Water-resistant rubber sealing strip for automobiles and method for manufacturing the same

Abstract

The application relates to the technical field of sealing strips, and discloses a water-resistant rubber sealing strip for automobiles and a preparation method thereof. The water-resistant rubber sealing strip for automobiles comprises the following components in parts by weight: 100 parts of a ternary ethylene-propylene-diene rubber pretreatment, 10-16 parts of carbon black, 3-5 parts of a vulcanizing agent, 1-2 parts of a vulcanizing accelerator, 1-3 parts of a dispersing agent, 4-6 parts of stearic acid and 1-2 parts of an antioxidant; the ternary ethylene-propylene-diene rubber pretreatment comprises the following components in parts by weight: 50 parts of ternary ethylene-propylene-diene rubber, 12-22 parts of nitrile rubber, 4-12 parts of phthalonitrile resin, 0.5-1.2 parts of a curing agent and 6-15 parts of four acicular zinc oxide whiskers. The technical scheme can solve the problem of poor oil resistance of rubber sealing strips in the related art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sealing strips, in particular to a water-resistant rubber sealing strip for automobiles and a preparation method thereof. BACKGROUND

[0002] Automobile sealing strips are key components in the automobile body sealing system, and are widely used in parts such as vehicle doors and vehicle windows, playing an important role in waterproofing, dustproofing, sound insulation, and shock absorption. With the rapid development of the automobile industry, the performance requirements for sealing strips are becoming higher and higher, especially in terms of comprehensive performance such as water resistance and oil resistance.

[0003] Ethylene-propylene-diene rubber (EPDM) has a high molecular structure stability because its main chain is composed of saturated hydrocarbons and only the side chain contains unsaturated double bonds, and it has excellent weather resistance and basic water resistance, so it can meet the basic sealing requirements in conventional environments and is widely used in sealing strip manufacturing. However, the inherent properties of ethylene-propylene-diene rubber also cause certain performance defects in the sealing strips prepared therefrom. The intermolecular cohesion of ethylene-propylene-diene rubber is low, and it is a non-polar rubber, so it has poor resistance to oil substances (such as engine oil leakage, road oil stains, gasoline vapor, etc.). Oil molecules easily penetrate into the rubber interior, causing swelling, which in turn damages the structural integrity of the sealing strip, leading to loss of elasticity, increased sealing gap, and in severe cases, cracking and falling off of the sealing strip.

[0004] Therefore, it is important to develop a rubber sealing strip for automobiles that not only has good water resistance but also has good oil resistance, in order to meet the performance requirements of rubber sealing strips for automobiles. SUMMARY

[0005] The present application provides a water-resistant rubber sealing strip for automobiles and a preparation method thereof, which solves the problem of poor oil resistance of rubber sealing strips in related technologies.

[0006] The technical scheme of the present application is as follows:

[0007] The present application provides a water-resistant rubber sealing strip for automobiles, which comprises the following components by weight:

[0008] 100 parts of ethylene-propylene-diene rubber pretreatment, 10-16 parts of carbon black, 3-5 parts of vulcanizing agent, 1-2 parts of vulcanization accelerator, 1-3 parts of dispersing agent, 4-6 parts of stearic acid, and 1-2 parts of antioxidant.

[0009] The ethylene-propylene-diene rubber pretreatment comprises the following components by weight:

[0010] 50 parts of ethylene-propylene-diene rubber, 12-22 parts of nitrile rubber, 4-12 parts of phthalonitrile resin, 0.5-1.2 parts of curing agent, and 6-15 parts of four-needle-shaped zinc oxide whiskers.

[0011] The automobile rubber sealing strip of the present application takes ethylene-propylene-diene rubber as the main base material. The main chain of the ethylene-propylene-diene rubber is composed of saturated hydrocarbons, and only the side chain contains unsaturated double bonds. The stability is relatively high. Meanwhile, the ethylene-propylene-diene rubber itself has good water resistance. After nearly 100 hours in 230℃ superheated water vapor, the appearance does not change. When nitrile rubber, phthalonitrile resin, curing agent and four acicular zinc oxide whiskers are used to pretreat the ethylene-propylene-diene rubber, and then the pretreated ethylene-propylene-diene rubber is subjected to plasticizing treatment, and then combined with carbon black, vulcanizing agent, vulcanizing accelerator, dispersing agent, stearic acid and antioxidant, the automobile rubber sealing strip with compact and stable internal structure can be prepared under the combined action of the components. The automobile rubber sealing strip has good water resistance and good oil resistance.

