.

[0012] In some possible implementations, the first polyether polyol and / or the second polyether polyol has a functionality of 2 to 3, a number average molecular weight of 200 to 5000, and a viscosity of 50 to 1000 mPa·s.

[0013] In some possible implementations, the first polyester polyol and / or the second polyester polyol has a functionality of 2, a number average molecular weight of 1500 to 1800, and a viscosity of 1000 to 1500 mPa·s.

[0014] In some possible implementations, the thermally conductive filler includes one or more of aluminum hydroxide, aluminum oxide, zinc oxide, magnesium oxide, boron nitride, and aluminum nitride;

[0015] And / or, the average particle size of the thermally conductive filler is 1 μm to 70 μm;

[0016] And / or, the shape of the thermally conductive filler is one or more of spherical, quasi-spherical, flaky, and irregular.

[0017] In some possible implementations, the isocyanate includes one or more of hexamethylene diisocyanate, isophorone diisocyanate, 4,4′-diphenylmethane diisocyanate, and toluene diisocyanate.

[0018] In some possible embodiments, the catalyst includes one or more of bismuth isooctanoate, bismuth neodecanoate, bismuth laurate, zirconium isooctanoate, dibutyltin dilaurate, and zinc neodecanoate.

[0019] In some possible embodiments, the molecular sieve includes one or more of 3A molecular sieve, 4A molecular sieve, and 5A molecular sieve;

[0020] In some possible embodiments, the antioxidant includes one or more of organic thioethers, hindered phenols, and phosphites;

[0021] In some possible implementations, the wetting and dispersing agent includes one or more of BYK W9010, BYK 9076, and BYK 145.

[0022] In some possible implementations, the water scavenger is p-toluenesulfonyl isocyanate.

[0023] A second aspect of the present invention provides a method for preparing a silicone-free polyurethane thermally conductive gel, comprising:

[0024] Prepare a first component, wherein the first component includes: a first polyether polyol, a first polyester polyol, a molecular sieve, a catalyst, an antioxidant, a first wetting and dispersing agent, and a first thermally conductive filler;

[0025] preparing a second component, wherein the second component comprises: a second polyether polyol, a second polyester polyol, an isocyanate, a water scavenger, a second wetting and dispersing agent, and a second thermally conductive filler;

[0026] The first component and the second component are mixed uniformly at room temperature, vacuum degassed, and then aged at room temperature or under heating conditions to obtain a silicone-free polyurethane thermal conductive gel.

[0027] In some possible embodiments, it is characterized in that preparing the first component comprises:

[0028] Dehydrating the first polyether polyol and the first polyester polyol under vacuum at a temperature of 110 to 130° C. for 2 to 3 hours, and then cooling to 50 to 55° C. to obtain a first mixed solution;

[0029] Dehydrating the first thermally conductive filler at a temperature of 120 to 130° C. for 24 to 26 hours, cooling to 70 to 80° C., and then adding the wetting and dispersing agent and stirring for 30 to 60 minutes; obtaining a standby powder, and dividing the standby powder into a first standby powder and a second standby powder according to a weight ratio;

[0030] Adding the first mixed liquid to the first reserved powder, and then sequentially adding the molecular sieve, the catalyst, and the antioxidant, grinding and stirring, and vacuum degassing to obtain a first component;

[0031] Preparing the second component comprises:

[0032] Dehydrating the second polyether polyol under vacuum at a temperature of 110 to 130° C. for 2 to 3 hours, and then cooling to 50 to 55° C. to obtain a second mixed solution;

[0033] Adding isocyanate to the second mixed liquid, heating to 70-80° C. and performing vacuum reaction for 2-3 hours to obtain a polyurethane prepolymer;

[0034] The second standby powder is added to the polyurethane prepolymer, and then a dehydrating agent is added, followed by grinding, stirring, and vacuum degassing to obtain a second component.

[0035] In some possible implementations, the volume ratio of the first component to the second component is 4:1.

[0036] Compared with the prior art, the beneficial effects of the present invention include at least:

[0037] 1. The silicone-free polyurethane thermally conductive gel of the present invention has a high thermal conductivity, which is stable at above 4.0 W / m·K, and can effectively improve the thermal conductivity between electronic components and radiators, thereby solving the heat dissipation problem in modern electronic equipment and improving equipment performance and life.

