Removable polyurethane two-component adhesive, method for its production and method for its removal

Abstract

The application provides a detachable polyurethane two-component adhesive for power batteries and a preparation method and a detaching method thereof, and relates to the technical field of adhesives. The detachable polyurethane two-component adhesive for power batteries comprises component A and component B. In terms of weight parts, component A comprises 10-45 parts of polyhydric alcohol, 5-20 parts of a weak-coupling-bond-containing chain extender, 40-60 parts of a first heat-conducting filler, 0.01-0.5 parts of a catalyst, 1-4 parts of a water absorber and 1-4 parts of a thixotropic agent. The polyhydric alcohol is one or two or more of bio-based oil polyhydric alcohol, polyether polyhydric alcohol and polyester polyhydric alcohol. The weak-coupling-bond-containing chain extender has the structure: wherein R1 and R4 are active groups that can react with NCO, and R2 and R3 can be any group. Component B comprises 15-35 parts of an isocyanate prepolymer, 50-80 parts of a second heat-conducting filler and 0.05-0.3 parts of a water absorber. The application solves the problems that the heat-conducting structural adhesive of a battery pack is difficult to remove and a high temperature is used in the removal process.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, and in particular to a removable two-component polyurethane adhesive for power batteries, as well as its preparation and disassembly methods. Background Technology

[0002] In recent years, electric vehicles have developed rapidly and are gradually replacing gasoline vehicles. As a core component of electric vehicles, the battery pack has received increasing attention. A battery pack consists of battery modules and a liquid cooling plate. There are two methods for fixing the battery modules to the liquid cooling plate. One method is to use mechanical fastening, but this method is costly, has difficulties in heat dissipation, and is prone to damaging internal battery components during collisions or disassembly. The other method uses thermally conductive structural adhesive to fix the battery modules to the liquid cooling plate, using the adhesive as a heat-conducting medium to transfer the heat generated by the battery during operation, thus ensuring the reliability of the battery pack.

[0003] Polyurethane resin is a widely used material. Its excellent properties make it a crucial matrix resin material in battery pack thermally conductive structural adhesives. However, the stable structure of existing polyurethane thermally conductive structural adhesives makes disassembly, repair, and reassembly for reuse difficult when cells or modules malfunction. During battery manufacturing, if process errors cause battery pack performance to fail to meet requirements, the difficulty in disassembling and reworking the thermally conductive structural adhesive often necessitates scrapping the entire battery pack, resulting in low tolerance for errors and difficulties in resource reuse. The lifespan of batteries for new energy vehicles is approximately eight years, after which they are retired. Retired battery packs, after disassembly and cell reassembly, can be reused in home lighting, small electric vehicles, and energy storage. However, the uncontrollable bonding properties of existing thermally conductive structural adhesives make disassembly difficult after battery retirement, significantly hindering the successful implementation of the reuse of batteries for new energy vehicles.

[0004] In the closest prior art, Chinese patent CN113025259A discloses a detachable two-component polyurethane adhesive. This adhesive incorporates expandable microspheres and a low-temperature foaming agent in its formulation, enabling disassembly of bonded structural components at 80-100°C. However, the safe operating temperature for power batteries is below 60°C. Existing technologies require disassembly at 80-100°C; temperatures above 60°C will cause irreversible damage to battery performance, reducing reusability. Furthermore, the high stress generated between the adhesive and the bonding surface during disassembly can easily cause deformation of the bonding surface.

[0005] Therefore, there is an urgent need to develop a removable two-component polyurethane adhesive for power batteries, as well as its preparation and disassembly methods, to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a removable two-component polyurethane adhesive for power batteries, as well as its preparation and disassembly methods, so as to achieve on-demand control of bonding performance and solve the problems of difficult removal of thermally conductive structural adhesives in battery packs and high temperatures used during the disassembly process.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a removable two-component polyurethane adhesive, the removable two-component polyurethane adhesive comprising component A and component B.

[0008] By weight, component A comprises 10-45 parts of a polyol, 5-20 parts of a chain extender containing weak coupling bonds, 40-60 parts of a first thermally conductive filler, 0.01-0.5 parts of a catalyst, 1-4 parts of a water absorbent, and 1-4 parts of a thixotropic agent; the polyol is one or more of bio-based oily polyols, polyether polyols, and polyester polyols; the chain extender containing weak coupling bonds has the following structure: R1 and R4 are active groups that can react with NCO, while R2 and R3 can be any groups;

[0009] Component B comprises 15-35 parts of isocyanate prepolymer, 50-80 parts of a second thermally conductive filler, and 0.05-0.3 parts of a water-absorbing agent.

