WO2018130193A1

WO2018130193A1 - Rubber composite, processing method, applications, and capacitor sealing element comprising composite

Info

Publication number: WO2018130193A1
Application number: PCT/CN2018/072363
Authority: WO
Inventors: 徐涛; 傅智盛; 吴安洋
Original assignee: 杭州星庐科技有限公司
Priority date: 2017-01-13
Filing date: 2018-01-12
Publication date: 2018-07-19

Abstract

A rubber composite, a processing method, a capacitor sealing element applying the rubber composite. The rubber composite comprises a rubber substrate and essential components. The rubber substrate comprises branched polyethylene, ethylene propylene monomer rubber, and ethylene propylene diene monomer rubber. The content of branched polyethylene is a: 0 < a ≤ 100 parts; the content of ethylene propylene monomer rubber and ethylene propylene diene monomer rubber is b: 0 ≤ b < 100 parts. The essential components comprise: a crosslinking agent 1.5-10 parts and a reinforcing filler 45-150 parts, where the reinforcing filler comprises carbon black, and the parts by weigh of the carbon black is 0 < a ≤ 30 parts. The rubber composite is applicable in manufacturing the capacitor sealing element. The capacitor sealing element manufactured utilizing the rubber composite has a high volume resistivity and great performance in the resistance against permanent deformation under compression.

Description

Rubber composition, processing method and application thereof, and capacitor sealing device including the same

Technical field

The present invention relates to the field of rubber, and in particular to a rubber composition and a processing method thereof, and to a sealing member for a capacitor to which the rubber composition is applied.

Background technique

Ethylene-propylene rubber is widely used in the manufacture of capacitor seals due to its good electrical insulation, heat aging resistance, medium resistance and low compression set. Sulfur vulcanization and peroxide vulcanization are two conventional vulcanization methods for ethylene-propylene rubber. In order to avoid the deterioration of electrolyte performance by free sulfur molecules in the sulfur vulcanization system, the peroxide crosslinking system is gradually becoming more and more, but the capacitor is sealed. The requirements for tear resistance are higher, and the tear strength of peroxide-cured ethylene-propylene rubber is lower than that of sulfur-vulcanized ethylene-propylene rubber, which may lead to an increased risk of damage to the capacitor seal during actual use. It is not good for security, so this is a contradiction that needs to be resolved urgently. How to further balance the improvement of electrical insulation, aging resistance and mechanical strength of ethylene propylene rubber is a problem.

Ethylene-propylene rubber is a synthetic rubber with saturated molecular chain. It can be divided into two major categories: ethylene-propylene rubber and EPDM rubber. Both of them have good aging resistance. They are commonly used in ethylene-propylene rubber products. It is EPDM rubber, but because EPDM rubber contains a third monomer, the molecular chain contains double bonds, and the ethylene-propylene rubber molecular chain is completely saturated, so the ethylene-propylene rubber has more excellent resistance to aging. Sex, therefore, in the case of high requirements for aging resistance, it is a common technical solution to improve the aging resistance of EPDM by using ethylene propylene diene rubber together. However, the mechanical strength of the binary ethylene propylene rubber is low, which will affect the overall physical and mechanical properties.

Diethylene propylene rubber is a copolymer of ethylene and propylene and belongs to the copolymer of ethylene and α-olefin. Ethylene and α-olefin copolymers are polymers containing only hydrocarbon elements and saturated molecular chains. The common types of carbon atoms in such polymers are generally classified into primary, secondary and tertiary carbons, while tertiary carbons are the most It is easy to be trapped by hydrogen to form free radicals, so the ratio of tertiary carbon atoms to all carbon atoms is generally considered to be a major factor affecting the aging resistance of ethylene and α-olefin copolymers. The lower the ratio, the better the aging resistance. The ratio can be expressed by the degree of branching. For example, a diethylene propylene rubber having a propylene content of 60% by weight can be calculated to contain 200 propylene units per 1000 carbon atoms, that is, 200 tertiary carbon atoms or 200. One methyl branch, so its degree of branching is 200 branches / 1000 carbons. Ethylene ethylene propylene rubber generally has a weight percentage of 40% to 65% or 40% to 60%, so its branching degree is generally 117 to 200 branches/1000 carbons or 133 to 200 branches/ This degree of branching can be considered to be higher than other common ethylene and alpha-olefin copolymers in the 1000 carbon range.

In the prior art, the α-olefin in the common ethylene and α-olefin copolymer may be an α-olefin having a carbon number of not less than 4 in addition to propylene, and may be selected from a C ₄ - C ₂₀ α-olefin. It is usually selected from the group consisting of 1-butene, 1-hexene and 1-octene. If the degree of branching of the copolymer of ethylene and α-olefin is too low, the melting point and crystallinity are too high, and it is not suitable for use as a rubber component. If the degree of branching is high, the content of α-olefin is high, which may result in Process difficulty and raw material cost are high, and operability and economy are low. In the prior art, a polyolefin obtained by copolymerizing ethylene with 1-butene or ethylene and 1-octene may be referred to as a polyolefin plastomer or a polyolefin elastomer according to the degree of crystallinity and melting point, and a part of the polyolefin is elastic. Due to its proper crystallinity and melting point, it can be used well with ethylene propylene rubber and has a low degree of branching. It is considered to be an ideal material for improving the aging resistance of ethylene propylene rubber. It can replace ethylene propylene rubber to a certain extent. use. Since the molecular chain of ethylene and 1-octene copolymer is softer, more rubbery and has good physical and mechanical properties relative to the copolymer of ethylene and 1-butene, the polyolefin elastomer commonly used in rubber products is generally ethylene. And the copolymer of 1-octene, the octene weight percentage is generally not higher than 45%, more commonly not higher than 40%, the corresponding degree of branching is generally not higher than 56 branches / 1000 carbon, The more commonly used degree of branching is not higher than 50 branches/1000 carbons, which is much lower than the degree of branching of ethylene dipropylene rubber, so it has excellent aging resistance and good physical and mechanical properties.