[0038] 2. The silicone-free polyurethane thermally conductive gel of the present invention has good high temperature resistance. In the high temperature aging test at 125°C for 1000h, its flexibility and thermal conductivity remain stable, which can meet the use requirements in high temperature environments and greatly expand the application range of polyurethane thermally conductive gel.

[0039] 3. The silicone-free polyurethane thermal conductive gel of the present invention does not contain silicone, which can effectively avoid the phenomenon of oil discharge during use of the existing thermal conductive gel of the silicone resin system, reduce the pollution to electronic components, ensure the safe operation of electronic equipment, and thus increase the service life of electronic products; it has better environmental friendliness and biocompatibility, and meets the current environmental protection and health needs.

[0040] 4. The preparation method of the silicone-free polyurethane thermally conductive gel of the present invention is relatively simple, low in cost, conducive to large-scale application, and has good commercial value.

[0041] 5. The silicone-free polyurethane thermally conductive gel of the present invention has good thermal conductivity and flexibility, and also has excellent high temperature resistance and aging resistance, thereby improving the comprehensive performance of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a flow chart of the steps of a method for preparing a silicone-free polyurethane thermally conductive gel according to an embodiment of the present invention;

[0043] Figure 2 is a flow chart of steps for preparing the first component according to an embodiment of the present invention;

[0044] Figure 3 1 is a flow chart of the steps of preparing the second component in an embodiment of the present invention. DETAILED DESCRIPTION

[0045] The exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, the exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; on the contrary, these embodiments are provided to make the present invention more comprehensive and complete and to fully convey the concept of the exemplary embodiments to those skilled in the art.

[0046] The present application provides a silicone-free polyurethane thermally conductive gel, comprising a first component and a second component.

[0047] The first component comprises, by weight: 0.5 to 2.5 parts of a first polyether polyol, 3 to 4.5 parts of a first polyester polyol, 0.4 to 0.6 parts of a molecular sieve, 0.05 to 0.1 parts of a catalyst, 0.3 to 0.5 parts of an antioxidant, 0.3 to 0.5 parts of a first wetting and dispersing agent, and 92 to 94 parts of a thermally conductive filler;

[0048] The second component comprises, by weight: 1 to 2 parts of a second polyether polyol, 0.5 to 1.5 parts of a second polyester polyol, 3 to 5 parts of isocyanate, 0.1 to 0.2 parts of a dehydrating agent, 0.3 to 0.5 parts of a second wetting dispersant, and 92 to 94 parts of a thermally conductive filler.

[0049] In some specific embodiments, the volume ratio of the first component to the second component is 4: 1. The silicone-free polyurethane thermally conductive gel at this volume ratio has good thermal conductivity, flexibility, high temperature resistance and aging resistance, does not contain silicone, and is environmentally friendly.

[0050] In some specific embodiments, the first polyether polyol and / or the second polyether polyol has a functionality of 2 to 3, a number average molecular weight of 200 to 5000, and a viscosity of 50 to 1000 mPa·s.

[0051] Furthermore, the first polyether polyol and / or the second polyether polyol includes at least one of the following: a polyether polyol with a number average molecular weight of 400 and a functionality of 2, and a viscosity of 60-80 mPa·s; a polyether polyol with a number average molecular weight of 1000 and a functionality of 2, and a viscosity of 120-180 mPa·s; a polyether polyol with a number average molecular weight of 3000 and a functionality of 3, and a viscosity of 800-1000 mPa·s; a polyether polyol with a number average molecular weight of 2000 and a functionality of 2, and a viscosity of 250-350 mPa·s.

[0052] In some specific embodiments, the first polyester polyol and / or the second polyester polyol has a functionality of 2, a number average molecular weight of 1500-1800, and a viscosity of 1000-1500 mPa·s.

[0053] Furthermore, the first polyester polyol and / or the second polyester polyol comprises at least one of the following: a polyester polyol having a number average molecular weight of 1700 and a functionality of 2, and a viscosity of 1100-1300 mPa·s; a polyester polyol having a number average molecular weight of 1700 and a functionality of 2, and a viscosity of 1100-1200 mPa·s.

[0054] In some specific embodiments, the thermally conductive filler includes one or more of aluminum hydroxide, aluminum oxide, zinc oxide, magnesium oxide, boron nitride, and aluminum nitride.

