Ethylene-butylene rubber sealing material and preparation method therefor

Abstract

The present invention relates to the technical field of rubber materials. Disclosed are an ethylene-butylene rubber (EBT) sealing material and a preparation method therefor. The material uses dibutyl maleate as a reaction starting material to graft with modified EBT resin as a masterbatch, which not only has ideal low-temperature retraction performance, but also has significantly improved mechanical properties and low-temperature compression set performance compared with existing EBT sealing materials, thereby meeting the reliability requirements for long-term sealing of cabinets in extreme low-temperature environments.

Description

Ethylene butylene rubber sealing material and preparation method thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of rubber materials, in particular to an ethylene butylene rubber sealing material and a preparation method thereof. BACKGROUND

[0002] The terminal row for controlling the primary setting, the secondary cable, the element, the air switch and the like in the transformer substation, the secondary control and signal circuit and the power supply circuit are all installed in the equipment box such as the terminal box, the mechanism box and the control box. Once the sealing of the box cabinet fails, it will cause the corrosion of the control circuit element, the jamming of the transmission mechanism, the burning of the split coil and the burning of the spring energy storage motor and other equipment failures, and will cause the reduction of the insulation of the operation circuit, the DC grounding and other defects, and even cause the short circuit or burning between the terminals of the terminal row, the protection misoperation or refusal, and the accident trip, which causes great harm to the safe and stable operation of the power grid equipment.

[0003] The commonly used sealing material of the box cabinet is the ethylene propylene rubber material. This material has good mechanical properties and pressure change properties under normal conditions, but the low temperature resistance of this material is poor, especially in some extremely cold areas (below-40 DEG C), the material performance deteriorates very seriously. Although the low temperature performance of the ethylene propylene rubber material can be improved by adding a low temperature plasticizer, the mechanical properties and pressure change properties of the product will be affected, and the plasticizer will be separated during the use of the material.

[0004] Therefore, people try to use a new non-polar saturated rubber, ethylene butylene rubber (EBT) instead of ethylene propylene rubber in low temperature environment. The molecular chain spacing of this material is larger than that of ethylene propylene rubber, so the free movement space between the molecular chains is large, and the intrinsic low temperature performance is excellent, and no further low temperature plasticizer needs to be introduced. However, the mechanical properties of this product still do not meet the basic index requirements of the sealing of the box cabinet. SUMMARY

[0005] Based on the defects of the prior art, the purpose of the present application is to provide an ethylene butylene rubber sealing material. The EBT resin grafted and modified by maleic acid dibutyl ester as the base rubber not only has ideal low temperature retraction performance, but also has significantly improved mechanical properties and low temperature pressure change performance compared with the existing EBT sealing material, which meets the reliability requirements of the long-term sealing of the box cabinet in the extreme low temperature environment.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows:

[0007] A maleic acid dibutyl ester grafted and modified EBT base rubber comprises the following preparation raw materials by weight:

[0008] EBT raw rubber 100 parts, dibutyl maleate 2-10 parts and initiator 0.1-0.5 parts.

[0009] Preferably, the initiator is dicumyl peroxide (DCP);

[0010] Preferably, the EBT raw rubber is non-oil-extended raw rubber;

[0011] More preferably, the EBT raw rubber is Mitsui Chemical K9330M ethyl butyl rubber raw rubber.

[0012] EBT rubber is a terpolymer of ethylene, butene and 5-ethylidene-2-norbornene (ENB) synthesized by a metallocene catalyst, the molecular chain spacing of the material is large, the free movement space of the molecular chain is large, and good retraction performance can be achieved at low temperature without the introduction of plasticizer, however, the mechanical properties of the material are poorer than those of the more widely used ethylene-propylene-diene rubber. At present, commercial EBT rubber includes oil-extended rubber and non-oil-extended rubber, the oil in the former will leave holes when volatilized, so it is difficult to be applied in sealing products, in the present application, the inventor selects non-oil-extended K9330M ethyl butyl rubber raw rubber as the base of the sealing material, and introduces a specific amount of dibutyl maleate under the condition of initiator, introduces polar groups on the non-polar rubber matrix, thereby improving the intermolecular force in the EBT rubber, and achieving the purpose of improving the mechanical properties and low temperature compression set performance of the rubber, while not damaging the low temperature retraction performance of the EBT rubber itself, so that it can achieve high mechanical properties, high low temperature compression set performance and high low temperature retraction performance as a sealing material.

