Ethylene-butadiene rubber sealing material and preparation method thereof

Abstract

The invention discloses an ethylene-butadiene rubber sealing material and a preparation method thereof, and belongs to the technical field of rubber materials, the material uses EBT resin grafted and modified by using dibutyl maleate as a reaction raw material as a rubber master batch, has ideal low-temperature retraction performance, and also has good sealing performance. Compared with an existing EBT sealing material, the mechanical property and the low-temperature pressure change performance of the sealing material are remarkably improved, and the reliability requirement for long-term sealing of a cabinet in an extremely low-temperature environment is met.

Description

Technical Field

[0001] The invention relates to the technical field of rubber materials, and in particular to an ethylene-butadiene rubber sealing material and a preparation method thereof. Background Art

[0002] The terminal blocks, secondary cables, components, circuit breakers and other secondary control and signal circuits and power supply circuits that control the primary settings in the substation are all installed in equipment boxes such as terminal boxes, mechanism boxes, and control boxes. Once the cabinet seal fails, the control circuit components will rust and the transmission mechanism will get stuck, causing equipment failures such as the burning of the opening and closing coils and the burning of the spring energy storage motor, as well as defects such as reduced insulation of the operating circuit and DC grounding, and even causing short circuits or burning between the terminal blocks, malfunction or refusal of protection, causing accidental tripping, which has caused great harm to the safe and stable operation of the power grid equipment.

[0003] Currently, the commonly used cabinet sealing material is EPDM rubber material, which has good mechanical properties and compression properties under normal conditions, but this material has poor low-temperature resistance, especially in some extremely cold areas (below -40°C), the material performance deteriorates very seriously; although adding low-temperature plasticizers to EPDM rubber materials can improve the low-temperature performance of the material, the mechanical and compression properties of the product will be affected, and the plasticizer will precipitate during the use of the material.

[0004] To this end, people have tried to use a new type of non-polar saturated rubber, ethylene-butadiene rubber (EBT), instead of EPDM for use in low-temperature environments. The molecular chain spacing of this material is larger than that of EPDM, so the free movement space between the molecular chains is large, and the intrinsic low-temperature performance is excellent, without the need to further introduce low-temperature plasticizers. However, the mechanical properties of this product still do not meet the basic index requirements for cabinet sealing. Summary of the invention

[0005] Based on the defects of the prior art, the purpose of the present invention is to provide an ethylene-butadiene rubber sealing material, which uses dibutyl maleate as the reaction raw material and EBT resin grafted and modified as the masterbatch. The material not only has ideal low-temperature shrinkage performance, but also has significantly improved mechanical properties and low-temperature compression performance compared to existing EBT sealing materials, thereby meeting the reliability requirements of long-term sealing of cabinets in extreme low temperature environments.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A dibutyl maleate grafted modified EBT masterbatch comprises the following raw materials in parts by weight:

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

[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 K9330M ethylene-butadiene rubber raw rubber produced by Mitsui Chemicals.

[0012] EBT rubber is a terpolymer of ethylene, butene and 5-ethylidene-2-norbornene (ENB) synthesized by metallocene catalyst. The molecular chain spacing of the material is large, and the free movement space of the molecular chain is large. It can achieve good retraction performance at low temperature without introducing plasticizers. However, the mechanical properties of the material are poorer than those of the more widely used EPDM rubber. At present, commercialized EBT rubber includes oil-filled rubber and non-oil-filled rubber. The oil in the former will leave holes when volatilizing, so it is difficult to be used in sealing products. Based on the non-oil-filled K9330M ethylene-butadiene rubber raw rubber selected as a sealing material in the present invention, the inventor introduces a specific amount of dibutyl maleate under initiator conditions, and introduces polar groups on the non-polar rubber matrix, thereby enhancing the intermolecular force in the EBT rubber, thereby achieving the purpose of improving the mechanical properties and low-temperature compression performance of the rubber, and at the same time, it will not damage the low-temperature retraction performance of the EBT rubber itself, so that it can take into account the realization of high mechanical properties, high and low temperature compression performance and high and low temperature retraction performance when used as a masterbatch of a sealing material.

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

[0014] More preferably, in the raw materials for preparing the dibutyl maleate grafted modified EBT masterbatch, the weight proportion of dibutyl maleate is 4 to 8 parts;

[0015] More preferably, in the raw materials for preparing the dibutyl maleate grafted modified EBT masterbatch, the weight portion of the initiator is 0.2 to 0.4 parts.