[0055] Furthermore, the average particle size of the thermal conductive filler is 1 μm to 70 μm.

[0056] In the present application, the shape of the thermally conductive filler may be one or more of spherical, quasi-spherical, flaky, and irregular shapes.

[0057] In some specific embodiments, the isocyanate includes one or more of hexamethylene diisocyanate, isophorone diisocyanate, 4,4′-diphenylmethane diisocyanate, and toluene diisocyanate.

[0058] In some specific embodiments, the catalyst includes one or more of bismuth isooctanoate, bismuth neodecanoate, bismuth laurate, zirconium isooctanoate, dibutyltin dilaurate, and zinc neodecanoate.

[0059] In some specific embodiments, the molecular sieve includes one or more of 3A molecular sieve, 4A molecular sieve, and 5A molecular sieve.

[0060] In some specific embodiments, the antioxidant comprises one or more of an organic thioether, a hindered phenol, and a phosphite.

[0061] In some specific embodiments, the wetting and dispersing agent includes one or more of BYK W9010, BYK 9076, and BYK 145.

[0062] In some specific embodiments, the water scavenger is p-toluenesulfonyl isocyanate.

[0063] See attached Figure 1 As shown, this embodiment also provides a preparation method for preparing the above-mentioned silicone-free polyurethane thermal conductive gel, including steps S1 to S3.

[0064] Step S1: Prepare the first component, see Appendix Figure 2 As shown, it specifically includes steps S11 to S13.

[0065] Step S11: vacuum dehydrating the first polyether polyol and the first polyester polyol at a temperature of 110-130° C., and cooling to 50-55° C. after vacuum dehydrating for 2-3 hours to obtain a first mixed solution.

[0066] Step S12: dehydrate the first thermally conductive filler at a temperature of 120-130° C. for 24-26 hours, then cool to 70-80° C., and then add a wetting dispersant and stir for 30-60 minutes; obtain a standby powder, and divide the standby powder into a first standby powder and a second standby powder by weight.

[0067] Step S13: adding the first mixed liquid to the first reserved powder, and then sequentially adding the molecular sieve, the catalyst, and the antioxidant, grinding and stirring, and vacuum degassing to obtain the first component, and sealing and packaging the prepared first component.

[0068] Step S2: Prepare the second component, see Appendix Figure 3 As shown, it specifically includes steps S21 to S23.

[0069] Step S21: vacuum dehydrating the second polyether polyol at a temperature of 110-130° C. for 2-3 hours and then cooling to 50-55° C. to obtain a second mixed solution.

[0070] Step S22: adding isocyanate to the second mixed liquid, heating to a temperature of 70-80° C. and performing vacuum reaction for 2-3 hours to obtain a polyurethane prepolymer.

[0071] Step S23: adding the second reserved powder to the polyurethane prepolymer, then adding a dehydrating agent, grinding and stirring, and vacuum degassing to obtain a second component, and sealing and packaging the prepared second component.

[0072] Wherein, the dehydrating agent is p-toluenesulfonyl isocyanate.

[0073] Step S3: Evenly mix the first component and the second component at room temperature, perform vacuum degassing, and then mature at room temperature or under heating conditions to obtain a silicone-free polyurethane thermal conductive gel.

[0074] In some specific embodiments, the volume ratio of the first component to the second component is 4:1.

[0075] The technical solution of the present application will be described in more detail below, but it should be understood that the following examples are only for explaining and illustrating the technical solution, but do not limit the scope of the present application. Moreover, unless otherwise specified, the various raw materials, reaction equipment, detection equipment and methods used in the following examples are all known in the art.

[0076] Example 1

[0077] Step S1: preparing a first component, including steps S11 to S13.

[0078] Step S11: 0.5 parts of the first polyether polyol and 4.5 parts of the first polyester polyol are vacuum dried and dehydrated at 120° C. for 2 hours, and then cooled to 50° C. to obtain a first mixed solution.

[0079] Among them, the first polyether polyol includes: 0.25 parts of a polyether polyol with a number average molecular weight of 400 and a functionality of 2, whose viscosity is 70mPa·s; 0.25 parts of a polyether polyol with a number average molecular weight of 1000 and a functionality of 2, whose viscosity is 150mPa·s; the first polyester polyol includes: 4.5 parts of a polyester polyol with a number average molecular weight of 1700 and a functionality of 2, whose viscosity is 1200mPa·s.

