Heat-conducting TPU (thermoplastic polyurethane) hot melt adhesive as well as preparation method and application thereof

Abstract

The invention provides a heat-conducting TPU (thermoplastic polyurethane) hot melt adhesive as well as a preparation method and application thereof. The preparation raw materials of the heat-conducting TPU hot melt adhesive comprise a main material and an auxiliary material, the main material is prepared from the following components in percentage by mass: 50 to 75 percent of polymer dihydric alcohol, 20 to 45 percent of diisocyanate and 1 to 5 percent of dihydric alcohol chain extender on the basis that the mass percentage of the main material is 100 percent. The auxiliary material comprises a heat conduction auxiliary agent, and the heat conduction auxiliary agent accounts for 0.3%-1.5% of the mass of the main material; the heat conduction auxiliary agent comprises reduced graphene oxide and / or modified graphene oxide, and a modified group of the modified graphene oxide can be subjected to a covalent binding reaction with an NCO group. The preparation raw materials of the heat-conducting TPU hot melt adhesive are designed, and the TPU hot melt adhesive with high heat resistance, high heat conductivity and good physical and mechanical properties is prepared.

Description

Technical Field

[0001] The present invention belongs to the technical field of TPU hot melt adhesive materials, and particularly relates to a heat-conducting TPU hot melt adhesive, a preparation method thereof, and an application thereof. Background Art

[0002] Polyurethane adhesives have developed rapidly due to their excellent adhesion, outstanding elasticity, wear resistance, low temperature resistance and other characteristics, and have been widely used in industrial sectors such as shoe-making, packaging, wood processing, automobiles, light textiles, electromechanics, aerospace and aviation. Most of the polyurethane adhesives on the market at present are two-component and one-component solution types. During the construction process, a large amount of organic solvents are often consumed, which not only increases the production cost, but also causes environmental pollution and affects human health. With the increasingly strict environmental protection laws and the continuous enhancement of people's environmental protection awareness, environmentally friendly adhesives have become the mainstream development direction of adhesives.

[0003] Thermoplastic polyurethane hot melt adhesive, namely TPU hot melt adhesive. TPU hot melt adhesive has a typical block structure and basically no cross-linked structure. Its strength mainly comes from the covalent bond force within the molecule and the van der Waals force and hydrogen bond between macromolecules. The structure, proportion, hydrogen bond formation ability and crystallization performance of the hard and soft segments in the macromolecular chain determine the properties of the material such as elasticity, strength, elongation, water resistance, wear resistance, high and low temperature performance, etc.

[0004] CN104232005A discloses a high heat-resistant polyurethane hot melt adhesive and a preparation method thereof. The raw material composition of the polyurethane hot melt adhesive is 60-80 parts of polyester polyol, 25-40 parts of diisocyanate, 3-6 parts of chain extender, and 0.1-2 parts of anti-aging agent UV-1164. The invented high heat-resistant polyurethane hot melt adhesive has good heat resistance and can pass the NIKE G41 heat resistance test, solving the problem of the decrease in the bonding performance of ordinary hot melt adhesive films at high temperatures.

[0005] CN117070180A discloses a reactive polyurethane hot melt adhesive and a preparation method thereof, including the following raw materials in parts by weight: 15-25 parts of polyester diol, 30-40 parts of polyether diol, 15-25 parts of flame-retardant polyol, 35-45 parts of p-phenylene diisocyanate, 3-5 parts of chain extender, 0.2-0.5 parts of coupling agent, 3-6 parts of modified nano-silica, and 0.1-0.5 parts of catalyst. By introducing hyperbranched polymers into nano-silica, its dispersibility and compatibility in the matrix are improved. The introduced terminal epoxy groups can chemically react with the free isocyanate groups in the system to form a cross-linked network structure, restricting the movement of molecular chains in the matrix, thereby improving the heat resistance of the matrix.