[0016] When different amounts of dibutyl maleate and initiator are added to carry out grafting modification of EBT raw rubber, the component composition of the final product is different, and the grafting rate is naturally different. The inventors have found through experiments that when the preparation raw materials are maintained within the above-mentioned preferred range, the prepared dibutyl maleate grafted modified EBT masterbatch has better comprehensive performance when further prepared into ethylene-butadiene rubber sealing material.

[0017] Another object of the present invention is to provide a method for preparing the dibutyl maleate grafted modified EBT masterbatch, comprising the following steps:

[0018] The speed of the internal mixer is set at 50-70 r / min, the EBT raw rubber is put into the internal mixer and mixed for 1-3 minutes, then the modifier and dibutyl maleate are added to carry out grafting reaction for 5-10 minutes, the rubber is discharged and the sheet is cooled to obtain the dibutyl maleate grafted modified EBT masterbatch.

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

[0020] At the set temperature, the EBT raw rubber begins to graft after the introduction of initiator and dibutyl maleate (DBM). First, the initiator DCP will decompose into the following groups at 150-170°C:

[0021]

[0022] Under the action of this group, EBT raw rubber and maleic acid diester begin to be grafted to form EBT-g-DBM, as shown in the following structure:

[0023]

[0024] At the same time, since the DCP only has an initiating effect, the dibutyl maleate grafted modified EBT masterbatch of the present invention is not limited to DCP as the type of initiator for the grafting reaction. It is well known to those skilled in the art that other peroxides can also be selected as initiators for the grafting reaction of the acid ester on the EBT raw rubber, as long as appropriate temperature conditions are adopted to decompose it and play a role in initiating the grafting reaction.

[0025] The preparation method of the dibutyl maleate grafted modified EBT masterbatch of the present invention has simple operation steps and can be implemented for industrial scale production.

[0026] Another object of the present invention is to provide an ethylene-butadiene rubber sealing material, comprising the dibutyl maleate grafted modified EBT masterbatch of the present invention.

[0027] Preferably, the ethylene-butadiene rubber sealing material comprises the following components in parts by weight:

[0028] 102-111 parts of dibutyl maleate grafted modified EBT masterbatch, 35-75 parts of reinforcing filler, 3.5-7.5 parts of activator, 1.5-4 parts of antioxidant and 1-3 parts of vulcanizing agent.

[0029] Preferably, the reinforcing filler comprises carbon black.

[0030] More preferably, the carbon black is at least one of carbon black N774, carbon black N550, and carbon black N990.

[0031] Preferably, the active agent is at least one of stearic acid and zinc oxide.

[0032] Preferably, the antioxidant is at least one of an amine antioxidant and an imidazole antioxidant.

[0033] Preferably, the vulcanizing agent comprises a peroxide.

[0034] More preferably, the peroxide is at least one of dicumyl peroxide, 2,4-di-tert-butylcumyl peroxide, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

[0035] When the dibutyl maleate grafted modified EBT masterbatch of the present invention is used to prepare ethylene-butadiene rubber sealing materials, there is no need to introduce additional low-temperature toughening agents or change the proportion of reinforcing fillers in the product to a specific range, even if the low-temperature shrinkage, low-temperature compression deformation and mechanical strength during use are taken into account. At the same time, it should be noted that, in addition to the masterbatch, the types of other components of the ethylene-butadiene rubber sealing material of the present invention are not limited to the above-mentioned preferred types, as long as the selected types do not affect the normal effect of the masterbatch.

[0036] Another object of the present invention is to provide a method for preparing the ethylene-butadiene rubber sealing material, comprising the following steps:

[0037] After the dibutyl maleate grafted modified EBT masterbatch is placed into the thin-rolled roll of the open mixing mill, the other components are then added and mixed for 0.5 to 1 hour, and the sheet is produced to obtain the ethylene-butyl rubber sealing material.