[0080] Step S12: Dry 93.5 parts of thermal conductive filler in an oven at 120°C for 24 hours, cool to 70°C, add 0.45 parts of wetting dispersant, and stir to obtain a standby powder, and divide the standby powder into a first standby powder and a second standby powder of equal weight at a weight ratio of 1:1.

[0081] The thermal conductive filler includes: 17 parts of aluminum oxide with an average particle size of 1 μm, 26.5 parts of aluminum oxide with an average particle size of 5 μm, 26.5 parts of aluminum oxide with an average particle size of 40 μm, and 23.5 parts of aluminum oxide with an average particle size of 70 μm.

[0082] The wetting and dispersing additive is BYK 9076.

[0083] Step S13: Add the first standby powder prepared in step S12 to the first mixed solution prepared in step S11, then add 0.5 parts of molecular sieve, 0.1 parts of catalyst and 0.4 parts of antioxidant, grind and stir thoroughly in a homogenizer, vacuum to remove mechanical bubbles, and seal and package to obtain the first component.

[0084] The molecular sieve is 3A molecular sieve, the catalyst is dibutyltin dilaurate, and the antioxidant is organic thioether.

[0085] Step S2: preparing the second component, including steps S21 to S23.

[0086] Step S21: 1.65 parts of the second polyether polyol and 1 part of the second polyester polyol are vacuum dried and dehydrated at 120° C. for 4 hours, and then cooled to 50° C. to obtain a second mixed solution.

[0087] The second polyether polyol includes: 1.65 parts of a polyether polyol having a number average molecular weight of 3000 and a functionality of 3, and a viscosity of 900 mPa·s.

[0088] The second polyester polyol includes: 1 part of a polyester polyol having a number average molecular weight of 1700 and a functionality of 2, and having a viscosity of 1150 mPa·s.

[0089] Step S22: adding 4 parts of isocyanate to the second mixed solution obtained in step S21, heating to 80° C. and performing vacuum reaction for 2.5 hours to obtain a polyurethane prepolymer.

[0090] Wherein, the isocyanate is isophorone diisocyanate.

[0091] Step S23: adding the second standby powder prepared in step S12 to the polyurethane prepolymer prepared in step S22, and then adding 0.15 parts of dehydrating agent, grinding and stirring in a planetary mixer, vacuuming to remove mechanical bubbles, and sealing and packaging to obtain the second component.

[0092] Wherein, the water removing agent is p-toluenesulfonyl isocyanate.

[0093] Step S3: uniformly mix the first component and the second component at a volume ratio of 4:1 at room temperature, perform vacuum degassing and mature at room temperature to obtain a silicone-free polyurethane thermal conductive gel.

[0094] Example 2

[0095] The preparation method is the same as that of Example 1, except that:

[0096] 2 parts of the first polyether polyol and 3 parts of the first polyester polyol.

[0097] The first polyether polyol includes: 1.54 parts of a polyether polyol with a number average molecular weight of 2000 and a functionality of 2, and a viscosity of 300 mPa·s; and 0.41 parts of a polyether polyol with a number average molecular weight of 1000 and a functionality of 2, and a viscosity of 150 mPa·s.

[0098] 0.5 parts of wetting and dispersing agent, wherein the wetting and dispersing agent is BYK 145.

[0099] The antioxidants are blocked phenols.

[0100] 1.4 parts of the second polyether polyol and 0.5 parts of the second polyester polyol.

[0101] 4.5 parts of isocyanate, wherein the isocyanate is hexamethylene diisocyanate.

[0102] Example 3

[0103] The preparation method is the same as that of Example 1, except that:

[0104] 2.5 parts of the first polyether polyol and 4.4 parts of the first polyester polyol.

[0105] The first polyether polyol includes: 2.18 parts of a polyether polyol with a number average molecular weight of 3000 and a functionality of 3, and a viscosity of 900 mPa·s; and 0.32 parts of a polyether polyol with a number average molecular weight of 1000 and a functionality of 2, and a viscosity of 150 mPa·s.

[0106] 92 parts of thermal conductive filler, including: 17 parts of aluminum oxide with an average particle size of 1 μm, 26 parts of aluminum oxide with an average particle size of 5 μm, 26 parts of aluminum oxide with an average particle size of 40 μm, and 23 parts of aluminum oxide with an average particle size of 70 μm.

