High-thermal-conductivity high-performance two-component polyurethane structural adhesive and preparation method thereof

Abstract

The invention discloses a high-thermal-conductivity and high-performance two-component polyurethane structural adhesive and a preparation method thereof, and belongs to the field of adhesives. The structural adhesive is prepared from a component A and a component B which are matched for use according to the volume ratio of (0.9-1.1): 1, the component A is prepared from the following raw materials in parts by weight: 5 to 10 parts of polyether polyol, 1 to 5 parts of castor oil polyol, 4 to 8 parts of bio-based modified polyol, 2 to 4 parts of a chain extender, 0.01 to 0.1 part of a catalyst, 0.5 to 1 part of an auxiliary agent, 1.5 to 2.5 parts of a molecular sieve, 0.1 to 0.5 part of a dispersing agent, 50 to 60 parts of first modified heat-conducting filler and 20 to 25 parts of second modified heat-conducting filler; the component B is prepared from the following raw materials in parts by weight: 15 to 30 parts of isocyanate-terminated polyurethane prepolymer, 0.5 to 0.8 part of water absorbent, 0.04 to 0.08 part of pigment and 75 to 85 parts of third modified heat-conducting filler. The structural adhesive has the advantages of high heat-conducting property, excellent mechanical property, good bonding strength and toughness, high and low temperature cycle resistance and excellent storage stability, meets the environment-friendly requirement, is moderate in viscosity and easy to glue, and adapts to the construction requirement.

Description

Technical Field

[0001] The present invention relates to the technical field of adhesives, and in particular to a high-thermal-conductivity and high-performance two-component polyurethane structural adhesive and a preparation method thereof. Background Art

[0002] Amidst the global push to develop new energy, the lithium-ion battery, photovoltaic module, and new energy vehicle industries are experiencing rapid growth. For example, as lithium-ion batteries continue to increase in energy density, the heat generated during charging and discharging increases significantly. If this heat cannot be dissipated promptly, it can lead to uneven temperature distribution within the battery, accelerating the aging of battery materials and even causing safety issues such as thermal runaway. Key components in new energy vehicles, such as battery packs and motors, require adhesives with not only excellent thermal conductivity and heat dissipation properties, but also stringent requirements for mechanical properties, weather resistance, and long-term storage stability.

[0003] Polyurethane adhesives have found certain applications in the new energy sector due to their excellent flexibility, adhesion, and chemical resistance. However, the performance of traditional polyurethane adhesives can no longer meet the industry's growing demands. From a thermal conductivity perspective, traditional polyurethane adhesives have a relatively low thermal conductivity coefficient and cannot efficiently meet the rapid heat dissipation needs of new energy equipment. Currently, in the new energy sector, high thermal conductivity has transformed from a performance optimization item to a technical necessity. Its value is not only reflected in the efficiency improvement of a single device, but also supports a synergistic breakthrough in energy density, safety, and economy through the thermal-electrical-mechanical-environmental multi-field coupling effect.

[0004] However, the requirement for high thermal conductivity can easily lead to problems such as construction difficulties, high viscosity, poor mechanical properties, and poor storage stability. Although some technologies have attempted to improve the thermal conductivity of polyurethane adhesives by adding more thermally conductive fillers, ordinary thermally conductive fillers have poor dispersion in the polyurethane matrix and are prone to agglomeration. This not only limits the improvement of thermal conductivity and affects the efficiency of adhesive application, but also further weakens its mechanical properties and storage stability. Therefore, how to develop a polyurethane structural adhesive that combines high thermal conductivity (thermal conductivity ≥ 2.0 W / mK), medium viscosity, high mechanical properties, and long-term storage stability is a key technical issue in promoting the high-quality development of the new energy industry.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The purpose of the present invention is to provide a high thermal conductivity and high performance two-component polyurethane structural adhesive and a preparation method thereof, which has moderate viscosity, is suitable for construction technology and rhythm, and has high thermal conductivity, excellent mechanical properties, good toughness, and long-term storage stability, thereby solving the above-mentioned technical problems existing in the prior art.

[0007] The purpose of the present invention is achieved through the following technical solutions: A high thermal conductivity and high performance two-component polyurethane structural adhesive, the polyurethane structural adhesive consists of component A and component B, the volume ratio of component A to component B is 0.9-1.1:1; wherein, Component A includes the following raw materials in parts by weight: 5-10 parts of polyether polyol, 1-5 parts of castor oil polyol, 4-8 parts of bio-based modified polyol, 2-4 parts of chain extender, 0.01-0.1 parts of catalyst, 0.5-1 parts of additive, 1.5-2.5 parts of molecular sieve, 0.1-0.5 parts of dispersant, 50-60 parts of first modified thermal conductive filler and 20-25 parts of second modified thermal conductive filler; Component B comprises the following raw materials in parts by weight: 15 to 30 parts of isocyanate-terminated polyurethane prepolymer, 0.5 to 0.8 parts of water absorbent, 0.04 to 0.08 parts of pigment and 75 to 85 parts of third modified thermal conductive filler.

[0008] Preferably, in the above structural adhesive, the isocyanate-terminated polyurethane prepolymer in component B is produced by the reaction of polyol and isocyanate, and the mass fraction of NCO is controlled to be 16-20%.

[0009] Preferably, in the above structural adhesive, the polyol in the isocyanate-terminated polyurethane prepolymer is one or more of polypropylene glycol, dimer acid polyol, polytetramethylene glycol, polyethylene glycol, and polyethylene adipate diol; The isocyanate is one or more of diphenylmethane diisocyanate, liquefied MDI, polymeric MDI, and HMDI.

[0010] Preferably, in the above structural adhesive, in the component A, the bio-based modified polyol is one or more of castor oil-modified polyol, soybean oil-modified polyol, rapeseed oil-modified polyol, cashew nut shell oil bio-based modified polyol, and palm oil-modified polyol.

