High-strength two-component polyurethane pouring sealant and preparation method thereof

Abstract

The application discloses high-strength two-component polyurethane pouring sealant and a preparation method thereof, and belongs to the field of chemical industry. The product is matched by special two components, and can realize controllable strength and hardness of the product, is suitable for a fixing scene of a cylindrical electric core, and has good bonding strength, toughness, moisture and heat resistance, flame retardance and electric insulation, and the like, and has excellent comprehensive performance.

Description

Technical Field

[0001] This invention relates to the chemical industry, specifically to a high-strength two-component polyurethane potting compound and its preparation method. Background Technology

[0002] In recent years, with the continuous improvement of my country's new energy vehicle industry chain, new energy vehicles have flourished. As a core component of new energy vehicles, power batteries have undergone innovative development in line with the times. Cylindrical cells, due to their high energy density and fast charging characteristics, have become the mainstream development direction for power batteries. However, compared to prismatic cells, they place higher demands on automotive BMS (Battery Management System), and the risk of accidents is higher if thermal management fails.

[0003] Currently, cylindrical battery cells are generally bonded and fixed using potting compounds. However, the strength of these potting compounds still cannot meet the safety requirements of cylindrical battery cells. In addition, in this application field, potting compounds are also required to have sufficient thermal conductivity, flame retardancy, resistance to damp heat, electrical insulation, and hardness. Summary of the Invention

[0004] Based on the shortcomings of existing technologies, the purpose of this invention is to provide a high-strength two-component polyurethane potting compound. This product, through the combination of two specially formulated components, not only achieves controllable strength and hardness, making it suitable for fixing cylindrical battery cells, but also possesses good toughness, resistance to damp heat, flame retardancy, and electrical insulation, exhibiting excellent overall performance.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A high-strength two-component polyurethane potting compound, comprising component A and component B;

[0007] Component A comprises the following components in parts by weight:

[0008] The ingredients include 10-30 parts of polyol, 40-70 parts of aluminum hydroxide, 2-5 parts of molecular sieve activated powder, 2-10 parts of flame retardant, 0.1-0.2 parts of defoamer, 1-2 parts of coupling agent, and 0-0.01 parts of catalyst.

[0009] The polyol is a mixture of polyether polyol and castor oil polyol, with a mass ratio of 1:(1-3);

[0010] Component B comprises the following components in parts by weight:

[0011] 20-60 parts of polyurethane prepolymer, 0-20 parts of isocyanate and 20-50 parts of diluent;

[0012] The polyurethane prepolymer is obtained by reacting polyether polyol, urethane polyol and isocyanate.

[0013] The urethane polyol is an urethane polyol obtained by reacting a cyclic carbonate with an aromatic primary amine, wherein the aromatic primary amine has a melting point ≤100℃;

[0014] The mass ratio of component A to component B is (4-6):1.

[0015] In the high-strength two-component polyurethane potting compound of the present invention, the polyether polyol and castor oil polyol in component A, when compounded in the specified ratio, can effectively improve the elongation and damp heat resistance of the product. In component B, the polyurethane prepolymer is obtained by reacting a urethane polyol with a specific structure, a polyether polyol, and an isocyanate. Since the urethane polyol contains a large number of polar urethane bonds and rigid benzene rings after the reaction preparation, and has a high crosslinking density, the final polyurethane prepared can have sufficient strength and hardness. At the same time, since low-melting-point aromatic primary amines and cyclic carbonates are selected as raw materials for the preparation of urethane polyols, the two can react fully under relatively mild conditions, and the performance of the product is superior to that of components prepared from other types of raw materials.

[0016] Preferably, the polyether polyol in component A has a molecular weight of 300-3000, the castor oil polyol has a hydroxyl value of 160-168 mgKOH / g, and a functionality of 2.5-3.

[0017] At the specified molecular weight, the two can achieve a good synergistic effect. However, if only polyether polyols are used or the content of added castor oil polyols is too low, the molecular structure of the product contains a large number of ether bonds, resulting in low cohesive energy and weak mechanical properties, but strong flexibility. Conversely, as the castor oil content increases, the molecular structure of the product contains ester groups and carbon-carbon double bonds, forming a highly cross-linked flexible network, which increases the cross-linking density of the polymer and enhances mechanical properties, but reduces flexibility. However, if only castor oil polyols are used or the content of added polyether polyols is too low, the mechanical properties will actually decrease.