[0107] 0.3 parts of wetting and dispersing agent, wherein the wetting and dispersing agent is BYK W9010.

[0108] 0.4 parts of molecular sieve and 0.05 parts of catalyst.

[0109] 0.3 parts of antioxidant, wherein the antioxidant is phosphite.

[0110] 1 part of the second polyether polyol and 1.5 parts of the second polyester polyol.

[0111] 4 parts of isocyanate, wherein the isocyanate is 4,4′-diphenylmethane diisocyanate.

[0112] 0.2 parts of water remover.

[0113] Example 4

[0114] The preparation method is the same as that of Example 1, except that:

[0115] 0.57 parts of the first polyether polyol and 3.8 parts of the first polyester polyol.

[0116] The first polyether polyol comprises: 0.33 parts of a polyether polyol with a number average molecular weight of 400 and a functionality of 2, and a viscosity of 70 mPa·s; and 0.24 parts of a polyether polyol with a number average molecular weight of 1000 and a functionality of 2, and a viscosity of 150 mPa·s.

[0117] 94 parts of thermal conductive filler, including: 17.5 parts of aluminum oxide with an average particle size of 1 μm, 26.5 parts of aluminum oxide with an average particle size of 5 μm, 26.5 parts of aluminum oxide with an average particle size of 40 μm, and 23.5 parts of aluminum oxide with an average particle size of 70 μm.

[0118] 0.3 parts of wetting and dispersing agent.

[0119] 0.4 parts of molecular sieve and 0.05 parts of catalyst.

[0120] 0.3 parts of antioxidant, wherein the antioxidant is inhibited phenol.

[0121] 1.15 parts of the second polyether polyol and 1.45 parts of the second polyester polyol.

[0122] 3 parts of isocyanate, wherein the isocyanate is toluene diisocyanate.

[0123] 0.1 part of water remover.

[0124] Example 5

[0125] The preparation method is the same as that of Example 1, except that:

[0126] 2.6 parts of the first polyether polyol and 4.3 parts of the first polyester polyol.

[0127] The first polyether polyol includes: 2.2 parts of a polyether polyol with a number average molecular weight of 3000 and a functionality of 3, and a viscosity of 900 mPa·s; and 0.4 parts of a polyether polyol with a number average molecular weight of 1000 and a functionality of 2, and a viscosity of 150 mPa·s.

[0128] 92 parts of thermal conductive filler, including: 17 parts of aluminum oxide with an average particle size of 1 μm, 26 parts of aluminum oxide with an average particle size of 5 μm, 26 parts of aluminum oxide with an average particle size of 40 μm, and 23 parts of aluminum oxide with an average particle size of 70 μm.

[0129] 0.3 parts of wetting and dispersing agent, wherein the wetting and dispersing agent is BYK 9076.

[0130] 0.4 parts of molecular sieve and 0.05 parts of catalyst.

[0131] 0.3 parts of antioxidant.

[0132] 2 parts of the second polyether polyol and 1.3 parts of the second polyester polyol.

[0133] Isocyanate 4.3 parts.

[0134] 0.2 parts of water remover.

[0135] Example 6

[0136] The preparation method is the same as that of Example 1, except that:

[0137] 1.27 parts of the first polyether polyol and 3.1 parts of the first polyester polyol.

[0138] The first polyether polyol includes: 0.74 parts of a polyether polyol with a number average molecular weight of 2000 and a functionality of 2, and a viscosity of 300 mPa·s; and 0.53 parts of a polyether polyol with a number average molecular weight of 1000 and a functionality of 2, and a viscosity of 150 mPa·s.

[0139] 94 parts of thermal conductive filler, including: 17.5 parts of aluminum oxide with an average particle size of 1 μm, 26.5 parts of aluminum oxide with an average particle size of 5 μm, 26.5 parts of aluminum oxide with an average particle size of 40 μm, and 23.5 parts of aluminum oxide with an average particle size of 70 μm.

[0140] 0.4 parts of wetting and dispersing agent, wherein the wetting and dispersing agent is BYK 145.

[0141] 0.6 parts of molecular sieve and 0.08 parts of catalyst.

[0142] 0.5 parts of antioxidant, wherein the antioxidant is inhibited phenol.