[0011] Preferably, in the structural adhesive, in the component A, the chain extender is one or more of dipropylene glycol and diethylene glycol; The auxiliary agent includes a silane coupling agent and a pigment; The catalyst is one or more of organic tin, organic zinc and organic bismuth.

[0012] Preferably, in the above structural adhesive, in the component A, the first modified thermally conductive filler is formed by modifying a first thermally conductive filler with a first modifier, wherein the first modifier is one or a combination of two or more of a titanate coupling agent, a hydroxy silane coupling agent, and an epoxy silane coupling agent; and the first thermally conductive filler is one or a combination of two of aluminum oxide and aluminum hydroxide. The second modified thermally conductive filler is formed by modifying a second thermally conductive filler with a second modifier, wherein the second modifier is hydroxy silicone oil with a molecular weight of 5000 to 15000; the second thermally conductive filler is one or a combination of aluminum oxide and aluminum hydroxide.

[0013] Preferably, in the above structural adhesive, in the component B, the water absorbent is p-toluenesulfonyl isocyanate; The third modified thermally conductive filler is formed by modifying a third thermally conductive filler with a third modifier, wherein the third modifier is stearic acid; and the thermally conductive filler is one or a combination of aluminum oxide and aluminum hydroxide.

[0014] A method for preparing the high thermal conductivity and high performance two-component polyurethane structural adhesive of the present invention comprises the following steps: Prepare component A and component B separately, wherein, Prepare component A, comprising: According to the formula of the high thermal conductivity and high performance two-component polyurethane structural adhesive of the present invention, the raw materials of component A are taken, and the polyether polyol, castor oil polyol, bio-based modified polyol, chain extender, catalyst, additive and dispersant in the raw materials of component A are added to a reactor, stirred and dispersed at room temperature, with a planetary speed of 10 to 15 Hz and a dispersion speed of 300 rpm, and vacuum is required during the stirring process; after stirring for 30 minutes, molecular sieve, a first modified thermal conductive filler and a second modified thermal conductive filler are added, and then the dispersion speed is increased to 600 rpm and vacuum is applied; stirring for 1 hour, during which the reactor is cleaned twice, and degassing is carried out for 30 minutes after the stirring is completed, to obtain component A; Prepare component B, comprising: According to the formula of the high thermal conductivity and high performance two-component polyurethane structural adhesive of the present invention, the raw materials of component B are taken, the terminal isocyanate polyurethane prepolymer, water absorbent and pigment in the raw materials of component B are added to a reaction kettle, stirred and dispersed at room temperature, the planetary speed is 10-15 Hz, the dispersion speed is 300 rpm, and vacuum is required during the stirring process; after stirring for 30 minutes, the third modified thermal conductive filler is added, and then the dispersion speed is increased to 600 rpm and vacuum is applied; stirring for 1 hour, during which the kettle is cleaned twice, and degassing is carried out for 30 minutes after the stirring is completed, to obtain component B; When used, component A and component B are weighed in a volume ratio of 0.9 to 1.1:1, and stirred and mixed evenly to obtain the high thermal conductivity and high performance two-component polyurethane structural adhesive of the present invention.

[0015] Preferably, in the above method, the first modified thermally conductive filler in component A is pre-prepared in the following manner, including: Deionized water and ethanol are mixed in a certain volume ratio, a coupling agent is first added, and hydrolysis is carried out for 15 to 20 minutes to obtain a first modifier, and then a first thermally conductive filler is added to the first modifier, wherein the amount of the silane coupling agent added is 1 to 3% of the mass of the first thermally conductive filler, and magnetic stirring is carried out at room temperature for 12 hours. The modified first thermally conductive filler is washed three times with deionized water and ethanol respectively, filtered, placed in a vacuum drying oven, and dried at 110° C. for 2 hours to obtain a first modified thermally conductive filler; The second modified thermally conductive filler in component A is pre-prepared in the following manner, including: The second thermally conductive filler is dried at 100-120°C for 2-4 hours, placed in a high-speed stirrer and rapidly stirred at a speed of 300-600 rpm, and hydroxy silicone oil as a third modifier is slowly added dropwise to the high-speed stirred powder in an amount of 0.5%-2% of the mass of the third thermally conductive filler. Stirring is continued for 60-120 minutes. After the stirring is completed, it is continued to be dried at 90-110°C for 1-2 hours to obtain a second modified thermally conductive filler.

[0016] Preferably, in the above method, the isocyanate-terminated polyurethane prepolymer in component B is pre-prepared in the following manner, including: Add the polyol into the reaction kettle and disperse and stir, heat to 110-120°C, evacuate at the same time, dehydrate for 1-3 hours, cool, take out and reserve; add a certain amount of dehydrated polyol and a theoretical amount of isocyanate into a clean reaction kettle and disperse and stir, heat to 75-85°C, continue to react for 1-2 hours, until the NCO content does not change after titration, end the reaction, and cool to room temperature to obtain an isocyanate-terminated polyurethane prepolymer; The third modified thermally conductive filler in component B is pre-prepared in the following manner, including: The third thermally conductive filler and stearic acid as the third modifier are placed in a high-speed mixer and rapidly stirred. The amount of stearic acid used is 0.1-0.5% of the mass of the third thermally conductive filler. The temperature is raised to 80-100° C. and stirring is continued for 60-120 minutes. After the stirring is completed, the third modified thermally conductive filler is obtained.

