Medium-temperature fast-curing aluminum alloy sealant and preparation method thereof

Abstract

The invention provides a medium-temperature fast-curing aluminum alloy sealant and a preparation method thereof, and the medium-temperature fast-curing aluminum alloy sealant is prepared by mixing the following components: solid rubber, liquid rubber, a tackifier, a vulcanizing agent, an accelerant, an antioxidant and a filler; wherein the solid rubber is butadiene rubber BR9000; the liquid rubber is at least one kind of polybutadiene with 75-99% of 1, 4-butadienyl and the molecular weight of 2000-5000; the accelerant is a mixture of a thiazole accelerant and a dithiocarbamate accelerant; the thiazole type accelerant is dibenzothiazyl disulfide; the dithiocar-bamate accelerant is zinc dibenzyl dithiocar-bamate, and the adding weight percentage of the dithiocar-bamate accelerant is 0.2-0.5%. According to the aluminum alloy sealant, through synergistic matching and proportional control of the two accelerators, low-medium-temperature rapid curing is achieved, meanwhile, long normal-temperature storage stability is kept, and the aluminum alloy sealant can be widely applied to spot welding parts such as aluminum automobile bodies, hubs and floors of new energy automobiles, reinforcing structures and sealing automobile bodies.

Description

Technical Field

[0001] The invention relates to the technical field of sealants, and in particular to a medium-temperature fast-curing aluminum alloy sealant and a preparation method thereof. Background Art

[0002] In the development of the modern automobile industry, sealants play a pivotal role and are widely used in key spot welding parts such as the car body, wheel hub, and floor. On the one hand, at the bonding level, it uses strong bonding force to ensure that each component is closely connected, making the car body structure stable and reliable; on the other hand, in terms of sealing function, it can seal the gaps in the car body and effectively block the invasion of external water vapor, dust and various impurities; in addition, it also has excellent protective capabilities, which can provide comprehensive protection for the spot welding parts to avoid rust due to the inability to apply paint, greatly extending the service life of the spot welding parts of the car body, thereby ensuring the durability of the entire car body structure.

[0003] At present, the sealants used in automobile production at home and abroad mainly include epoxy resin adhesives, polyvinyl chloride adhesives, synthetic rubber adhesives, etc. However, each of them has many defects. As for polyvinyl chloride sealants, they have low strength, corrosive gas is released during spot welding, and there are problems with environmental protection and corrosion of steel plates. The application of polyvinyl chloride sealants in automobile production is on the verge of being eliminated.

[0004] Let's look at epoxy resin sealants. They are mainly based on dicyandiamide-epoxy resin system, and have the advantages of excellent bonding performance, wide source of raw materials, and low cost. They are the most commonly used type of sealant adhesive in the current automobile manufacturing process. However, their curing temperature is quite high, which means that a lot of extra energy is needed on the automobile production line to meet their curing conditions, which not only increases production costs but also reduces production efficiency. In addition, their resistance to moisture and heat is poor. When the car is in a hot and humid environment, the performance of the sealant will drop sharply, and the bonding effect and sealing function will be weakened, which will lead to a series of problems such as leakage and loosening in the spot welding parts of the car body, seriously affecting the overall quality and reliability of the car.

[0005] In summary, in order to overcome the technical difficulties of existing sealants, it has become an urgent task to develop an aluminum alloy sealant that can achieve rapid curing under medium temperature conditions and is resistant to moisture and heat. Summary of the invention

[0006] To solve the above problems, the present invention proposes a medium-temperature fast-curing aluminum alloy sealant and a preparation method thereof, which solves the technical problems of the high curing temperature and poor moisture and heat resistance of the sealant in the prior art, so as to achieve fast curing at a relatively low medium temperature while maintaining a longer storage stability at room temperature.