[0012] As a further technical solution, the preparation method of the ethylene-propylene-diene rubber pretreatment product comprises the following steps:

[0013] A1, blending and melting phthalonitrile resin and curing agent, cooling, crushing to obtain pretreated phthalonitrile resin;

[0014] A2, blending the pretreated phthalonitrile resin, nitrile rubber and ethylene-propylene-diene rubber, adding four acicular zinc oxide whiskers, mixing uniformly, cooling to obtain the ethylene-propylene-diene rubber pretreatment product.

[0015] In the preparation process of the ethylene-propylene-diene rubber pretreatment product, the nitrile rubber and the ethylene-propylene-diene rubber are first subjected to blending treatment with the phthalonitrile resin, so that the nitrile rubber is wound around the ethylene-propylene-diene rubber, and the phthalonitrile resin acts on the nitrile rubber and the ethylene-propylene-diene rubber, so that the phthalonitrile resin is filled in the winding structure of the nitrile rubber and the ethylene-propylene-diene rubber, thereby preliminarily improving the stability of the ethylene-propylene-diene rubber. Then, the four acicular zinc oxide whiskers are added to further fill and stabilize the structure of the ethylene-propylene-diene rubber.

[0016] As a further technical solution, the weight ratio of the phthalonitrile resin to the nitrile rubber is 1.5-4:1.

[0017] In the automobile water-resistant rubber sealing strip of the present application, when the weight ratio of the phthalonitrile resin to the nitrile rubber is 1.5-4:1, the oil resistance of the automobile rubber sealing strip can be further improved. After the automobile rubber sealing strip sample is soaked in No. 3 national standard gasoline for 90 hours, the tensile strength retention rate can reach 94.7% or more.

[0018] As a further technical solution, the curing agent comprises one or both of hexamethylene diamine and maleic anhydride, and the maleic anhydride is preferred.

[0019] As a further technical solution, the average particle size of the pretreated phthalonitrile resin is 40-80 µm, for example, it can be 40 µm, 50 µm, 60 µm, 70 µm, 80 µm, and preferably 50 µm.

[0020] As a further technical solution, in step A1, the temperature during melting is 185-190 ℃, and the time is 2-3 h.

[0021] In the preparation process of the EPDM pretreatment of the present application, when the curing agent is used for curing the phthalonitrile resin, the curing agent can be fully dispersed in the phthalonitrile resin at a temperature of 185-190 ℃, which is conducive to the curing reaction.

[0022] As a further technical solution, in step A2, the temperature during blending is 130-140 ℃, and the time is 20-30 min.

[0023] As a further technical solution, the EPDM includes ENB type EPDM and DCPD type EPDM in a weight ratio of 1-4:1, for example, the weight ratio can be 1:1, 1.5:1, 2:1, 7:3, 2.5:1, 3:1, 3.5:1, 4:1, and preferably 1.5:1-7:3.

[0024] In the present application, the EPDM includes two types of EPDM, namely DCPD type EPDM and ENB type EPDM. The third monomer contained in the side chain of the ENB type EPDM is ethylidene norbornene, which has strong vulcanization activity and fast vulcanization speed, and can quickly form a cross-linked structure to improve processing efficiency, but its heat resistance is relatively poor. The third monomer contained in the side chain of the DCPD type EPDM is dicyclopentadiene, which has relatively low double bond activity and relatively slow vulcanization speed. The cross-linked structure formed after vulcanization is more stable, and the thermal motion between molecular chains is hindered at high temperatures. By using both DCPD type EPDM and ENB type EPDM, the heat resistance of EPDM can be improved, thereby improving the heat resistance of the rubber sealing strip for automobiles.