[0006] At present, with the application requirements in the fields of electronic components and the automotive industry, higher requirements are put forward for the high heat resistance and high thermal conductivity of TPU hot melt adhesives. Therefore, how to provide a TPU hot melt adhesive with high heat resistance, high thermal conductivity and good physical and mechanical properties has become an urgent technical problem to be solved at present. Summary of the Invention

[0007] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a thermally conductive TPU hot melt adhesive, its preparation method and application. By designing the raw materials for the preparation of the thermally conductive TPU hot melt adhesive, the present invention prepares a TPU hot melt adhesive with high heat resistance, high thermal conductivity and good physical and mechanical properties.

[0008] To achieve this purpose, the present invention adopts the following technical solutions:

[0009] In the first aspect, the present invention provides a thermally conductive TPU hot melt adhesive, and the raw materials for the preparation of the thermally conductive TPU hot melt adhesive include main materials and auxiliary materials;

[0010] Calculated based on the mass percentage content of the main materials being 100%, the main materials include the following components with mass percentage contents:

[0011] Polymeric diol 50% - 75%;

[0012] Diisocyanate 20% - 45%;

[0013] Diol chain extender 1% - 5%;

[0014] The auxiliary materials include a thermal conductivity aid, and the thermal conductivity aid accounts for 0.3% - 1.5% of the mass of the main materials;

[0015] The thermal conductivity aid includes reduced graphene oxide and / or modified graphene oxide, and the modification groups of the modified graphene oxide can undergo a covalent bonding reaction with the NCO group.

[0016] By designing the raw materials for the preparation of the thermally conductive TPU hot melt adhesive and using a specific thermal conductivity aid, the present invention prepares a TPU hot melt adhesive with high heat resistance, high thermal conductivity and good physical and mechanical properties. The possible reason for the analysis is that compared with graphene oxide, reduced graphene oxide reduces the oxygen-containing groups on the surface of graphene oxide and is not prone to agglomeration. The modification groups in the modified graphene oxide can covalently bond with the NCO group and are introduced into the polymer chain segment of the thermally conductive TPU hot melt adhesive in the form of covalent bonds, enhancing the thermal conductivity of the thermally conductive TPU hot melt adhesive.

[0017] In the present invention, by selecting reduced graphene oxide and / or modified graphene oxide as the heat conduction assistant and controlling the dosage of the heat conduction assistant within a specific range, a TPU hot melt adhesive with high heat resistance, high heat conductivity, and good physical and mechanical properties is prepared. If the dosage of the heat conduction assistant is too small, a co-continuous heat network structure cannot be formed in the TPU hot melt adhesive, and the heat conduction performance of the hot melt adhesive is not obvious. If the dosage of the heat conduction assistant is too large, it will have an adverse impact on the bonding ability and mechanical properties of the TPU hot melt adhesive.

[0018] In the present invention, the mass percentage content of the polymer diol in the main material can be 50%, 52%, 55%, 57%, 60%, 63%, 66%, 68%, 70%, 72%, or 75%, etc.

[0019] The mass percentage content of the diisocyanate in the main material can be 20%, 23%, 25%, 27%, 30%, 33%, 36%, 38%, 40%, 42%, or 45%, etc.

[0020] The mass percentage content of the diol chain extender in the main material can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, or 5%, etc.

[0021] The auxiliary material includes a heat conduction assistant, and the heat conduction assistant accounts for 0.3% - 1.5% of the mass of the main material. For example, it can be 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, or 1.5%, etc.

[0022] The following are the preferred technical solutions of the present invention, but do not limit the technical solutions provided by the present invention. Through the following preferred technical solutions, the objectives and beneficial effects of the present invention can be better achieved.

[0023] As a preferred technical solution of the present invention, the mass percentage content of NCO in the heat-conducting TPU hot melt adhesive is 1.5% - 5%. For example, it can be 1.5%, 1.8%, 2%, 2.4%, 2.7%, 3%, 3.3%, 3.6%, 4%, 4.2%, 4.6%, 4.8%, or 5%, etc.