[0010] Optionally, the chain extender containing weak coupling bonds is one or more of hydroxyethyl disulfide, 3,3'-dithiobis(1-hexanol), 2,2'-dithiobis-1-propanol, and 3,3'-dihydroxydiphenyl disulfide.

[0011] Optionally, the bio-based oily polyol is at least one of refined castor oil polyol, modified castor oil polyol, cashew oil modified polyol, soybean oil polyol, olive oil polyol, palm oil polyol, and tung oil polyol; the polyether polyol is at least one of polyethylene glycol, polypropylene glycol, polytetrahydrofuran diol, and trifunctional or higher polyfunctional polyols.

[0012] Optionally, the isocyanate prepolymer is obtained by prepolymerization of isocyanate monomer and polyol, and the NCO content of the isocyanate prepolymer is 15-35%.

[0013] Optionally, the isocyanate monomer is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, polymethylene polyphenyl isocyanate, carboimide-modified toluene diisocyanate, and 4,4-dicyclohexylmethane diisocyanate.

[0014] Optionally, both the first thermally conductive filler and the second thermally conductive filler are selected from one or more of alumina, aluminum hydroxide, boron nitride, copper powder, silver powder, carbon nanotubes, and graphene; the catalyst is selected from at least one of organotin compounds, organobismuth compounds, organozinc compounds, and organolead compounds.

[0015] Optionally, component A further includes 0.1-0.5 parts of color paste, and component B further includes 0.1-0.5 parts of color paste.

[0016] Secondly, the present invention provides a method for preparing a detachable two-component polyurethane adhesive, comprising the following steps:

[0017] Preparation of component A: Prepare raw materials according to the formula, stir the raw materials required for component A under vacuum, and mix them evenly to obtain component A;

[0018] Preparation of component B: First, under stirring conditions, the polyol is added dropwise to the isocyanate monomer, and a prepolymerization reaction is carried out at 60-100℃ to obtain the isocyanate prepolymer; then, the corresponding weight parts of the isocyanate prepolymer and the raw materials required for component B are stirred under vacuum and mixed evenly to obtain component B.

[0019] The prepared component A and component B are mixed in a volume ratio of 1:1 or 1:2.

[0020] Thirdly, the present invention provides a method for disassembling a removable two-component polyurethane adhesive, wherein several structural components are bonded together using the above-mentioned removable two-component polyurethane adhesive or the removable two-component polyurethane adhesive prepared by the above-mentioned preparation method to form a removable adhesive component, and the removable adhesive component is immersed in a degradation solution, wherein the removable two-component polyurethane adhesive is allowed to degrade statically at room temperature.

[0021] Optionally, the degradation solution is composed of a reducing agent and a solvent. The reducing agent is at least one of organophosphorus compounds, thiols, organometallic compounds, and inorganic reducing agents, preferably tributylphosphine, mercaptoethanol, dithiothreitol, or sodium borohydride. The solvent is selected from amides, esters, ethers, ketones, benzenes, and lower alcohols, preferably N,N'-dimethylformamide or the environmentally friendly solvent Hbchem1366.

[0022] Optionally, the concentration of the reducing substance in the degradation solution is 0.05-1 mol / L.

[0023] The beneficial effects of this invention include:

[0024] 1. The removable two-component polyurethane adhesive of this application has high thermal conductivity and bonding strength.

[0025] 2. The removable polyurethane two-component adhesive for power batteries of this application allows for rapid and non-destructive disassembly of the battery pack at room temperature after bonding, which is beneficial for the cascade utilization of power batteries.

[0026] 3. The preparation process of the removable polyurethane two-component adhesive for power batteries in this application is simple and easy, and the degraded resin and filler can be recycled and reused, thereby reducing the cost of disassembly and reuse.

[0027] 4. The removable polyurethane two-component adhesive for power batteries of this application meets the requirements of adhesives for new energy vehicle batteries in all aspects, and its performance is not much different from that of thermally conductive adhesives for power batteries on the market. Attached Figure Description

[0028] Figure 1 This is a schematic flowchart of a method for preparing a removable two-component polyurethane adhesive for power batteries according to an embodiment of the present invention.

[0029] Figure 2 This is a schematic diagram illustrating the degradation of the removable two-component polyurethane adhesive of Example 1 and the comparative example of the present invention in the degradation solution.

[0030] Figure 3 This is a schematic diagram showing the degradation of the adhesive components of Example 1 and the comparative example of the present invention in the degradation solution. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The technical problem to be solved by this invention is that the thermally conductive structural adhesive of the battery pack is difficult to remove and the temperature used in the removal process is high. The removable polyurethane two-component adhesive for power batteries of this application can achieve rapid and non-destructive disassembly of the battery pack under mild conditions, which reduces the cost of disassembly and reuse and improves the utilization rate of resources.

