A low-hardness, lightweight, flame-retardant sealant and its preparation method and application

Abstract

The present invention provides a low-hardness, lightweight, flame-retardant sealant, and its preparation method and application. The sealant is mainly prepared by mixing the following raw materials: a 20,000 viscosity end-hydroxyl polydimethylsiloxane polymer, a high-viscosity end-hydroxyl polydimethylsiloxane polymer (viscosity of 450,000-550,000 cps at 25°C), a plasticizer, a flame-retardant filler, a lightweight additive, a thixotropic agent, a cross-linking agent, a curing agent, and an organic titanium catalyst; wherein the plasticizer is prepared by mixing the following raw materials: dimethyldimethoxysilane, methylphenyldimethoxysilane, trifluoropropylmethyldimethoxysilane, hexamethyldisiloxane, anhydrous methanol, concentrated hydrochloric acid, and deionized water. The prepared sealant has a Shore A hardness of less than 8, is resistant to high and low temperatures, resistant to aging, and has good flexibility, and can be applied to the field of power batteries.

Description

Technical Field

[0001] The present invention belongs to the field of preparation of sealants for power batteries, and specifically relates to a low-hardness, lightweight, flame-retardant sealant and a preparation method and application thereof. Background Art

[0002] Power batteries are generally composed of several battery cells, a thermal management system, a battery management system, an electrical system, and structural components. However, with the development of battery technology, in pursuit of higher energy density and improved vehicle range, the market trend is to directly assemble battery packs from battery cells, eliminating structures such as battery modules. This reduces the use of non-energy-supplying structural components, freeing up more space for battery cells to increase the energy density of the battery system while reducing the weight of the battery pack. This places even more stringent demands on sealant technology. In addition to considering the lightweight requirements of the battery, heat generation during charging and discharging, and shrinkage and deformation of the sealant seam during cooling, the sealant's high and low temperature resistance and flame retardant safety performance must also be considered. Summary of the Invention

[0003] In view of this, the present invention provides a plasticizer and a preparation method thereof, and a flame retardant sealant containing the plasticizer and a preparation method thereof.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A low-hardness, lightweight, flame-retardant sealant is prepared by mixing the following raw materials in parts by weight: 100 parts of a 20,000 viscosity end-hydroxyl polydimethylsiloxane polymer, 70-120 parts of a high-viscosity end-hydroxyl polydimethylsiloxane polymer, 70-130 parts of a plasticizer, 180-240 parts of a flame-retardant filler, 45-70 parts of a lightweight additive, 4-10 parts of a thixotropic agent, 10-20 parts of a cross-linking agent, 2-5 parts of a curing agent, and 5-10 parts of an organic titanium catalyst;

[0006] The plasticizer is prepared by mixing the following raw materials in parts by weight: 100 parts of dimethyldimethoxysilane, 40-80 parts of methylphenyldimethoxysilane, 30-50 parts of trifluoropropylmethyldimethoxysilane, 10-20 parts of hexamethyldisiloxane, 100-150 parts of anhydrous methanol, 0.4-0.7 parts of concentrated hydrochloric acid, and 20-30 parts of deionized water;

[0007] The high-viscosity hydroxy-terminated polydimethylsiloxane polymer has a viscosity of 450,000-550,000 cps at 25°C.

[0008] Furthermore, the low-hardness lightweight flame-retardant sealant is prepared by mixing the following raw materials in parts by weight: 100 parts of 20,000 viscosity end-hydroxyl polydimethylsiloxane polymer, 100 parts of high viscosity end-hydroxyl polydimethylsiloxane polymer, 110 parts of plasticizer, 210 parts of flame-retardant filler, 60 parts of lightweight additive, 7 parts of thixotropic agent, 15 parts of cross-linking agent, 3.5 parts of curing agent, and 8 parts of organic titanium catalyst.

[0009] Furthermore, the preparation steps of the plasticizer are as follows:

[0010] Dimethyldimethoxysilane, methylphenyldimethoxysilane, trifluoropropylmethyldimethoxysilane, hexamethyldisiloxane and anhydrous methanol were added under nitrogen and stirred uniformly to obtain a mixed material;

[0011] The mixture was heated to 50°C and a mixture of concentrated hydrochloric acid and deionized water was added dropwise. After the addition was complete, the temperature was raised to 65°C and the reaction was continued for 4 hours to obtain a crude product.