[0013] Preferably, the grafting rate of the dibutyl maleate grafted EBT masterbatch is 0.75-1.5%.

[0014] More preferably, in the preparation raw materials of the dibutyl maleate grafted EBT masterbatch, the weight fraction of dibutyl maleate is 4-8 parts;

[0015] More preferably, in the preparation raw materials of the dibutyl maleate grafted EBT masterbatch, the weight fraction of the initiator is 0.2-0.4 parts.

[0016] When the grafting modification of EBT raw rubber is carried out by using different amounts of dibutyl maleate and initiator, the composition of the final product is different, and the grafting rate is naturally different, the inventor has found through experiments that when the preparation raw materials are maintained within the above preferred range, the comprehensive performance of the dibutyl maleate grafted EBT masterbatch prepared from the preparation raw materials is better when the EBT masterbatch is further prepared into ethyl butyl rubber sealing material.

[0017] Another object of the present application is to provide a preparation method of the maleic acid dibutyl ester graft modified EBT masterbatch, comprising the following steps:

[0018] The speed of the internal mixer is set to 50-70 r / min, the EBT raw rubber is put into the internal mixer and mixed for 1-3 min, then the modifier and maleic acid dibutyl ester are added for grafting reaction for 5-10 min, the rubber is discharged and cooled, and the maleic acid dibutyl ester graft modified EBT masterbatch is obtained.

[0019] Preferably, the temperature of the internal mixer is 150-170℃.

[0020] At the set temperature, the EBT raw rubber starts grafting reaction after the introduction of the initiator and maleic acid dibutyl ester (DBM), and the initiator DCP is first decomposed into the following group at 150-170℃:

[0021] Under the action of the group, the EBT raw rubber and maleic acid dibutyl ester start grafting to form EBT-g-DBM, as shown in the following structure:

[0022] At the same time, since the DCP only plays an initiating role, the maleic acid dibutyl ester graft modified EBT masterbatch of the present application is not limited to DCP as the initiator for grafting reaction, and it is known to those skilled in the art that other peroxides can also be selected as initiators for the grafting reaction of the acid ester in the EBT raw rubber, as long as appropriate temperature conditions are used to make them decompose and play an initiating role in the grafting reaction.

[0023] The preparation method of the maleic acid dibutyl ester graft modified EBT masterbatch of the present application has simple operation steps and can be implemented in industrial scale production.

[0024] Another object of the present application is to provide an ethylene-butene rubber sealing material comprising the maleic acid dibutyl ester graft modified EBT masterbatch of the present application.

[0025] Preferably, the ethylene-butene rubber sealing material comprises the following components by weight:

[0026] Maleic acid dibutyl ester graft modified EBT masterbatch 102-111 parts, reinforcing filler 35-75 parts, active agent 3.5-7.5 parts, antioxidant 1.5-4 parts, and vulcanizing agent 1-3 parts.

[0027] Preferably, the reinforcing filler comprises carbon black.

[0028] More preferably, the carbon black is at least one of carbon black N774, carbon black N550, and carbon black N990.

[0029] Preferably, the active agent is at least one of stearic acid, zinc oxide.

[0030] Preferably, the anti-aging agent is at least one of amine anti-aging agent, imidazole anti-aging agent.

[0031] Preferably, the vulcanizing agent comprises peroxide.

[0032] More preferably, the peroxide is at least one of dicumyl peroxide, 2,4-di-tert-butylperoxyisopropyl benzene, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

[0033] The maleic acid dibutyl ester grafted EBT masterbatch for preparing the ethylene-butene rubber sealing material does not need to introduce additional low-temperature toughening agent or change the proportion of reinforcing fillers in the product to a special range, so as to take into account the low-temperature retraction, low-temperature pressure change and mechanical strength in the use process, and it needs to be pointed out that the ethylene-butene rubber sealing material of the application is not limited to the above-mentioned preferred selection of other components, as long as the selected type does not affect the normal effect of the masterbatch.

[0034] Another purpose of the application is to provide a preparation method of the ethylene-butene rubber sealing material, comprising the following steps:

[0035] The maleic acid dibutyl ester grafted EBT masterbatch is placed into the thin pass bag roller of the open mill, and then other components are added and mixed for 0.5-1h, and the sheet is discharged, so as to obtain the ethylene-butene rubber sealing material.