[0038] The beneficial effect of the present invention is that the present invention provides an ethylene-butadiene rubber sealing material, which uses dibutyl maleate as a reaction raw material and EBT resin grafted and modified as a masterbatch. The material not only has ideal low-temperature shrinkage performance, but also has significantly improved mechanical properties and low-temperature compression performance compared to existing EBT sealing materials, and meets the reliability requirements of long-term sealing of cabinets in extremely low temperature environments. DETAILED DESCRIPTION

[0039] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments and comparative examples, the purpose of which is to understand the content of the present invention in detail, rather than to limit the present invention. All other embodiments obtained by those of ordinary skill in the art without making creative work premise belong to the protection scope of the present invention. The experimental reagents and instruments involved in the implementation of the present invention, unless otherwise specified, are all commonly used common reagents and instruments.

[0040] Examples 1 to 9

[0041] An embodiment of an ethylene-butadiene rubber sealing material and a preparation method thereof according to the present invention, the components of the ethylene-butadiene rubber sealing material are shown in Table 1.

[0042] The preparation method of the ethylene-butadiene rubber sealing material comprises the following steps:

[0043] (1) Preparation of dibutyl maleate grafted modified EBT masterbatch: setting the internal mixer speed to 60 r / min and the temperature to 160° C., adding the EBT raw rubber into the internal mixer and mixing for 2 min, adding the modifier and dibutyl maleate to carry out grafting reaction for 8 min, draining the rubber, removing the sheet, and cooling to obtain the dibutyl maleate grafted modified EBT masterbatch;

[0044] (2) Preparation of ethylene-butadiene rubber sealing material: After the EBT masterbatch modified by dibutyl maleate is placed in a thin roll of an open mixing mill, the other components are then added and mixed at 50-60° C. for 0.5 h, and the ethylene-butadiene rubber sealing material is obtained by forming a sheet.

[0045] Comparative Example 1

[0046] An ethylene-butadiene rubber sealing material and a preparation method thereof, which differs from Example 1 in that the dibutyl maleate grafted modified EBT masterbatch is not prepared, and when the ethylene-butadiene rubber sealing material is prepared, the dibutyl maleate grafted modified EBT masterbatch originally added is replaced with 100 parts by weight of EBT raw rubber.

[0047] Comparative Example 2

[0048] An ethylene-butadiene rubber sealing material and a preparation method thereof, which differs from Example 1 in that no dibutyl maleate grafted modified EBT masterbatch is prepared. When preparing the ethylene-butadiene rubber sealing material, the dibutyl maleate grafted modified EBT masterbatch originally added is replaced with 100 parts by weight of EPDM raw rubber.

[0049] Among the components described in each embodiment and comparative example,

[0050] The EBT raw rubber is K9330M produced by Mitsui Chemicals;

[0051] The EPDM raw rubber is 4090J produced by PetroChina Jilin Chemical Industry;

[0052] The dibutyl maleate is a commercially available product, CAS 105-76-0;

[0053] The zinc oxide is a commercially available product, and the sieve residue (45 μm test sieve) has a mass loss of ≤0.1%.

[0054] Unless otherwise specified, the components and raw materials used in the embodiments and comparative examples of the present invention are all commercially available raw materials, and the components and raw materials used in each parallel experiment are all of the same kind.

[0055] Table 1

[0056]

[0057]

[0058] In order to verify the performance of the ethylene-butadiene rubber sealing material of the present invention, the products prepared in each embodiment and comparative example were vulcanized by a two-stage vulcanization process after standing for 16 hours, with the temperature of the first stage vulcanization being 175°C, the pressure being 18 MPa, and the time being 15 minutes, and the temperature of the second stage vulcanization being 150°C, and the time being 4 hours; and then the following performance test was carried out, and the specific steps are as follows:

[0059] (1) Tensile strength test: Tested according to GB / T 528-2009;

[0060] (2) Low temperature shrinkage performance TR10 test: tested according to GB / T 7758-2020;

[0061] (3) Low temperature compression performance test: According to GB / T 7759.2-2014, the test is carried out at -40℃×48h.

[0062] The test results are shown in Table 2.

[0063] Table 2

[0064]

[0065] As can be seen from Table 2, the ethylene-butadiene rubber sealing material of the present invention has excellent comprehensive performance, and can take into account mechanical strength, low-temperature shrinkage and low-temperature compression performance. By comparing the products of Comparative Example 1 and Comparative Example 2, it can be seen that the product prepared by using EBT raw rubber without any modification as the masterbatch has better low-temperature compression and low-temperature shrinkage performance than the product prepared by EPDM raw rubber as the masterbatch, but the difference in tensile strength is large. The product of Example 1 prepared by using EBT masterbatch modified by dibutyl maleate grafting has basically no change in low-temperature shrinkage performance, but its tensile strength is significantly improved compared with the product of Comparative Example 1, and the low-temperature compression performance is also improved. It can completely replace the existing products prepared by EPDM raw rubber for cabinet sealing applications in extreme low temperature environments.