The rubber generally needs to be used after cross-linking. In the cross-linking mode commonly used for ethylene-propylene rubber, the copolymer of ethylene and α-olefin may be peroxide cross-linking or irradiation cross-linking, both of which are mainly obtained by capturing tertiary carbon. a hydrogen atom forms a tertiary carbon radical, and then forms a carbon-carbon crosslink by radical bonding, but a copolymer of ethylene and 1-octene (hereinafter referred to as POE) has fewer tertiary carbon atoms and is attached to a tertiary carbon atom. Chain length, large steric hindrance, difficulty in radical reaction, resulting in difficulty in crosslinking, affecting processing efficiency and product performance, such as compression set resistance is unsatisfactory.

Therefore, there is a need for a better technical solution to improve the aging resistance of ethylene propylene rubber, while having good physical and mechanical properties and cross-linking performance, and it is expected to target specific functional indicators (such as electricity) for rubber products. Insulation, compression set resistance, etc.) have a good performance.

Summary of the invention

In view of the contradictions existing in the prior art, the present invention provides a novel rubber composition and processing method, and a capacitor sealing member comprising the rubber composition to improve the performance of the capacitor sealing member.

In order to achieve the above object, the present invention adopts the following technical solution: a rubber composition comprising: a rubber matrix and a necessary component, the rubber matrix comprising: the content of branched polyethylene is a: 0 by weight <a ≤ 100 parts, the content of the binary ethylene propylene rubber and the ethylene propylene diene rubber b: 0 ≤ b < 100 parts; the necessary components include: 1.5 to 10 parts of the crosslinking agent based on 100 parts by weight of the rubber matrix Reinforcing filler 45 to 150 parts, wherein the reinforcing filler comprises carbon black, and the weight fraction of the carbon black is 0 < a ≤ 30 parts, wherein the branching degree of the branched polyethylene is not less than 50 Branched / 1000 carbon, weight average molecular weight of not less than 50,000, Mooney viscosity ML (1 + 4) 125 ° C not less than 2.

"Branched polyethylene" in the prior art means, in addition to a branched ethylene homopolymer, a branched saturated vinyl copolymer, such as an ethylene-α-olefin copolymer, which may be POE, although POE performs well in physical and mechanical properties and aging resistance, but cross-linking performance is not good, although the branched polyethylene of the present invention can contain both branched ethylene homopolymer and POE, but a better choice It is a branched polyethylene having a high proportion of branched polyethylene or a branched ethylene homopolymer. In a preferred embodiment of the invention, the branched polyethylene contains only branched ethylene homopolymer.

In the further elaboration of the technical solution of the present invention, the branched polyethylene used is a branched ethylene homopolymer unless otherwise specified.

The branched polyethylene used in the present invention is a kind of ethylene homopolymer having a branching degree of not less than 50 branches/1000 carbons, and can be called Branched Polyethylene or Branched PE. Currently, the synthesis method is mainly composed of a late transition metal catalyst. The homopolymerization of ethylene is catalyzed by a "chain walking mechanism", and the preferred late transition metal catalyst may be one of (α-diimine) nickel/palladium catalysts. The nature of the chain walking mechanism refers to the late transition metal catalyst. For example, the (α-diimine) nickel/palladium catalyst is more likely to undergo β-hydrogen elimination reaction and re-insertion reaction in the process of catalyzing olefin polymerization, thereby causing branching. Branched chains of such branched polyethylenes may have different numbers of carbon atoms, specifically 1 to 6, or more carbon atoms.

The production cost of the (α-diimine) nickel catalyst is significantly lower than that of the (α-diimine) palladium catalyst, and the (α-diimine) nickel catalyst catalyzes the high rate of ethylene polymerization and high activity, and is more suitable for industrial applications. Therefore, the branched polyethylene prepared by the ethylene polymerization of the (α-diimine) nickel catalyst is preferred in the present invention.

The degree of branching of the branched polyethylene used in the present invention is preferably 50 to 130 branches/1000 carbons, further preferably 60 to 130 branches/1000 carbons, further preferably 60 to 116 branches/1000. A carbon, the degree of branching between POE and ethylene-propylene rubber, is a new technical solution that is different from the prior art, and can have excellent aging resistance and good cross-linking performance.

Cross-linking performance includes factors such as crosslink density and cross-linking rate, which is the specific performance of the cross-linking ability of the rubber matrix during processing.