[0012] After distilling off the low-boiling substances from the crude product, the plasticizer is obtained by vacuum drying.

[0013] Furthermore, the flame retardant filler is surface-treated and modified active aluminum hydroxide with a particle size of 1500 mesh.

[0014] Furthermore, the lightweight additive is modified hollow glass microspheres containing inert gas with a bulk density of 0.11-0.13 g / cm3 and a D90 of 60-70 μm.

[0015] Furthermore, the thixotropic agent is one or more of polyamide wax, modified castor oil derivatives, and polyether-modified silicone oil.

[0016] Furthermore, the cross-linking agent is methyltrimethoxysilane.

[0017] Furthermore, the curing agent is obtained by mixing the following raw materials in parts by weight and then leaving them for 2 days: 60 parts of aminopropyltriethoxysilane, 30 parts of glycidyloxypropyltrimethoxysilane, and 2 parts of tin acetate.

[0018] A method for preparing the above-mentioned low-hardness lightweight flame-retardant sealant is characterized by comprising the following steps:

[0019] Mix 20,000 viscosity end-hydroxyl polydimethylsiloxane polymer, high viscosity end-hydroxyl polydimethylsiloxane polymer, plasticizer, flame retardant filler, lightweight additive, and thixotropic agent evenly, then vacuum heat at 130±10℃ for 1.5 hours to dehydrate;

[0020] After cooling to below 40°C, add the cross-linking agent, curing agent and organic titanium catalyst in sequence at intervals of 20 minutes, stir evenly and then discharge the material to obtain the flame retardant sealant.

[0021] Application of the above-mentioned low-hardness, lightweight, flame-retardant sealant in power batteries.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) The present invention adds a plasticizer to the formula, introduces a phenyl group, a trifluoropropyl group, and a dimethylsiloxane chain, so that the product has good high and low temperature resistance, good flexibility, aging resistance, and chain extension effect; the three groups can be flexibly designed in proportion, the molecular chain is adjustable and controllable, and they work together to achieve the product with a Shore A hardness of less than 8, high and low temperature resistance, aging resistance, and good flexibility.

[0024] (2) The flame retardant sealant prepared by the present invention is a one-component dealcoholized room temperature vulcanized silicone sealant. Glass microspheres containing inert gas are added to the formula to meet the lightweight requirements of the product and achieve a density of 0.85g / cm 3 , and the inert gas can play a flame retardant role, killing two birds with one stone.

[0025] (3) The curing agent in the present invention is combined with an organic titanium catalyst to solve the problem of slow surface curing introduced by high-viscosity polymers. The product dries quickly and is non-sticky, meeting construction requirements.

[0026] (4) The sealant prepared by the present invention meets the requirements of lightweight, heat generation during charging and discharging, shrinkage and deformation of the sealant seam during cooling, high and low temperature resistance and flame retardant safety performance in battery applications. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below with reference to specific embodiments so that those skilled in the art can understand the present invention more clearly.

[0028] Sources of key test materials and physical and chemical parameters:

[0029] Hexamethyldisiloxane, dimethyldimethoxysilane, methylphenyldimethoxysilane, etc. are selected from Zhejiang Xin'an Chemical Group Co., Ltd.;

[0030] Anhydrous methanol and concentrated hydrochloric acid were purchased from Sinopharm Chemical Reagent Co., Ltd.

[0031] The flame retardant filler aluminum hydroxide was purchased from Zhejiang Xusen Non-Halogen Smoke Suppression Flame Retardant Co., Ltd., brand ACW1500;

[0032] Lightweight additives were purchased from Zhengzhou Shenglait New Materials Co., Ltd., brand HS22D;

[0033] 20,000 cps and 500,000 cps hydroxy-terminated polydimethylsiloxane polymers come from Xingfa Group;

[0034] The thixotropic agent is selected from Hemmings Chemical, brand thixotropic agent R; or selected from Tianci New Materials, brand TC204;

[0035] Aminopropyltriethoxysilane and glycidyloxypropyltrimethoxysilane were selected from Jianghan Fine Chemical Co., Ltd.;

[0036] Other raw materials or structures not specifically described in the present invention already exist in the prior art and can be directly purchased from the market.