[0018] It should be noted that the "castor oil polyol" in the technical solution of this invention refers to castor oil containing hydroxyl polyols, which is known to those skilled in the art. It is generally obtained by further refining crude castor oil, and is not a product synthesized by modifying castor oil with polyols. The latter mainly refers to "castor oil modified polyols", such as castor oil-based polyether polyols, which are different from the substances described in this invention.

[0019] More preferably, the mass ratio of the polyether polyol to the castor oil polyol is 1:(1 to 1.5).

[0020] Preferably, the particle size D50 of the aluminum hydroxide is 10–20 μm;

[0021] More preferably, the aluminum hydroxide is treated with a silane coupling agent.

[0022] When aluminum hydroxide is pretreated with a silane coupling agent, the compatibility of this inorganic component with other components is significantly improved, achieving high dispersibility. This not only strengthens the component but also coordinates the flame retardant to achieve a synergistic flame retardant effect, meeting the UL94 V0 standard. However, if the aluminum hydroxide is small, the potting compound will have a high viscosity, which is detrimental to potting. If the aluminum hydroxide is too large, its specific surface area will be small, reducing the probability of contact between the same amount of aluminum hydroxide and the potting compound. This results in a sparse char layer formed during combustion, which is not conducive to blocking heat and oxygen intrusion, leading to poor flame retardant effect. Additionally, the shear strength and tensile strength of the product will also decrease. Within the optimal range, the product can achieve a good balance between viscosity range and flame retardant performance, as well as good adhesion and mechanical properties.

[0023] Preferably, the molecular sieve activation powder is at least one of 3A molecular sieve activation powder, 4A molecular sieve activation powder, and 5A molecular sieve activation powder.

[0024] More preferably, the molecular sieve activated powder is present in 1 to 3 parts by weight in component A.

[0025] Preferably, the flame retardant is at least one of ammonium polyphosphate and phosphate ester.

[0026] More preferably, the flame retardant is microcapsule particles or core-shell structured particles.

[0027] Preferably, the defoamer is an organically modified polysiloxane.

[0028] Preferably, the coupling agent is at least one of γ-glycidoxypropyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, ureopropyltriethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, and γ-ureopropyltrimethoxysilane.

[0029] Preferably, the catalyst is at least one of organobismuth, organozinc, and dibutyltin dilaurate.

[0030] More preferably, the catalyst is a mixture of organobismuth and organozinc.

[0031] Preferably, the isocyanate is at least one of diphenylmethane diisocyanate and polyphenylmethylene polyisocyanate.

[0032] Preferably, the diluent is at least one of phthalates and aliphatic diacids.

[0033] Preferably, the cyclic carbonate is at least one of propylene carbonate and ethylene carbonate, and the aromatic primary amine is at least one of m-phenylenediamine (melting point 14°C), 4,4'-methylenebis(2-ethylaniline) (melting point 46°C), m-phenylenediamine (melting point 64-66°C), 4,4'-diaminodiphenylmethane (melting point 89-91°C), and 1,3,5-triaminobenzene (melting point 84-85°C).

[0034] Low-melting-point aromatic primary amines require a lower temperature to melt into a liquid state compared to high-melting-point amines, and the liquid state facilitates a full reaction with cyclic carbonates. High-melting-point aromatic primary amines, on the other hand, require a higher temperature to melt into a liquid state, and the reaction is more vigorous when added to cyclic carbonates, making the reaction difficult to control and prone to oxidation, resulting in impure reaction products.

[0035] More preferably, the molar ratio of the cyclic carbonate to the aromatic primary amine is f:1, where f is the functionality of the aromatic primary amine.

[0036] More preferably, the urethane polyol is obtained by reacting a cyclic carbonate and an aromatic primary amine at 60–90°C for 3–6 h.

[0037] More preferably, the preparation method of the urethane polyol is as follows: a specified amount of cyclic carbonate is placed in a reactor dish, then heated to the reaction temperature, and under nitrogen protection, a specified amount of aromatic primary amine is added dropwise and the reaction is carried out to obtain urethane polyol.

[0038] Preferably, in the raw materials for preparing the polyurethane prepolymer, the mass ratio of polyether polyol to urethane polyol is 5:(1-3), more preferably 5:(1.5-2.5).

[0039] Optimization revealed that when the amount of urethane polyol added is small, the improvement in the strength of the polyurethane potting compound is minimal; when the amount added is too high, it will greatly increase the viscosity of the polyurethane prepolymer, making the potting compound difficult to apply.

[0040] More preferably, the polyurethane prepolymer is prepared by mixing polyether polyol and urethane polyol in the specified proportions and vacuum drying at 100-120°C for 2-3 hours, then cooling to below 40°C, adding isocyanate under nitrogen protection, and heating to 50-60°C for 2-3 hours to obtain the polyurethane prepolymer.