[0033] This invention provides a removable two-component polyurethane adhesive for power batteries, the removable two-component polyurethane adhesive comprising component A and component B.

[0034] By weight, component A comprises 10-45 parts of a polyol, 5-20 parts of a chain extender containing weak coupling bonds, 40-60 parts of a first thermally conductive filler, 0.01-0.5 parts of a catalyst, 1-4 parts of a water absorbent, and 1-4 parts of a thixotropic agent; the polyol is one or more of bio-based oily polyols, polyether polyols, and polyester polyols; the chain extender containing weak coupling bonds has the following structure: R1 and R4 are active groups that can react with NCO, while R2 and R3 can be any groups;

[0035] Component B comprises 15-35 parts of isocyanate prepolymer, 50-80 parts of a second thermally conductive filler, and 0.05-0.3 parts of a water-absorbing agent.

[0036] In some embodiments of the present invention, the chain extender containing weak coupling bonds is one or more of hydroxyethyl disulfide, 3,3'-dithiobis(1-hexanol), 2,2'-dithiobis-1-propanol, and 3,3'-dihydroxydiphenyl disulfide.

[0037] In some embodiments of the present invention, the bio-based oily polyol includes at least one of refined castor oil polyol, modified castor oil polyol, cashew oil modified polyol, soybean oil polyol, olive oil polyol, palm oil polyol, and tung oil polyol, and the polyether polyol includes at least one of polyethylene glycol, polypropylene glycol, polytetrahydrofuran diol, and trifunctional or higher polyfunctional polyols.

[0038] In some specific embodiments of the present invention, the polyethylene glycol and the polytetrahydrofuran diol are derived from BASF; the polypropylene glycol is derived from Haian Petrochemical Plant; the trifunctional and higher-functional polyols include trifunctional polyols, tetrafunctional polyols and polyether polyols with higher functionality, wherein the trifunctional polyols can be glycerol and pentaerythritol, and the tetrafunctional polyols can be diglycerol and dipentaerythritol.

[0039] In some specific embodiments of the present invention, the CAS number of the hydroxyethyl disulfide is 1892-29-1, derived from THICA; the CAS number of the 3,3'-dithiobis(1-hexanol) is 344738-34-7, derived from Jinan Aochen Chemical Co., Ltd.; the CAS number of the 2,2'-dithiobis-1-propanol is 177854-95-4, derived from Berry & Associates, Inc.; and the CAS number of the 3,3'-dihydroxydiphenyl disulfide is 21101-56-4, derived from Aladdin.

[0040] In some embodiments of the present invention, both the first thermally conductive filler and the second thermally conductive filler include at least one of alumina, aluminum hydroxide, boron nitride, copper powder, silver powder, carbon nanotubes, and graphene; the particle size is 1-100 micrometers.

[0041] In some embodiments of the present invention, the catalyst comprises at least one of organotin compounds, organobismuth compounds, organozinc compounds, and organolead compounds. Specifically, the organotin compounds include dibutyltin dilaurate, stannous octanoate, di(dodecyl sulfide)dibutyltin, and dibutyltin diacetate; the organobismuth compounds include bismuth neodecanoate, bismuth laurate, bismuth isooctanoate, and bismuth naphthenate; the organozinc compounds include zinc isooctanoate, zinc neodecanoate, zinc naphthenate, zinc acetate, and zinc lactate; and the organolead compounds include n-butyl lead ester and isopropyl lead ester.

[0042] In some specific embodiments of the present invention, the catalyst is preferably an organotin type, and the organotin type is preferably dibutyltin dilaurate.

[0043] In some embodiments of the present invention, the isocyanate prepolymer is obtained by prepolymerization reaction of isocyanate monomer and polyol, and the NCO content of the isocyanate prepolymer is 15-35%.

[0044] In some embodiments of the present invention, the preparation steps of the isocyanate prepolymer include: slowly adding a polyol dropwise to an isocyanate monomer to carry out a prepolymerization reaction to obtain the isocyanate prepolymer, wherein the NCO content of the isocyanate prepolymer is 15-35%. Specifically, the NCO content of the isocyanate prepolymer = the mass of isocyanate groups contained in the isocyanate prepolymer ÷ the mass of the isocyanate prepolymer × 100%.

[0045] In some embodiments of the present invention, the isocyanate monomer includes at least one selected from toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, polymethylene polyphenyl isocyanate, carboimide-modified toluene diisocyanate, and 4,4-dicyclohexylmethane diisocyanate.

