Polyurethane as well as preparation method and application thereof

Abstract

The invention provides polyurethane as well as a preparation method and application thereof. The polyurethane is prepared from a component A and a component B, the component A comprises an isocyanate terminated polymer; the component B is prepared from the following components in parts by weight: 30 to 50 parts of first polyhydric alcohol, 1 to 5 parts of citric acid, 1 to 5 parts of L-carnitine and 0.001 to 0.1 part of catalyst. The polyurethane has both high adhesion and excellent tensile property, is good in fluidity, and can be used for potting and adhesion of related components of new energy automobiles.

Description

Technical Field

[0001] The present invention belongs to the technical field of adhesives, and particularly relates to a polyurethane and its preparation method and application. Background Art

[0002] With the continuous enhancement of people's environmental protection awareness, the attention to new energy vehicles is gradually increasing. The overall performance of new energy vehicles depends to a large extent on the performance of their motors, batteries, and electronic controls, among which thermal management is of utmost importance. Currently, most power batteries for new energy vehicles are lithium-ion batteries. During the charging and discharging process of lithium-ion batteries in a vehicle battery pack, heat is generated. In order to transfer the heat generated by the battery to the cooling system of the battery pack, thermal conductive materials are required.

[0003] Thermal conductive potting adhesives are a type of thermal management material that is widely used in current new energy electric vehicles. Thermal conductive potting adhesives are mainly divided into three categories: epoxy thermal conductive potting adhesives, polyurethane thermal conductive potting adhesives, and silicone thermal conductive potting adhesives. Among them, epoxy thermal conductive potting adhesives have poor toughness, are prone to cracking, and are not resistant to thermal shock. Silicone thermal conductive potting adhesives have low hardness and low bonding strength. Polyurethane potting adhesives have characteristics such as adjustable soft hardness, moderate bonding strength, high elasticity, high impact resistance, high wear resistance, and excellent low-temperature performance, and are increasingly widely used in new energy batteries.

[0004] However, due to the compact battery assembly structure in a new energy battery pack and the small gaps between batteries, it is required that the thermal conductive material has excellent fluidity before curing, so as to be able to fill the gaps between the batteries. In addition, during the driving of the vehicle, the battery pack will inevitably be vibrated, so it is required that the thermal conductive material has excellent bonding performance. In order to improve the bonding performance of polyurethane potting adhesives, it is usually achieved by adding a bonding promoter. However, the addition of the bonding promoter often leads to a significant decrease in the elongation at break.

[0005] Therefore, developing a polyurethane potting adhesive with both high bonding performance and tensile performance, and good fluidity is an urgent problem to be solved in this field. Summary of the Invention

[0006] Aiming at the deficiencies existing in the prior art, the purpose of the present invention is to provide a polyurethane and its preparation method and application. The polyurethane has both high adhesiveness and excellent tensile performance, and good fluidity, and can be used for the potting and bonding of components related to new energy vehicles.

[0007] To achieve this purpose, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a polyurethane, and the raw materials for preparing the polyurethane include component A and component B; component A includes an isocyanate-terminated polymer; by weight, component B includes 30-50 parts of a first polyol, 1-5 parts of citric acid, 1-5 parts of L-carnitine, and 0.001-0.1 part of a catalyst.

[0009] In the present invention, by using a specific content of citric acid and L-carnitine in component B in combination, it is beneficial to improve the crosslinking degree of the polyurethane, thereby enabling the polyurethane to have both high adhesiveness and excellent tensile properties, and at the same time having good fluidity.

[0010] In the present invention, the amount of the first polyol is 30-50 parts, for example, it can be 30 parts, 32 parts, 35 parts, 38 parts, 40 parts, 42 parts, 44 parts, 46 parts, 48 parts, 50 parts, etc.

[0011] In the present invention, the amount of citric acid is 1-5 parts, for example, it can be 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts, 3 parts, 3.2 parts, 3.4 parts, 3.6 parts, 3.8 parts, 4 parts, 4.2 parts, 4.4 parts, 4.6 parts, 4.8 parts, 5 parts, etc.

[0012] In the present invention, the amount of L-carnitine is 1-5 parts, for example, it can be 1 part, 1.2 parts, 1.4 parts, 1.6 parts, 1.8 parts, 2 parts, 2.2 parts, 2.4 parts, 2.6 parts, 2.8 parts, 3 parts, 3.2 parts, 3.4 parts, 3.6 parts, 3.8 parts, 4 parts, 4.2 parts, 4.4 parts, 4.6 parts, 4.8 parts, 5 parts, etc.