[0041] More preferably, the NCO content of the polyurethane prepolymer is 10-25%, more preferably 16-23%.

[0042] Another object of the present invention is to provide a method for preparing the high-strength two-component polyurethane potting compound, comprising the following steps:

[0043] Polyol, aluminum hydroxide and flame retardant are mixed and heated to 110-130°C, then vacuum dried for 2-4 hours, cooled to 40-60°C, and then other components are added and mixed evenly under vacuum to obtain component A.

[0044] The diluent is pre-dried and dehydrated, and then mixed evenly with polyurethane prepolymer and isocyanate under vacuum to obtain component B.

[0045] The preparation method of the high-strength two-component polyurethane potting compound described in this invention has simple operation steps, low requirements for production conditions and setup, and can achieve industrial production.

[0046] The beneficial effects of this invention are that it provides a high-strength two-component polyurethane potting compound. This product, through the combination of two specially formulated components, not only achieves controllable strength and hardness, making it suitable for fixing cylindrical battery cells, but also possesses good toughness, resistance to damp heat, flame retardancy, and electrical insulation, resulting in excellent overall performance. Detailed Implementation

[0047] To better illustrate the purpose, technical solution, and advantages of this invention, the invention will be further described below with reference to specific embodiments and comparative examples. The purpose of this description is to provide a detailed understanding of the invention, not to limit its scope. All other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this invention. Unless otherwise specified, the experimental reagents and instruments involved in the implementation of this invention are commonly used reagents and instruments.

[0048] Examples 1-12

[0049] An embodiment of the high-strength polyurethane potting compound and its preparation method according to the present invention includes the following steps:

[0050] Polyol, aluminum hydroxide and flame retardant are mixed and heated to 120°C, then vacuum dried for 3 hours, cooled to 50°C, and then other components are added and mixed evenly under vacuum to obtain component A.

[0051] The diluent is pre-dried and dehydrated, and then mixed evenly with polyurethane prepolymer and isocyanate under vacuum to obtain component B.

[0052] The composition ratio of components A and B is shown in Table 1.

[0053] In component A, polyether polyol 1 is a polyether diol with a molecular weight of 1000; polyether polyol 2 is a polyether diol with a molecular weight of 2000; and the castor oil polyol is first-grade castor oil produced by Fucheng Huanyu Oil Co., Ltd., with an alcohol hydroxyl value of 163 mgKOH / g and a functionality of 2.7.

[0054] In component A, aluminum hydroxide 1 is aluminum hydroxide with a particle size D50 = 10 μm activated by a silane coupling agent; aluminum hydroxide 2 is aluminum hydroxide with a particle size D50 = 20 μm activated by a silane coupling agent; aluminum hydroxide 3 is aluminum hydroxide with a particle size D50 = 5 μm activated by a silane coupling agent; and aluminum hydroxide 4 is aluminum hydroxide with a particle size D50 = 50 μm activated by a silane coupling agent.

[0055] The molecular sieve activation powder in component A is 3A molecular sieve activation powder, which is produced by Jiangxi Xintao Technology Co., Ltd.

[0056] The flame retardant in component A is microencapsulated ammonium polyphosphate, which is produced by Shenzhen Zhongherun Technology Co., Ltd.

[0057] The catalyst in component A is a commercially available organic bismuth-zinc catalyst complex.

[0058] The defoamer in component A is an organically modified polysiloxane, and LeAd 220 defoamer is produced by Guangzhou Wenbo Chemical Co., Ltd.

[0059] The coupling agent in component A is γ-glycidoxypropyltrimethoxysilane.

[0060] In component B, the polyurethane prepolymers 1-3 are obtained by reacting polyether polyol, urethane polyol and isocyanate. The preparation method is as follows: the polyether polyol and urethane polyol are mixed at a ratio of 5:2 (total 100g), and vacuum dried at 120°C for 3h. Then, the temperature is lowered to below 40°C, and under nitrogen protection, isocyanate is added (410g isocyanate is added to polyurethane prepolymer 1, 410g isocyanate is added to polyurethane prepolymer 2, and 190g isocyanate is added to polyurethane prepolymer 3) for end capping and heated to 60°C for 3h to obtain the polyurethane prepolymer with an NCO content of 16-23%.

[0061] Among them, polyether polyol a is a polyether triol with a molecular weight of 3000 and a functionality of 3, polyether polyol b is a polyether diol with a molecular weight of 2000 and a functionality of 2; and isocyanate is a mixture of diphenylmethane diisocyanate and polyphenylmethylene polyisocyanate.