[0046] The abbreviation for the toluene diisocyanate is TDI, CAS number 584-84-9; the abbreviation for the diphenylmethane diisocyanate is MDI, CAS number 101-68-8; the abbreviation for the isophorone diisocyanate is IPDI, CAS number 4098-71-9; the abbreviation for the hexamethylene diisocyanate is HDI, CAS number 822-06-0; the abbreviation for the polymethylene polyphenyl isocyanate is PAPI, CAS number 9016-87-9; the carboimide-modified toluene diisocyanate is purchased from BASF, brand name Lupranate MM103C; and the abbreviation for the 4,4-dicyclohexylmethane diisocyanate is HMDI, CAS number 5124-30-1.

[0047] In some embodiments of the present invention, component A further includes 0.1-0.5 parts of color paste, and component B further includes 0.1-0.5 parts of color paste. The color paste is a commercially available common color paste. The water-absorbing agent is preferably a physical water-absorbing agent, specifically a molecular sieve.

[0048] This invention provides a method for preparing a removable two-component polyurethane adhesive, comprising the following steps:

[0049] Preparation of component A: Prepare raw materials according to the formula, stir the raw materials required for component A under vacuum, and mix them evenly to obtain component A;

[0050] Preparation of component B: First, under stirring conditions, the polyol is added dropwise to the isocyanate monomer, and a prepolymerization reaction is carried out at 60-100℃ to obtain the isocyanate prepolymer; then, the corresponding weight parts of the isocyanate prepolymer and the raw materials required for component B are stirred under vacuum and mixed evenly to obtain component B.

[0051] The prepared component A and component B are mixed at a volume ratio of 1:1 or 1:2.

[0052] Some embodiments of the present invention are described with reference to Figure 1 This includes the following steps:

[0053] S1: Preparation of component A: Mix 10-45 parts of polyol, 5-20 parts of chain extender containing weak coupling bonds, 40-60 parts of first thermally conductive filler, 0.01-0.5 parts of catalyst, 1-4 parts of water absorbent, 1-4 parts of thixotropic agent, and 0.1-0.5 parts of color paste evenly to obtain component A.

[0054] S2: Preparation of component B: Mix 15-35 parts of isocyanate prepolymer, 50-80 parts of second thermally conductive filler, 0.05-0.3 parts of water absorbent, and 0.1-0.5 parts of color paste evenly to obtain component B;

[0055] S3: Mix component A and component B in a volume ratio of 1:1 or 1:2 to obtain the removable polyurethane two-component adhesive.

[0056] In some embodiments of the present invention, the order of preparation of component A and component B is not limited. Component B may be prepared first and then component A may be prepared, or component A may be prepared first and then component B may be prepared, or components A and B may be prepared simultaneously.

[0057] This invention provides a method for disassembling a removable two-component polyurethane adhesive. Several structural components are bonded together using the removable two-component polyurethane adhesive to form a removable bonded component. The removable bonded component is then immersed in a degradation solution, and the removable two-component polyurethane adhesive is allowed to degrade at room temperature.

[0058] In some embodiments of the present invention, the degradation solution is composed of a reducing agent and a solvent. The reducing agent is at least one of organophosphorus compounds, thiols, organometallic compounds, and inorganic reducing agents, preferably tributylphosphine, mercaptoacetic acid, dithiothreitol, or sodium borohydride. The solvent is selected from amides, esters, ethers, ketones, benzenes, and lower alcohols, preferably N,N'-dimethylformamide or the environmentally friendly solvent Hbchem1366.

[0059] Specifically, the CAS number of the tributylphosphine is 998-40-3, the CAS number of the mercaptoacetic acid is 68-11-1, the CAS number of the dithiothreitol is 3483-12-3, the CAS number of the N,N'-dimethylformamide is 68-12-2, and the environmentally friendly solvent Hbchem1366 is sourced from Guangzhou Zhongheng Composite Materials Co., Ltd.

[0060] In some embodiments of the present invention, the concentration of the reducing substance in the degradation solution is 0.05-1 mol / L. Specifically, the concentration of the reducing substance in the degradation solution is any one of 0.05 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, and 1 mol / L.