[0007] The technical solution of the present invention to solve the above technical problems is as follows: In a first aspect, the present invention provides a medium-temperature fast-curing aluminum alloy sealant prepared by mixing the following components, each component including: solid rubber, liquid rubber, tackifier, vulcanizer, accelerator, antioxidant and filler; The solid rubber is butadiene rubber BR9000; the liquid rubber is at least one polybutadiene having 75-99% 1,4-butadiene groups and a molecular weight between 2000 and 5000; The accelerator is a mixture of a thiazole accelerator and a dithiocarbamate accelerator; the thiazole accelerator is dibenzothiazole disulfide; the dithiocarbamate accelerator is zinc dibenzyl dithiocarbamate, and the added weight percentage is 0.2-0.5%.

[0008] Furthermore, the medium temperature fast curing aluminum alloy sealant component includes the following raw materials in weight percentage: Solid rubber 3.0%~6.0%; Liquid rubber 30.0%~40.0%; Thickener 4.0%~8.0%; Vulcanizing agent 4.0%~10.0%; Accelerator 6.0%~10.0%; Antioxidant 0.2%~1.0%; Filler 30.0%~50.0%.

[0009] Furthermore, the medium temperature fast curing aluminum alloy sealant component includes the following raw materials in weight percentage: Solid rubber 4.0%; Liquid rubber 30.0%; Thickener 8.0%; Curing agent 4.0%; Accelerator 9.3%; Antioxidant 0.5%; Filling 44.2%.

[0010] Furthermore, the tackifier is maleic anhydride modified polybutadiene, which is synthesized from maleic anhydride and polybutadiene; Among them, the mass content of maleic anhydride is 5~10%; polybutadiene has 75~99% 1,4-butadiene group and the molecular weight is between 2000~5000.

[0011] Furthermore, the vulcanizing agent is sulfur or a sulfur donor.

[0012] Furthermore, the antioxidant is at least one of aromatic amine antioxidants, hindered phenol antioxidants, thiodipropionic acid diesters and phosphites.

[0013] Further, the filler is at least one of magnesium silicate, aluminum silicate, graphite, calcium carbonate, and metal oxide; Wherein, the calcium carbonate is nano calcium carbonate surface treated with stearic acid; The metal oxide is at least one of zinc oxide, calcium oxide and magnesium oxide.

[0014] In a second aspect, the present invention further provides a method for preparing the medium-temperature fast-curing aluminum alloy sealant as described in the first aspect, comprising the following steps: S1: Weigh various raw materials with a specific preset mass ratio, including solid rubber, liquid rubber, tackifier, vulcanizer, accelerator, antioxidant, and filler; S2: Stir and mix the weighed solid rubber and liquid rubber at 60-70° C. until they are completely dissolved to obtain a liquid mixture; S3: adding the liquid mixture obtained in step S2 and the tackifier, vulcanizer, accelerator, antioxidant, and filler weighed in step S1 to a dynamic mixer, respectively, and stirring at 30-40° C. until the mixture is evenly dispersed to obtain an intermediate mixture; S4: placing the intermediate mixture obtained in step S3 in a vacuum environment for stirring and degassing treatment, thereby obtaining a medium-temperature fast-curing aluminum alloy sealant.

[0015] Compared with the prior art, the technical solution of this application has the following beneficial technical effects: The medium-temperature fast-curing aluminum alloy sealant and its preparation method are a single-component rubber vulcanized adhesive with excellent moisture and heat resistance, mainly used for bonding and sealing of spot welding parts such as automobile bodies, wheels, floors, etc. By using non-polar 1,4-polybutadiene rubber, adding suitable tackifiers, lamellar structures and hydrophobic fillers, the sealant can achieve the performance characteristics of medium-temperature fast curing, excellent aluminum alloy adhesion, and excellent moisture and heat aging resistance; through the coordinated coordination and proportion control of two accelerators, it can achieve low medium-temperature fast curing while maintaining a long storage stability at room temperature. It is widely used in spot welding parts such as aluminum bodies, wheels, floors, etc. of new energy vehicles to enhance the structure and seal the body.