[0143] 1.3 parts of the second polyether polyol and 0.95 parts of the second polyester polyol.

[0144] 3.65 parts of isocyanate, wherein the isocyanate is hexamethylene diisocyanate.

[0145] 0.1 part of water remover.

[0146] Comparative Example 1

[0147] The difference from Example 1 is that no antioxidant is added to the first component and the second component.

[0148] Comparative Example 2

[0149] The difference from Example 1 is that no molecular sieve is added to the first component.

[0150] Comparative Example 3

[0151] A conventional method for preparing a silicone thermally conductive gel comprises steps S1 to S3.

[0152] Step S1: Prepare the first component: 7.7 g of castor oil-modified polyether polyol with a number average molecular weight of 1200, a functionality of 2, and a viscosity of 400 mPa·s (a value of 300-500 mPa·s) is vacuum dried and dehydrated at 100°C for 2 h, cooled to room temperature, 1.3 g of diphenylmethane diisocyanate (MDI) is added, and stirred at 800 rpm for 10 min to mix well to form a prepolymer, which is placed at room temperature in a sealed container, 69 g of dodecyltrimethoxysilane-modified boron nitride (BN), 15 g of dodecyltrimethoxysilane Alkyltrimethoxysilane-modified aluminum hydroxide (AL(OH)3), 6 g of glass microspheres and 1 g of dioctyl terephthalate (DOTP) were vacuum dried and dehydrated at 110°C for 2 h, cooled to room temperature, 0.1 g of p-toluenesulfonyl isocyanate (PISI) was added, and stirred at 1000 rpm for 10 min. After cooling to room temperature, the prepolymer was added and stirred at 800 rpm for 10 min to mix evenly. The mixture was placed in a vacuum degassing box with a vacuum degree of -0.08 MPa and vibrated for degassing for 20 min to obtain the first component.

[0153] Step S2: preparing the second component: 1.6 g of castor oil-modified polyether polyol with a number-average molecular weight of 700, a functionality of 2, and a viscosity of 300 mPa·s (a value of 200-400 mPa·s), 8.4 g of hydroxy-terminated polybutadiene (HTPB, Mn (Number-average Molecular Weight, number-average molecular weight) = 2800), 66 g of dodecyltrimethoxysilane-modified boron nitride (BN), 15 g of dodecyltrimethoxysilane-modified aluminum hydroxide (AL(OH)3), 6 g of glass microspheres and 3 g of dioctyl terephthalate (DOTP) were dried and dehydrated at 100° C. in vacuum and cooled to room temperature for 2 h, 0.5 g of stannous octoate (T-9) was added, and the mixture was stirred at 1000 rpm for 10 min to mix evenly, and the mixture was placed in a vacuum degassing box with a vacuum degree of -0.08 MPa and vibrated for degassing for 20 min to obtain the second component.

[0154] Step S3: Stir the first component and the second component of the same weight at 600 rpm for 10 minutes to mix them evenly, place them in a vacuum degassing box with a vacuum degree of -0.08 MPa, and vibrate and degas for 20 minutes to obtain a thermal conductive gel. Place the thermal conductive gel in an 80°C oven for curing for 6 hours to obtain a silicone thermal conductive gel.

[0155] Note: The brands and manufacturers of wetting and dispersing agents are shown in Table 1.

[0156] The thermally conductive gels of the above embodiments and comparative examples were subjected to performance tests, including: apparent state (visual inspection), thermal conductivity and hardness Shore OO before and after high temperature aging test. The test data are shown in Table 2.

[0157] The high temperature aging test is specifically as follows: the thermally conductive gels of the embodiment and the comparative example are aged at 125° C. for 1000 h.

[0158] The thermal conductivity is measured using a TIM thermal resistance tester LW9389 on a thermal conductive gel with a length of 60 mm, a width of 60 mm, and a height of 6 mm. The test standard is the ASTM D5470 test standard issued by the American Society for Testing and Materials (ASTM International).

[0159] The hardness is measured using a Shore OO hardness tester on a thermally conductive gel with a length of 60 mm, a width of 60 mm, and a height of 6 mm. The test standard uses the ASTM D2240 test standard published by the American Society for Testing and Materials.