[0062] The urethane polyols 1 and 2 are urethane polyols obtained by reacting cyclic carbonates and aromatic primary amines. The preparation method is as follows: a specified amount of cyclic carbonate is placed in a reactor dish, then heated to 80°C, and under nitrogen protection, a specified amount of aromatic primary amine is added dropwise and the reaction is carried out for 5 hours to obtain urethane polyols.

[0063] The molar ratio of cyclic carbonate to aromatic primary amine is f:1, where f is the functionality of the aromatic primary amine. Amino ester polyol 1 is obtained by reacting cyclic carbonate 1 and aromatic primary amine 1, and amino ester polyol 2 is obtained by reacting cyclic carbonate 2 and aromatic primary amine 2. Cyclic carbonate 1 is propylene carbonate, cyclic carbonate 2 is ethylene carbonate, aromatic primary amine 1 is m-phenylenediamine, and aromatic primary amine 2 is 4,4'-diaminodiphenylmethane.

[0064] The details are shown in the table below.

[0065]

[0066] Comparative Examples 1-3

[0067] A polyurethane potting compound and its preparation method are disclosed, which differ from Example 1 only in the difference in the proportion of each component, as shown in Table 2.

[0068] Comparative Example 4

[0069] A polyurethane potting compound and its preparation method differ from Example 1 only in that the polyurethane prepolymer 5 is obtained by reacting polyether polyol, polyethylene glycol (molecular weight 400 g / mol) and isocyanate. The preparation method is as follows: the polyether polyol and urethane polyol are mixed at a ratio of 5:2 and vacuum dried at 120°C for 3 hours. Then, the temperature is lowered to below 40°C, and under nitrogen protection, isocyanate is added and heated to 60°C for 3 hours to obtain the polyurethane prepolymer 4.

[0070] Comparative Example 5

[0071] A polyurethane potting compound and its preparation method differ from Example 1 only in that the polyurethane prepolymer 6 is obtained by reacting polyether polyol, urethane polyol and isocyanate. The preparation method is as follows: the polyether polyol and urethane polyol are mixed in a ratio of 5:2 and vacuum dried at 120°C for 3 hours, then cooled to below 40°C, and under nitrogen protection, isocyanate is added and heated to 60°C for 3 hours to obtain the polyurethane prepolymer 5.

[0072] The urethane polyol is a urethane polyol obtained by reacting a cyclic carbonate with an aliphatic primary amine propylenediamine. The preparation method is as follows: a specified amount of cyclic carbonate 1 is placed in a reactor dish, then heated to 80°C, a specified amount of aromatic primary amine is added dropwise, and the reaction is carried out for 5 hours to obtain the urethane polyol.

[0073] Comparative Example 6

[0074] A polyurethane potting compound and its preparation method differ from Example 1 only in that the polyurethane prepolymer 7 is obtained by reacting polyether polyol, urethane polyol and isocyanate. The preparation method is as follows: the polyether polyol and urethane polyol are mixed in a ratio of 5:2 and vacuum dried at 120°C for 3 hours, then cooled to below 40°C, and under nitrogen protection, isocyanate is added and heated to 60°C for 3 hours to obtain the polyurethane prepolymer 6.

[0075] The urethane polyol is a urethane polyol obtained by reacting a cyclic carbonate with an aliphatic primary amine, ethylenediamine. The preparation method is as follows: a specified amount of cyclic carbonate 1 is placed in a reactor dish, then heated to 80°C, a specified amount of ethylenediamine is added dropwise, and the reaction is carried out for 5 hours to obtain the urethane polyol.

[0076] Table 1

[0077]

[0078]

[0079] Table 2

[0080]

[0081]

[0082] Example 1

[0083] To verify the performance of the high-strength two-component polyurethane potting compound described in this invention, the following tests were conducted on the various embodiments, comparative examples, and commercially available Bonacon Technology Co., Ltd. RE 12464-1010 polyurethane potting compound:

[0084] Table 3

[0085]

[0086]