[0016] Specifically, the aluminum alloy sealant completes curing at 140°C×20min, the shear strength of the aluminum alloy test piece reaches more than 2MPa, and it has cohesive failure. After 70°C×100%RH×21 days of wet heat aging, the shear strength retention rate at room temperature can reach 121.7%, and it has cohesive failure. It has very good strength retention rate and failure form, and can be stored at room temperature of 23°C for more than 6 months. DETAILED DESCRIPTION

[0017] The specific implementation of the present invention is described in detail below. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the protection scope of the present invention.

[0018] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0019] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0020] In the present invention, the sources of raw materials are described as follows: Solid rubber: BR9000 was purchased from Sinopec.

[0021] Liquid rubber: polybutadiene POLYVEST 110 purchased from Evonik, Polybutadiene POLYVEST 130 was purchased from Evonik. Polybutadiene LITHENE AL was purchased from Syntema.

[0022] Tackifier: polybutadiene POLYVEST MA75 purchased from Evonik.

[0023] Vulcanizing agent: Sulfur SS200 purchased from Jincheng Boqiang Chemical Co., Ltd. Dithiodimorpholine (DTDM) was purchased from Hubei Hongfuda Biotechnology.

[0024] Accelerator: Dibenzothiazole disulfide DM was purchased from Weilin Chemical. Zinc dibenzyldithiocarbamate (ZBEC) was purchased from Weilin Chemical.

[0025] Antioxidant: 2, 2′-methylenebis(4-methyl-6-tert-butylphenol) 2246 was purchased from Nanjing Datang Chemical.

[0026] Filler: Calcium carbonate SP200 purchased from Shanxi Lanhua, Calcium carbonate CC905 was purchased from Guangxi Kelong. Magnesium silicate CMS444 was purchased from Heshan Chemical, Calcium oxide was purchased from Zibo Hainuo. Zinc oxide was purchased from Weifang Longda Zinc Industry. The remaining reagents are commercially available.

[0027] The medium-temperature fast-curing aluminum alloy sealant provided by the present invention is prepared by mixing the following components, each of which includes: solid rubber, liquid rubber, tackifier, vulcanizer, accelerator, antioxidant and filler; The solid rubber is butadiene rubber BR9000; the liquid rubber is at least one polybutadiene having 75-99% 1,4-butadiene groups and a molecular weight between 2000 and 5000.

[0028] The accelerator is a mixture of a thiazole accelerator and a dithiocarbamate accelerator; the thiazole accelerator is dibenzothiazole disulfide; the dithiocarbamate accelerator is zinc dibenzyl dithiocarbamate, and the added weight percentage is 0.2-0.5%.

[0029] Preferably, the medium temperature fast curing aluminum alloy sealant component comprises the following raw materials in weight percentage: Solid rubber 3.0%~6.0%; Liquid rubber 30.0%~40.0%; Thickener 4.0%~8.0%; Vulcanizing agent 4.0%~10.0%; Accelerator 6.0%~10.0%; Antioxidant 0.2%~1.0%; Filler 30.0%~50.0%.

[0030] More preferably, the medium temperature fast curing aluminum alloy sealant component comprises the following raw materials in weight percentage: Solid rubber 4.0%; Liquid rubber 30.0%; Thickener 8.0%; Curing agent 4.0%; Accelerator 9.3%; Antioxidant 0.5%; Filling 44.2%.

[0031] The tackifier is maleic anhydride modified polybutadiene, which is synthesized from maleic anhydride and polybutadiene; the mass content of maleic anhydride is 5-10%; the polybutadiene has 75-99% 1,4-butadiene groups and a molecular weight between 2000 and 5000.

[0032] The vulcanizing agent is sulfur or a sulfur donor.

[0033] The antioxidant is at least one of aromatic amine antioxidants, hindered phenol antioxidants, thiodipropionic acid diesters and phosphites.

[0034] The filler is at least one of magnesium silicate, aluminum silicate, graphite, calcium carbonate, and metal oxides; wherein the calcium carbonate is nano calcium carbonate surface-treated with stearic acid; The metal oxide is at least one of zinc oxide, calcium oxide and magnesium oxide.