[0061] In Examples 1-3 and the comparative examples of this invention, the following raw materials were used: refined castor oil polyol, purchased from Ito Oil Co., Ltd., grade H-52; polyether diol, purchased from Shandong Lanxing Dongda Chemical Co., Ltd., grade DL400; hydroxyethyl disulfide, purchased from THICA, CAS number 1892-29-1; 3,3'-dihydroxydiphenyl disulfide, purchased from Aladdin; and isophorone diisocyanate, purchased from Wanhua Chemical, grade [not specified]. IPDI; carboimide-modified toluene diisocyanate, purchased from BASF Chemicals, grade Lupranate MM103C. The catalyst is dibutyl dilaurate, the water absorbent is 3A molecular sieve powder, the thixotropic agent is fumed silica, and the colorant, etc., are all commercially available and of the same type. For the thermally conductive fillers (corresponding to the first and second thermally conductive fillers), aluminum hydroxide or alumina, commercially available with a particle size range of 1-100 micrometers, is acceptable. Tributylphosphide (Bu3P) for degradation is purchased from Shanghai Titan Technology Co., Ltd., N,N'-dimethylformamide (DMF) is also purchased from Shanghai Titan Technology Co., Ltd., and the environmentally friendly solvent Hbchem1366 is purchased from Guangzhou Zhongheng Composite Materials Co., Ltd.

[0062] Example 1

[0063] Component A includes: 28 parts refined castor oil polyol, 8 parts hydroxyethyl disulfide, 60 parts aluminum hydroxide, 0.3 parts dibutyltin dilaurate, 2 parts 3A molecular sieve, 1.5 parts fumed silica, and 0.2 parts color paste;

[0064] Component B includes: 27 parts isocyanate prepolymer, 63 parts second thermally conductive filler, 0.1 parts water absorbent and 0.3 parts color paste, wherein the second thermally conductive filler is composed of aluminum hydroxide and aluminum oxide in a weight ratio of 10:1;

[0065] Preparation of Component A: Refined castor oil polyol and hydroxyethyl disulfide were vacuum dehydrated at 120°C for 2 hours. The dehydrated refined castor oil polyol and hydroxyethyl disulfide were then mixed with aluminum hydroxide, dibutyltin dilaurate, 3A molecular sieve, silica gel, and color paste under vacuum in parts by weight to obtain Component A.

[0066] Preparation of Component B: Under stirring conditions, 16.7g of refined castor oil polyol was slowly added dropwise to 100g of isophorone diisocyanate at 80℃, and 0.01% of dibutyltin dilaurate was added. Then, nitrogen gas was introduced and the reaction was continued for 2 hours to obtain an isocyanate prepolymer with an NCO content of 30%. The isocyanate prepolymer was mixed with the second thermally conductive filler, water absorbent, and color paste under vacuum according to the weight proportions to obtain Component B.

[0067] The obtained components A and B were packed into tubes with a volume ratio of 1:1 and stored at room temperature.

[0068] Disassembly method: Mix components A and B from the adhesive tube using a glue gun and apply between the surfaces of the first and second aluminum sheets. Allow to cure at room temperature for 7 days until complete curing, forming a detachable adhesive joint between the first and second aluminum sheets. Immerse the detachable adhesive joint (the bonded first and second aluminum sheets) in a degradation solution at room temperature for degradation treatment. After standing for 10 hours, the detachable polyurethane two-component adhesive degrades into small molecules that dissolve in the degradation solution, causing the bonded first and second aluminum sheets to separate naturally. The degradation rate of the detachable polyurethane two-component adhesive is 100%. The degradation solution consists of 0.1M Bu3P and the environmentally friendly solvent Hbchem 1366 (M stands for mol / L). The dimensions of both the first and second aluminum sheets are 23mm × 25mm.

[0069] The filler in the removable polyurethane two-component adhesive was separated by filtration and dried for direct use in the preparation of thermally conductive adhesive; Bu3P and the environmentally friendly solvent Hbchem1366 were recovered by vacuum distillation and used for the disassembly of the removable polyurethane two-component adhesive; the remaining material was the degraded polyurethane resin.

[0070] Example 2

[0071] Component A includes: 22 parts refined castor oil polyol, 8 parts polyether diol DL400, 15 parts 3,3'-dihydroxydiphenyl disulfide, 51 parts aluminum hydroxide, 0.3 parts dibutyltin dilaurate, 2 parts 3A molecular sieve, 1.5 parts fumed silica and 0.2 parts color paste;

[0072] Component B comprises: 28 parts isocyanate prepolymer, 71 parts second thermally conductive filler, 0.1 parts water absorbent and 0.3 parts color paste, wherein the second thermally conductive filler is composed of aluminum hydroxide and aluminum oxide in a weight ratio of 10:1;

[0073] Preparation of Component A: Refined castor oil polyol, polyether diol DL400, and 3,3'-dihydroxydiphenyl disulfide were vacuum dehydrated at 120°C for 2 hours. The dehydrated refined castor oil polyol, polyether diol DL400, 3,3'-dihydroxydiphenyl disulfide, aluminum hydroxide, dibutyltin dilaurate, 3A molecular sieve, fumed silica, and color paste were stirred and mixed evenly under vacuum to obtain Component A.