[0024] In the present invention, the test method for the mass content of NCO in the heat-conducting TPU hot melt adhesive is the dibutylamine / hydrochloric acid standard titration solution method.

[0025] As a preferred technical solution of the present invention, the heat conduction assistant includes reduced graphene oxide and modified graphene oxide.

[0026] By selecting the combination of reduced graphene oxide and modified graphene oxide as the thermal conductivity additive, the comprehensive performance of the thermally conductive TPU hot melt adhesive can be further optimized and improved in the present invention.

[0027] Preferably, the reduced graphene oxide accounts for 0.3% to 0.6% of the mass of the main material, and can be, for example, 0.3%, 0.33%, 0.36%, 0.4%, 0.42%, 0.45%, 0.48%, 0.5%, 0.52%, 0.55%, 0.56%, 0.58% or 0.6%, etc.

[0028] Preferably, the modified graphene oxide accounts for 0.3% to 0.7% of the mass of the main material, and can be, for example, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65% or 0.7%, etc.

[0029] By controlling the amounts of the reduced graphene oxide and the modified graphene oxide within specific ranges respectively, the comprehensive performance of the thermally conductive TPU hot melt adhesive can be further optimized and improved in the present invention.

[0030] Preferably, the mass ratio of the reduced graphene oxide to the modified graphene oxide is (0.4 - 2):1, and can be, for example, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2:1, etc.

[0031] By controlling the mass ratio of the reduced graphene oxide to the modified graphene oxide within a specific range, the comprehensive performance of the thermally conductive TPU hot melt adhesive is further improved in the present invention.

[0032] As a preferred technical solution of the present invention, the modified graphene oxide includes amino - modified graphene oxide;

[0033] The modifier of the amino - modified graphene oxide is selected from any one or a combination of at least two of 3 - aminopropyltriethoxysilane, 11 - aminoundecyltrimethoxysilane, N-(2 - aminoethyl)-3 - aminopropyltriethoxysilane, 3-[2-(2 - aminoethylamino)ethylamino]propyl - trimethoxysilane.

[0034] As a preferred technical solution of the present invention, the polymer diol includes polyester diol and / or polyether diol.

[0035] Preferably, the number-average molecular weight of the polymer diol is 500 to 3000, and for example, it can be 500, 800, 1000, 1200, 1400, 1600, 1800, 2000, 2200, 2400, 2600, 2800 or 3000, etc.

[0036] In the present invention, the number-average molecular weight of the polymer diol can be obtained by testing with gel permeation chromatography (GPC).

[0037] Preferably, the raw materials for preparing the polyester diol include at least one small molecule diol and at least one small molecule dibasic acid.

[0038] Preferably, the small molecule diol includes any one or a combination of at least two of ethylene glycol, propylene glycol, butylene glycol, pentylene glycol, hexylene glycol, heptylene glycol, octylene glycol or nonylene glycol.

[0039] Preferably, the small molecule dibasic acid includes any one or a combination of at least two of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid or azelaic acid.

[0040] Preferably, the polyether diol includes any one or a combination of at least two of polyethylene oxide diol, polypropylene oxide diol, polyethylene oxide - propylene oxide diol or polytetramethylene ether glycol (PTMEG).

[0041] As a preferred technical solution of the present invention, the diisocyanate is selected from any one or a combination of at least two of diphenylmethane - 2,2'-diisocyanate, diphenylmethane - 2,4'-diisocyanate, diphenylmethane - 4,4'-diisocyanate, naphthylene - 1,5 - diisocyanate, toluene - 2,4 - diisocyanate, toluene - 2,6 - diisocyanate, 3,3'-dimethyl diphenyl diisocyanate or 1,2 - diphenylethane diisocyanate.

