Polyurethane sealant for power battery and preparation method thereof

Abstract

The application relates to a polyurethane sealant for power batteries, which comprises the following components in parts by weight: self-made silicon modified dihydric alcohol 30-50 parts, polyether dihydric alcohol 10-20 parts, polyester dihydric alcohol 10-20 parts, polyisocyanate 12-25 parts, and gaseous silicon 4-8 parts. The polyurethane sealant prepared by the method has good high and low temperature resistance, has a relatively low storage modulus in the range of-30 DEG C to 60 DEG C, greatly reduces the occurrence of phenomena such as opening caused by temperature change, can effectively bond different materials and meet the double 85 test for 1000 hours without obvious strength attenuation, and can meet the vehicle use demand under most working conditions.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane adhesive technology, and particularly relates to polyurethane sealant for power batteries and its preparation method. Background Technology

[0002] With the development of technology, new energy vehicles have entered thousands of households. However, the range of new energy vehicles and their performance under harsh conditions are not satisfactory. In order to solve these problems, on the one hand, in order to improve the energy density of the battery, some power battery manufacturers have eliminated the original bolt fixing of the PACK seal and replaced it with adhesive. This puts forward higher requirements for the performance of the adhesive under various working conditions.

[0003] While traditional polyurethane sealants can form good adhesion, their high modulus at low temperatures leads to detachment due to vibrations and bumps in a vehicle. Traditional silicone sealants, although performing well at low temperatures, do not offer sufficient adhesive strength to meet current requirements. Therefore, there is an urgent need to develop a sealant with excellent low-temperature flexibility and high adhesive strength to meet technological advancements, representing a significant market potential. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the present invention provides a polyurethane sealant for power batteries and its preparation method.

[0005] The specific technical solution is as follows:

[0006] One objective of this invention is to provide a polyurethane sealant for power batteries, which comprises the following components in parts by weight:

[0007] The ingredients are: 30-50 parts of self-made silicone-modified diol, 10-20 parts of polyether diol, 10-20 parts of polyester diol, 12-25 parts of polyisocyanate, and 4-8 parts of gaseous silicon.

[0008] Furthermore, the polyether diol is a polyoxypropylene polyether with a molecular weight of 1000-3000.

[0009] Furthermore, the polyester diol is at least one of polycaprolactone diol, polycarbonate diol, adipic acid-based polyester diol, and phthalic anhydride polyester diol.

[0010] Furthermore, the polyisocyanate is a carbodiimide-modified diphenylmethane diisocyanate.

[0011] A second objective of this invention is to provide a method for preparing the above-mentioned polyurethane sealant for power batteries, which includes the following steps:

[0012] By weight, 30-50 parts of self-made silicone-modified diol, 10-20 parts of polyether diol, 10-20 parts of polyester diol, and 4-8 parts of fumed silica are dehydrated at 120℃ and -0.095MPa for 2 hours. After dehydration, 12-25 parts of polyisocyanate are added and reacted at 100-120℃ for 1-3 hours to obtain polyurethane sealant for power batteries.

[0013] Furthermore, the self-made silicon-modified diol has the following structural formula:

[0014] .

[0015] Furthermore, the method for synthesizing the self-made silicon-modified diol includes the following steps: taking 1 mol of maleic anhydride-modified polybutadiene and 1.1 mol of heptamethyltrisiloxane, using toluene as solvent, reacting at 75°C for 24 h under chloroplatinic acid catalysis and nitrogen protection, and then removing the solvent under reduced pressure rotary evaporation to obtain silanized maleic anhydride-modified butadiene.

[0016] The molecular weight of the maleic anhydride-modified polybutadiene is 1000-5400;

[0017] Silanized maleic anhydride butadiene was reacted with 1 mol of (1,4-butanediol) BDO in a device equipped with a reflux condenser and under a nitrogen atmosphere at 80°C until the acid value of the system was half of the initial acid value, yielding silanized maleic anhydride butadiene 1,4-butanediol monoester. Then, 1 mol of KH-560 was added, and the reaction was carried out at 110°C under the catalysis of tetramethylammonium chloride until the acid value was <5 mg KOH / g, yielding the target product. The reaction equation is as follows:

[0018] .