The branched polyethylene used in the present invention preferably has a methyl branch content of 40% or more or 50% or more, and has a certain similarity with the structure of the ethylene propylene diene rubber. In terms of cross-linking ability, the degree of branching (tertiary carbon atom content) and the steric hindrance around the tertiary carbon atom are the two main factors affecting the cross-linking ability of the saturated polyolefin. The branched polyethylene used in the present invention is low in degree of branching relative to the ethylene propylene rubber, and since the branched polyethylene has a branch having a carbon number of not less than 2, the branched polycondensation used in the present invention The steric hindrance around the tertiary carbon atom of ethylene is theoretically larger than that of ethylene propylene rubber. It can be judged by combining two factors that the crosslinking ability of the branched polyethylene used in the present invention should be weaker than that of the ethylene propylene rubber. In EPDM rubber. However, the actual cross-linking ability of the partially branched polyethylene used in the present invention is close to that of EPDM rubber, and may even be equal to or better than EPDM rubber. This means that the rubber composition of the present invention can obtain a good aging resistance, can also not weaken the crosslinking ability, and can even have excellent crosslinking performance to achieve an unexpected beneficial effect.

This may be explained by the fact that there may be an appropriate number of secondary branched structures on the branched polyethylene used in the preferred embodiment of the present invention, and the so-called secondary branched structure refers to a structure in which branches are further branched. This is also known as "branch-on-branch" during chain walking. Because of the low steric hindrance around the tertiary carbon atoms of the secondary branches, cross-linking reactions are more likely to occur. Having a secondary branched structure is a distinct distinction between the branched polyethylene used in the preferred embodiment of the invention and the prior art ethylene dipropylene rubber or the conventional ethylene-α-olefin copolymer.

It is a new technical solution to improve the cross-linking ability of saturated polyolefin elastomer by using the secondary steric structure with lower steric hindrance. Under the technical solution of the present invention, it is also considered to be within the technical protection of the present invention to include a vinyl copolymer having a secondary branched structure or other saturated hydrocarbon polymer in the rubber matrix. The vinyl copolymer refers to a copolymer of ethylene and a branched α-olefin, and has a secondary branched structure, wherein the branched α-olefin may be selected from the group consisting of isobutylene and 3-methyl-1- Butylene, 4-methyl-1-pentene, 3-methyl-1-pentene, 2-methyl-1-heptene, 3-methyl-1-heptene, 4-methyl-1- The heptene, 5-methyl-1-heptene, 6-methyl-1-heptene, and the like, the comonomer may also contain a common linear alpha-olefin.

It is generally believed in the prior art that the branched polyethylene prepared by the (α-diimine) nickel catalyst is difficult to exist in the secondary branched structure, and at least it is difficult to sufficiently distinguish it. The technical solution of the present invention is also to analyze the branched polycondensation. The structure of ethylene provides a new idea.

Compared with ethylene propylene rubber, when the branched polyethylene has an appropriate number of secondary branched structures, the cross-linking point of the branched polyethylene can be generated on the tertiary chain of the main chain during the peroxide crosslinking process. It can also be produced on the branched tertiary carbon of the secondary structure, so the rubber network formed by the cross-linking of the branched polyethylene has a richer CC connecting segment between the main chains than the ethylene-propylene rubber. The length can effectively avoid stress concentration and help to obtain better mechanical properties, including tear strength. On the other hand, better cross-linking ability can effectively increase the cross-linking density, and the molecular weight distribution of the branched polyethylene is close to 2, which is narrower than that of the general ethylene-propylene rubber, so that it is also expected to obtain better compression set resistance.

A further technical solution is that the selected ethylene-propylene rubber and ethylene propylene diene rubber have a Mooney viscosity ML (1+4) of preferably 40 to 80 at 125 ° C and an ethylene content of preferably 45% to 70%.

A further technical solution is that the content of the branched polyethylene in the 100 parts by weight of the rubber matrix is a: 10 ≤ a ≤ 100 parts; the content of the binary ethylene propylene rubber and the ethylene propylene diene rubber is b: 0 ≤ b ≤ 90 The branched polyethylene is characterized by being an ethylene homopolymer having a degree of branching of 60 to 130 branches/1000 carbons, a weight average molecular weight of 66,000 to 518,000, and a Mooney viscosity ML (1+). 4) 125 ° C is 6 to 102.

A further technical solution is that the content of the branched polyethylene in the 100 parts by weight of the rubber matrix is a: 10 ≤ a ≤ 100 parts; the content of the binary ethylene propylene rubber and the ethylene propylene diene rubber is b: 0 ≤ b ≤ 90 The branched polyethylene is an ethylene homopolymer having a degree of branching of 70 to 116 branches/1000 carbons, a weight average molecular weight of 201,000 to 436,000, and a Mooney viscosity of ML (1+4) 125. °C is 23-101;

A further technical solution is that the content of the branched polyethylene in the 100 parts by weight of the rubber matrix is a: 10 ≤ a ≤ 100 parts; the content of the binary ethylene propylene rubber and the ethylene propylene diene rubber is b: 0 ≤ b ≤ 90 The branched polyethylene is an ethylene homopolymer having a degree of branching of 80 to 105 branches/1000 carbons, a weight average molecular weight of 250,000 to 400,000, and a Mooney viscosity of ML (1+4) 125. °C is 40 to 95.

A further technical solution is that the content of the branched polyethylene in the 100 parts by weight of the rubber matrix is a: 10 ≤ a ≤ 100 parts; the content of the binary ethylene propylene rubber and the ethylene propylene diene rubber is b: 0 ≤ b ≤ 90 The branched polyethylene is an ethylene homopolymer having a degree of branching of 80 to 105 branches/1000 carbons, a weight average molecular weight of 268,000 to 356,000, and a Mooney viscosity of ML (1+4) 125. °C is 42-80.