[0025] In the present application, by optimizing and adjusting the content ratio of ENB type EPDM and DCPD type EPDM, when the weight ratio of ENB type EPDM and DCPD type EPDM is 1.5:1-7:3, the heat resistance of the rubber sealing strip for automobiles can be further improved. After air aging test in an air aging oven, the tensile strength retention rate can still reach 91.9% or more.

[0026] As a further technical solution, the vulcanizing agent includes one or both of sulfur and dicumyl peroxide, and preferably dicumyl peroxide.

[0027] The vulcanization accelerator comprises one or both of vulcanization accelerator TMTD and vulcanization accelerator CBS, preferably vulcanization accelerator TMTD.

[0028] As a further technical solution, the anti-aging agent comprises one or more of anti-aging agent RD, anti-aging agent NB, and anti-aging agent DNP, preferably anti-aging agent NB.

[0029] As a further technical solution, the dispersant comprises one or more of polyethylene glycol, polyvinyl alcohol, and polyvinylpyrrolidone, preferably polyethylene glycol.

[0030] The application provides a preparation method of a water-resistant rubber sealing strip for automobiles.

[0031] After the pretreated EPDM is plasticized, the remaining components are added for mixing and vulcanization molding to obtain the water-resistant rubber sealing strip for automobiles.

[0032] As a further technical solution, during the vulcanization molding, the temperature is 165-170 DEG C, and the vulcanization time is 25-35 min.

[0033] The working principle and beneficial effects of the application are as follows:

[0034] In the water-resistant rubber sealing strip for automobiles, the nitrile rubber, phthalocyanine resin, curing agent, and four acicular zinc oxide whiskers are mixed and pretreated with the EPDM, which can effectively improve the oil resistance of the rubber sealing strip for automobiles. The EPDM is a non-polar rubber, and the intermolecular cohesion is low, which leads to poor oil resistance. Therefore, the nitrile rubber, phthalocyanine resin, and four acicular zinc oxide whiskers are used to pretreat the EPDM. The nitrile rubber can be entangled with the EPDM molecules, and the nitrile group polar group reduces the affinity of the EPDM for oil. Meanwhile, the four acicular zinc oxide whiskers and the crosslinked phthalocyanine resin are filled in the entangled structure of the EPDM and the nitrile rubber, thereby enhancing the cohesion of the overall structure of the EPDM, effectively preventing the penetration of oil molecules, and reducing the swelling degree of the EPDM. After the pretreated EPDM is applied to the preparation of the sealing strip, the oil resistance of the sealing strip can be significantly improved. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative work, are within the scope of protection of the present application.

[0036] In the following examples and comparative examples, the model of ENB type EPDM rubber is KEP-330, and the ENB content is 8wt%; the model of DCPD type EPDM rubber is 301T; the model of nitrile rubber is 3305E; the model of phthalonitrile resin is PN-2524; the average diameter of four acicular zinc oxide whiskers is 2um, and the average length is 20um; the model of carbon black is N660.

[0037] Example 1

[0038] The preparation method of the EPDM rubber pretreatment product comprises the following steps:

[0039] A1, 4 parts of phthalonitrile resin and 0.5 parts of maleic anhydride are blended, and melt treated at 185℃ for 3h, cooled, and crushed to obtain pretreated phthalonitrile resin with an average particle size of 50um;

[0040] A2, the pretreated phthalonitrile resin, 22 parts of nitrile rubber and 50 parts of ENB type EPDM rubber are mixed at 130℃ for 30min, then 6 parts of four acicular zinc oxide whiskers are added, mixed uniformly, and cooled to obtain an EPDM rubber pretreatment product;

[0041] A preparation method of a water-resistant rubber sealing strip for automobiles comprises the following steps:

[0042] After 100 parts of the EPDM rubber pretreatment product is plasticated, 10 parts of carbon black, 3 parts of dicumyl peroxide, 1 part of vulcanization accelerator TMTD, 1 part of polyethylene glycol, 4 parts of stearic acid and 1 part of antioxidant NB are added and mixed, and then vulcanized at 165℃ for 35min to form a water-resistant rubber sealing strip for automobiles.