[0017] Compared with the prior art, the high thermal conductivity and high performance two-component polyurethane structural adhesive and its preparation method provided by the present invention have the following beneficial effects: By using a first modified thermally conductive filler and a second modified thermally conductive filler in component A and a third modified thermally conductive filler in component B, the filler dosage can be increased by modifying the fillers, ensuring high thermal conductivity (≥2.0 W / mK). A balance between strength and toughness is achieved by combining multiple types of polyols. The addition of a chain extender increases the degree of crosslinking and molecular weight, improving the strength of the system. Achieving high thermal conductivity requires a significant amount of thermally conductive filler. Conventional fillers significantly increase viscosity, reduce bonding strength and toughness, and particularly affect modulus. The first modified filler improves the compatibility between the filler and the system, effectively reducing the viscosity of the system while ensuring good mechanical properties. The second modified filler introduces a tough silicon-oxygen (Si-O) chain structure, effectively improving the toughness of the system. Component B contains a large amount of filler, which is detrimental to viscosity and tack-free time. The third modified filler, stearic acid, effectively improves the tack-free time of component B, reduces the system viscosity, and improves storage stability. DETAILED DESCRIPTION

[0018] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the specific content of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments, and do not constitute a limitation of the present invention. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0019] First, the following terms may be used in this article: The term "and / or" means that either or both of them can be realized at the same time. For example, X and / or Y includes both "X" or "Y" and "X and Y".

[0020] The terms "include," "comprises," "contains," "has," or other similar expressions should be interpreted as non-exclusive. For example, "including certain technical features (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, procedures, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products, or manufactured articles)" should be interpreted as including not only the technical features explicitly listed, but also other technical features known in the art that are not explicitly listed.

[0021] The term "consisting of" excludes any technical features not explicitly listed. If used in a claim, this term renders the claim closed, excluding any technical features other than those explicitly listed, except for conventional impurities associated with them. If this term appears only in a clause of a claim, it limits only the elements explicitly listed in that clause; elements listed in other clauses are not excluded from the claim as a whole.

[0022] The term "parts by mass" refers to the mass ratio of multiple components. For example, if component X is x parts by mass and component Y is y parts by mass, then the mass ratio of component X to component Y is x:y. One part by mass can represent any mass, for example, 1 kg or 3.1415926 kg. The sum of the parts by mass of all components is not necessarily 100 parts; it can be greater than, less than, or equal to 100 parts. Unless otherwise specified, parts, ratios, and percentages herein are by mass.

[0023] When concentration, temperature, pressure, size or other parameters are expressed in the form of a numerical range, the numerical range should be understood to specifically disclose all ranges formed by the pairing of any upper limit, lower limit, or preferred value within the numerical range, regardless of whether the range is explicitly stated. For example, if a numerical range of "2 to 8" is stated, the numerical range should be interpreted as including ranges of "2 to 7," "2 to 6," "5 to 7," "3 to 4 and 6 to 7," "3 to 5 and 7," "2 and 5 to 7," etc. Unless otherwise specified, the numerical ranges stated herein include both their endpoints and all integers and fractions within the numerical range.

[0024] The scheme provided by the present invention is described in detail below. The contents not described in detail in the examples of the present invention belong to the prior art known to professionals in this field. If specific conditions are not specified in the examples of the present invention, they are carried out according to conventional conditions in the field or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used in the examples of the present invention is not specified, they are all conventional products that can be purchased commercially.

[0025] The embodiment of the present invention provides a high thermal conductivity and high performance two-component polyurethane structural adhesive, which is composed of component A and component B, and the volume ratio of component A to component B is 0.9 to 1.1:1, preferably 1:1; wherein, Component A includes the following raw materials in parts by weight: 5-10 parts of polyether polyol, 1-5 parts of castor oil polyol, 4-8 parts of bio-based modified polyol, 2-4 parts of chain extender, 0.01-0.1 parts of catalyst, 0.5-1 parts of additive, 1.5-2.5 parts of molecular sieve, 0.1-0.5 parts of dispersant, 50-60 parts of first modified thermal conductive filler, and 20-25 parts of second modified thermal conductive filler.

[0026] Component B comprises the following raw materials in parts by weight: 15 to 30 parts of isocyanate-terminated polyurethane prepolymer, 0.5 to 0.8 parts of water absorbent, 0.04 to 0.08 parts of pigment, and 75 to 85 parts of third modified thermal conductive filler.

[0027] Isocyanate-based polyurethane prepolymer includes the following raw materials in parts by weight: 20-40 parts of polyol, 60-75 parts of isocyanate

[0028] Preferably, in the above structural adhesive, the isocyanate-based polyurethane prepolymer is produced by the reaction of polyol and isocyanate, and the mass fraction of NCO is controlled to be 16-20%; The polyol in the isocyanate-based polyurethane prepolymer is one or more of polypropylene glycol, dimer acid polyol, polytetramethylene glycol, polyethylene glycol, and polyethylene adipate diol; the isocyanate in the isocyanate-based polyurethane prepolymer is one or more of diphenylmethane diisocyanate, liquefied MDI, polymeric MDI, and HMDI.

[0029] Preferably, in component A of the structural adhesive, the polyether polyol is at least one of polyether polyols with 2 to 3 functionalities, and the molecular weight of the polyether polyol is 500 to 3000.

[0030] Preferably, in component A of the structural adhesive, the bio-based modified polyol is one or more of castor oil-modified polyol, soybean oil-modified polyol, rapeseed oil-modified polyol, cashew nut shell liquid bio-based modified polyol, and palm oil-modified polyol; The chain extender is one or more of dipropylene glycol and diethylene glycol; The auxiliary agent includes a silane coupling agent and a pigment; The catalyst is one or more of organic tin, organic zinc and organic bismuth.

[0031] The first modified thermally conductive filler is formed by modifying the first thermally conductive filler with a first modifier, wherein the first modifier is one or a combination of two or more of a titanate coupling agent, a hydroxy silane coupling agent, and an epoxy silane coupling agent, preferably a titanate coupling agent; the first thermally conductive filler is selected from one or a combination of two of alumina and aluminum hydroxide.