A further technical solution is that the third monomer of the ethylene propylene diene monomer is preferably a diene monomer, specifically selected from the group consisting of 5-ethylidene-2-norbornene and 5-vinyl-2-nor Borneene, dicyclopentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,4-pentadiene, 2-methyl-1,4-pentadiene, 3-methyl- 1,4-Hexadiene, 4-methyl-1,4-hexadiene, 1,9-decadiene, 5-methylene-2-norbornene, 5-pentylene-2-nor Borbornene, 1,5-cyclooctadiene, 1,4-cyclooctadiene, and the like. Specifically, the ethylene propylene rubber may contain two or more kinds of diene monomers at the same time, such as 5-ethylidene-2-norbornene and 5-vinyl-2-norbornene. The functional group of the diene monomer can play the same role as the intrinsic co-crosslinking agent in the peroxide vulcanization, thereby improving the crosslinking efficiency. This helps to reduce the amount and residual amount of crosslinker and co-crosslinker required and the cost of adding them. The weight specific gravity of the diene monomer to the ethylene propylene rubber is preferably from 1% to 14%, more preferably from 3% to 10%, still more preferably from 4% to 7%.

In a further technical solution, the reinforcing filler further includes at least one of calcium carbonate, talc, calcined clay, magnesium silicate, and magnesium carbonate.

In a further technical solution, the crosslinking agent comprises at least one of a peroxide crosslinking agent and a sulfur, and the peroxide crosslinking agent is di-tert-butyl peroxide, dicumyl peroxide, Tert-butyl cumyl peroxide, 1,1-di-tert-butyl peroxide-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(tert-butyl) Base oxidized) hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, bis(tert-butylperoxyisopropyl)benzene, 2,5-di At least one of methyl-2,5-bis(benzoyl peroxy)hexane, tert-butyl peroxybenzoate, and t-butylperoxy-2-ethylhexyl carbonate.

According to a further technical proposal, the rubber composition further comprises an auxiliary component, which comprises: 0.2 to 12 parts of a co-crosslinking agent, 1 to 5 parts of a plasticizer, and a metal oxide, based on 100 parts by weight of the rubber matrix. 2 to 10 parts, vulcanization accelerator 0 to 3 parts.

A further technical solution is that the co-crosslinking agent comprises triallyl cyanurate, triallyl isocyanurate, ethylene glycol dimethacrylate, and triethylene glycol dimethacrylate. , triallyl trimellitate, trimethylolpropane trimethacrylate, N,N'-m-phenylene bismaleimide, N,N'-bis-indenylacetone, 1,2 At least one of polybutadiene, a metal salt of an unsaturated carboxylic acid, and sulfur. The unsaturated carboxylic acid metal salt contains at least one of zinc acrylate, zinc methacrylate, magnesium methacrylate, calcium methacrylate, and aluminum methacrylate.

In a further technical solution, the plasticizer is at least one of pine tar, engine oil, naphthenic oil, paraffin oil, coumarone, RX-80, stearic acid, paraffin wax, and liquid polyisobutylene. The rational use of plasticizers can increase the flexibility of the compound and the plasticity suitable for process operation. In order to increase the viscosity, it is also preferred to use an adhesion promoter such as pine tar, coumarone, RX-80, liquid polyisobutylene or the like.

In a further technical solution, the metal oxide is at least one of zinc oxide, magnesium oxide, and calcium oxide.

According to a further technical proposal, the vulcanization accelerator comprises 2-thiol benzothiazole, dibenzothiazyl disulfide, tetramethyl thiuram monosulfide, tetramethyl thiuram disulfide, tetrazyl disulfide Kethiram, N-cyclohexyl-2-benzothiazolyl sulfenamide, N,N-dicyclohexyl-2-benzothiazolyl sulfenamide, bismaleimide, ethylene thiourea At least one of them.

The rubber composition of the present invention may be present in the form of an uncrosslinked rubber compound, and may be present in the form of a vulcanized rubber after further crosslinking reaction. Vulcanized rubber can also be referred to simply as vulcanizate.

The present invention also provides a method of processing the above rubber composition, the processing method comprising the steps of:

(1) Rubber kneading: setting the temperature of the internal mixer and the rotation speed of the rotor, firstly adding the rubber composition other than the crosslinking system to the internal mixer for mixing by weight, and then adding the crosslinking system to be kneaded. After uniformly discharging, the rubber mixture is obtained, and the rubber compound is thinned on the open mill, and then the film is left to be vulcanized, wherein the crosslinking system contains a crosslinking agent, and may further include a crosslinking agent and a vulcanization accelerator. ;

(2) Vulcanization: The rubber compound is filled into the cavity of the mold, and after being vulcanized by vulcanization on a flat vulcanizer, the vulcanized rubber is obtained by demolding. In order to improve the compression set resistance of the vulcanizate, it is further possible to carry out vulcanization using a two-stage vulcanization process.

The present invention also provides a seal for a capacitor comprising the above rubber composition.