[0013] In the present invention, the amount of the catalyst is 0.001-0.1 part, for example, it can be 0.001 part, 0.002 part, 0.004 part, 0.006 part, 0.008 part, 0.01 part, 0.02 part, 0.04 part, 0.06 part, 0.08 part, 0.1 part, etc.

[0014] Preferably, the isocyanate index (R value) of the isocyanate-terminated polymer > 2.5, for example, it can be 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 12, 14, 16, etc.

[0015] Preferably, the raw materials for preparing the isocyanate-terminated prepolymer include a polyisocyanate and a second polyol.

[0016] Preferably, the polyisocyanate includes any one or a combination of at least two of toluene diisocyanate, polymethylene polyphenyl polyisocyanate, or diphenylmethane diisocyanate.

[0017] Preferably, the second polyol includes polyether diol and / or polyether triol.

[0018] Preferably, the hydroxyl value of the second polyol is 20-300 mgKOH / g, and can be, for example, 20 mgKOH / g, 40 mgKOH / g, 60 mgKOH / g, 80 mgKOH / g, 100 mgKOH / g, 120 mgKOH / g, 140 mgKOH / g, 160 mgKOH / g, 180 mgKOH / g, 200 mgKOH / g, 220 mgKOH / g, 240 mgKOH / g, 260 mgKOH / g, 280 mgKOH / g, 300 mgKOH / g, etc.

[0019] In the present invention, the second polyol can be obtained by commercial purchase, including but not limited to DL2000, DL1000, DL4000 of Dongda Chemical, C2010D, C2020, C2030, C2040D, WANOL F3156D, F3147, F3147D, F3135 of Wanhua Chemical; VORANOL2110TB, VORANOL2120, VORANOL3000LM, VORANOL4240, VORANOL222-056 of Dow Chemical, etc.

[0020] Preferably, the raw materials for preparing the isocyanate-terminated polymer further include any one or a combination of at least two of a diluent, a plasticizer or a flame retardant.

[0021] In the present invention, in the component A, based on 100 parts by mass of the second polyol, the mass of the diluent, the plasticizer or the flame retardant is 15-70 parts, and can be, for example, 15 parts, 16 parts, 18 parts, 20 parts, 22 parts, 25 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, etc.; the diluent includes but not limited to epoxidized soybean oil; the flame retardant includes any one or a combination of at least two of tris(isopropylphenyl) phosphate, tricresyl phosphate, and tolyldiphenyl phosphate; the plasticizer includes any one or a combination of at least two of diisononyl phthalate (DINP), dioctyl phthalate (DOP), dibutyl phthalate, dioctyl adipate (DOA), and dioctyl sebacate (DOS).

[0022] Preferably, the viscosity of the component A is 200 to 2000 mPa·s, and for example, it can be 200 mPa·s, 400 mPa·s, 600 mPa·s, 800 mPa·s, 1000 mPa·s, 1200 mPa·s, 1400 mPa·s, 1600 mPa·s, 1800 mPa·s, 2000 mPa·s, etc.

[0023] Preferably, by weight, the first polyol includes 10 to 20 parts of oil-based polyol (for example, it can be) and 20 to 30 parts of polyether polyol.

[0024] In the present invention, 10 to 20 parts of oil-based polyol, for example, can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts, 20 parts, etc.

[0025] In the present invention, 20 to 30 parts of polyether polyol, for example, can be 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, etc.

[0026] Preferably, the oil-based polyol includes any one or a combination of at least two of cashew shell oil polyol, castor oil polyol, soybean oil polyol, or palm oil polyol.

[0027] In the present invention, by way of example, the cashew shell oil polyol includes but is not limited to at least one of Cardolite cashew shell polyol NX-9001, NX9001LV, NX9005, NX9007, NX9011, and the castor oil polyol includes but is not limited to at least one of castor oil, castor oil polyol A4130, A4100, A35, A32, AF4320 of Shanghai Jingri New Materials Technology Co., Ltd.

[0028] Preferably, the functionality of the oil-based polyol is 2.5 to 5, and for example, it can be 2.5, 3, 3.5, 4, 4.5, 5, etc.