[0043] Example 2

[0044] The preparation method of the EPDM rubber pretreatment product comprises the following steps:

[0045] A1, 4 parts of phthalonitrile resin and 0.8 parts of maleic anhydride are blended, and melt treated at 190℃ for 2h, cooled, and crushed to obtain pretreated phthalonitrile resin with an average particle size of 50um;

[0046] A2, after mixing the pretreated phthalonitrile resin, 20 parts of nitrile rubber and 50 parts of ENB type ethylene propylene rubber at 135℃ for 25 min, 10 parts of four needle-shaped zinc oxide whiskers were added, mixed uniformly, cooled, and the ethylene propylene rubber pretreatment was obtained;

[0047] A method for preparing a water-resistant rubber sealing strip for automobiles, comprising the following steps:

[0048] After plasticizing 100 parts of the ethylene propylene rubber pretreatment, 14 parts of carbon black, 4 parts of dicumyl peroxide, 1.5 parts of vulcanization accelerator TMTD, 2 parts of polyethylene glycol, 5 parts of stearic acid and 1.5 parts of antioxidant NB were mixed, and vulcanized at 170℃ for 30 min, and then molded to obtain the water-resistant rubber sealing strip for automobiles.

[0049] Example 3

[0050] The method for preparing the ethylene propylene rubber pretreatment comprises the following steps:

[0051] A1, 12 parts of phthalonitrile resin and 1.2 parts of maleic anhydride were blended, and then melt treated at 190℃ for 2h, cooled, and crushed to obtain pretreated phthalonitrile resin with an average particle size of 50µm;

[0052] A2, after mixing the pretreated phthalonitrile resin, 20 parts of nitrile rubber and 50 parts of ENB type ethylene propylene rubber at 135℃ for 25 min, 10 parts of four needle-shaped zinc oxide whiskers were added, mixed uniformly, cooled, and the ethylene propylene rubber pretreatment was obtained;

[0053] A method for preparing a water-resistant rubber sealing strip for automobiles, comprising the following steps:

[0054] After plasticizing 100 parts of the ethylene propylene rubber pretreatment, 14 parts of carbon black, 4 parts of dicumyl peroxide, 1.5 parts of vulcanization accelerator TMTD, 2 parts of polyethylene glycol, 5 parts of stearic acid and 1.5 parts of antioxidant NB were mixed, and vulcanized at 170℃ for 30 min, and then molded to obtain the water-resistant rubber sealing strip for automobiles.

[0055] Example 4

[0056] The difference between this embodiment and Example 2 is only that in the method for preparing the ethylene propylene rubber pretreatment of this embodiment, the amount of nitrile rubber added is 12 parts, and the amount of phthalonitrile resin added is 12 parts.

[0057] Example 5

[0058] The difference between this embodiment and Example 2 is only that in the method for preparing the ethylene propylene rubber pretreatment of this embodiment, the amount of nitrile rubber added is 14.4 parts, and the amount of phthalonitrile resin added is 9.6 parts.

[0059] Example 6

[0060] The difference between this example and Example 2 is only that in the preparation method of the EPDM pretreatment of this example, the amount of nitrile rubber added is 19.2 parts, and the amount of phthalonitrile resin added is 4.8 parts.

[0061] Example 7

[0062] The difference between this example and Example 6 is only that in the preparation method of the EPDM pretreatment of this example, the ENB type EPDM is replaced with an equal amount of DCPD type EPDM.

[0063] Example 8

[0064] The difference between this example and Example 6 is only that in the preparation method of the EPDM pretreatment of this example, 50 parts of ENB type EPDM is replaced with 25 parts of DCPD type EPDM and 25 parts of ENB type EPDM.

[0065] Example 9

[0066] The difference between this example and Example 6 is only that in the preparation method of the EPDM pretreatment of this example, 50 parts of ENB type EPDM is replaced with 30 parts of ENB type EPDM and 20 parts of DCPD type EPDM.

[0067] Example 10

[0068] The difference between this example and Example 6 is only that in the preparation method of the EPDM pretreatment of this example, 50 parts of ENB type EPDM is replaced with 35 parts of ENB type EPDM and 15 parts of DCPD type EPDM.