[0019] The features and beneficial effects of this invention are as follows:

[0020] (1) The present invention is a polyurethane sealant for power batteries. Compared with traditional polyurethane sealants, the addition of silicon groups greatly reduces the surface energy of the system, enabling effective bonding with various materials. At the same time, the introduction of traditional silicon groups greatly improves the low-temperature flexibility of the sealant, allowing it to maintain a low modulus at lower temperatures.

[0021] (2) The maleic anhydride butadiene used in this invention introduces the rubber structure into the molecular chain, which not only gives the system excellent elongation at break, but also improves the system’s low temperature resistance in synergy with silicon. At the same time, since butadiene can greatly improve its compatibility with other resins in the system after maleic anhydride treatment, the stability of the system is greatly increased.

[0022] (3) This invention uses self-made silicon-modified diols in combination with polyester and polyether diols, which not only gives the original polyurethane sealant excellent bonding performance, but also gives the system rubber and silicone characteristics to a large extent due to the introduction of rubber and silicone, which can better meet the needs of power battery sealants. Detailed Implementation

[0023] The present invention will be described below with reference to examples. These examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0024] In the specific implementation, the term "parts" refers to parts by weight.

[0025] Example 1

[0026] The method for synthesizing the self-made silicon-modified diol includes the following steps: 1 mol of maleic anhydride polybutadiene with a molecular weight of 1000 and 1.1 mol of heptamethyltrisiloxane are taken, and the mixture is reacted at 75°C for 24 h under the catalysis of chloroplatinic acid and the protection of nitrogen with toluene as solvent. The solvent is then removed under reduced pressure rotary evaporation to obtain silanized maleic anhydride butadiene.

[0027] Silanized maleic anhydride butadiene was reacted with 1 mol of BDO in a device equipped with a reflux condenser and under a nitrogen atmosphere at 80°C until the acid value of the system was half of the initial acid value, yielding silanized maleic anhydride butadiene 1,4-butanediol monoester. Then, 1 mol of KH-560 was added, and the reaction was carried out at 110°C under the catalysis of tetramethylammonium chloride until the acid value was <5 mg KOH / g, yielding the target product. The reaction equation is as follows:

[0028] .

[0029] 50 parts of self-made silicon-modified diol, 10 parts of polypropylene oxide polyether with a molecular weight of 1000, 10 parts of polycarbonate diol with a molecular weight of 2000, and 8 parts of fumed silica were dehydrated at 120℃ and -0.095MPa for 2 hours. After dehydration, 22 parts of carbodiimide-modified diphenylmethane diisocyanate were added, and the mixture was reacted at 120℃ for 3 hours to obtain polyurethane sealant for power batteries.

[0030] Example 2

[0031] The method for synthesizing the self-made silicon-modified diol includes the following steps: taking 1 mol of maleic anhydride polybutadiene with a molecular weight of 2700 and 1.1 mol of heptamethyltrisiloxane, using toluene as solvent, reacting at 75°C for 24 h under chloroplatinic acid catalysis and nitrogen protection, and then removing the solvent under reduced pressure rotary evaporation to obtain silanized maleic anhydride butadiene.

[0032] Silanized maleic anhydride butadiene was reacted with 1 mol of BDO in a device equipped with a reflux condenser and under a nitrogen atmosphere at 80°C until the acid value of the system was half of the initial acid value, yielding silanized maleic anhydride butadiene 1,4-butanediol monoester. Then, 1 mol of KH-560 was added, and the reaction was carried out at 110°C under the catalysis of tetramethylammonium chloride until the acid value was <5 mg KOH / g, yielding the target product. The reaction equation is as follows:

[0033] .

[0034] 30 parts of self-made silicon-modified diol, 20 parts of polypropylene oxide polyether with a molecular weight of 2000, 20 parts of polycarbonate diol with a molecular weight of 1000, and 4 parts of fumed silica were dehydrated at 120℃ and -0.095MPa for 2 hours. After dehydration, 18 parts of carbodiimide-modified diphenylmethane diisocyanate were added, and the mixture was reacted at 120℃ for 3 hours to obtain polyurethane sealant for power batteries.