[0160] Table 1: Brands and manufacturers of wetting and dispersing agents

[0161]

[0162] Table 2: Performance test data of thermally conductive gels of Examples and Comparative Examples

[0163]

[0164]

[0165] It can be seen from the data in Table 2 above that the thermal conductivity of the thermally conductive gel prepared in the present application is stable at more than 4 W / m·K before and after the high-temperature aging test, and the variation range does not exceed 2%, indicating that it has good thermal conductivity and stability under high temperature and aging conditions; its hardness Shore OO is stable between 50-60 before and after the high-temperature aging test, and the variation range does not exceed 4%, indicating that it has good flexibility and stability under high temperature and aging conditions; in summary, the thermally conductive gel of the present application has good thermal conductivity, flexibility, and high temperature and aging resistance stability.

[0166] It can be seen from Examples 1-6 and Comparative Example 3 that the comparative example adopts a thermally conductive gel made of a material containing silicone, while the present application prepares a silicone-free polyurethane thermally conductive gel without adding silicone, and its thermal conductivity can be stabilized at more than 4 W / m·K, which is similar to the thermal conductivity of Comparative Example 3, and the Shore OO hardness is below 60. Moreover, after the high-temperature aging test at 125°C and 1000 h, the change range of its Shore OO hardness and thermal conductivity is significantly smaller, not exceeding 4% and 2%, respectively; while after the high-temperature aging test at 125°C and 1000 h, the change range of its Shore OO hardness and thermal conductivity of Comparative Example 3 is significantly larger, reaching about 12.2% and 50%, respectively. This shows that the silicone-free polyurethane thermally conductive gel prepared by the present application has more stable flexibility and thermal conductivity.

[0167] Therefore, the silicone-free polyurethane thermal conductive gel of the present application can effectively avoid the oil leakage of the existing thermal conductive gel of the silicone resin system during use while maintaining good thermal conductivity, thereby reducing the pollution to electronic components, ensuring the safe operation of electronic equipment, and also avoiding the pollution caused by silicone during high-temperature curing.

[0168] It can be seen from Example 1 and Comparative Example 1 that the change ranges of Shore OO hardness and thermal conductivity of the thermal conductive gel in Comparative Example 1 before and after the high-temperature aging test are approximately 51.8% and 6.45%, respectively, which are significantly higher than those in Example 1, indicating that the addition of antioxidants to the silicone-free polyurethane thermal conductive gel significantly increases the thermal decomposition temperature and slows down the hardness increase and thermal conductivity decrease during the thermal aging process.

[0169] It can be seen from Example 1 and Comparative Example 1 that the thermal conductivity of the thermally conductive gel in Comparative Example 2 is below 4 W / m·K, which is significantly lower than that in Example 1; and the changes in Shore OO hardness and thermal conductivity before and after the high-temperature aging test are approximately 69.2% and 5.5%, respectively, which are significantly higher than those in Example 1. This indicates that adding molecular sieves to the silicone-free polyurethane thermally conductive gel can improve its thermal conductivity and significantly reduce the increase in hardness and the decrease in thermal conductivity during the thermal aging process.

[0170] In Comparative Example 2, obvious bubbles appeared in the silicone-free polyurethane thermally conductive gel, and adding molecular sieves can prevent the bubbles from having an adverse effect on the silicone-free polyurethane thermally conductive gel.

[0171] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, substitute and modify the above embodiments within the scope of the invention without departing from the principles and purpose of the present invention. All such changes should fall within the scope of protection of the claims of the present invention.

Claims

1. A silicone-free polyurethane thermally conductive gel, characterized in that: comprising a first component and a second component; The first component comprises, by weight: 0.5 to 2.5 parts of a first polyether polyol, 3 to 4.5 parts of a first polyester polyol, 0.4 to 0.6 parts of a molecular sieve, 0.05 to 0.1 parts of a catalyst, 0.3 to 0.5 parts of an antioxidant, 0.3 to 0.5 parts of a wetting and dispersing agent, and 92 to 94 parts of a thermally conductive filler; The second component comprises, by weight: 1 to 2 parts of a second polyether polyol, 0.5 to 1.5 parts of a second polyester polyol, 3 to 5 parts of isocyanate, 0.1 to 0.2 parts of a dewatering agent, 0.3 to 0.5 parts of a wetting dispersant, and 92 to 94 parts of a thermally conductive filler.