[0035] The method for preparing the medium-temperature fast-curing aluminum alloy sealant comprises the following steps: S1: Weigh various raw materials with a specific preset mass ratio, including solid rubber, liquid rubber, tackifier, vulcanizer, accelerator, antioxidant, and filler; S2: Stir and mix the weighed solid rubber and liquid rubber at 60-70° C. until they are completely dissolved to obtain a liquid mixture; S3: adding the liquid mixture obtained in step S2 and the tackifier, vulcanizer, accelerator, antioxidant, and filler weighed in step S1 to a dynamic mixer, respectively, and stirring at 30-40° C. until the mixture is evenly dispersed to obtain an intermediate mixture; S4: placing the intermediate mixture obtained in step S3 in a vacuum environment for stirring and degassing, thereby obtaining a medium-temperature fast-curing aluminum alloy sealant; Among them, the process parameters of vacuum stirring degassing are: vacuum pressure is not less than -0.09MPa, and degassing stirring time is 30min-40min.

[0036] The following is further introduced in conjunction with specific embodiments: Example 1 This embodiment provides a sealant, which is prepared from the raw materials shown in Table 1 below: Table 1 Composition of sealant provided in Example 1

[0037] The preparation method of the sealant of this embodiment comprises the following steps: S1, weigh each raw material according to the component ratio provided in Table 1.

[0038] S2, stirring and mixing the synthetic rubber and the diluent at 60° C. until they are completely dissolved to obtain a liquid mixture.

[0039] S3, respectively add the liquid mixture, tackifier, vulcanizer, accelerator, antioxidant and filler into a dynamic mixer, stir at 30° C. until dispersed evenly, to obtain an intermediate mixture.

[0040] S4, carry out vacuum degassing for 30 minutes at a vacuum pressure above -0.09 MPa.

[0041] Example 2 This embodiment provides a sealant, which is prepared from the raw materials shown in Table 2 below: Table 2 Composition of sealant provided in Example 2

[0042] The preparation method of the sealant of this embodiment comprises the following steps: S1, weigh each raw material according to the component ratio provided in Table 2.

[0043] S2, stirring and mixing the synthetic rubber and the diluent at 70° C. until they are completely dissolved to obtain a liquid mixture.

[0044] S3, respectively adding the liquid mixture, tackifier, vulcanizer, accelerator, antioxidant and filler into a dynamic mixer, stirring at 40° C. until uniformly dispersed, to obtain an intermediate mixture.

[0045] S4, at a vacuum pressure of above -0.09 MPa, perform vacuum degassing for 40 minutes to obtain.

[0046] Example 3 This embodiment provides a sealant, which is prepared from the raw materials shown in Table 3 below: Table 3 Composition of sealant provided in Example 3

[0047] The preparation method of the sealant in this embodiment is basically the same as that in Embodiment 1, and will not be described in detail here.

[0048] Example 4 This embodiment provides a sealant, which is prepared from the raw materials shown in Table 4 below: Table 4 Composition of sealant provided in Example 4

[0049] The preparation method of the sealant in this embodiment is basically the same as that in Embodiment 1, and will not be described in detail here.

[0050] Example 5 This embodiment provides a sealant, which is prepared from the raw materials shown in Table 5 below: Table 5 Composition of sealant provided in Example 5

[0051] The preparation method of the sealant in this embodiment is basically the same as that in Embodiment 1, and will not be described in detail here.

[0052] Example 6 This embodiment provides a sealant, which is prepared from the raw materials shown in Table 6 below: Table 6 Composition of sealant provided in Example 6

[0053] The preparation method of the sealant in this embodiment is basically the same as that in Embodiment 1, and will not be described in detail here.

[0054] Example 7 This embodiment provides a sealant, which is prepared from the raw materials shown in Table 7 below: Table 7 Composition of sealant provided in Example 7

[0055] The preparation method of the sealant in this embodiment is basically the same as that in Embodiment 1, and will not be described in detail here.

[0056] Example 8 This embodiment provides a sealant, which is prepared from the raw materials shown in Table 8 below: Table 8 Composition of sealant provided in Example 8

[0057] The preparation method of the sealant in this embodiment is basically the same as that in Embodiment 1, and will not be described in detail here.