[0036] The application has the beneficial effect that the application provides an ethylene-butene rubber sealing material, which uses the EBT resin grafted and modified by maleic acid dibutyl ester as the masterbatch, not only has ideal low-temperature retraction performance, but also significantly improves the mechanical properties and low-temperature pressure change performance compared with the existing EBT sealing material, and meets the reliability requirements of long-term sealing of cabinets in extreme low-temperature environments. DETAILED DESCRIPTION

[0037] In order to better illustrate the purpose, technical scheme and advantages of the application, the application will be further described below in combination with specific examples and comparative examples, the purpose of which is to understand the content of the application in detail, rather than to limit the application. All other examples obtained by those of ordinary skill in the art without creative labor fall within the protection scope of the application. The experimental reagents and instruments involved in the implementation of the application are common ordinary reagents and instruments unless otherwise specified.

[0038] Examples 1-9

[0039] An embodiment of the ethyl butyl rubber sealing material and the preparation method thereof, the composition of the ethyl butyl rubber sealing material is shown in Table 1.

[0040] The preparation method of the ethyl butyl rubber sealing material comprises the following steps:

[0041] (1) Preparation of maleic acid dibutyl ester grafted modified EBT masterbatch: set the speed of the internal mixer to 60 r / min and the temperature to 160℃, put the EBT raw rubber into the internal mixer and mix for 2 min, then add the modifier and maleic acid dibutyl ester for grafting reaction for 8 min, discharge the rubber and cool, thus obtaining the maleic acid dibutyl ester grafted modified EBT masterbatch;

[0042] (2) Preparation of ethyl butyl rubber sealing material: place the maleic acid dibutyl ester grafted modified EBT masterbatch into the thin pass bag roller of the open mill, then add other components and mix at 50-60℃ for 0.5 h, and then discharge the sheet, thus obtaining the ethyl butyl rubber sealing material.

[0043] Comparative Example 1

[0044] An ethyl butyl rubber sealing material and a preparation method thereof, which are different from Example 1 in that the maleic acid dibutyl ester grafted modified EBT masterbatch is not prepared, and in the preparation of the ethyl butyl rubber sealing material, the maleic acid dibutyl ester grafted modified EBT masterbatch originally added is replaced by 100 parts by weight of EBT raw rubber.

[0045] Comparative Example 2

[0046] An ethyl butyl rubber sealing material and a preparation method thereof, which are different from Example 1 in that the maleic acid dibutyl ester grafted modified EBT masterbatch is not prepared, and in the preparation of the ethyl butyl rubber sealing material, the maleic acid dibutyl ester grafted modified EBT masterbatch originally added is replaced by 100 parts by weight of EPDM raw rubber.

[0047] In the components of each embodiment and comparative example,

[0048] The EBT raw rubber is K9330M produced by Mitsui Chemical;

[0049] The EPDM raw rubber is 4090J produced by PetroChina Jilin Petrochemical;

[0050] The maleic acid dibutyl ester is a commercially available product with CAS 105-76-0;

[0051] The zinc oxide is a commercially available product with a residue (45 μm test sieve) and a mass loss of ≤0.1%.

[0052] The component raw materials used in each embodiment and comparative example of the present application are commercially available raw materials unless otherwise specified, and the component raw materials used in each parallel experiment are the same.

[0053] Table 1

[0054] In order to verify the performance of the ethyl butyl rubber sealing material described in the application, the products prepared in each example and the comparative example were vulcanized after standing for 16 h using a two-stage vulcanization process, the temperature of the first stage vulcanization was 175℃, the pressure was 18 MPa, and the time was 15 min, the temperature of the second stage vulcanization was 150℃, and the time was 4 h; then the following performance tests were carried out, the specific steps are as follows:

[0055] (1) Tensile strength test: tested according to GB / T 528-2009;

[0056] (2) Low temperature retraction performance TR10 test: tested according to GB / T 7758-2020;

[0057] (3) Low temperature compression set performance test: tested according to GB / T 7759.2-2014 under the condition of -40℃x48h.

[0058] The test results are shown in Table 2.

[0059] Table 2

[0060] As can be seen from Table 2, the ethyl butyl rubber sealing material described in the application has excellent comprehensive performance, and can take into account the mechanical strength, low temperature retraction and low temperature compression set performance. By comparing the products of Comparative Example 1 and Comparative Example 2, it can be seen that although the product prepared by using EBT raw rubber without any modification as the base rubber has better low temperature compression set and low temperature retraction performance than the product prepared by using EPDM raw rubber as the base rubber, there is a large gap in tensile strength. However, the product of Example 1 prepared by using maleic acid dibutyl ester grafted EBT base rubber has basically no change in low temperature retraction performance, but its tensile strength is significantly improved compared with the product of Comparative Example 1, and its low temperature compression set performance is also improved, and it can completely replace the product prepared by using existing EPDM raw rubber for use in the sealing application of cabinets in extremely low temperature environments.