[0042] Preferably, the diol chain extender is selected from any one or a combination of at least two of ethylene glycol, 1,3 - propanediol, 1,2 - propanediol, 1,4 - butanediol, diethylene glycol, pentylene glycol, 1,4 - cyclohexanedimethanol, dipropylene glycol or 1,6 - hexanediol.

[0043] As a preferred technical solution of the present invention, the auxiliary materials further include other additives.

[0044] Preferably, the other additives include any one or a combination of at least two of catalysts, antioxidants, lubricants, anti - UV additives or hydrolysis - resistant agents.

[0045] It should be noted that the present invention has no special limitation on the specific dosage of other additives, and the dosages of other additives commonly used in the art are applicable.

[0046] In a second aspect, the present invention provides a method for preparing the thermally conductive TPU hot melt adhesive as described in the first aspect, and the preparation method includes the following steps:

[0047] Extruding and blending the main materials and auxiliary materials of the thermally conductive TPU hot melt adhesive to obtain the thermally conductive TPU hot melt adhesive;

[0048] The mass percentage content of NCO in the thermally conductive TPU hot melt adhesive is 1.5% - 5%, and for example, it can be 1.5%, 1.8%, 2%, 2.4%, 2.7%, 3%, 3.3%, 3.6%, 4%, 4.2%, 4.6%, 4.8% or 5%, etc.

[0049] As a preferred technical solution of the present invention, the method of extrusion blending includes performing extrusion blending in a twin-screw extruder, and the length-diameter ratio of the twin-screw extruder is (30 - 50):1, and for example, it can be 30:1, 32:1, 34:1, 36:1, 38:1, 40:1, 42:1, 44:1, 46:1, 48:1 or 50:1, etc.

[0050] Preferably, the temperature for performing extrusion blending in the twin-screw extruder is 170°C - 210°C, and for example, it can be 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C or 210°C, etc.

[0051] Preferably, the rotational speed for performing extrusion blending in the twin-screw extruder is 100 rpm - 250 rpm, and for example, it can be 100 rpm, 120 rpm, 150 rpm, 180 rpm, 200 rpm, 220 rpm, 240 rpm or 250 rpm, etc.

[0052] Preferably, after the extrusion blending, it further includes a post-treatment step, and the post-treatment method includes pelletizing, centrifugal drying and curing, and the post-treatment is a conventional step.

[0053] In a third aspect, the present invention provides an application of the thermally conductive TPU hot melt adhesive as described in the first aspect, and the thermally conductive TPU hot melt adhesive is used for preparing clothing, 3C products, automotive supplies, sports products or electronic photovoltaic products.

[0054] Compared with the prior art, the present invention has the following beneficial effects:

[0055] (1) By designing the specific composition of the thermally conductive TPU hot melt adhesive, the present invention prepares a thermally conductive TPU hot melt adhesive with excellent performance. This thermally conductive TPU hot melt adhesive has excellent thermal conductivity, good adhesiveness and mechanical properties, and is expected to be used as a thermal interface material. Its Shore hardness A is 64 - 70, tensile strength is 23.1 MPa - 31.2 MPa, melt viscosity is 61923 MPa·s - 68945 MPa·s, and thermal conductivity is 2.1 W / (m·K) - 4.2 W / (m·K).

[0056] (2) By further preferably using a combination of reduced graphene oxide and modified graphene oxide as a thermal conductivity aid and controlling the mass ratio of reduced graphene oxide and modified graphene oxide within a specific range, the comprehensive performance of the thermally conductive TPU hot melt adhesive is further improved. Its Shore hardness A is 65 - 70, tensile strength is 26.1 MPa - 31.2 MPa, melt viscosity is 63718 MPa·s - 68945 MPa·s, and thermal conductivity is 3.5 W / (m·K) - 4.2 W / (m·K). Detailed implementation manners

[0057] To facilitate the understanding of the present invention, the following examples are listed. Those skilled in the art should understand that the examples are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0058] The sources of some components in the examples and comparative examples are shown in Table 1 below:

[0059] Table 1

[0060]

[0061]

[0062] Among them, the preparation method of amino-modified graphene oxide 1 is as follows: 4 g of graphene oxide is uniformly dispersed in an ethanol aqueous solution (50 mL), the mass ratio of ethanol to water is 9:1, 0.5 g of 3-aminopropyltriethoxysilane is added dropwise, and after heating and reacting with water at 60°C, it is washed with ethylene glycol and dried to obtain amino-modified amino-modified graphene oxide 1;

[0063] The preparation methods of amino-modified graphene oxide 2, amino-modified graphene oxide 3 and amino-modified graphene oxide 4 are the same as above, except that 3-aminopropyltriethoxysilane is respectively replaced with an equimolar amount of 11-aminoundecyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane or 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane.

[0064] Example 1

[0065] This embodiment provides a thermally conductive TPU hot melt adhesive and a preparation method thereof. The thermally conductive TPU hot melt adhesive includes a main material and an auxiliary material;

[0066] Based on the mass percentage of the main material being 100%, the main material includes the following components in mass percentage:

[0067] Polybutylene adipate diol - 1000 67.36%;

[0068] Diphenylmethane - 4,4'-diisocyanate 31.10%;

[0069] Ethylene glycol 1.54%;

[0070] Based on the percentage of the auxiliary material in the main material, it includes the following components in mass percentage:

[0071]

[0072] The preparation method of the above thermally conductive TPU hot melt adhesive is as follows:

[0073] Using a twin-screw extruder, the main material and the auxiliary material of the thermally conductive TPU hot melt adhesive are extruded and blended, pelletized, centrifugally dried, and cured to obtain a thermally conductive TPU hot melt adhesive with an NCO mass percentage of 2.59%;

[0074] Among them, the length-diameter ratio of the twin-screw extruder is 40:1, the temperature of the extrusion blending is 200 °C, and the rotation speed is 200 rpm.

[0075] Example 2

[0076] This embodiment provides a thermally conductive TPU hot melt adhesive and a preparation method thereof. The thermally conductive TPU hot melt adhesive includes a main material and an auxiliary material;

[0077] Based on the mass percentage of the main material being 100%, the main material includes the following components in mass percentage:

[0078]

[0079] Based on the percentage of the auxiliary material in the main material, it includes the following components in mass percentage:

[0080]

[0081]

[0082] The preparation method of the above thermally conductive TPU hot melt adhesive is as follows:

[0083] Using a twin-screw extruder, the main materials and auxiliary materials of the thermally conductive TPU hot melt adhesive are extruded and blended, pelletized, centrifugally dried, and cured to obtain a thermally conductive TPU hot melt adhesive with an NCO mass percentage of 2.08%;

[0084] Among them, the length-diameter ratio of the twin-screw extruder is 40:1, the extrusion and blending temperature is 200 °C, and the rotation speed is 200 rpm.

[0085] Example 3

[0086] This example provides a thermally conductive TPU hot melt adhesive and a preparation method thereof. The thermally conductive TPU hot melt adhesive includes main materials and auxiliary materials;

[0087] Calculated based on the mass percentage of the main materials being 100%, the main materials include the following components with the following mass percentages:

[0088] Polybutylene adipate diol - 600 52.91%;

[0089] Diphenylmethane - 4,4'-diisocyanate 42.33%;

[0090] 1,6-Hexanediol 4.76%;

[0091] Calculated based on the percentage of the auxiliary materials in the main materials, it includes the following components with the following mass percentages:

[0092]

[0093] The preparation method of the above thermally conductive TPU hot melt adhesive is as follows:

[0094] Using a twin-screw extruder, the main materials and auxiliary materials of the thermally conductive TPU hot melt adhesive are extruded and blended, pelletized, centrifugally dried, and cured to obtain a thermally conductive TPU hot melt adhesive with an NCO mass percentage of 3.24%;

[0095] Among them, the length-diameter ratio of the twin-screw extruder is 40:1, the extrusion and blending temperature is 200 °C, and the rotation speed is 200 rpm.