[0087] As shown in the table, the viscosity of the high-strength two-component polyurethane potting compound prepared by this invention can be maintained within the range of 3500–7000 ± 500 cps, without affecting construction due to excessively high or low viscosity. Simultaneously, its hardness is significantly higher than commercially available products, with a shear strength of 12.5 MPa or higher on aluminum substrates and a tensile strength of 13.5 MPa or higher. Its flame retardancy reaches UL94 V0, demonstrating excellent overall performance and making it a complete replacement for existing commercially available products. In contrast, Comparative Example 1 had an excessive amount of polyurethane prepolymer added during compounding, resulting in excessively high viscosity, making construction impossible. Furthermore, its flame retardant performance was lower than that of Example 1. In Comparative Examples 2 and 3, the polyol compounding ratio was inappropriate, significantly reducing the shear and tensile strength of the products. Comparative Examples 4–6 used inappropriate types of raw materials during the preparation of the polyurethane prepolymer, and none of the prepared products achieved the comprehensive performance of the example products.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A high-strength two-component polyurethane potting compound, characterized in that, Includes component A and component B; Component A comprises the following components in parts by weight: The ingredients include 10-30 parts of polyol, 40-70 parts of aluminum hydroxide, 2-5 parts of molecular sieve activated powder, 2-10 parts of flame retardant, 0.1-0.2 parts of defoamer, 1-2 parts of coupling agent, and 0-0.01 parts of catalyst. The polyol is a mixture of polyether polyol and castor oil polyol, with a mass ratio of 1:(1~3). Component B comprises the following components in parts by weight: 20-60 parts of polyurethane prepolymer, 0-20 parts of isocyanate, and 20-50 parts of diluent; The polyurethane prepolymer is obtained by reacting polyether polyol, urethane polyol and isocyanate. The urethane polyol is an urethane polyol obtained by reacting a cyclic carbonate with an aromatic primary amine, wherein the aromatic primary amine has a melting point ≤100℃; The NCO content of the polyurethane prepolymer is 10-25%; The mass ratio of component A to component B is (4~6):

1.

2. The high-strength two-component polyurethane potting compound as described in claim 1, characterized in that, The molecular weight of the polyether polyol in component A is 300~3000, the hydroxyl value of the castor oil polyol is 160~168mgKOH / g, and the functionality is 2.5~3.

3. The high-strength two-component polyurethane potting compound as described in claim 1, characterized in that, The particle size D50 of the aluminum hydroxide is 5~20μm.

4. The high-strength two-component polyurethane potting compound as described in claim 1, characterized in that, Includes at least one of the following (a) to (f): (a) The molecular sieve activated powder is at least one of 3A molecular sieve activated powder, 4A molecular sieve activated powder, and 5A molecular sieve activated powder; (b) The flame retardant is at least one of ammonium polyphosphate and phosphate ester; (c) The defoamer is an organically modified polysiloxane; (e) The coupling agent is at least one of γ-glycidoxypropyltrimethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, ureopropyltriethoxysilane, β-(3,4-epoxycyclohexyl)-ethyltrimethoxysilane, and γ-ureopropyltrimethoxysilane. (f) The catalyst is at least one of organobismuth, organozinc, and dibutyltin dilaurate.

5. The high-strength two-component polyurethane potting compound as described in claim 1, characterized in that, The isocyanate is at least one of diphenylmethane diisocyanate and polyphenylmethylene polyisocyanate.

6. The high-strength two-component polyurethane potting compound as described in claim 1, characterized in that, The diluent is at least one of phthalates and aliphatic diacids.

7. The high-strength two-component polyurethane potting compound as described in claim 1, characterized in that, The cyclic carbonate is at least one of propylene carbonate and ethylene carbonate, and the aromatic primary amine is at least one of m-phenylenediamine, 4,4'-methylenebis(2-ethylaniline), m-phenylenediamine, 4,4'-diaminodiphenylmethane, and 1,3,5-triaminobenzene.

8. The high-strength two-component polyurethane potting compound as described in claim 1, characterized in that, The urethane polyol is obtained by reacting cyclic carbonate and aromatic primary amine at 60-90°C for 3-6 hours.

9. The high-strength two-component polyurethane potting compound as described in claim 1, characterized in that, In the raw materials for preparing the polyurethane prepolymer, the mass ratio of polyether polyol to urethane polyol is 5:(1~3); the preparation method of the polyurethane prepolymer is as follows: the polyether polyol and urethane polyol in the specified proportions are mixed and vacuum dried at 100~120℃ for 2~3h, then cooled to below 40℃, and under nitrogen protection, isocyanate is added and heated to 50~60℃ for 2~3h to obtain the polyurethane prepolymer.

10. The method for preparing the high-strength two-component polyurethane potting compound according to any one of claims 1 to 9, characterized in that, Includes the following steps: Polyol, aluminum hydroxide and flame retardant are mixed and heated to 110~130℃, then vacuum dried for 2~4h, cooled to 40~60℃, and then other components are added and mixed evenly under vacuum to obtain component A. The diluent is pre-dried and dehydrated, and then mixed evenly with polyurethane prepolymer and isocyanate under vacuum to obtain component B.

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