[0029] Preferably, the hydroxyl value of the oil-based polyol is 100 to 300 mgKOH / g, and for example, it can be 100 mgKOH / g, 120 mgKOH / g, 140 mgKOH / g, 160 mgKOH / g, 180 mgKOH / g, 200 mgKOH / g, 220 mgKOH / g, 240 mgKOH / g, 260 mgKOH / g, 280 mgKOH / g, 300 mgKOH / g, etc.

[0030] Preferably, the polyether polyol includes polypropylene oxide ether triol.

[0031] In the present invention, the polyether polyol can be commercially purchased, including but not limited to WANOL F3156D, F3147, F3147D, F3135, F3056D of Wanhua Chemical; Donol 3056, Donol 3054 of Bluestar Dongda, etc.

[0032] Preferably, the hydroxyl value of the polyether polyol is 10 - 60 mgKOH / g, and for example, it can be 10 mgKOH / g, 15 mgKOH / g, 20 mgKOH / g, 25 mgKOH / g, 30 mgKOH / g, 35 mgKOH / g, 40 mgKOH / g, 45 mgKOH / g, 50 mgKOH / g, 55 mgKOH / g, 60 mgKOH / g, etc.

[0033] Preferably, the mass ratio of citric acid to L-carnitine is 1:(0.5 - 2.5), and the specific values in (0.5 - 2.5) can be, for example, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, 1.85, 1.9, 1.95, 2, 2.1, 2.2, 2.3, 2.4, 2.5, etc.

[0034] Preferably, the catalyst includes any one or a combination of at least two of bismuth neodecanoate, bismuth laurate, bismuth isooctanoate or bismuth naphthenate.

[0035] Preferably, by weight, the component B further includes 35 - 60 parts of heat-conducting filler and / or 5 - 15 parts of flame retardant.

[0036] In the present invention, 35 - 60 parts of heat-conducting filler can be, for example, 35 parts, 38 parts, 40 parts, 42 parts, 44 parts, 46 parts, 48 parts, 50 parts, 52 parts, 54 parts, 56 parts, 58 parts, 60 parts, etc.

[0037] Preferably, the heat-conducting filler includes any one or a combination of at least two of aluminum hydroxide, magnesium hydroxide, alumina, magnesia or silicon nitride.

[0038] Preferably, the D90 particle size of the heat-conducting filler < 20 μm, and for example, it can be 1 μm, 2 μm, 4 μm, 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, etc.

[0039] Preferably, the flame retardant includes any one or a combination of at least two of tris(isopropylphenyl) phosphate, tricresyl phosphate, tolyldiphenyl phosphate.

[0040] Preferably, the viscosity of the component B is 4000 - 7000 mPa·s, and for example, it can be 4000 mPa·s, 4500 mPa·s, 5000 mPa·s, 5500 mPa·s, 6000 mPa·s, 6500 mPa·s, 7000 mPa·s, etc.

[0041] Preferably, the mass ratio of the component A to the component B is (10 - 50):100, and the specific values in (10 - 50) can be, for example, 10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 38, 40, 42, 45, 48, 50, etc.

[0042] In a second aspect, the present invention provides a preparation method of the polyurethane described in the first aspect, and the preparation method includes the following steps:

[0043] Mix component A and component B to obtain the polyurethane.

[0044] Preferably, the preparation method of the component A includes:

[0045] S1: Mix a polyisocyanate, a second polyol, and optionally a diluent, a plasticizer, or a flame retardant, and react to obtain component A.

[0046] In the present invention, before the reaction, the second polyol, the diluent, the plasticizer, and the flame retardant further include vacuum dehydration at 100 - 150 °C for 1 - 4 h.

[0047] Preferably, the temperature of the reaction in S1 is 40 - 70 °C, and for example, it can be 40 °C, 45 °C, 50 °C, 55 °C, 60 °C, 65 °C, 70 °C, etc.; the time is 1 - 4 h, and for example, it can be 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, etc.

[0048] Preferably, the preparation method of the component B includes:

[0049] S2: Mix a first polyol, citric acid, L-carnitine, a catalyst, and optionally a heat-conducting filler, a flame retardant, and react to obtain component B.

[0050] In the present invention, before the reaction, the first polyol, the heat-conducting filler, and the flame retardant further include vacuum dehydration at 100 - 150 °C for 1 - 4 h.

[0051] Preferably, the temperature of the reaction in S2 is 70-100°C, for example, it can be 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, etc.; the time is 1-5h, for example, it can be 1h, 1.2h, 1.5h, 1.8h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, etc.