The invention has the beneficial effects that the partial or complete replacement of the ethylene-propylene rubber in the rubber composition with the branched polyethylene adopts a peroxide vulcanization system, the principle is that the branched polyethylene has more branches in its molecular structure. And the length of the branch has a certain length and length distribution. When the branched polyethylene has an appropriate number of secondary branched structures, the cross-linking point of the branched polyethylene can be generated on the tertiary carbon of the main chain during the peroxide crosslinking process. It can also be produced on the branched tertiary carbon of the secondary structure, so the rubber network formed by the cross-linking of the branched polyethylene has a richer CC chain between the main chains than the ethylene-propylene rubber. The length of the segment can effectively avoid stress concentration and help to obtain better mechanical properties, including tear strength. And since the molecular weight distribution of the branched polyethylene is narrow, generally lower than 2.5, the rubber composition of the present invention has a lower compression set after vulcanization. The vulcanized rubber has improved tensile strength, tear strength and volume resistivity, and can simultaneously obtain better mechanical properties, electrical insulation properties and compression set resistance properties. Therefore, the novel rubber composition provided by the present invention is more suitable for the manufacture of capacitor seals.

detailed description

The following examples are given to further illustrate the present invention, but are not intended to limit the scope of the present invention, and some non-essential improvements and adjustments made by those skilled in the art based on the present invention remain within the scope of the present invention. .

In order to more clearly describe the embodiments of the present invention, the materials to which the present invention relates are defined below.

The Mooney viscosity ML (1+4) of the ethylene-propylene rubber used is preferably 20 to 50, more preferably 40 to 50, and preferably 4 to 60%.

The Mooney viscosity ML (1+4) of the ethylene propylene diene rubber used is preferably 20 to 100, more preferably 40 to 80, the ethylene content is preferably 50% to 75%, and the third monomer is 5-ethylene-2. - norbornene, 5-vinyl-2-norbornene or dicyclopentadiene, the third monomer content being from 1% to 7%.

The branched polyethylene used can be obtained by catalyzing the homopolymerization of ethylene by a (α-diimine) nickel catalyst under the action of a cocatalyst. The structure, synthesis method and method for preparing branched polyethylene by using the (α-diimine) nickel catalyst are disclosed in the prior art, and can be used but are not limited to the following documents: CN102827312A, CN101812145A, CN101531725A, CN104926962A, US6103658, US6660677.

The branched polyethylenes involved in the examples are characterized by a branching degree of 60 to 130 branches/1000 carbons, a weight average molecular weight of 66,000 to 518,000, and a Mooney viscosity of ML (1+4) of 125 ° C of 6 ~102.

In an embodiment of the present invention, there is provided a formulation of a rubber composition comprising: a rubber matrix and a necessary component, the rubber matrix comprising: a branched polyethylene content of a: 0 < a ≤ 100 parts, a binary ethylene propylene rubber And the content of ethylene propylene diene monomer b: 0 ≤ b < 100 parts; based on 100 parts by weight of the rubber matrix, the necessary components include: 1.5 to 10 parts of a crosslinking agent, 45 to 150 parts of a reinforcing filler, wherein The reinforcing filler contains carbon black and contains 0 < a ≤ 30 parts by weight of carbon black. The reinforcing filler further includes at least one of calcium carbonate, talc, calcined clay, magnesium silicate, and magnesium carbonate.

The crosslinking agent includes at least one of a peroxide crosslinking agent and a sulfur crosslinking agent, and the peroxide crosslinking agent is di-tert-butyl peroxide, dicumyl peroxide, and tert-butyl cumyl peroxide. 1,1-di-tert-butyl peroxide-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 2 ,5-Dimethyl-2,5-di(tert-butylperoxy)hexyne-3, bis(tert-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di At least one of (benzoyl peroxide) hexane, tert-butyl peroxybenzoate, and t-butylperoxy-2-ethylhexyl carbonate.

Further, the rubber composition may further include an auxiliary component comprising 0.2 to 12 parts of a co-crosslinking agent, 1 to 5 parts of a plasticizer, 2 to 10 parts of a metal oxide, and 0 to 3 parts of a vulcanization accelerator. Wherein the co-crosslinking agent comprises triallyl cyanurate, triallyl isocyanurate, ethylene glycol dimethacrylate, ethyl dimethacrylate, triethylene dimethacrylate Ester, triallyl trimellitate, trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, N,N'-m-phenylene bismaleimide, N,N' - at least one of bis-indenyl acetonide, 1,2-polybutadiene, a metal salt of an unsaturated carboxylic acid, and sulfur. The unsaturated carboxylic acid metal salt contains at least one of zinc acrylate, zinc methacrylate, magnesium methacrylate, calcium methacrylate, and aluminum methacrylate. The plasticizer is at least one of pine tar, motor oil, naphthenic oil, paraffin oil, coumarone, RX-80, stearic acid, paraffin wax, and liquid polyisobutylene.

The metal oxide is at least one of zinc oxide, magnesium oxide, and calcium oxide. The vulcanization accelerator comprises 2-thiol benzothiazole, dibenzothiazole disulfide, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, N-ring At least one of hexyl-2-benzothiazolylsulfenamide, N,N-dicyclohexyl-2-phenylthiazolylsulfenamide, bismaleimide, and ethylenethiourea.

A method of processing a rubber composition is also provided in an embodiment of the present invention, the processing method comprising the steps of:

(1) Rubber kneading: setting the temperature of the internal mixer and the rotation speed of the rotor. First, the rubber composition other than the crosslinking system is sequentially added to the internal mixer according to the weight fraction for kneading, and then the crosslinking system is added and kneaded. After uniform discharge, the mixture is obtained. The mixture is thinned on the open mill and then discharged, and is parked for vulcanization, wherein the crosslinking system comprises a crosslinking agent, and may further include at least one of a crosslinking agent and a vulcanization accelerator;

(2) Vulcanization: The rubber compound is filled into the cavity of the mold, and after being vulcanized by vulcanization on a flat vulcanizer, the vulcanized rubber is obtained by demolding.