[0032] The second modified thermally conductive filler is formed by modifying the second thermally conductive filler with a second modifier, the second modifier is at least one of hydroxy silicone oils, and the molecular weight is 5000 to 15000; the second thermally conductive filler is selected from one or a combination of aluminum oxide and aluminum hydroxide.

[0033] Preferably, in the component B of the structural adhesive, the water absorbent is p-toluenesulfonyl isocyanate; The third modified thermally conductive filler is formed by modifying a third thermally conductive filler with a third modifier, and the third modifier is stearic acid; the third thermally conductive filler is selected from one or a combination of aluminum oxide and aluminum hydroxide.

[0034] The present invention also provides a method for preparing a high-thermal-conductivity, high-performance two-component polyurethane structural adhesive, comprising the following steps: The first modified thermally conductive filler and the second modified thermally conductive filler in component A are separately prepared in advance, and the isocyanate-based polyurethane prepolymer and the third modified thermally conductive filler in component B are prepared in advance, wherein: The preparation of the first modified thermally conductive filler includes: Deionized water and ethanol were mixed in a specific volume ratio. A coupling agent was added first, and hydrolysis was carried out for 15–20 minutes. A thermally conductive filler (the silane coupling agent was added at a concentration of 1–3% of the filler mass) was then added. The mixture was magnetically stirred at room temperature for 12 hours. The modified filler was washed three times with deionized water and three times with ethanol, filtered, and dried in a vacuum drying oven at 110°C for 2 hours to obtain the first modified filler.

[0035] The preparation of the second modified thermally conductive filler comprises: Dry the thermally conductive filler at 100-120°C for 2-4 hours, then rapidly stir in a high-speed blender. Slowly add hydroxy silicone oil (0.5%-2% of the thermally conductive filler) dropwise to the powder while stirring. Continue stirring for 60-120 minutes. After stirring, continue drying at 90-110°C for 1-2 hours to produce the second modified thermally conductive filler.

[0036] The preparation of the isocyanate-terminated polyurethane prepolymer includes: Add the polyol to the reactor and disperse and stir, heat to 110-120°C, evacuate at the same time, dehydrate for 1-3 hours, cool, take out and retain; add a certain amount of dehydrated polyol and a theoretical amount of isocyanate to a clean reactor and disperse and stir, heat to 75-85°C, continue to react for 1-2 hours, until the titration NCO content no longer changes, end the reaction, and cool to room temperature to obtain an isocyanate-terminated polyurethane prepolymer.

[0037] The preparation of the third modified thermally conductive filler includes: Place the thermally conductive filler and stearic acid (the amount of stearic acid is 0.1% to 0.5% of the thermally conductive filler) in a high-speed blender and rapidly stir. Raise the temperature to 80-100°C and continue stirring for 60-120 minutes. After stirring, a third modified thermally conductive filler is obtained.

[0038] Prepare component A and component B separately, wherein, Preparation of component A includes: The polyether polyol, castor oil polyol, bio-based modified polyol, chain extender, catalyst, additive, and dispersant required for component A are added to a reactor, stirred and dispersed at room temperature, with a planetary speed of 10-15 Hz and a dispersion speed of 300 rpm. Vacuuming is required during the stirring process. After stirring for 30 minutes, molecular sieves, a first modified thermal conductive filler, and a second modified thermal conductive filler are added. The dispersion speed is then increased to 600 rpm and vacuuming is performed. Stirring is continued for 1 hour, during which the reactor is cleared twice. After stirring, degassing is performed for 30 minutes to obtain component A. Preparation of component B includes: The isocyanate-terminated polyurethane prepolymer, water absorbent, and pigment required for component B are added to a reaction kettle, stirred and dispersed at room temperature, with a planetary speed of 10-15 Hz and a dispersion speed of 300 rpm. Vacuuming is required during the stirring process. After stirring for 30 minutes, the third modified thermal conductive filler is added, and then the dispersion speed is increased to 600 rpm and vacuuming is carried out. Stirring for 1 hour, during which the kettle is cleared twice, and degassing is carried out for 30 minutes after the stirring is completed, thereby preparing component B. Component A and component B are weighed in a volume ratio of (0.9-1.1):1, and stirred and mixed evenly to form the high thermal conductivity and high performance two-component polyurethane structural adhesive of the present invention.

[0039] Compared with the prior art, the advantages of the present invention are: By modifying the thermally conductive filler, the addition amount of thermally conductive filler can be increased to ensure high thermal conductivity (≥2.0 W / mK); by combining various types of polyols, a balance between strength and toughness can be achieved; by adding chain extenders, the degree of crosslinking and molecular weight can be increased, thereby improving the strength of the system; achieving high thermal conductivity requires a large amount of thermally conductive filler. Ordinary thermally conductive fillers will greatly increase viscosity, reduce bonding strength and toughness, and especially affect modulus. By using the first modified thermally conductive filler, the compatibility between the filler and the system is improved, effectively reducing the viscosity of the system while ensuring good mechanical properties; by using the second modified thermally conductive filler, a silicon-oxygen bond (Si-O) chain structure with good toughness is introduced, which can effectively improve the toughness of the system; the large amount of filler in component B is not conducive to viscosity and surface-free time. By using the third modified thermally conductive filler, stearic acid is introduced, which can effectively improve the surface-free time of component B, reduce the viscosity of the system, and improve storage stability.

[0040] In summary, the high thermal conductivity and high performance two-component polyurethane structural adhesive of the present invention is environmentally friendly, has excellent thermal conductivity, has excellent viscosity, can achieve good construction effects, and can achieve firm bonding to the substrate, has good mechanical properties, good toughness and low modulus, and has excellent storage stability.

[0041] In order to more clearly demonstrate the technical solution and technical effects provided by the present invention, the solution provided by the embodiment of the present invention is described in detail with reference to specific embodiments below.