[0069] Example 11

[0070] The difference between this example and Example 6 is only that in the preparation method of the EPDM pretreatment of this example, 50 parts of ENB type EPDM is replaced with 40 parts of ENB type EPDM and 10 parts of DCPD type EPDM.

[0071] Comparative Example 1

[0072] The difference between this example and Example 2 is only that the preparation method of the EPDM pretreatment of this example is different, specifically: 24 parts of nitrile rubber and 50 parts of ENB type EPDM are mixed at 135°C for 25 min, then 10 parts of four-needle zinc oxide whiskers are added, mixed uniformly, cooled, and the EPDM pretreatment is obtained.

[0073] Comparative Example 2

[0074] The difference between the present comparative example and Example 2 is only that the preparation method of the ethylene-propylene-diene rubber pretreatment material in the present comparative example is different, specifically:

[0075] A1, 24 parts of phthalonitrile resin and 0.8 parts of maleic anhydride were blended and melt treated at 190°C for 2h, cooled, and pulverized to obtain a pretreated phthalonitrile resin with an average particle size of 50µm;

[0076] A2, the pretreated phthalonitrile resin and 50 parts of ENB type ethylene-propylene-diene rubber were mixed at 135°C for 25min, then 10 parts of four-needle-shaped zinc oxide whiskers were added and mixed uniformly, and cooled to obtain an ethylene-propylene-diene rubber pretreatment material.

[0077] Comparative Example 3

[0078] The difference between the present comparative example and Example 2 is only that the ethylene-propylene-diene rubber pretreatment material in the present comparative example is replaced by an equal amount of ENB type ethylene-propylene-diene rubber.

[0079] Experimental Example 1

[0080] The automobile water-resistant rubber sealing strips prepared in Examples 1-11 and Comparative Examples 1-3 were tested for the following properties:

[0081] (1) The tensile strength was tested according to the method in GB / T 528-2009 “Determination of tensile stress-strain properties of vulcanized or thermoplastic rubber”, wherein the sealing strip sample was a 1A dumbbell-shaped sample and the tensile speed was 100mm / min during testing;

[0082] (2) The automobile water-resistant rubber sealing strips prepared in Examples 1-11 and Comparative Examples 1-3 were immersed in No. 3 national standard gasoline for 90h, and then the tensile strength after gasoline immersion was tested according to the above-mentioned tensile strength test method, and the test results are shown in Table 1.

[0083] Table 1 Test results of oil resistance of Examples 1-11 and Comparative Examples 1-3

[0084]

[0085] The retention rate of tensile strength after gasoline immersion was calculated according to the formula: retention rate of tensile strength after gasoline immersion = tensile strength after gasoline immersion / tensile strength x 100%. Compared with Comparative Examples 1-3, the retention rate of tensile strength after gasoline immersion of the automobile water-resistant rubber sealing strips prepared in Examples 1-11 was obviously improved, indicating that the pretreatment of the ethylene-propylene-diene rubber with the nitrile rubber, the phthalonitrile resin, the curing agent and the four acicular zinc oxide whiskers improved the oil resistance of the automobile water-resistant rubber sealing strips, so that the retention rate of tensile strength after gasoline immersion could be increased to 92.2% or more after immersion in No. 3 national standard gasoline for 90 h.

[0086] Experimental Example 2

[0087] The automobile water-resistant rubber sealing strip samples prepared in Examples 6-11 were subjected to a hot air aging test according to the method in GB / T 3512-2014 “Vulcanized or thermoplastic rubber Hot air accelerated aging and heat resistance test” using an air aging oven, and the tensile strength after heat resistance test was tested according to the above-mentioned tensile strength test method. The test results are shown in Table 2. During the hot air aging test, the temperature was 100°C and the time was 168 h.

[0088] Table 2 Heat resistance test results of Examples 6-11

[0089]

[0090] The retention rate of tensile strength after heat resistance test was calculated according to the formula: retention rate of tensile strength after heat resistance test = tensile strength after heat resistance test / tensile strength x 100%. Compared with Examples 6-7, the retention rate of tensile strength after heat resistance test of the automobile water-resistant rubber sealing strips prepared in Examples 8-11 was obviously improved, indicating that the use of DCPD type ethylene-propylene-diene rubber and ENB type ethylene-propylene-diene rubber could improve the heat resistance of the automobile water-resistant rubber sealing strips without affecting the oil resistance, so that the retention rate of tensile strength after heat resistance test could be increased to 91.9% or more after the hot air aging test.