[0037] Example 1

[0038] This embodiment provides a method for preparing a flame retardant sealant, and the specific operations are as follows:

[0039] (1) Preparation of Plasticizer P1: In a 500 mL four-necked flask equipped with a stirrer, a reflux condenser, a thermometer, a constant pressure dropping funnel and a nitrogen gas supply, 100 parts of dimethyldimethoxysilane, 60 parts of methylphenyldimethoxysilane, 40 parts of trifluoropropylmethyldimethoxysilane, 15 parts of hexamethyldisiloxane and 120 parts of anhydrous methanol were added, and the temperature was raised to 50°C. A mixture consisting of 0.6 parts of concentrated hydrochloric acid and 25 parts of deionized water was slowly added dropwise. After the addition was complete, the temperature was raised to 65°C and the reaction was continued for 4 hours. After the low-boiling substances were evaporated, the plasticizer was dried under reduced pressure to obtain the plasticizer, which was named Plasticizer P1.

[0040] (2) Preparation of curing agent: Add 60 parts of aminopropyltriethoxysilane, 30 parts of glycidyloxypropyltrimethoxysilane and 2 parts of tin acetate into a 150 ml container, cover the bottle tightly, shake vigorously for 3 minutes, and let it stand for 2 days before use.

[0041] (3) Preparation of flame retardant sealant: 100 parts of 20,000 viscosity end-hydroxyl polydimethylsiloxane polymer, 100 parts of 500,000 viscosity end-hydroxyl polydimethylsiloxane polymer, 110 parts of plasticizer P1, 210 parts of aluminum hydroxide, 60 parts of glass microspheres, 7 parts of TC204 polyether modified silicone oil, and 1 part of green color paste were added into a dynamic mixer, vacuum-heated at 130±10℃ for dehydration for 1.5 hours, and then cooled to a temperature below 40℃ and continued to add methyltrimethoxysilane, composite curing agent, and organic titanium catalyst step by step every 20 minutes. After stirring evenly, the material was discharged to obtain a low-hardness and lightweight flame retardant sealant.

[0042] Example 2

[0043] This embodiment provides a method for preparing a flame retardant sealant, and the specific operations are as follows:

[0044] (1) The preparation method of plasticizer P2 is the same as that of Example 1, except that the material ratios are different, specifically: 100 parts of dimethyldimethoxysilane, 50 parts of methylphenyldimethoxysilane, 35 parts of trifluoropropylmethyldimethoxysilane, 12 parts of hexamethyldisiloxane, 120 parts of anhydrous methanol, 0.5 parts of concentrated hydrochloric acid and 21 parts of deionized water.

[0045] (2) The preparation method of the curing agent is the same as that in Example 1.

[0046] (3) Preparation of flame retardant sealant: 100 parts of 20,000 viscosity end-hydroxyl polydimethylsiloxane polymer, 80 parts of 500,000 viscosity end-hydroxyl polydimethylsiloxane polymer, 120 parts of plasticizer P2, 210 parts of aluminum hydroxide, 58 parts of glass microspheres, 7 parts of TC204 polyether modified silicone oil, and 1 part of green color paste were added into a dynamic mixer under vacuum and heated at 130±10℃ for 1.5 hours, and then cooled to a temperature below 40℃ and continued to add methyltrimethoxysilane, composite curing agent, and organic titanium catalyst step by step every 20 minutes. After stirring evenly, the material was discharged to obtain a low-hardness and lightweight flame retardant sealant.

[0047] Example 3

[0048] This embodiment provides a method for preparing a flame retardant sealant, and the specific operations are as follows:

[0049] (1) The preparation method of plasticizer P3 is the same as that of Example 1, except that the material ratios are different, specifically: 100 parts of dimethyldimethoxysilane, 70 parts of methylphenyldimethoxysilane, 45 parts of trifluoropropylmethyldimethoxysilane, 12 parts of hexamethyldisiloxane, 120 parts of anhydrous methanol, 0.65 parts of concentrated hydrochloric acid and 21 parts of deionized water.

[0050] (2) The preparation method of the curing agent is the same as that in Example 1.

[0051] (3) Preparation of flame retardant sealant: 100 parts of 20,000 viscosity end-hydroxyl polydimethylsiloxane polymer, 120 parts of 500,000 viscosity end-hydroxyl polydimethylsiloxane polymer, 130 parts of plasticizer P3, 185 parts of aluminum hydroxide, 65 parts of glass beads, 10 parts of Hemmings R thixotropic agent, and 1 part of green color paste were added into a dynamic mixer, vacuum-heated at 130±10℃ for dehydration for 1.5 hours, and then cooled to a temperature below 40℃ and continued to add methyltrimethoxysilane, composite curing agent, and organic titanium catalyst step by step every 20 minutes. After stirring evenly, the material was discharged to obtain a low-hardness and lightweight flame retardant sealant.