[0042] Example 1 This embodiment provides a high thermal conductivity and high performance two-component polyurethane structural adhesive, the preparation method of which includes the following steps (each raw material is calculated by weight): The first modified thermally conductive filler and the second modified thermally conductive filler in component A and the terminal isocyanate polyurethane prepolymer and the third modified thermally conductive filler in component B are respectively prepared in advance, wherein: a. The preparation of the first modified thermally conductive filler comprises: Deionized water and ethanol were mixed in a certain volume ratio. 10g of titanate coupling agent was added first and hydrolyzed for 20 minutes. Then, 1kg of aluminum hydroxide was added and magnetically stirred at room temperature for 12 hours. The modified thermally conductive filler was washed three times with deionized water and three times with ethanol, filtered, and dried in a vacuum drying oven at 110°C for 2 hours to produce the first modified thermally conductive filler.

[0043] b. The preparation of the second modified thermally conductive filler comprises: Dry 1 kg of aluminum hydroxide at 100°C for 2–4 hours, then rapidly stir in a high-speed blender. Slowly add 5 g of hydroxy silicone oil (6,000–7,000 molecular weight) dropwise to the stirred aluminum hydroxide, stirring continuously for 80 minutes. After stirring, continue drying at 110°C for 2 hours to produce the second modified thermally conductive filler.

[0044] c. The preparation of the isocyanate-terminated polyurethane prepolymer comprises: 100 parts of polypropylene glycol were added to a reactor and dispersed and stirred, heated to 115°C, and vacuumed to 400 Pa. After dehydration for 2 hours, the temperature was lowered to 50°C and the product was taken out for use. 25 parts of dehydrated polypropylene glycol and 70 parts of liquefied MDI were added to a clean reactor and dispersed and stirred, and the temperature was raised to 80°C. The reaction was continued for 1.5 hours. After the reaction was completed, the product was cooled to room temperature to obtain an isocyanate-terminated polyurethane prepolymer.

[0045] d. The preparation of the third modified thermally conductive filler comprises: 1 kg of aluminum hydroxide and 2 g of stearic acid were placed in a high-speed blender and rapidly stirred. The mixture was heated to 100° C. and stirred for 60 minutes. After the stirring was completed, a third modified thermally conductive filler was obtained.

[0046] Prepare component A and component B separately, wherein, e. The preparation of component A includes: 8 parts of 2-functionality polyether polyol (molecular weight 2000), 4 parts of castor oil modified polyol, 4 parts of cashew nut shell liquid bio-based modified polyol, 2 parts of dipropylene glycol, 1 part of diethylene glycol, 0.03 parts of organic tin catalyst (dibutyltin dilaurate), 0.02 parts of organic bismuth catalyst (bismuth isooctanoate), 0.6 parts of silane coupling agent (KH-550), 0.4 parts of pigment, and 0.3 parts of dispersant were added to the reactor in sequence. The mixture was stirred and dispersed at room temperature under the control of the planetary speed of 12 Hz and the dispersion speed of 300 rpm, and vacuum was simultaneously evacuated to -0.08 MPa. After stirring for 30 minutes, 2 parts of molecular sieves, 50 parts of the first modified thermally conductive filler, and 23 parts of the second modified thermally conductive filler were added. The dispersion speed was then increased to 600 rpm and vacuum was continued to be evacuated to -0.09 MPa. Stirring was continued for 1 hour, and stirring was continued for 45 minutes. and 75 minutes, the kettle was cleaned; after the stirring was completed, the vacuum state was maintained for degassing for 30 minutes, thereby obtaining component A; f. The preparation of component B comprises: 20 parts of an isocyanate-terminated polyurethane prepolymer, 0.6 parts of p-toluenesulfonyl isocyanate, and 0.05 parts of a pigment were added to a reaction kettle and stirred and dispersed at room temperature. The planetary speed was set to 12 Hz, the dispersion speed was set to 300 rpm, and vacuum was turned on during stirring to maintain the vacuum degree in the reaction kettle at -0.07 MPa. After stirring for 30 minutes, 80 parts of a third modified thermally conductive filler was added, and the dispersion speed was increased to 600 rpm. The vacuum state was maintained and the vacuum degree was adjusted to -0.09 MPa. During the subsequent 1 hour of stirring, the kettle was cleaned every 30 minutes, for a total of two times. After stirring, degassing was performed for 30 minutes to prepare component B. g. Composition of polyurethane structural adhesive: Weigh component A and component B in a volume ratio of 1:1, stir and mix them evenly to obtain the high thermal conductivity and high performance two-component polyurethane structural adhesive of this embodiment.

[0047] Example 2 This embodiment provides a high thermal conductivity and high performance two-component polyurethane structural adhesive, the preparation method of which includes the following steps (each raw material is calculated by weight): The first modified thermally conductive filler and the second modified thermally conductive filler in component A and the terminal isocyanate polyurethane prepolymer and the third modified thermally conductive filler in component B are respectively prepared in advance, wherein: a. The preparation of the first modified thermally conductive filler comprises: Deionized water and ethanol were mixed in a certain volume ratio. 10g of titanate coupling agent was added first and hydrolyzed for 20 minutes. Then, 1kg of aluminum hydroxide was added and magnetically stirred at room temperature for 12 hours. The modified thermally conductive filler was washed three times with deionized water and three times with ethanol, filtered, and dried in a vacuum drying oven at 110°C for 2 hours to produce the first modified thermally conductive filler.

[0048] b. The preparation of the second modified thermally conductive filler comprises: Dry 1 kg of aluminum hydroxide at 100°C for 2–4 hours, then rapidly stir in a high-speed blender. Slowly add 5 g of hydroxy silicone oil (6,000–7,000 molecular weight) dropwise to the stirred aluminum hydroxide, stirring continuously for 80 minutes. After stirring, continue drying at 110°C for 2 hours to produce the second modified thermally conductive filler.