The above rubber composition can be used to manufacture a seal for a capacitor.

The degree of branching of the branched polyethylene in the present invention is measured by nuclear magnetic resonance spectroscopy, and the molar percentages of various branches are measured by nuclear magnetic carbon spectroscopy, as shown in the following table:

Rubber performance test method:

1. Hardness test: According to the national standard GB/T 531.1-2008, the test is carried out with a hardness tester, and the test temperature is room temperature;

2, tensile strength, elongation at break performance test: in accordance with the national standard GB/T528-2009, using an electronic tensile testing machine for testing, the tensile speed is 500mm / min, the test temperature is 23 ± 2 ° C, the sample is type 2 Dumbbell sample

3, tear strength test: in accordance with the national standard GB/T529-2008, using an electronic tensile test machine for testing, the tensile speed is 500mm / min, the test temperature is 23 ± 2 ° C, the sample is a rectangular sample;

4, compression permanent deformation test: in accordance with the national standard GB/T7759-1996, using a compression permanent deformation device for testing, type B, the compression is 25%, the test temperature is 70 ° C;

5, Mooney viscosity test: in accordance with the national standard GB/T1232.1-2000, with Mooney viscosity meter for testing, the test temperature is 125 ° C, preheat 1 minute, test 4 minutes;

6, hot air accelerated aging test: in accordance with the national standard GB/T3512-2001, in the heat aging test chamber, the test conditions are 150 ° C × 72h;

7. Positive curing time Tc90 test: According to the national standard GB/T16584-1996, it is carried out in a rotorless vulcanizer, and the test temperature is 160 °C.

The vulcanization conditions of the following Examples 1 to 10 and Comparative Examples 1 and 2 were uniform: temperature: 160 ° C; pressure: 16 MPa; time was Tc90 + 2 min.

Example 1:

The branched polyethylene used was numbered PER-7.

The processing steps are as follows:

(1) Mixing: set the internal temperature of the mixer to 80 ° C, the rotor speed to 50 rpm, add 50 parts of ethylene propylene diene rubber and 50 parts of branched polyethylene for 90 seconds; 20 parts of carbon black N774 and 80 parts of calcined clay, mixing for 3 minutes; finally adding 4 parts of cross-linking agent dicumyl peroxide (DCP) and 1 part of cross-linking agent triallyl isocyanurate (TAIC), mixing Discharge the glue after 2 minutes. The kneaded rubber was thinly passed through an open mill having a roll temperature of 60 ° C to obtain a sheet having a thickness of about 2.5 mm, and was left to stand for 20 hours.

(2) After the vulcanization, the test was carried out for 16 hours.

Example 2:

The branched polyethylene used was numbered PER-7.

The processing steps are as follows:

(1) Mixing: set the temperature of the mixer to 80 ° C, the rotor speed to 50 rpm, add 100 parts of branched polyethylene pre-pressed and kneaded for 90 seconds; add 20 parts of carbon black N774 and 80 parts of calcined clay, mix For 3 minutes; finally, 4 parts of cross-linking agent dicumyl peroxide (DCP) and 1 part of cross-linking agent triallyl isocyanurate (TAIC) were added, and the mixture was mixed for 2 minutes and then discharged. The kneaded rubber was thinly passed through an open mill having a roll temperature of 60 ° C to obtain a sheet having a thickness of about 2.5 mm, and was left to stand for 20 hours.

(2) After the vulcanization, the test was carried out for 16 hours.

Comparative Example 1:

The branched polyethylene used was numbered PER-7.

The processing steps are as follows:

(1) Mixing: set the temperature of the mixer to 80 ° C, the rotor speed to 50 rpm, add 100 parts of EPDM rubber for 90 seconds, and add 20 parts of carbon black N774 and 80 parts of calcined clay. The mixture was kneaded for 3 minutes; finally, 4 parts of a cross-linking agent, dicumyl peroxide (DCP) and 1 part of a co-crosslinking agent, triallyl isocyanurate (TAIC), were added, and the mixture was kneaded for 2 minutes and then discharged. The kneaded rubber was thinly passed through an open mill having a roll temperature of 60 ° C to obtain a sheet having a thickness of about 2.5 mm, and was left to stand for 20 hours.

(2) After the vulcanization, the test was carried out for 16 hours.

Example 3:

The branched polyethylene used was numbered PER-9.

The processing steps are as follows:

(1) Mixing: set the temperature of the internal mixer to 80 ° C, the rotor speed to 50 rpm, add 90 parts of ethylene propylene diene rubber and 10 parts of branched polyethylene for 90 seconds; then add 5 parts of oxidation. Zinc and 1 part stearic acid, mixing for 1 minute; adding 25 parts of carbon black N774, 100 parts of calcined clay and 2 parts of paraffin, mixing for 3 minutes; finally adding 6 parts of cross-linking dicumyl peroxide (DCP) And 2 parts of the co-crosslinking agent, triallyl isocyanurate (TAIC), was mixed for 2 minutes and then discharged. The kneaded rubber was thinly passed through an open mill having a roll temperature of 60 ° C to obtain a sheet having a thickness of about 2.5 mm, and was left to stand for 20 hours.

(2) After the vulcanization, the test was carried out for 16 hours.

Example 4:

The branched polyethylene used was numbered PER-8.