[0058] Comparative Example 1 This comparative example provides a sealant, which is prepared from the raw materials shown in Table 9 below: Table 9 Composition of sealant provided in Comparative Example 1

[0059] The preparation method of the sealant in this comparative example is basically the same as that in Example 1, and will not be described in detail here.

[0060] Comparative Example 2 This comparative example provides a sealant, which is prepared from the raw materials shown in Table 10 below: Table 10 Composition of sealant provided in Comparative Example 2

[0061] The preparation method of the sealant in this comparative example is basically the same as that in Example 1, and will not be described in detail here.

[0062] Comparative Example 3 This comparative example provides a sealant, which is prepared from the raw materials shown in Table 11 below: Table 11 Composition of sealant provided in Comparative Example 3

[0063] The preparation method of the sealant in this comparative example is basically the same as that in Example 1, and will not be described in detail here.

[0064] Comparative Example 4 This comparative example provides a sealant, which is prepared from the raw materials shown in Table 12 below: Table 12 Composition of sealant provided in Comparative Example 4

[0065] The preparation method of the sealant in this comparative example is basically the same as that in Example 1, and will not be described in detail here.

[0066] The sealants obtained in the above examples and comparative examples were tested for performance, and the testing method is as follows: 1. Shear strength: The test pieces used are all Nanshan 174A-1 series aluminum alloy test pieces (100mm*25mm*1.5mm). The test pieces are cleaned with acetone (or butanone), and then evenly coated with anti-rust oil (QUAKER 6130N) on the surface after drying, with an oil coating amount of about 2.5g / m2.

[0067] According to GB / T 7124 standard, the vibration-damping adhesive was adhered between the two test pieces, with an overlap area of ​​25mm*25mm and an adhesive layer thickness of 3.0mm. The fixed test pieces were cured at 140℃×20min, taken out, placed at room temperature for 1h, and the clamps were removed.

[0068] The shear strength and failure mode are tested at 23±1℃ and the unit is expressed in MPa / %AF (or CF).

[0069] 2. H21 moisture and heat resistance Cut and weigh the absorbent cotton according to the size requirements of about 180 mm × 500 mm in length × width and 45 g ± 5 g in weight. Wrap the cured test piece with absorbent cotton. Put the whole piece into a polyethylene bag, add deionized water 10 times the weight of the absorbent cotton, exhaust the air to the maximum extent, and seal the polyethylene bag.

[0070] Place the polyethylene bag in a 70°C oven and take it out after 21 days. Place the test piece in a -20°C refrigerator and take it out after 2 hours. Place it at room temperature for 2 hours to 4 hours. Test the shear strength and fracture appearance.

[0071] 3. Storage stability The test method of pressure flow viscosity is as follows: temperature 23±1℃, pressure 0.5MPa, nozzle diameter 4mm, length 22.5mm, test the weight of the glue sample squeezed from the nozzle for 1 minute, expressed in g / min.

[0072] The initial squeeze flow viscosity and the squeeze flow viscosity after storage at 23°C for 6 months were tested respectively, and the squeeze flow viscosity change value: the viscosity change rate of the initial squeeze flow viscosity was used as the representation of storage stability.

[0073] Performance Test Results Table 13 Performance test results statistics

[0074] Note: CF is cohesive failure, AF is interfacial failure Combined with the performance test result table, it can be seen that compared with comparative examples 1 to 4, the medium-temperature fast-curing aluminum alloy sealants of Examples 1 to 8 can achieve the performance characteristics of medium-temperature fast curing, excellent aluminum alloy adhesion, and excellent resistance to wet heat aging by preferably using non-polar 1,4-polybutadiene rubber, adding suitable tackifiers, lamellar structures, and hydrophobic fillers. Through the synergistic coordination and proportion control of the two accelerators, while achieving low medium-temperature fast curing, it maintains a long storage stability at room temperature, and is widely used in spot welding parts such as aluminum bodies, wheels, floors, etc. of new energy vehicles to enhance the structure and seal the body.