[0049] c. The preparation of the isocyanate-terminated polyurethane prepolymer comprises: 100 parts of polypropylene glycol were added to a reactor and dispersed and stirred, heated to 115°C, and vacuumed to 400 Pa. After dehydration for 2 hours, the temperature was lowered to 50°C and the product was taken out for use. 25 parts of dehydrated polypropylene glycol and 70 parts of liquefied MDI were added to a clean reactor and dispersed and stirred, and the temperature was raised to 80°C. The reaction was continued for 1.5 hours. After the reaction was completed, the product was cooled to room temperature to obtain an isocyanate-terminated polyurethane prepolymer.

[0050] d. The preparation of the third modified thermally conductive filler comprises: 1 kg of aluminum hydroxide and 2 g of stearic acid were placed in a high-speed blender and rapidly stirred. The mixture was heated to 100° C. and stirred for 60 minutes. After the stirring was completed, a third modified thermally conductive filler was obtained.

[0051] Prepare component A and component B separately, wherein, e. The preparation of component A includes: 6 parts of a trifunctional polyether polyol (molecular weight 1000), 5 parts of a soybean oil-modified polyol, 3 parts of a castor oil-modified polyol, 2.5 parts of dipropylene glycol, 1.5 parts of diethylene glycol, 0.05 parts of an organozinc catalyst (zinc neodecanoate), 0.5 parts of a silane coupling agent (KH-560), 0.5 parts of a pigment, and 0.2 parts of a dispersant were added to a reactor. The mixture was stirred and dispersed at room temperature at a planetary speed of 10 Hz and a dispersion speed of 300 rpm. The pressure was evacuated to -0.08 MPa. After stirring for 30 minutes, 1.5 parts of a molecular sieve, 50 parts of a first modified thermally conductive filler, and 20 parts of a second modified thermally conductive filler were added. The dispersion speed was increased to 600 rpm, and the vacuum was maintained at -0.09 MPa. During stirring for 1 hour, the reactor was cleaned at 45 and 75 minutes. After the stirring was completed, the mixture was degassed under vacuum for 30 minutes to obtain component A. f. The preparation of component B comprises: 15 parts of terminal isocyanate polyurethane prepolymer, 0.5 parts of p-toluenesulfonyl isocyanate, and 0.04 parts of pigment are put into the reactor, and stirring and dispersion are started at room temperature. The planetary speed is set to 10 Hz, the dispersion speed is set to 300 rpm, and the vacuum is evacuated to -0.06 MPa in the reactor; after stirring for 30 minutes, 85 parts of the third modified thermal conductive filler are added, and then the dispersion speed is increased to 600 rpm, and the vacuum state is maintained, and the vacuum degree is maintained at -0.08 MPa; during the 1-hour stirring period, the reactor is cleaned once every 20 minutes, and a total of three times; after the stirring is completed, a 30-minute degassing operation is performed to obtain component B.

[0052] g. Composition of polyurethane structural adhesive: Weigh component A and component B according to a volume ratio of 1:1, stir and mix evenly to obtain the high thermal conductivity and high performance two-component polyurethane structural adhesive of this embodiment.

[0053] Example 3 This embodiment provides a high thermal conductivity and high performance two-component polyurethane structural adhesive, the preparation method of which includes the following steps (each raw material is calculated by weight): The first modified thermally conductive filler and the second modified thermally conductive filler in component A and the terminal isocyanate polyurethane prepolymer and the third modified thermally conductive filler in component B are respectively prepared in advance, wherein: a. The preparation of the first modified thermally conductive filler comprises: Deionized water and ethanol were mixed in a certain volume ratio. 10g of titanate coupling agent was added first and hydrolyzed for 20 minutes. Then, 1kg of aluminum hydroxide was added and magnetically stirred at room temperature for 12 hours. The modified thermally conductive filler was washed three times with deionized water and three times with ethanol, filtered, and dried in a vacuum drying oven at 110°C for 2 hours to produce the first modified thermally conductive filler.

[0054] b. The preparation of the second modified thermally conductive filler comprises: Dry 1 kg of aluminum hydroxide at 100°C for 2–4 hours, then rapidly stir in a high-speed blender. Slowly add 5 g of hydroxy silicone oil (6,000–7,000 molecular weight) dropwise to the stirred aluminum hydroxide, stirring continuously for 80 minutes. After stirring, continue drying at 110°C for 2 hours to produce the second modified thermally conductive filler.

[0055] c. The preparation of the isocyanate-terminated polyurethane prepolymer comprises: 100 parts of polypropylene glycol were added to a reactor and dispersed and stirred, heated to 115°C, and vacuumed to 400 Pa. After dehydration for 2 hours, the temperature was lowered to 50°C and the product was taken out for use. 25 parts of dehydrated polypropylene glycol and 70 parts of liquefied MDI were added to a clean reactor and dispersed and stirred, and the temperature was raised to 80°C. The reaction was continued for 1.5 hours. After the reaction was completed, the product was cooled to room temperature to obtain an isocyanate-terminated polyurethane prepolymer.

[0056] d. The preparation of the third modified thermally conductive filler comprises: 1 kg of aluminum hydroxide and 2 g of stearic acid were placed in a high-speed blender and rapidly stirred. The mixture was heated to 100° C. and stirred for 60 minutes. After the stirring was completed, a third modified thermally conductive filler was obtained.