[0091] Experimental Example 3

[0092] The automobile water-resistant rubber sealing strip samples prepared in Examples 1-3 were subjected to a water resistance test according to the method in QC / T 639-2004 “Automobile rubber sealing strip”, and the tensile strength after water immersion was tested according to the above-mentioned tensile strength test method. The test results are shown in Table 3. During the water resistance test, the temperature was 50°C and the time was 168 h.

[0093] Table 3 Water resistance test results of Examples 1-3

[0094]

[0095] According to the calculation of the tensile strength retention rate after water immersion = the tensile strength after water immersion / the tensile strength × 100%, the tensile strength retention rate after water immersion of the rubber sealing strips prepared in Examples 1-3 can reach 94.8% or more after being immersed in water at 50℃ for 168h, indicating that the rubber sealing strips prepared by the application have good water resistance and meet the use requirements in a water-containing environment.

[0096] The above only describes preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A water-resistant rubber sealing strip for automobiles, characterized in that, The components include the following weight parts: The ternary ethylene-propylene rubber pretreatment 100 parts, carbon black 10~16 parts, vulcanizing agent 3~5 parts, vulcanization accelerator 1~2 parts, dispersing agent 1~3 parts, stearic acid 4~6 parts, antioxidant 1~2 parts; The ternary ethylene-propylene rubber pretreatment includes the following weight parts of components: Ternary ethylene-propylene rubber 50 parts, nitrile rubber 12~22 parts, phthalonitrile resin 4~12 parts, curing agent 0.5~1.2 parts, four acicular zinc oxide whiskers 6~15 parts; The preparation method of the ternary ethylene-propylene rubber pretreatment includes the following steps: A1, blending phthalonitrile resin and curing agent, melting, cooling, crushing, obtaining pretreated phthalonitrile resin; A2, after blending the pretreated phthalonitrile resin, nitrile rubber and ternary ethylene-propylene rubber, adding four acicular zinc oxide whiskers, mixing uniformly, cooling, obtaining ternary ethylene-propylene rubber pretreatment.

2. The water-resistant rubber sealing strip for a vehicle according to claim 1, characterized by The weight ratio of the phthalonitrile resin to the nitrile rubber is 1.5~4:

1.

3. The water-resistant rubber sealing strip for a vehicle according to claim 1, wherein In step A1, the temperature is 185~190℃ during melting, and the time is 2~3h.

4. The water-resistant rubber sealing strip for a vehicle according to claim 1, wherein In step A2, the temperature is 130~140℃ during blending, and the time is 20~30min.

5. The water-resistant rubber sealing strip for an automobile according to claim 1, wherein The ternary ethylene-propylene rubber includes ENB type ternary ethylene-propylene rubber and DCPD type ternary ethylene-propylene rubber with a weight ratio of 1~4:

1.

6. The water-resistant rubber sealing strip for an automobile according to claim 1, wherein The vulcanizing agent includes one or both of sulfur and dicumyl peroxide; The vulcanization accelerator includes one or both of vulcanization accelerator TMTD and vulcanization accelerator CBS.

7. The water-resistant rubber sealing strip for a vehicle according to claim 1, wherein The antioxidant includes one or more of antioxidant RD, antioxidant NB and antioxidant DNP.

8. The water-resistant rubber sealing strip for a vehicle according to claim 1, wherein The dispersing agent includes one or more of polyethylene glycol, polyvinyl alcohol and polyvinylpyrrolidone.

9. A method for producing a water-resistant rubber weather strip for an automobile, for producing a water-resistant rubber weather strip for an automobile as claimed in any one of claims 1 to 8, characterized by, The steps include: After plasticizing the ternary ethylene-propylene rubber pretreatment, the remaining components are added for mixing, vulcanization and molding to obtain the water-resistant rubber sealing strip for automobiles.

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