2. The silicone-free polyurethane thermally conductive gel according to claim 1, characterized in that: The volume ratio of the first component to the second component is 4:

1.

3. The silicone-free polyurethane thermally conductive gel according to claim 1, characterized in that: The functionality of the first polyether polyol and / or the second polyether polyol is 2-3, the number average molecular weight is 200-5000, and the viscosity is 50-1000 mPa·s.

4. The silicone-free polyurethane thermally conductive gel according to claim 1, characterized in that: The functionality of the first polyester polyol and / or the second polyester polyol is 2, the number average molecular weight is 1500-1800, and the viscosity is 1000-1500 mPa·s.

5. The silicone-free polyurethane thermally conductive gel according to claim 1, characterized in that: The thermally conductive filler includes one or more of aluminum hydroxide, aluminum oxide, zinc oxide, magnesium oxide, boron nitride, and aluminum nitride; And / or, the average particle size of the thermally conductive filler is 1 μm to 70 μm; And / or, the shape of the thermally conductive filler is one or more of spherical, quasi-spherical, flaky, and irregular.

6. The silicone-free polyurethane thermally conductive gel according to claim 1, characterized in that: The isocyanate includes one or more of hexamethylene diisocyanate, isophorone diisocyanate, 4,4′-diphenylmethane diisocyanate and toluene diisocyanate.

7. The silicone-free polyurethane thermally conductive gel according to claim 1, characterized in that: The catalyst includes one or more of bismuth isooctanoate, bismuth neodecanoate, bismuth laurate, zirconium isooctanoate, dibutyltin dilaurate, and zinc neodecanoate.

8. The silicone-free polyurethane thermally conductive gel according to claim 1, characterized in that: The molecular sieve includes one or more of 3A molecular sieve, 4A molecular sieve and 5A molecular sieve.

9. The silicone-free polyurethane thermally conductive gel according to claim 1, characterized in that: The antioxidant includes one or more of organic thioethers, hindered phenols, and phosphites.

10. The silicone-free polyurethane thermally conductive gel according to claim 1, characterized in that: The wetting and dispersing agent includes one or more of BYKW9010, BYK 9076 and BYK 145.

11. The silicone-free polyurethane thermally conductive gel according to claim 1, characterized in that: The dewatering agent is p-toluenesulfonyl isocyanate.

12. A method for preparing a silicone-free polyurethane thermally conductive gel, characterized in that: include: Prepare a first component, wherein the first component includes: a first polyether polyol, a first polyester polyol, a molecular sieve, a catalyst, an antioxidant, a first wetting and dispersing agent, and a first thermally conductive filler; preparing a second component, wherein the second component comprises: a second polyether polyol, a second polyester polyol, an isocyanate, a water scavenger, a second wetting and dispersing agent, and a second thermally conductive filler; The first component and the second component are mixed uniformly at room temperature, vacuum degassed, and then aged at room temperature or under heating conditions to obtain a silicone-free polyurethane thermal conductive gel.

13. The preparation method according to claim 12, characterized in that: Preparing the first component includes: Dehydrating the first polyether polyol and the first polyester polyol under vacuum at a temperature of 110 to 130° C. for 2 to 3 hours, and then cooling to 50 to 55° C. to obtain a first mixed solution; Dehydrating the first thermally conductive filler at a temperature of 120 to 130° C. for 24 to 26 hours, cooling to 70 to 80° C., and then adding the wetting and dispersing agent and stirring for 30 to 60 minutes; obtaining a standby powder, and dividing the standby powder into a first standby powder and a second standby powder according to a weight ratio; Adding the first mixed liquid to the first reserved powder, and then sequentially adding the molecular sieve, the catalyst, and the antioxidant, grinding and stirring, and vacuum degassing to obtain a first component; Preparing the second component comprises: Dehydrating the second polyether polyol under vacuum at a temperature of 110 to 130° C. for 2 to 3 hours, and then cooling to 50 to 55° C. to obtain a second mixed solution; Adding isocyanate to the second mixed liquid, heating to 70-80° C. and performing vacuum reaction for 2-3 hours to obtain a polyurethane prepolymer; The second standby powder is added to the polyurethane prepolymer, and then a dehydrating agent is added, followed by grinding, stirring, and vacuum degassing to obtain a second component.

14. The preparation method according to claim 12, characterized in that: The volume ratio of the first component to the second component is 4:1.

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