[0052] In a third aspect, the present invention provides a thermally conductive potting adhesive, and the material of the thermally conductive potting adhesive includes the polyurethane described in the first aspect.

[0053] In a fourth aspect, the present invention provides an application of the polyurethane described in the first aspect or the thermally conductive potting adhesive described in the second aspect in an electric vehicle.

[0054] The numerical ranges described in the present invention not only include the above-listed point values, but also include any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific point values included in the ranges.

[0055] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0056] For the polyurethane provided by the present invention, the B component is compounded with a specific content of citric acid and L-carnitine. At the same time, the A component and the B component are compounded, so that the polyurethane has both high adhesiveness and excellent tensile properties, and also has good fluidity; it can be used for potting and bonding of components related to new energy vehicles; the bonding strength of the polyurethane is ≥2.43 MPa, the tensile strength is ≥4.12 MPa, and the elongation at break is ≥97%. Specific Embodiments

[0057] The technical solutions of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0058] The materials used in the present invention can all be obtained through commercial purchase or prepared by conventional methods.

[0059] In the present invention, the calculation method of the R value is the ratio of the molar number of isocyanate groups in the A component to the molar number of hydroxyl groups of the second polyol.

[0060] Example 1

[0061] This embodiment provides a polyurethane, which comprises component A and component B with a mass ratio of 40:100; component A is an isocyanate-terminated polymer with an R value of 5.3; the raw materials for preparing component A include difunctional polyether polyol DL2000, diphenylmethane diisocyanate and tris(isopropylphenyl) phosphate; based on 100 parts by mass of the difunctional polyether polyol DL2000, the mass of the tris(isopropylphenyl) phosphate is 55.6 parts; by weight, the raw materials for preparing component B include 15 parts of castor oil, 25 parts of polyether polyol F3056D, 50 parts of aluminum hydroxide (HWF3, Chalco Shandong), 5 parts of tris(isopropylphenyl) phosphate, 3 parts of L-carnitine, 2 parts of citric acid and 0.02 part of bismuth laurate.

[0062] This embodiment provides a method for preparing a polyurethane, which specifically comprises the following steps:

[0063] S1: After dehydrating the difunctional polyether polyol DL2000 and tris(isopropylphenyl) phosphate under vacuum at 100°C for 3 h, cooling to 65°C, adding diphenylmethane diisocyanate thereto, and stirring and reacting for 2 h to obtain component A.

[0064] S2: Stirring the castor oil, polyether polyol F3056D, aluminum hydroxide and tris(isopropylphenyl) phosphate under vacuum at 120°C for 2 h, then cooling to 90°C, adding L-carnitine, citric acid and bismuth laurate thereto, stirring under vacuum for 90 min, and cooling and discharging to obtain component B.

[0065] S3: Mixing component A and component B according to the formula amounts to obtain the polyurethane.

[0066] Example 2

[0067] This embodiment provides a polyurethane, which comprises component A and component B with a mass ratio of 40:100; component A is an isocyanate-terminated polymer with an R value of 5.3; the raw materials for preparing component A include difunctional polyether polyol DL2000, diphenylmethane diisocyanate and DINP; based on 100 parts by mass of the difunctional polyether polyol DL2000, the mass of the DINP is 55.6 parts; by weight, the raw materials for preparing component B include 15 parts of cashew shell polyol NX-9001, 27 parts of polyether polyol F3056D, 45 parts of aluminum hydroxide (505D, Xusen Zhejiang), 7 parts of tris(isopropylphenyl) phosphate, 3 parts of L-carnitine, 3 parts of citric acid and 0.03 part of bismuth laurate.

[0068] This embodiment provides a method for preparing a polyurethane, which specifically comprises the following steps:

[0069] S1: After dehydrating difunctional polyether polyol DL2000 and DINP under vacuum at 100 °C for 3 h, the temperature is lowered to 67 °C, and diphenylmethane diisocyanate is added thereto, followed by stirring and reacting for 2 h to obtain the A component.

[0070] S2: Cashew shell polyol NX-9001, polyether polyol F3056D, aluminum hydroxide, and tris(isopropylphenyl) phosphate are stirred under vacuum at 120 °C for 2 h, then the temperature is lowered to 95 °C, and L-carnitine, citric acid, and bismuth laurate are added thereto, followed by vacuum stirring for 90 min, and then cooling and discharging to obtain the B component.

[0071] S3: Mix the A component and the B component according to the formulated amounts to obtain the polyurethane.