[0066] According to Examples 1 to 5, it can be seen that when preparing the dibutyl maleate grafted modified EBT masterbatch, the amount of dibutyl maleate graft added at the time of introduction affects the grafting rate and application effect of the product. As the amount of dibutyl maleate added increases, the grafting of the prepared masterbatch product first increases and then decreases, and the finally prepared ethylene-butadiene rubber sealing material has no obvious change in low-temperature shrinkage performance, but there is a floating trend in tensile strength and low-temperature compression set performance, and the preparation effect is best when 4 to 8 parts of dibutyl maleate are added; similarly, when preparing the grafted modified EBT masterbatch of the products of Examples 1 and Examples 6 to 9, the amount of initiator DCP added is also different, resulting in differences in the performance of the prepared products, and there are certain changes in tensile strength and low-temperature compression set performance. The products prepared when 0.2 to 0.4 parts of the additive are added can take into account better tensile strength and low-temperature compression set performance.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A dibutyl maleate grafted modified EBT masterbatch, characterized in that: The preparation comprises the following raw materials in parts by weight: 100 parts of EBT raw rubber, 2-10 parts of dibutyl maleate and 0.1-0.5 parts of initiator.

2. The dibutyl maleate grafted modified EBT masterbatch as claimed in claim 1, characterized in that: The initiator is dicumyl peroxide (DCP); the EBT raw rubber is non-oil-extended raw rubber.

3. The dibutyl maleate grafted modified EBT masterbatch as claimed in claim 1, characterized in that: The grafting rate of the dibutyl maleate grafted modified EBT masterbatch is 0.75-1.5%.

4. The dibutyl maleate grafted modified EBT masterbatch as claimed in claim 1, characterized in that: In the raw materials for preparing the dibutyl maleate grafted modified EBT masterbatch, the weight proportion of dibutyl maleate is 4 to 8 parts.

5. The dibutyl maleate grafted modified EBT masterbatch as claimed in claim 1, characterized in that: In the raw materials for preparing the dibutyl maleate grafted modified EBT masterbatch, the weight portion of the initiator is 0.2 to 0.4 parts.

6. The method for preparing the dibutyl maleate grafted modified EBT masterbatch according to any one of claims 1 to 5, characterized in that: The following steps are involved: The speed of the internal mixer is set at 50-70 r / min, the EBT raw rubber is put into the internal mixer and mixed for 1-3 minutes, then the modifier and dibutyl maleate are added to carry out grafting reaction for 5-10 minutes, the rubber is discharged and the sheet is cooled to obtain the dibutyl maleate grafted modified EBT masterbatch.

7. An ethylene-butadiene rubber sealing material, characterized in that: The invention comprises the dibutyl maleate grafted modified EBT masterbatch as described in any one of claims 1 to 5.

8. The ethylene-butadiene rubber sealing material according to claim 7, characterized in that: The ethylene-butadiene rubber sealing material comprises the following components in parts by weight: 102-111 parts of dibutyl maleate grafted modified EBT masterbatch, 35-75 parts of reinforcing filler, 3.5-7.5 parts of activator, 1.5-4 parts of antioxidant and 1-3 parts of vulcanizing agent.

9. The ethylene-butadiene rubber sealing material according to claim 8, characterized in that: Include at least one of the following (a) to (d): (a) The reinforcing filler comprises 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 an amine antioxidant and an imidazole antioxidant; (d) The vulcanizing agent includes a peroxide; the peroxide is at least one of dicumyl peroxide, 2,4-di-tert-butylcumyl peroxide, and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane.

10. The method for preparing the ethylene-butadiene rubber sealing material according to any one of claims 7 to 9, characterized in that: The following steps are involved: After the dibutyl maleate grafted modified EBT masterbatch is placed into the thin-rolled roll of the open mixing mill, the other components are then added and mixed for 0.5 to 1 hour, and the sheet is produced to obtain the ethylene-butyl rubber sealing material.

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