[0096] Example 4

[0097] This example provides a thermally conductive TPU hot melt adhesive and a preparation method thereof. The difference from Example 1 is only that, calculated based on the percentage of the auxiliary materials in the main materials, it includes the following components with the following mass percentages:

[0098]

[0099] Other conditions are the same as those in Example 1.

[0100] Example 5

[0101] This embodiment provides a thermally conductive TPU hot melt adhesive and a preparation method thereof. The difference from Embodiment 1 is only that the amino-modified graphene oxide 1 in the auxiliary materials is replaced with amino-modified graphene oxide 2 with the same mass percentage content;

[0102] Other conditions are the same as those in Embodiment 1.

[0103] Embodiment 6

[0104] This embodiment provides a thermally conductive TPU hot melt adhesive and a preparation method thereof. The difference from Embodiment 1 is only that the amino-modified graphene oxide 1 in the auxiliary materials is replaced with amino-modified graphene oxide 3 with the same mass percentage content;

[0105] Other conditions are the same as those in Embodiment 1.

[0106] Embodiment 7

[0107] This embodiment provides a thermally conductive TPU hot melt adhesive and a preparation method thereof. The difference from Embodiment 1 is only that the amino-modified graphene oxide 1 in the auxiliary materials is replaced with amino-modified graphene oxide 4 with the same mass percentage content;

[0108] Other conditions are the same as those in Embodiment 1.

[0109] Embodiment 8

[0110] This embodiment provides a thermally conductive TPU hot melt adhesive and a preparation method thereof. The difference from Embodiment 1 is only that, calculated by the percentage of the auxiliary materials in the main materials, it includes the following components with the following mass percentage contents:

[0111]

[0112] Other conditions are the same as those in Embodiment 1.

[0113] Embodiment 9

[0114] This embodiment provides a thermally conductive TPU hot melt adhesive and a preparation method thereof. The difference from Embodiment 1 is only that, calculated by the percentage of the auxiliary materials in the main materials, it includes the following components with the following mass percentage contents:

[0115]

[0116] Other conditions are the same as those in Embodiment 1.

[0117] Embodiment 10

[0118] This embodiment provides a thermally conductive TPU hot melt adhesive and a preparation method thereof. The difference from Embodiment 2 is only that, calculated by the percentage of the auxiliary materials in the main materials, it includes the following components with the following mass percentage contents:

[0119]

[0120] Other conditions are the same as those in Example 2.

[0121] Example 11

[0122] This example provides a thermally conductive TPU hot melt adhesive and its preparation method. The difference from Example 3 is only that, calculated as the percentage of auxiliary materials in the main materials, it includes the following components with mass percentages:

[0123]

[0124] Other conditions are the same as those in Example 3.

[0125] Comparative Example 1

[0126] This comparative example provides a thermally conductive TPU hot melt adhesive and its preparation method. The difference from Example 1 is only that, calculated as the percentage of auxiliary materials in the main materials, it includes the following components with mass percentages:

[0127]

[0128] Other conditions are the same as those in Example 1.

[0129] Comparative Example 2

[0130] This comparative example provides a thermally conductive TPU hot melt adhesive and its preparation method. The difference from Example 4 is only that, calculated as the percentage of auxiliary materials in the main materials, it includes the following components with mass percentages:

[0131]

[0132] Other conditions are the same as those in Example 1.

[0133] Comparative Example 3

[0134] This comparative example provides a thermally conductive TPU hot melt adhesive and its preparation method. The difference from Example 1 is only that, calculated as the percentage of auxiliary materials in the main materials, it includes the following components with mass percentages:

[0135] Antioxidant 1010 0.10%;

[0136] Stearamide 0.30%;

[0137] Stannous octoate 0.01%;

[0138] Other conditions are the same as those in Example 1.