[0035] Comparative Example 1

[0036] Compared with Example 1, ordinary polypropylene oxide polyether diol was used to replace the self-made silicone-modified diol.

[0037] Comparative Example 2

[0038] Conventional silicone sealant

[0039] test

[0040] The polyurethane sealant prepared in Examples 1-2 and the polyurethane sealant prepared in the comparative example were subjected to shear strength, DMA modulus and double 85 aging tests according to the adhesive test standard. The elongation at break was tested according to GB / T30776-2014. The data results are shown in Tables 1 and 2. The bonding materials for the shear strength test were 3003 aluminum-3003 aluminum and 3003 aluminum-electrophoretic aluminum, and cured at room temperature for 7 days.

[0041] Table 1. Comparison of shear strength and elongation at break of the polyurethane sealants obtained in Examples 1-2 and the comparative examples.

[0042]

[0043] Table 2. Comparison of aging resistance and modulus of polyurethane sealants obtained in Examples 1-2 and Comparative Examples 1-2

[0044]

[0045] A comparison of the data in Tables 1 and 2 shows that the performance test analysis of the polyurethane sealants obtained in Examples 1-2 and Comparative Examples 1-2 indicates that the polyurethane sealant prepared by this invention can bond with 3003 aluminum and electrophoretic aluminum materials. Furthermore, this sealant has a low low-temperature modulus, thus imparting excellent low-temperature resistance to the material. The introduction of silane and butadiene structures not only improves the product's double 85 aging performance but also gives the adhesive superior high-temperature resistance, resulting in a relatively high high-temperature modulus and excellent elongation at break. Therefore, the polyurethane sealant prepared by the method of this invention can meet the requirements for bonding and high and low temperature stability under the premise of high energy density, which is of great significance for the next stage of power battery development.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A polyurethane sealant for power batteries, comprising the following components by weight: 30-50 parts of self-made silicone-modified diol, 10-20 parts of polyether diol, 10-20 parts of polyester diol, 12-25 parts of polyisocyanate, and 4-8 parts of fumed silica. The self-made silicon-modified diol has the following structural formula: 。 2. The polyurethane sealant for power batteries according to claim 1, characterized in that, The method for synthesizing the self-made silicon-modified diol includes the following steps: 1 mol of maleic anhydride-modified polybutadiene and 1.1 mol of heptamethyltrisiloxane are reacted with toluene as solvent at 75°C for 24 h under chloroplatinic acid catalysis and nitrogen protection. The solvent is then removed by rotary evaporation under reduced pressure to obtain silanized maleic anhydride butadiene. Next, silanized maleic anhydride butadiene is reacted with 1 mol of 1,4-butanediol at 80°C under a nitrogen atmosphere and a reflux condenser until the acid value is half of the initial acid value, yielding silanized maleic anhydride butadiene 1,4-butanediol monoester. Finally, 1 mol of KH-560 is added and reacted at 110°C under tetramethylammonium chloride catalysis until the acid value is <5 mg KOH / g, yielding the target product. The reaction equation is as follows: 。 3. The polyurethane sealant for power batteries according to claim 2, characterized in that, The molecular weight of the maleic anhydride-modified polybutadiene is 1000-5400.

4. The polyurethane sealant for power batteries according to claim 1, characterized in that, The polyether diol is a polyoxypropylene polyether with a molecular weight of 1000-3000; the polyester diol is at least one of polycaprolactone diol, polycarbonate diol, adipic acid-based polyester diol, and phthalic anhydride polyester diol.

5. The polyurethane sealant for power batteries according to claim 1, characterized in that, The polyisocyanate is carbodiimide-modified diphenylmethane diisocyanate.

6. The method for preparing polyurethane sealant for power batteries according to any one of claims 1-5, characterized in that, Includes the following steps: By weight, 30-50 parts of self-made silicon-modified diol, 10-20 parts of polyether diol, 10-20 parts of polyester diol, and 4-8 parts of fumed silica are dehydrated at 120℃ and -0.095MPa for 2 hours. After dehydration, 12-25 parts of polyisocyanate are added and reacted at 100-120℃ for 1-3 hours to obtain polyurethane sealant for power batteries.

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