[0074] Preparation of Component B: Under stirring conditions, 25.7g of refined castor oil polyol was slowly added dropwise to 100g of carboimide-modified toluene diisocyanate at 65℃, and then nitrogen gas was introduced to continue the reaction for 2h to obtain an isocyanate prepolymer with an NCO content of 20%; according to the weight parts, the isocyanate prepolymer was stirred and mixed evenly under vacuum with the second thermally conductive filler, water absorbent, and color paste to obtain Component B;

[0075] The obtained components A and B were packed into tubes with a volume ratio of 1:2 and stored at room temperature.

[0076] Disassembly method: Mix components A and B in the adhesive tube using a glue gun and apply between the surfaces of the first and second aluminum sheets. Allow to cure at room temperature for 7 days until complete curing. The first and second aluminum sheets will then form a detachable adhesive joint. Immerse the detachable adhesive joint (the bonded first and second aluminum sheets) in a degradation solution at room temperature for degradation treatment. After standing for 10 hours, the detachable polyurethane two-component adhesive will degrade into small molecules that dissolve in the degradation solution, and the bonded first and second aluminum sheets will naturally separate. The degradation rate of the detachable polyurethane two-component adhesive is 100%. The degradation solution consists of 0.1M Bu3P and the environmentally friendly solvent Hbchem1366. The dimensions of both the first and second aluminum sheets are 23mm × 25mm.

[0077] The filler in the removable polyurethane two-component adhesive was separated by filtration and dried for direct use in the preparation of thermally conductive adhesive; Bu3P and the environmentally friendly solvent Hbchem1366 were recovered by vacuum distillation and used for the disassembly of the removable polyurethane two-component adhesive; the remaining material was the degraded polyurethane resin.

[0078] Example 3

[0079] Component A includes: 28 parts refined castor oil polyol, 10 parts hydroxyethyl disulfide, 64 parts aluminum hydroxide, 0.3 parts dibutyltin dilaurate, 2 parts 3A molecular sieve, 1.5 parts fumed silica and 0.2 parts color paste;

[0080] Component B includes: 32 parts isocyanate prepolymer, 71 parts second thermally conductive filler, 0.1 parts water absorbent and 0.3 parts color paste, wherein the second thermally conductive filler is composed of aluminum hydroxide and aluminum oxide in a weight ratio of 10:1;

[0081] Preparation of Component A: Refined castor oil polyol and hydroxyethyl disulfide were vacuum dehydrated at 120°C for 2 hours. The dehydrated refined castor oil polyol and hydroxyethyl disulfide were then mixed with aluminum hydroxide, dibutyltin dilaurate, 3A molecular sieve, silica gel, and color paste under vacuum in parts by weight to obtain Component A.

[0082] Preparation of Component B: Under stirring conditions, 50g of refined castor oil polyol was slowly added dropwise to 100g of isophorone diisocyanate at 80℃, and 0.01% dibutyltin dilaurate was added. Then, nitrogen gas was introduced and the reaction was continued for 2 hours to obtain an isocyanate prepolymer with an NCO content of 20%. The isocyanate prepolymer was mixed with the second thermally conductive filler, water absorbent, and color paste in parts by weight under vacuum to obtain Component B.

[0083] The obtained components A and B were packed into tubing with a volume ratio of 1:1 and stored at room temperature.

[0084] Disassembly method: Mix components A and B in the adhesive tube using a glue gun and apply between the surfaces of the first and second aluminum sheets. Allow to cure at room temperature for 7 days until complete curing. The first and second aluminum sheets will then form a detachable adhesive joint. Immerse the detachable adhesive joint (the bonded first and second aluminum sheets) in a degradation solution at room temperature for degradation treatment. After standing for 8 hours, the detachable polyurethane two-component adhesive will degrade into small molecules that dissolve in the degradation solution, and the bonded first and second aluminum sheets will naturally separate. The degradation rate of the detachable polyurethane two-component adhesive is 100%. The degradation solution consists of 0.1M Bu3P and DMF. The dimensions of both the first and second aluminum sheets are 23mm × 25mm.

[0085] The filler in the removable polyurethane two-component adhesive was separated by filtration and dried for direct use in the preparation of thermally conductive adhesive; Bu3P and DMF were recovered by vacuum distillation for disassembly of the removable polyurethane two-component adhesive; the remaining material was the degraded polyurethane resin.