[0052] Example 4

[0053] This embodiment provides a method for preparing a flame retardant sealant. The raw materials and method are basically the same as those in Example 1, except that ordinary aluminum hydroxide and ordinary glass microspheres not filled with inert gas are used.

[0054] Example 5

[0055] This embodiment provides a method for preparing a flame retardant sealant. The raw materials and method are basically the same as those in Example 1, except that propyltriethoxysilane is used instead of methyltrimethoxysilane as a cross-linking agent.

[0056] Comparative Example 1

[0057] This comparative example provides a method for preparing a flame retardant sealant. The raw materials and method are basically the same as those in Example 1, except that calcium carbonate is used instead of glass microspheres.

[0058] Comparative Example 2

[0059] This comparative example provides a method for preparing a flame retardant sealant. The raw materials and method are basically the same as those in Example 1, except that ordinary 100 viscosity dimethyl silicone oil is used instead of plasticizer P1.

[0060] Comparative Example 3

[0061] This comparative example provides a method for preparing a flame retardant sealant. The raw materials and method are basically the same as those in Example 1, except that the high-viscosity hydroxyl-terminated polydimethylsiloxane polymer is replaced with a 20,000 viscosity hydroxyl-terminated polydimethylsiloxane polymer.

[0062] Comparative Example 4

[0063] This comparative example provides a method for preparing a flame retardant sealant. The raw materials and method are basically the same as those in Example 1, except that the 20,000 viscosity end-hydroxyl polydimethylsiloxane polymer is replaced with a high viscosity end-hydroxyl polydimethylsiloxane polymer.

[0064] The flame retardant sealants of Examples 1 to 5 and Comparative Examples 1 and 4 were subjected to performance tests. The test items and test methods are as follows:

[0065] (1) Surface drying time test: Under the conditions of temperature 23±2℃ and relative humidity 50±5%RH, squeeze the sealant onto the surface of the plastic film with a thickness of about 2-3mm and a length of >100mm. Every 5 minutes, touch the glue layer with your finger until the glue no longer sticks to your finger. The time from squeezing out to no longer sticking to your finger is recorded as the surface drying time.

[0066] (2) Hardness test: Use a scraper to prepare a 2 mm thick test piece, cure it at 23 ± 2 ° C, 50 ± 5% RH for 7 days, stack 3 pieces, and test with a Shore A hardness tester. Read the data after holding the pressure for 5 seconds.

[0067] (3) Flame retardancy: The test was conducted in accordance with GB / T2408-2008, using the vertical combustion method. Five sealant specimens were prepared in accordance with GB / T2408-2008, with dimensions of (125 ± 5) mm × (13.0 ± 0.3) mm × (3.0 ± 0.2) mm. The specimens were then cured under standard conditions for 21 days and then tested.

[0068] (4) Elongation test: The test was conducted in accordance with GB / T 528-2009, “Rubber, vulcanized or thermoplastic — Determination of tensile properties.” The specimens were cured at 23±2°C, 50±5% RH for 7 days and then cut into dumbbell shapes. The test area had a thickness of 2 mm and a width of 6 mm, and the tensile rate was 500 mm / min.

[0069] (5) High and low temperature resistance test: The specimens are placed in an alternating environment of -40±2℃ to 85±2℃. The conversion time between the two extreme temperatures is within 5 minutes. The test objects are kept in each extreme temperature environment for 30 minutes. After 1000 cycles, the specimens are taken out to observe whether they are cracked.

[0070] The test results are shown in Table 1 below:

[0071] Table 1 Sealant performance test results

[0072]

[0073] It can be seen from Table 1 above that:

[0074] Compared with Comparative Example 1, the flame retardant sealants of Examples 1 to 5 have lower Shore A hardness and density and better fire resistance; compared with Comparative Example 2, the flame retardant sealants of Examples 1 to 5 have lower Shore A hardness, higher elongation and better high and low temperature resistance.

[0075] Comparative Examples 3-4 show that the combination of high and low viscosity hydroxyl-terminated polydimethylsiloxanes can better unify the two indicators of hardness and elongation, obtaining low hardness and high elongation indicators rather than the excellence of a single indicator.