[0072] Example 3

[0073] This example provides a polyurethane, including an A component and a B component with a mass ratio of 35:100; the A component is an isocyanate-terminated polymer with an R value of 8.0; the raw materials for preparing the A component include difunctional polyether polyol DL2000, polymethylene polyphenyl polyisocyanate PM200, and tris(isopropylphenyl) phosphate; based on 100 parts by mass of the difunctional polyether polyol DL2000, the mass of the tris(isopropylphenyl) phosphate is 61.5 parts; by weight, the raw materials for preparing the B component include 15 parts of castor oil polyol A4130, 23 parts of polyether polyol F3135, 53 parts of aluminum hydroxide (HWF3), 4 parts of tris(isopropylphenyl) phosphate, 3 parts of L-carnitine, 2 parts of citric acid, and 0.04 part of bismuth laurate.

[0074] This example provides a method for preparing a polyurethane, specifically including the following steps:

[0075] S1: After dehydrating difunctional polyether polyol DL2000 and tris(isopropylphenyl) phosphate under vacuum at 120 °C for 2 h, the temperature is lowered to 65 °C, and polymethylene polyphenyl polyisocyanate PM200 is added thereto, followed by stirring and reacting for 2 h to obtain the A component.

[0076] S2: Castor oil polyol A1430, polyether polyol F3135, aluminum hydroxide, and tris(isopropylphenyl) phosphate are stirred under vacuum at 130 °C for 2 h, then the temperature is lowered to 95 °C, and L-carnitine, citric acid, and bismuth laurate are added thereto, followed by vacuum stirring for 80 min, and then cooling and discharging to obtain the B component.

[0077] S3: Mix the A component and the B component according to the formulated amounts to obtain the polyurethane.

[0078] Example 4

[0079] This embodiment provides a polyurethane, which includes component A and component B with a mass ratio of 20:100; component A is an isocyanate-capped polymer with an R value of 9.6; the raw materials for preparing component A include difunctional polyether polyol DL1000, polymethylene polyphenyl polyisocyanate PM200, and tris(isopropylphenyl) phosphate; based on 100 parts by mass of the difunctional polyether polyol DL1000, the mass of the tris(isopropylphenyl) phosphate is 60 parts; by weight, the raw materials for preparing component B include 15 parts of castor oil polyol AF4320, 23 parts of polyether polyol F3056D, 50 parts of activated aluminum hydroxide (1500, Zhejiang Xusen), 5 parts of tris(isopropylphenyl) phosphate, 3 parts of L-carnitine, 4 parts of citric acid, and 0.02 parts of bismuth laurate.

[0080] This embodiment provides a method for preparing a polyurethane, which specifically includes the following steps:

[0081] S1: After dehydrating the difunctional polyether polyol DL1000 and tris(isopropylphenyl) phosphate under vacuum at 130 °C for 1 h, cooling to 65 °C, adding polymethylene polyphenyl polyisocyanate PM200 thereto, and stirring and reacting for 2 h to obtain component A.

[0082] S2: Stir the castor oil polyol AF4320, polyether polyol F3056D, activated aluminum hydroxide, and tris(isopropylphenyl) phosphate under vacuum at 120 °C for 2 h, then cool to 90 °C, add L-carnitine, citric acid, and bismuth laurate thereto, stir under vacuum for 100 min, and cool and discharge to obtain component B.

[0083] S3: Mix component A and component B according to the formulated amounts to obtain the polyurethane.

[0084] Example 5

[0085] This embodiment provides a polyurethane, which includes component A and component B with a mass ratio of 30:100; component A is an isocyanate-capped polymer with an R value of 4; the raw materials for preparing component A include difunctional polyether polyol DL2000, diphenylmethane diisocyanate, and tris(isopropylphenyl) phosphate; based on 100 parts by mass of the difunctional polyether polyol DL2000, the mass of the tris(isopropylphenyl) phosphate is 16.7 parts; by weight, the raw materials for preparing component B include 12 parts of castor oil, 23 parts of polyether polyol F3135, 49 parts of aluminum hydroxide (505D), 10 parts of tricresyl phosphate, 4 parts of L-carnitine, 2 parts of citric acid, and 0.05 parts of bismuth laurate.