[0139] The performance of the thermally conductive TPU hot melt adhesives provided in the above examples was tested. The specific test methods are as follows:

[0140] (1) Hardness (Shore hardness A): Tested according to ASTM D2240;

[0141] (2) Tensile strength: Tested according to ASTM D412;

[0142] (3) Melt viscosity: Tested according to HG / T 3660-1999;

[0143] (4) Thermal conductivity: Tested according to ASTM D5470.

[0144] The results of the above performance tests are shown in Table 2 below:

[0145] Table 2

[0146]

[0147] As can be seen from the above, through the design of the specific composition of the thermally conductive TPU hot melt adhesive, and by using specific thermally conductive additives in combination, a thermally conductive TPU hot melt adhesive with excellent performance is prepared. This thermally conductive TPU hot melt adhesive has excellent thermal conductivity, good adhesion and mechanical properties. Its Shore hardness A is 64 - 70, tensile strength is 23.1 MPa - 31.2 MPa, melt viscosity is 61923 MPa·s - 68945 MPa·s, and thermal conductivity is 2.1 W / (m·K) - 4.2 W / (m·K).

[0148] As can be seen from Examples 1 - 3, Examples 5 - 7 and Examples 8 - 9, the present invention preferably uses a combination of reduced graphene oxide and modified graphene oxide as the thermally conductive additive, and controls the dosage of reduced graphene oxide and modified graphene oxide within a specific range, further improving the comprehensive performance of the thermally conductive TPU hot melt adhesive. Its Shore hardness A is 65 - 70, tensile strength is 26.1 MPa - 31.2 MPa, melt viscosity is 63718 MPa·s - 68945 MPa·s, and thermal conductivity is 3.5 W / (m·K) - 4.2 W / (m·K).

[0149] As can be seen from Examples 2 and 10, when the total addition amount of reduced graphene oxide and modified graphene oxide remains unchanged, too low an addition amount of reduced graphene oxide mainly affects the tensile and thermal conductivity of the hot melt adhesive.

[0150] As can be seen from Examples 3 and 11, when the total addition amount of reduced graphene oxide and modified graphene oxide remains unchanged, too high an addition amount of reduced graphene oxide mainly affects the tensile performance of the hot melt adhesive.

[0151] As can be seen from Examples 1, 4 and Comparative Examples 1 - 2, through the selection of the thermally conductive additive, the present invention prepares a thermally conductive TPU hot melt adhesive with excellent comprehensive performance.

[0152] As can be seen from Example 1 and Comparative Example 3, through the use of a heat conduction aid, a heat conduction TPU hot melt adhesive with excellent heat conduction performance was prepared according to the present invention.

[0153] In summary, through the design of the specific composition of the heat conduction TPU hot melt adhesive and the use of a specific heat conduction aid, a heat conduction TPU hot melt adhesive with excellent performance was prepared according to the present invention. The heat conduction TPU hot melt adhesive has excellent heat conduction performance, good adhesion and mechanical properties.

[0154] The applicant declares that the detailed process flow of the present invention is illustrated by the above examples, but the present invention is not limited to the above detailed process flow, that is, it does not mean that the present invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent substitution of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc. all fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A thermally conductive TPU hot melt adhesive, characterized in that: The raw materials for preparing the thermally conductive TPU hot melt adhesive include main materials and auxiliary materials; Taking the mass percentage of the main material as 100%, the main material includes the following components in mass percentage: Polymer diol 50% to 75%; Diisocyanate 20% to 45%; Diol chain extender 1% to 5%; The auxiliary material includes a thermal conductive additive, and the thermal conductive additive accounts for 0.3% to 1.5% of the mass of the main material; The thermal conductive additive includes reduced graphene oxide and / or modified graphene oxide, and the modified group of the modified graphene oxide can react with the NCO group by covalent bonding.