[0076] The comprehensive performance of the flame retardant sealants of Examples 1-3 is even better, with a hardness of less than 8, flame retardant properties that can reach FV0 level, and excellent high and low temperature resistance, which can meet the requirements for glue used in power batteries.

[0077] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0078] The above is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A low-hardness, lightweight, flame-retardant sealant, characterized in that: The invention is prepared by mixing the following raw materials in parts by weight: 100 parts of a 20,000 viscosity end-hydroxyl polydimethylsiloxane polymer, 70-120 parts of a high viscosity end-hydroxyl polydimethylsiloxane polymer, 70-130 parts of a plasticizer, 180-240 parts of a flame retardant filler, 45-70 parts of a lightweight additive, 4-10 parts of a thixotropic agent, 10-20 parts of a cross-linking agent, 2-5 parts of a curing agent, and 5-10 parts of an organic titanium catalyst; The plasticizer is prepared by mixing the following raw materials in parts by weight: 100 parts of dimethyldimethoxysilane, 40-80 parts of methylphenyldimethoxysilane, 30-50 parts of trifluoropropylmethyldimethoxysilane, 10-20 parts of hexamethyldisiloxane, 100-150 parts of anhydrous methanol, 0.4-0.7 parts of concentrated hydrochloric acid, and 20-30 parts of deionized water; The preparation steps of the plasticizer are: Dimethyldimethoxysilane, methylphenyldimethoxysilane, trifluoropropylmethyldimethoxysilane, hexamethyldisiloxane and anhydrous methanol were added under nitrogen and stirred uniformly to obtain a mixed material; The mixture was heated to 50°C and a mixture of concentrated hydrochloric acid and deionized water was added dropwise. After the addition was complete, the temperature was raised to 65°C and the reaction was continued for 4 hours to obtain a crude product. After distilling off the low-boiling substances from the crude product, the product is dried under reduced pressure to obtain the product. The lightweight additive is a modified hollow glass microsphere containing an inert gas with a bulk density of 0.11-0.13 g / cm³ and a D90 of 60-70 μm; The high-viscosity hydroxy-terminated polydimethylsiloxane polymer has a viscosity of 450,000-550,000 cps at 25°C.

2. The low-hardness, lightweight, flame-retardant sealant according to claim 1, characterized in that: The invention is prepared by mixing the following raw materials in parts by weight: 100 parts of 20,000 viscosity end-hydroxyl polydimethylsiloxane polymer, 100 parts of high viscosity end-hydroxyl polydimethylsiloxane polymer, 110 parts of plasticizer, 210 parts of flame retardant filler, 60 parts of lightweight additive, 7 parts of thixotropic agent, 15 parts of cross-linking agent, 3.5 parts of curing agent and 8 parts of organic titanium catalyst.

3. The low-hardness, lightweight, flame-retardant sealant according to claim 1 or 2, characterized in that: The flame retardant filler is surface-treated and modified active aluminum hydroxide with a particle size of 1500 meshes.

4. The low-hardness, lightweight, flame-retardant sealant according to claim 1 or 2, characterized in that: The thixotropic agent is one or more of polyamide wax, modified castor oil derivatives, and polyether modified silicone oil.

5. The low-hardness, lightweight, flame-retardant sealant according to claim 1 or 2, characterized in that: The crosslinking agent is methyltrimethoxysilane.

6. The low-hardness, lightweight, flame-retardant sealant according to claim 1 or 2, characterized in that: The curing agent is prepared by mixing the following raw materials in parts by weight and then leaving them for 2 days: 60 parts of aminopropyltriethoxysilane, 30 parts of glycidyloxypropyltrimethoxysilane and 2 parts of tin acetate.

7. A method for preparing the low-hardness, lightweight, flame-retardant sealant according to claim 1 or 2, characterized in that: The following steps are involved: Mix 20,000 viscosity end-hydroxyl polydimethylsiloxane polymer, high viscosity end-hydroxyl polydimethylsiloxane polymer, plasticizer, flame retardant filler, lightweight additive, and thixotropic agent evenly, then vacuum heat at 130±10℃ for 1.5 hours to dehydrate; After cooling to below 40°C, add the cross-linking agent, curing agent and organic titanium catalyst in sequence at intervals of 20 minutes, stir evenly and then discharge the material to obtain the flame retardant sealant.

8. Use of the low-hardness, lightweight, flame-retardant sealant according to claim 1 or 2 in power batteries.

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