[0086] This embodiment provides a method for preparing a polyurethane, which specifically includes the following steps:

[0087] S1: After dehydrating difunctional polyether polyol DL2000 and triisopropylphenyl phosphate under vacuum at 120°C for 2 h, the temperature was lowered to 65°C, and diphenylmethane diisocyanate was added thereto, followed by stirring and reacting for 2 h to obtain the A component.

[0088] S2: Castor oil, polyether polyol F3135, aluminum hydroxide, and tricresyl phosphate were stirred under vacuum at 130°C for 2 h, then the temperature was lowered to 85°C, and L-carnitine, citric acid, and bismuth laurate were added thereto, followed by vacuum stirring for 70 min, and then the temperature was lowered and the product was discharged to obtain the B component.

[0089] S3: The A component and the B component were mixed according to the formulated amounts to obtain the polyurethane.

[0090] Example 6

[0091] This example provides a polyurethane, which is different from Example 2 only in that in the B component, the amount of L-carnitine is 1 part and the amount of citric acid is 5 parts, and other components, dosages, and preparation methods are the same as those in Example 2.

[0092] Example 7

[0093] This example provides a polyurethane, which is different from Example 2 only in that in the B component, the amount of L-carnitine is 5 parts and the amount of citric acid is 1 part, and other components, dosages, and preparation methods are the same as those in Example 2.

[0094] Comparative Example 1

[0095] This comparative example provides a polyurethane, which is different from Example 1 only in that in the B component, there is no L-carnitine and the amount of citric acid is 5 parts, and other components, dosages, and preparation methods are the same as those in Example 1.

[0096] Comparative Example 2

[0097] This comparative example provides a polyurethane, which is different from Example 1 only in that in the B component, there is no citric acid and the amount of L-carnitine is 5 parts, and other components, dosages, and preparation methods are the same as those in Example 1.

[0098] Comparative Example 3

[0099] This comparative example provides a polyurethane, which is different from Example 1 only in that in the B component, the amount of citric acid is 0.2 part and the amount of L-carnitine is 0.3 part, and other components, dosages, and preparation methods are the same as those in Example 1.

[0100] Comparative Example 4

[0101] This comparative example provides a polyurethane, which is only different from that of Example 1 in that in the B component, castor oil polyol is replaced by polyether polyol (functionality is 3, molecular weight is 1000, Wanhua C3110A), and other components, dosages and preparation methods are the same as those of Example 1.

[0102] Comparative Example 5

[0103] This comparative example provides a polyurethane, which is only different from that of Example 1 in that in the B component, citric acid is replaced by an equal mass of malic acid, and other components, dosages and preparation methods are the same as those of Example 1.

[0104] Performance Test

[0105] The polyurethanes provided in Examples 1 to 7 and Comparative Examples 1 to 5 are used as two-component polyurethane potting adhesives, and the following performance tests are carried out on them:

[0106] (1) Viscosity: The test is carried out according to the provisions of GB / T 2794-2013, and the test is carried out under the condition of 25-75% torque range.

[0107] (2) Shear strength: Polyurethane (size 25×25×1 mm) is coated on the surface of the first substrate (6061 aluminum plate, size 100×25×2.5 mm) treated with alcohol, and then the second substrate (6061 aluminum plate, size 100×25×2.5 mm) is bonded to the surface of the polyurethane. After curing for 7 days at 25°C, the test is carried out according to GB / T 7124-2008, and the test speed is 5 mm / min.

[0108] (3) Tensile strength and elongation at break: The test is carried out according to GB / T 528-2009. The sample thickness is 2 mm, and the surface is flat, smooth and pollution-free. After curing for 7 days at 25°C, standard specimens are cut out with a Type 2 dumbbell cutter, and the tensile speed is 100 mm / min ± 10 mm / min.

[0109] The specific test results are shown in Table 1.

[0110] Table 1 Performance Table of Two-Component Polyurethane Potting Adhesives in Examples and Comparative Examples of the Invention

[0111]

[0112] As can be seen from Table 1, the viscosity of the polyurethane A component provided by the present invention is 500-1000 mPa·s; the viscosity of the B component is 5000-7000 mPa·s, indicating that the polyurethane has high fluidity; the shear strength of the polyurethane and aluminum is 2.43-3.76 MPa, and the bonding performance is good; the tensile strength of the polyurethane is 4.12-6.56 MPa, and the elongation at break is 97-150%, and the tensile performance is good; the B component of the polyurethane is compounded with specific contents of citric acid and L-carnitine. At the same time, the A component and the B component are compounded, so that the polyurethane has both high adhesiveness and excellent tensile performance, and also has good fluidity.