[0086] Comparative Example

[0087] Component A includes: 32 parts refined castor oil polyol, 63 parts aluminum hydroxide, 0.3 parts dibutyltin dilaurate, 2 parts 3A molecular sieve, 2 parts fumed silica and 0.2 parts color paste;

[0088] Component B comprises: 28 parts isocyanate prepolymer, 71 parts second thermally conductive filler, 0.1 parts water absorbent and 0.3 parts color paste, wherein the second thermally conductive filler is composed of aluminum hydroxide and aluminum oxide in a weight ratio of 10:1;

[0089] Preparation of Component A: Refined castor oil polyol was vacuum dehydrated at 120℃ for 2 hours. The dehydrated refined castor oil polyol was then mixed with aluminum hydroxide, dibutyltin dilaurate, 3A molecular sieve, fumed silica, and color paste under vacuum to obtain Component A.

[0090] Preparation of Component B: Under stirring conditions, 25.7g of refined castor oil polyol was slowly added dropwise to 100g of carboimide-modified toluene diisocyanate at 65℃, and then nitrogen gas was introduced to continue the reaction for 2h to obtain an isocyanate prepolymer with an NCO content of 20%; according to the weight parts, the isocyanate prepolymer was stirred and mixed evenly under vacuum with the second thermally conductive filler, water absorbent, and color paste to obtain Component B;

[0091] The obtained components A and B were packed into tubing with a volume ratio of 1:1 and stored at room temperature.

[0092] Disassembly method: Mix components A and B in the adhesive tube using a glue gun and apply between the surfaces of the first and second aluminum sheets. Allow to cure at room temperature for 7 days until complete curing, forming a detachable adhesive joint between the first and second aluminum sheets. Immerse the detachable adhesive joint (the bonded first and second aluminum sheets) in a degradation solution at room temperature for degradation treatment. After standing for 10 hours, the detachable adhesive joint still cannot be separated, indicating no degradation of the polyurethane two-component adhesive. The degradation solution consists of 0.1M Bu3P and the environmentally friendly solvent Hbchem1366.

[0093] The adhesives used in Examples 1-3 and the comparative examples were tested, and the test results are shown in Table 1.

[0094] Table 1 Test Results

[0095]

[0096] Note: DMA stands for Dynamic Thermomechanical Analyzer.

[0097] As shown in Table 1, compared with the comparative example polyurethane two-component adhesive, the elongation at break of the removable polyurethane two-component adhesives of Examples 1-3 is slightly inferior, but they still meet the requirements for removable polyurethane two-component adhesives for new energy vehicle batteries. Other properties of the removable polyurethane two-component adhesives of Examples 1-3 are not significantly different from those of the comparative example polyurethane two-component adhesive. Therefore, the removable polyurethane two-component adhesive of this application, while meeting the requirements for polyurethane two-component adhesives for new energy vehicle batteries in all aspects, can be 100% degraded in the degradation solution, achieving on-demand control of bonding performance and solving the problem of difficult removal of the thermally conductive structural adhesive in battery packs.

[0098] Reference Figure 1 The first reagent bottle 1 contains a degradation solution composed of 0.1M Bu3P and the environmentally friendly solvent Hbchem 1366, and the removable two-component polyurethane adhesive of Example 1. The second reagent bottle 2 contains a degradation solution composed of 0.1M Bu3P and the environmentally friendly solvent Hbchem 1366, and the comparative example's two-component polyurethane adhesive. Figure 1 It is evident that the comparative polyurethane two-component adhesive did not degrade at all in the degradation solution, while the removable polyurethane two-component adhesive of Example 1 was completely degraded in the degradation solution. The degraded substances from Actual Example 1 were separated to obtain filler, degraded resin, and Bu3P and solvent Hbchem1366. The third reagent bottle 3 contained the filtered and dried filler, and the fourth reagent bottle 4 contained the remaining degraded resin after vacuum distillation to recover Bu3P and Hbchem1366. (Refer to...) Figure 2The fifth reagent bottle 5 contains a detachable adhesive component (adhesive first and second aluminum sheets) as in the comparative example, and the sixth reagent bottle 6 contains a detachable adhesive component (adhesive first and second aluminum sheets) as in Example 1. Figure 2 and Figure 3 It can be clearly seen that the adhesive in the comparative example failed to degrade under the same conditions, and the detachable adhesive (the bonded first aluminum sheet and the second aluminum sheet) could not be separated. In Example 1, the detachable adhesive, namely the first aluminum sheet and the second aluminum sheet, was completely separated, and there was no residual detachable polyurethane two-component adhesive on the first aluminum sheet and the second aluminum sheet, indicating complete degradation.

[0099] While embodiments of the present invention have been described in detail above, it will be apparent to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations fall within the scope and spirit of the invention as set forth in the claims. Furthermore, the invention described herein may have other embodiments and can be implemented or carried out in various ways.