2. The thermally conductive TPU hot melt adhesive according to claim 1, characterized in that: The mass percentage of NCO in the thermally conductive TPU hot melt adhesive is 1.5% to 5%.

3. The thermally conductive TPU hot melt adhesive according to claim 1 or 2, characterized in that: The thermal conductive additive includes reduced graphene oxide and modified graphene oxide; Preferably, the reduced graphene oxide accounts for 0.3% to 0.6% of the mass of the main material; Preferably, the modified graphene oxide accounts for 0.3% to 0.7% of the mass of the main material; Preferably, the mass ratio of the reduced graphene oxide to the modified graphene oxide is (0.4-2):

1.

4. The thermally conductive TPU hot melt adhesive according to any one of claims 1 to 3, characterized in that: The modified graphene oxide includes amino-modified graphene oxide; Preferably, the modifier of the amino-modified graphene oxide is selected from any one of 3-aminopropyltriethoxysilane, 11-aminoundecyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, and 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane, or a combination of at least two thereof.

5. The thermally conductive TPU hot melt adhesive according to any one of claims 1 to 4, characterized in that: The polymer diol includes polyester diol and / or polyether diol; Preferably, the number average molecular weight of the polymer diol is 500 to 3000; Preferably, the raw materials for preparing the polyester diol include at least one small molecule diol and at least one small molecule dibasic acid; Preferably, the small molecule diol includes any one or a combination of at least two of ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol or nonanediol; Preferably, the small molecule dibasic acid comprises any one of oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid or azelaic acid, or a combination of at least two thereof; Preferably, the polyether diol includes any one of polyethylene oxide diol, polypropylene oxide diol, polyethylene oxide-propylene oxide diol or polytetramethylene ether diol, or a combination of at least two thereof.

6. The thermally conductive TPU hot melt adhesive according to any one of claims 1 to 5, characterized in that: The diisocyanate is selected from any one or a combination of at least two of diphenylmethane-2,2'-diisocyanate, diphenylmethane-2,4'-diisocyanate, diphenylmethane-4,4'-diisocyanate, naphthylene-1,5-diisocyanate, toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, 3,3'-dimethyl diphenyl diisocyanate or 1,2-diphenylethane diisocyanate; Preferably, the diol chain extender is selected from any one of ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,4-butanediol, diethylene glycol, pentanediol, 1,4-cyclohexanedimethanol, dipropylene glycol or 1,6-hexanediol, or a combination of at least two thereof.

7. The thermally conductive TPU hot melt adhesive according to any one of claims 1 to 6, characterized in that: The auxiliary materials also include other auxiliary agents; Preferably, the other additives include any one of a catalyst, an antioxidant, a lubricant, an anti-UV additive or an anti-hydrolysis agent, or a combination of at least two thereof.

8. A method for preparing the thermally conductive TPU hot melt adhesive according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: Extruding and blending the main material and auxiliary material of the thermally conductive TPU hot melt adhesive to obtain the thermally conductive TPU hot melt adhesive; The mass percentage of NCO in the thermally conductive TPU hot melt adhesive is 1.5% to 5%.

9. The preparation method according to claim 8, characterized in that: The extrusion blending method comprises using a twin-screw extruder for extrusion blending, wherein the aspect ratio of the twin-screw extruder is (30-50):1; Preferably, the temperature for extrusion blending in a twin-screw extruder is 170°C to 210°C; Preferably, the speed of extrusion blending in a twin-screw extruder is 100 rpm to 250 rpm; Preferably, the extrusion blending further includes a post-processing step, and the post-processing method includes pelletizing, centrifugal drying and aging.

10. An application of the thermally conductive TPU hot melt adhesive according to any one of claims 1 to 7, characterized in that: The thermally conductive TPU hot melt adhesive is used for preparing clothing, 3C products, automotive products, sports products or electronic photovoltaic products.

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