[0075] Specifically, the aluminum alloy sealant prepared in the embodiment of the present invention completes curing at 140°C×20min, the shear strength of the aluminum alloy test piece reaches more than 2MPa, and cohesive failure occurs. After wet heat aging at 70°C×100%RH×21 days, the shear strength retention rate at room temperature can reach 121.7% (Example 3), cohesive failure, and has good strength retention rate and failure form. It can be stored at room temperature of 23°C for more than 6 months, and at the same time meets the process requirements for automated construction of the sealant.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A medium temperature fast curing aluminum alloy sealant, characterized in that: It is prepared by mixing the following components, each of which includes: solid rubber, liquid rubber, tackifier, vulcanizer, accelerator, antioxidant and filler; The solid rubber is butadiene rubber BR9000; the liquid rubber is at least one polybutadiene having 75-99% 1,4-butadiene groups and a molecular weight between 2000 and 5000; The accelerator is a mixture of a thiazole accelerator and a dithiocarbamate accelerator; the thiazole accelerator is dibenzothiazole disulfide; the dithiocarbamate accelerator is zinc dibenzyl dithiocarbamate, and the added weight percentage is 0.2-0.5%.

2. The medium temperature fast curing aluminum alloy sealant according to claim 1, characterized in that: The medium temperature fast curing aluminum alloy sealant component includes the following raw materials in weight percentage: Solid rubber 3.0%~6.0%; Liquid rubber 30.0%~40.0%; Thickener 4.0%~8.0%; Vulcanizing agent 4.0%~10.0%; Accelerator 6.0%~10.0%; Antioxidant 0.2%~1.0%; Filler 30.0%~50.0%.

3. The medium temperature fast curing aluminum alloy sealant according to claim 2, characterized in that: The medium temperature fast curing aluminum alloy sealant component includes the following raw materials in weight percentage: Solid rubber 4.0%; Liquid rubber 30.0%; Thickener 8.0%; Curing agent 4.0%; Accelerator 9.3%; Antioxidant 0.5%; Filling 44.2%.

4. The medium temperature fast curing aluminum alloy sealant according to any one of claims 1 to 3, characterized in that: The tackifier is maleic anhydride modified polybutadiene, which is synthesized from maleic anhydride and polybutadiene; Among them, the mass content of maleic anhydride is 5~10%; polybutadiene has 75~99% 1,4-butadiene group and the molecular weight is between 2000~5000.

5. The medium temperature fast curing aluminum alloy sealant according to any one of claims 1 to 3, characterized in that: The vulcanizing agent is sulfur or a sulfur donor.

6. The medium temperature fast curing aluminum alloy sealant according to any one of claims 1 to 3, characterized in that: The antioxidant is at least one of aromatic amine antioxidants, hindered phenol antioxidants, thiodipropionic acid diesters and phosphites.

7. The medium temperature fast curing aluminum alloy sealant according to any one of claims 1 to 3, characterized in that: The filler is at least one of magnesium silicate, aluminum silicate, graphite, calcium carbonate, and metal oxide; Wherein, the calcium carbonate is nano calcium carbonate surface treated with stearic acid; The metal oxide is at least one of zinc oxide, calcium oxide and magnesium oxide.

8. A method for preparing the medium-temperature fast-curing aluminum alloy sealant according to any one of claims 1 to 7, characterized in that: The steps include: S1: Weigh various raw materials with a specific preset mass ratio, including solid rubber, liquid rubber, tackifier, vulcanizer, accelerator, antioxidant, and filler; S2: Stir and mix the weighed solid rubber and liquid rubber at 60-70° C. until they are completely dissolved to obtain a liquid mixture; S3: adding the liquid mixture obtained in step S2 and the tackifier, vulcanizer, accelerator, antioxidant, and filler weighed in step S1 to a dynamic mixer, respectively, and stirring at 30-40° C. until the mixture is evenly dispersed to obtain an intermediate mixture; S4: placing the intermediate mixture obtained in step S3 in a vacuum environment for stirring and degassing treatment, thereby obtaining a medium-temperature fast-curing aluminum alloy sealant.

Images