[0057] Prepare component A and component B separately, wherein, e. The preparation of component A includes: 7 parts of a difunctional polyether polyol (molecular weight 2000), 3 parts of a castor oil-modified polyol, 5 parts of a palm oil-modified polyol, 2 parts of dipropylene glycol, 0.04 parts of an organotin catalyst (dibutyltin dilaurate), 0.8 parts of a silane coupling agent (KH-560), 0.2 parts of a pigment, and 0.3 parts of a dispersant were added to a reactor. The mixture was stirred and dispersed at room temperature using a planetary speed of 15 Hz and a dispersion speed of 300 rpm while evacuating to -0.08 MPa. After stirring for 30 minutes, 2.5 parts of a molecular sieve, 60 parts of a first modified thermally conductive filler, and 21 parts of a second modified thermally conductive filler were added in sequence. The dispersion speed was adjusted to 600 rpm and the vacuum was maintained at -0.09 MPa. Stirring was continued for 1 hour, and the reactor was cleared at 45 and 75 minutes, respectively. After stirring, the mixture was degassed under vacuum for 30 minutes to obtain component A. f. The preparation of component B comprises: 15 parts of isocyanate-terminated polyurethane prepolymer, 0.5 parts of p-toluenesulfonyl isocyanate, and 0.04 parts of pigment were placed in a reactor. Stirring and dispersion were started at room temperature. The planetary speed was set to 10 Hz, the dispersion speed was set to 300 rpm, and the reactor was evacuated until the vacuum degree reached -0.06 MPa. After stirring for 30 minutes, 85 parts of the third modified thermally conductive filler were added. The dispersion speed was then increased to 600 rpm. The evacuation state was maintained and the vacuum degree was kept at -0.08 MPa. During the 1 hour stirring period, the reactor was cleaned once every 20 minutes, for a total of three times. After the stirring was completed, a degassing operation was performed for 30 minutes to obtain component B. g. Composition of polyurethane structural adhesive: Weigh component A and component B according to a volume ratio of 1:1, stir and mix evenly to obtain the high thermal conductivity and high performance two-component polyurethane structural adhesive of this embodiment.

[0058] The performance test is as follows: The following performance tests were performed on the high thermal conductivity and high performance two-component polyurethane structural adhesives prepared in Examples 1, 2, and 3 of the present invention: Mixed viscosity: Determined according to GB / T 2794-2013 "Adhesives - Determination of viscosity - Single cylinder rotational viscometer method".

[0059] Shear strength / 3003 aluminum: Determined in accordance with GB / T 7124-2008 "Adhesives - Determination of tensile shear strength (rigid material to rigid material)".

[0060] Tensile strength and elongation at break: measured in accordance with GB / T 528-2008 “Rubber, vulcanized or thermoplastic — Determination of tensile stress-strain properties”.

[0061] High temperature and high humidity: Test according to GB / T 2423.50 "Environmental testing Part 2: Test method Test Cy steady state damp heat mainly used for accelerated testing of components" for 1000 hours.

[0062] Surface drying time of component B: tested by finger touch method.

[0063] Thermal conductivity: Determined according to GB / T3399-1982 "Test method for thermal conductivity of plastics - Guarded hot plate method".

[0064] Table 1 is a performance test table of various products in the embodiments of the present invention.

[0065] As can be seen from the table above, this polyurethane structural adhesive has excellent high thermal conductivity, with thermal conductivity meeting actual use requirements. It also has excellent flame retardancy and can pass V0. The mixed viscosity is relatively low, with good workability and meeting production schedules. The shear strength, tensile strength, and elongation at break are all high, and the comprehensive mechanical properties are higher than the current level of high thermal conductivity polyurethane structural adhesives on the market. It has good bonding strength to aluminum substrates, and good bulk strength and toughness. It has good long-term storage stability and small viscosity changes. After 1000 hours of double 85 aging, the strength decay is low, and it has good weather resistance and aging resistance. In summary, this invention can effectively meet the requirements of polyurethane thermal conductive structural adhesives for the new energy field.

[0066] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or any form of implication that the information constitutes prior art already known to those skilled in the art.

Claims

1. A high thermal conductivity and high performance two-component polyurethane structural adhesive, characterized in that: The polyurethane structural adhesive consists of component A and component B, and the volume ratio of component A to component B is 0.9-1.1:1; wherein, Component A includes the following raw materials in parts by weight: 5-10 parts of polyether polyol, 1-5 parts of castor oil polyol, 4-8 parts of bio-based modified polyol, 2-4 parts of chain extender, 0.01-0.1 parts of catalyst, 0.5-1 parts of additive, 1.5-2.5 parts of molecular sieve, 0.1-0.5 parts of dispersant, 50-60 parts of first modified thermal conductive filler and 20-25 parts of second modified thermal conductive filler; Component B comprises the following raw materials in parts by weight: 15 to 30 parts of isocyanate-terminated polyurethane prepolymer, 0.5 to 0.8 parts of water absorbent, 0.04 to 0.08 parts of pigment and 75 to 85 parts of third modified thermal conductive filler.

2. The high thermal conductivity and high performance two-component polyurethane structural adhesive according to claim 1, characterized in that: The isocyanate-terminated polyurethane prepolymer in the B component is produced by the reaction of polyol and isocyanate, and the mass fraction of NCO is controlled to be 16-20%.

3. The high thermal conductivity and high performance two-component polyurethane structural adhesive according to claim 2, characterized in that: The polyol in the isocyanate-terminated polyurethane prepolymer is one or more of polypropylene glycol, dimer acid polyol, polytetramethylene glycol, polyethylene glycol, and polyethylene adipate glycol; The isocyanate is one or more of diphenylmethane diisocyanate, liquefied MDI, polymeric MDI, and HMDI.

4. The high thermal conductivity and high performance two-component polyurethane structural adhesive according to any one of claims 1 to 3, characterized in that: In the component A, the bio-based modified polyol is one or more of castor oil-modified polyol, soybean oil-modified polyol, rapeseed oil-modified polyol, cashew nut shell liquid bio-based modified polyol, and palm oil-modified polyol.