Claims

1. A removable two-component polyurethane adhesive, characterized in that, The removable two-component polyurethane adhesive comprises component A and component B. By weight, component A comprises 10-45 parts of a polyol, 5-20 parts of a chain extender containing weak coupling bonds, 40-60 parts of a first thermally conductive filler, 0.01-0.5 parts of a catalyst, 1-4 parts of a water absorbent, and 1-4 parts of a thixotropic agent; the polyol is one or more of bio-based oily polyols, polyether polyols, and polyester polyols; the chain extender containing weak coupling bonds has the following structure: R1 and R4 are active groups that can react with NCO, while R2 and R3 can be any groups; Component B comprises 15-35 parts of isocyanate prepolymer, 50-80 parts of a second thermally conductive filler, and 0.05-0.3 parts of a water-absorbing agent.

2. The removable two-component polyurethane adhesive according to claim 1, characterized in that, The chain extender containing weak coupling bonds is one or more of hydroxyethyl disulfide, 3,3'-dithiobis(1-hexanol), 2,2'-dithiobis-1-propanol, and 3,3'-dihydroxydiphenyl disulfide.

3. The removable two-component polyurethane adhesive according to claim 1, characterized in that, The bio-based oily polyol is at least one of refined castor oil polyol, modified castor oil polyol, cashew oil modified polyol, soybean oil polyol, olive oil polyol, palm oil polyol, and tung oil polyol; the polyether polyol is at least one of polyethylene glycol, polypropylene glycol, polytetrahydrofuran diol, and trifunctional or higher polyfunctional polyols.

4. The removable two-component polyurethane adhesive according to claim 1, characterized in that, The isocyanate prepolymer is obtained by prepolymerization reaction of isocyanate monomer and polyol, and the NCO content of the isocyanate prepolymer is 15-35%.

5. The removable two-component polyurethane adhesive according to claim 4, characterized in that, The isocyanate monomer is selected from one or more of toluene diisocyanate, diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, polymethylene polyphenyl isocyanate, carboimide-modified toluene diisocyanate, and 4,4-dicyclohexylmethane diisocyanate.

6. The removable two-component polyurethane adhesive according to claim 1, characterized in that, Both the first thermally conductive filler and the second thermally conductive filler are selected from one or more of alumina, aluminum hydroxide, boron nitride, copper powder, silver powder, carbon nanotubes, and graphene; the catalyst is selected from at least one of organotin compounds, organobismuth compounds, organozinc compounds, and organolead compounds.

7. The removable two-component polyurethane adhesive according to claim 1, characterized in that, Component A further includes 0.1-0.5 parts of color paste, and component B further includes 0.1-0.5 parts of color paste.

8. A method for preparing the removable two-component polyurethane adhesive according to any one of claims 1-7, characterized in that, Includes the following steps: Preparation of component A: Prepare raw materials according to the formula, stir the raw materials required for component A under vacuum, and mix them evenly to obtain component A; Preparation of component B: First, under stirring conditions, the polyol is added dropwise to the isocyanate monomer, and a prepolymerization reaction is carried out at 60-100℃ to obtain the isocyanate prepolymer; then, the corresponding weight parts of the isocyanate prepolymer and the raw materials required for component B are stirred under vacuum and mixed evenly to obtain component B. The prepared component A and component B are mixed in a volume ratio of 1:1 or 1:

2.

9. A method for disassembling a removable two-component polyurethane adhesive, characterized in that, Several structural components are bonded together using the removable two-component polyurethane adhesive as described in any one of claims 1-7 or the removable two-component polyurethane adhesive prepared by the preparation method described in claim 8 to form a removable adhesive component. The removable adhesive component is then immersed in a degradation solution, and the removable two-component polyurethane adhesive is allowed to degrade at room temperature.

10. The method for disassembling the removable two-component polyurethane adhesive according to claim 9, characterized in that, The degradation solution is composed of a reducing agent and a solvent. The reducing agent is at least one of organophosphorus compounds, thiols, organometallic compounds, and inorganic reducing agents. The solvent is selected from amides, esters, ethers, ketones, benzenes, and lower alcohols.

11. The method for disassembling the removable two-component polyurethane adhesive according to claim 10, characterized in that, The reducing agent is at least one of tributylphosphine, mercaptoacetic acid, dithiothreitol, and sodium borohydride, and the solvent is at least one of N,N'-dimethylformamide and the environmentally friendly solvent Hbchem1366.

12. The disassembly method according to claim 10, characterized in that, The concentration of the reducing agent in the degradation solution is 0.05-1 mol / L.

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