The processing steps are as follows:

(1) Mixing: set the temperature of the internal mixer to 80 ° C, the rotor speed to 50 rpm, add 20 parts of ethylene propylene diene rubber, 60 parts of ethylene propylene diene monomer and 20 parts of prepolymerized polyethylene. 90 seconds; then add 5 parts of zinc oxide and 1 part of stearic acid, mix for 1 minute; add 25 parts of carbon black N774, 100 parts of calcined clay and 2 parts of paraffin, mix for 3 minutes; finally add 6 parts of cross-linking agent Dicumyl oxide (DCP) and 2 parts of the co-crosslinking agent, triallyl isocyanurate (TAIC), were mixed for 2 minutes and then discharged. The kneaded rubber was thinly passed through an open mill having a roll temperature of 60 ° C to obtain a sheet having a thickness of about 2.5 mm, and was left to stand for 20 hours.

(2) After the vulcanization, the test was carried out for 16 hours.

Example 5:

The branched polyethylene used was numbered PER-5.

The processing steps are as follows:

(1) Mixing: set the temperature of the internal mixer to 80 ° C, the rotor speed to 50 rpm, add 50 parts of ethylene propylene diene rubber and 50 parts of branched polyethylene for 90 seconds; then add 5 parts of oxidation. Zinc and 1 part stearic acid, mixing for 1 minute; adding 25 parts of carbon black N774, 100 parts of calcined clay and 2 parts of paraffin, mixing for 3 minutes; finally adding 6 parts of cross-linking dicumyl peroxide (DCP) And 2 parts of the co-crosslinking agent, triallyl isocyanurate (TAIC), was mixed for 2 minutes and then discharged. The kneaded rubber was thinly passed through an open mill having a roll temperature of 60 ° C to obtain a sheet having a thickness of about 2.5 mm, and was left to stand for 20 hours.

(2) After the vulcanization, the test was carried out for 16 hours.

Example 6

The branched polyethylene used was numbered PER-6.

The processing steps are as follows:

(1) Mixing: set the temperature of the internal mixer to 80 ° C, the rotor speed to 50 rpm, and add 100 parts of branched polyethylene pre-pressed for 90 seconds; then add 5 parts of zinc oxide and 1 part of stearic acid. Mixing for 1 minute; adding 25 parts of carbon black N774, 100 parts of calcined clay and 2 parts of paraffin, mixing for 3 minutes; finally adding 6 parts of cross-linking agent dicumyl peroxide (DCP) and 2 parts of cross-linking agent Allyl isocyanurate (TAIC), after 2 minutes of mixing, drained. The kneaded rubber was thinly passed through an open mill having a roll temperature of 60 ° C to obtain a sheet having a thickness of about 2.5 mm, and was left to stand for 20 hours.

(2) After the vulcanization, the test was carried out for 16 hours.

Comparative Example 2:

The processing steps are as follows:

(1) Mixing: set the temperature of the internal mixer to 80 ° C, the rotor speed to 50 rpm, add 100 parts of EPDM rubber for 90 seconds, and then add 5 parts of zinc oxide and 1 part of stearic acid. , mixing for 1 minute; adding 25 parts of carbon black N774, 100 parts of calcined clay and 2 parts of paraffin, mixing for 3 minutes; finally adding 6 parts of cross-linking dicumyl peroxide (DCP) and 2 parts of cross-linking agent Triallyl isocyanurate (TAIC), after 2 minutes of mixing, the gum was discharged. The kneaded rubber was thinly passed through an open mill having a roll temperature of 60 ° C to obtain a sheet having a thickness of about 2.5 mm, and was left to stand for 20 hours.

(2) After the vulcanization, the test was carried out for 16 hours.

Performance test data is as follows

Performance test data analysis:

By comparison of Example 1, Example 2 and Comparative Example 1 and comparison of Examples 3 to 6 and Comparative Example 2, it can be found that the tensile strength of the obtained vulcanized rubber increases as the specific gravity of the branched polyethylene replaces the ethylene-propylene rubber increases. The strength, tear strength and volume resistivity are increased, and the compression set is lowered, indicating that the rubber composition containing the branched polyethylene can simultaneously obtain better mechanical properties, electrical insulation properties and compression set resistance.

Example 7

The branched polyethylenes used were numbered PER-1 and PER-7.

The processing steps are as follows:

(1) Mixing: set the temperature of the internal mixer to 80 ° C, the rotor speed to 50 rpm, add 30 parts of EPDM rubber, 50 parts of PER-7 and 20 parts of PER-1 pre-pressing and kneading for 90 seconds; Then add 5 parts of zinc oxide and 1 part of stearic acid, mix for 1 minute; add 15 parts of carbon black N774 and 30 parts of calcined clay, mix for 3 minutes; finally add 4 parts of cross-linking agent dicumyl peroxide (DCP) And 1 part of the co-crosslinking agent, triallyl isocyanurate (TAIC), was kneaded for 2 minutes and then discharged. The kneaded rubber was thinly passed through an open mill having a roll temperature of 60 ° C to obtain a sheet having a thickness of about 2.5 mm, and was left to stand for 20 hours.

(2) After the vulcanization, the test was carried out for 16 hours.

Example 8

The branched polyethylenes used were numbered PER-4 and PER-7.