5. The high thermal conductivity and high performance two-component polyurethane structural adhesive according to any one of claims 1 to 3, characterized in that: In the component A, the chain extender is one or more of dipropylene glycol and diethylene glycol; The auxiliary agent includes a silane coupling agent and a pigment; The catalyst is one or more of organic tin, organic zinc and organic bismuth.

6. The high thermal conductivity and high performance two-component polyurethane structural adhesive according to any one of claims 1 to 3, characterized in that: In the component A, the first modified thermally conductive filler is formed by modifying a first thermally conductive filler with a first modifier, wherein the first modifier is one or a combination of two or more of a titanate coupling agent, a hydroxy silane coupling agent, and an epoxy silane coupling agent; and the first thermally conductive filler is one or a combination of two of aluminum oxide and aluminum hydroxide. The second modified thermally conductive filler is formed by modifying a second thermally conductive filler with a second modifier, wherein the second modifier is hydroxy silicone oil with a molecular weight of 5000 to 15000; the second thermally conductive filler is one or a combination of aluminum oxide and aluminum hydroxide.

7. The high thermal conductivity and high performance two-component polyurethane structural adhesive according to any one of claims 1 to 3, characterized in that: In the component B, the water absorbent is p-toluenesulfonyl isocyanate; The third modified thermally conductive filler is formed by modifying a third thermally conductive filler with a third modifier, wherein the third modifier is stearic acid; and the thermally conductive filler is one or a combination of aluminum oxide and aluminum hydroxide.

8. A method for preparing the high thermal conductivity and high performance two-component polyurethane structural adhesive according to any one of claims 1 to 7, characterized in that: The following steps are involved: Prepare component A and component B separately, wherein, Prepare component A, comprising: The high thermal conductivity and high performance two-component polyurethane structural adhesive formula according to any one of claims 1 to 7 comprises the following steps: taking the raw materials of component A, adding the polyether polyol, castor oil polyol, bio-based modified polyol, chain extender, catalyst, additive and dispersant in the raw materials of component A to a reactor, stirring and dispersing at room temperature, with a planetary speed of 10 to 15 Hz and a dispersion speed of 300 rpm, and applying vacuum during the stirring process; after stirring for 30 minutes, adding the molecular sieve, the first modified thermal conductive filler and the second modified thermal conductive filler, then increasing the dispersion speed to 600 rpm and applying vacuum; stirring for 1 hour, during which the reactor is cleaned twice, and degassing for 30 minutes after the stirring is completed, to obtain component A; Prepare component B, comprising: The high thermal conductivity and high performance two-component polyurethane structural adhesive formula according to any one of claims 1 to 7 comprises the following steps: taking the raw materials of component B, adding the isocyanate-terminated polyurethane prepolymer, water absorbent, and pigment in the raw materials of component B into a reaction kettle, stirring and dispersing at room temperature, with a planetary speed of 10 to 15 Hz and a dispersion speed of 300 rpm, and applying vacuum during the stirring process; after stirring for 30 minutes, adding the third modified thermally conductive filler, then increasing the dispersion speed to 600 rpm and applying vacuum; stirring for 1 hour, during which the kettle is cleaned twice, and degassing for 30 minutes after the stirring is completed, to obtain component B; When used, component A and component B are weighed in a volume ratio of 0.9 to 1.1:1, and stirred and mixed evenly to obtain the high thermal conductivity and high performance two-component polyurethane structural adhesive according to any one of claims 1 to 7.

9. The method for preparing a high thermal conductivity and high performance two-component polyurethane structural adhesive according to claim 8, characterized in that: The first modified thermally conductive filler in component A is pre-prepared in the following manner, including: Deionized water and ethanol are mixed in a certain volume ratio, a coupling agent is first added, and hydrolysis is carried out for 15 to 20 minutes to obtain a first modifier, and then a first thermally conductive filler is added to the first modifier, wherein the amount of the silane coupling agent added is 1 to 3% of the mass of the first thermally conductive filler, and magnetic stirring is carried out at room temperature for 12 hours. The modified first thermally conductive filler is washed three times with deionized water and ethanol respectively, filtered, placed in a vacuum drying oven, and dried at 110° C. for 2 hours to obtain a first modified thermally conductive filler; The second modified thermally conductive filler in component A is pre-prepared in the following manner, including: The second thermally conductive filler is dried at 100-120°C for 2-4 hours, placed in a high-speed stirrer and rapidly stirred at a speed of 300-600 rpm, and hydroxy silicone oil as a third modifier is slowly added dropwise to the high-speed stirred powder in an amount of 0.5%-2% of the mass of the third thermally conductive filler. Stirring is continued for 60-120 minutes. After the stirring is completed, it is continued to be dried at 90-110°C for 1-2 hours to obtain a second modified thermally conductive filler.

10. The method for preparing a high thermal conductivity and high performance two-component polyurethane structural adhesive according to claim 8, characterized in that: The isocyanate-terminated polyurethane prepolymer in component B is prepared in advance in the following manner, including: Add the polyol to a reactor and disperse and stir it, heat it to 110-120°C, evacuate it, dehydrate it for 1-3 hours, cool it down, and take it out for later use; add the dehydrated polyol and a theoretical amount of isocyanate to a clean reactor and disperse and stir it, heat it to 75-85°C, continue the reaction for 1-2 hours, and terminate the reaction by titrating the NCO content until it stops changing, and cool it to room temperature to obtain an isocyanate-terminated polyurethane prepolymer; The third modified thermally conductive filler in component B is pre-prepared in the following manner, including: The third thermally conductive filler and stearic acid as the third modifier are placed in a high-speed mixer and rapidly stirred. The amount of stearic acid used is 0.1-0.5% of the mass of the third thermally conductive filler. The temperature is raised to 80-100° C. and stirring is continued for 60-120 minutes. After the stirring is completed, the third modified thermally conductive filler is obtained.

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