[0113] It can be seen from Comparative Examples 1, 2, and 5 that the combination of citric acid and L-carnitine is not used. Although the viscosity changes little, the adhesiveness and tensile performance decrease significantly. It can be seen from Comparative Example 3 that when the contents of citric acid and L-carnitine are too low, the adhesiveness and elongation at break decrease significantly. It can be seen from Comparative Example 4 that without oil-free polyol, the adhesiveness and tensile performance decrease significantly.

[0114] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A polyurethane, characterized in that, The raw materials for preparing the polyurethane include component A and component B; Component A includes an isocyanate-terminated polymer; By weight, component B includes 30 - 50 parts of a first polyol, 1 - 5 parts of citric acid, 1 - 5 parts of L-carnitine, and 0.001 - 0.1 part of a catalyst.

2. The polyurethane according to claim 1, wherein The isocyanate index of the isocyanate-terminated polymer > 2.5; Preferably, the raw materials for preparing the isocyanate-terminated prepolymer include a polyisocyanate and a second polyol; Preferably, the polyisocyanate includes any one or a combination of at least two of toluene diisocyanate, polymethylene polyphenyl polyisocyanate, or diphenylmethane diisocyanate; Preferably, the second polyol includes a polyether diol and / or a polyether triol; Preferably, the hydroxyl value of the second polyol is 20 - 300 mgKOH / g; Preferably, the raw materials for preparing the isocyanate-terminated polymer further include any one or a combination of at least two of a diluent, a plasticizer, or a flame retardant; Preferably, the viscosity of component A is 200 - 2000 mPa·s.

3. The polyurethane according to claim 1 or 2, characterized in that, By weight, the first polyol includes 10 - 20 parts of an oil-based polyol and 20 - 30 parts of a polyether polyol; Preferably, the oil-based polyol includes any one or a combination of at least two of cashew shell oil polyol, castor oil polyol, soybean oil polyol, or palm oil polyol; Preferably, the functionality of the oil-based polyol is 2.5 - 5; Preferably, the hydroxyl value of the oil-based polyol is 100 - 300 mgKOH / g; Preferably, the polyether polyol includes polypropylene oxide triol; Preferably, the hydroxyl value of the polyether polyol is 10 - 60 mgKOH / g.

4. The polyurethane according to any one of claims 1 to 3, characterized in that, The mass ratio of citric acid to L-carnitine is 1:(0.5 - 2.5); Preferably, the catalyst includes any one or a combination of at least two of bismuth neodecanoate, bismuth laurate, bismuth isooctanoate, or bismuth naphthenate.

5. The polyurethane according to any one of claims 1 to 4, characterized in that, By weight, component B further includes 35 - 60 parts of a thermal conductive filler and / or 5 - 15 parts of a flame retardant; Preferably, the thermal conductive filler includes any one or a combination of at least two of aluminum hydroxide, magnesium hydroxide, alumina, magnesia, or silicon nitride; Preferably, the flame retardant includes any one or a combination of at least two of triisopropylphenyl phosphate, tricresyl phosphate, or tolyldiphenyl phosphate.

6. The polyurethane according to any one of claims 1 to 5, characterized in that, The viscosity of component B is 4000 - 7000 mPa·s; Preferably, the mass ratio of component A to component B is (10 - 50):

100.

7. A method for preparing the polyurethane according to any one of claims 1 to 6, characterized in that, The preparation method includes the following steps: Mix component A and component B to obtain the polyurethane.

8. The preparation method according to claim 7, characterized in that, The preparation method of component A includes: S1: Mix a polyisocyanate, a second polyol, and optionally a diluent, a plasticizer, or a flame retardant, and react to obtain component A; Preferably, the temperature of the reaction in S1 is 40 - 70 °C, and the time is 1 - 4 h; Preferably, the preparation method of component B includes: S2: Mix a first polyol, citric acid, L-carnitine, a catalyst, and optionally a thermal conductive filler, a flame retardant, and react to obtain component B; Preferably, the temperature of the reaction in S2 is 70 to 100 °C, and the time is 1 to 5 h.

9. A thermally conductive potting adhesive, characterized in that, The material of the thermally conductive potting adhesive includes the polyurethane according to any one of claims 1 to 6.

10. An application of the polyurethane according to any one of claims 1 to 6 or the thermally conductive potting adhesive according to claim 9 in an electric vehicle.

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