[0061] As can be seen from the examples 1-5, in the preparation of the maleic acid dibutyl ester grafted EBT masterbatch, the addition amount of the maleic acid dibutyl ester grafting agent when introduced has an influence on the grafting rate of the product and the application effect, with the increase of the addition amount of the maleic acid dibutyl ester, the grafting rate of the prepared masterbatch product first increases and then decreases, while the low temperature retraction performance of the ethyl butyl rubber sealing material prepared finally has no obvious change, but there is a floating trend in the tensile strength and low temperature compression set performance, and the preparation effect is the best when the addition amount of the maleic acid dibutyl ester is 4-8 parts; similarly, the addition amount of the initiator DCP is different when the products of the example 1 and the examples 6-9 are used to prepare the grafted EBT masterbatch, which leads to the difference in the performance of the prepared products, and there is a certain change in the tensile strength and low temperature compression set performance, and the products prepared when the addition amount of the additive is 0.2-0.4 parts can take into account the better tensile strength and low temperature compression set performance.

[0062] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, but not to limit the protection scope of the present application, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A maleic acid dibutyl ester graft modified EBT masterbatch, characterized in that, The preparation raw materials include the following weight parts: EBT raw rubber 100 parts, dibutyl maleate 2-10 parts, and initiator 0.1-0.5 parts.

2. The maleic acid dibutyl ester grafted EBT masterbatch according to claim 1, wherein, The initiator is dicumyl peroxide (DCP); the EBT raw rubber is non-oil-extended raw rubber; 3. The maleic acid dibutyl ester grafted EBT masterbatch according to claim 1, wherein, The grafting rate of the dibutyl maleate grafted EBT masterbatch is 0.75-1.5%.

4. The maleic acid dibutyl ester grafted EBT masterbatch according to claim 1, wherein, In the preparation raw materials of the dibutyl maleate grafted EBT masterbatch, the weight parts of dibutyl maleate is 4-8 parts.

5. The maleic acid dibutyl ester grafted EBT masterbatch according to claim 1, wherein, In the preparation raw materials of the dibutyl maleate grafted EBT masterbatch, the weight parts of initiator is 0.2-0.4 parts.

6. The process for preparing the maleic acid dibutyl ester grafted EBT masterbatch according to any one of claims 1 to 5, characterized in that, The method includes the following steps: The mixer speed is set to 50-70 r / min, the EBT raw rubber is put into the mixer and mixed for 1-3 min, then the modifier and dibutyl maleate are added for grafting reaction for 5-10 min, the rubber is discharged and cooled, and the dibutyl maleate grafted EBT masterbatch is obtained.

7. An ethylene-butene rubber sealing material, characterized by, The dibutyl maleate grafted EBT masterbatch of any one of claims 1-5.

8. The ethylene-butene rubber sealing material according to claim 7, wherein The ethylene-butene rubber sealing material includes the following components by weight: Dibutyl maleate grafted EBT masterbatch 102-111 parts, reinforcing filler 35-75 parts, active agent 3.5-7.5 parts, antioxidant 1.5-4 parts, and vulcanizing agent 1-3 parts.

9. The ethylene-butene rubber sealing material according to claim 8, wherein The method includes at least one of the following (a)-(d): (a) The reinforcing filler includes carbon black; the carbon black is at least one of carbon black N774, carbon black N550, and carbon black N990. (b) The active agent is at least one of stearic acid and zinc oxide; (c) The antioxidant is at least one of amine antioxidant and imidazole antioxidant; (d) The vulcanizing agent includes peroxide; the peroxide is at least one of dicumyl peroxide, 2,4-di-tert-butylperoxyisopropyl benzene, and 2,5-dimethyl-2,5-bis(tert-butylperoxy) hexane.

10. The process for preparing an ethylene-butene rubber sealing material according to any one of claims 7 to 9, characterized in that, The method includes the following steps: The dibutyl maleate grafted EBT masterbatch is put into the thin pass roller of the open mill, then other components are added and mixed for 0.5-1 h, and the ethylene-butene rubber sealing material is obtained.

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