The processing steps are as follows:

(1) Mixing: set the temperature of the internal mixer to 80 ° C, the rotor speed to 50 rpm, add 50 parts of PER-4 and 50 parts of PER-7 pre-pressure mixing for 90 seconds; then add 5 parts of zinc oxide and 1 Stearic acid, mixing for 1 minute; adding 20 parts of carbon black N774, 80 parts of calcined clay and 2 parts of paraffin, mixing for 3 minutes; finally adding 10 parts of cross-linking dicumyl peroxide (DCP), 2 parts The co-crosslinking agent, triallyl isocyanurate (TAIC), and 8 parts of the co-crosslinking agent 1,2-polybutadiene, were mixed for 2 minutes and then discharged. The kneaded rubber was thinly passed through an open mill having a roll temperature of 60 ° C to obtain a sheet having a thickness of about 2.5 mm, and was left to stand for 20 hours.

(2) After the vulcanization, the test was carried out for 16 hours.

Example 9

The branched polyethylene used was numbered PER-3.

The processing steps are as follows:

(1) Mixing: set the temperature of the internal mixer to 80 ° C, the rotor speed to 50 rpm, add 50 parts of EPDM rubber and 50 parts of PER-3 pre-pressing for 90 seconds; then add 5 parts of zinc oxide. And 1 part stearic acid, mixing for 1 minute; adding 20 parts of carbon black N774 and 40 parts of calcined clay, mixing for 3 minutes; finally adding 1 part of cross-linking agent dicumyl peroxide (DCP), 0.3 parts of help A combination of triallyl isocyanurate (TAIC), 0.5 part of crosslinker sulfur, 1 part of N-cyclohexyl-2-benzothiazole sulfenamide (CZ) and 0.8 part of tetramethyl disulfide Lamb (TMTD), after 2 minutes of mixing, drain the glue. The kneaded rubber was thinly passed through an open mill having a roll temperature of 60 ° C to obtain a sheet having a thickness of about 2.5 mm, and was left to stand for 20 hours.

(2) After the vulcanization, the test was carried out for 16 hours.

Example 10:

The branched polyethylenes used were numbered PER-2 and PER-7.

The processing steps are as follows:

(1) Mixing: set the temperature of the internal mixer to 80 ° C, the rotor speed to 50 rpm, add 80 parts of PER-7 and 20 parts of PER-1 premix for 90 seconds; then add 10 parts of zinc oxide and 2 Stearic acid, mixing for 1 minute; adding 30 parts of carbon black N774, 120 parts of calcined clay and 2 parts of paraffin, mixing for 3 minutes; finally adding 10 parts of cross-linking dicumyl peroxide (DCP), 2 parts The co-crosslinking agent, triallyl isocyanurate (TAIC), and 10 parts of the co-crosslinking agent 1,2-polybutadiene, were mixed for 2 minutes and then discharged. The kneaded rubber was thinly passed through an open mill having a roll temperature of 60 ° C to obtain a sheet having a thickness of about 2.5 mm, and was left to stand for 20 hours.

(2) After the vulcanization, the test was carried out for 16 hours.

Example 11

The branched polyethylene used was numbered PER-11.

The processing steps are as follows:

(1) Mixing: set the temperature of the internal mixer to 90 ° C, the rotor speed to 50 rpm, and add 100 parts of branched polyethylene for pre-pressing and kneading for 90 seconds; then add 5 parts of zinc oxide and 1 part of stearic acid. Mixing for 1 minute; adding 25 parts of carbon black N774, 100 parts of calcined clay and 2 parts of paraffin, mixing for 3 minutes; finally adding 6 parts of cross-linking agent dicumyl peroxide (DCP) and 2 parts of cross-linking agent Allyl isocyanurate (TAIC), after 2 minutes of mixing, drained. The kneaded rubber was thinly passed through an open mill having a roll temperature of 60 ° C to obtain a sheet having a thickness of about 2.5 mm, and was left to stand for 20 hours.

(2) After the vulcanization, the test was carried out for 16 hours.

Example 12

The branched polyethylene used was numbered PER-12.

The processing steps are as follows:

(2) After the vulcanization, the test was carried out for 16 hours.

The performance test data is as follows:

Claims

A rubber composition comprising: a rubber matrix and a necessary component, wherein the rubber matrix comprises: a content of branched polyethylene a: 0 < a ≤ 100 parts by weight, The content of the binary ethylene propylene rubber and the ethylene propylene diene rubber is b: 0 ≤ b < 100 parts; the necessary components include: 1.5 to 10 parts of the crosslinking agent, and the reinforcing filler 45, based on 100 parts by weight of the rubber matrix. ～150 parts, wherein the reinforcing filler comprises carbon black, and the weight fraction of the carbon black is 0<a≤30 parts, wherein the branched polyethylene comprises an ethylene homopolymer, and the degree of branching is not less than 50 Branched / 1000 carbon, weight average molecular weight of not less than 50,000, Mooney viscosity ML (1 + 4) 125 ° C not less than 2.
The rubber composition according to claim 1, wherein the content of the branched polyethylene in the rubber matrix is a: 10 ≤ a ≤ 100 parts based on 100 parts by weight of the rubber base; the ethylene propylene rubber and The content of EPDM rubber is b: 0 ≤ b ≤ 90 parts; the branched polyethylene is characterized by: an ethylene homopolymer having a degree of branching of 60 to 130 branches/1000 carbons and a weight average molecular weight It is 66,000 to 518,000, and the Mooney viscosity ML (1+4) is 6 to 102 at 125 °C.
The rubber composition according to claim 1, wherein the reinforcing filler further comprises at least one of calcium carbonate, talc, calcined clay, magnesium silicate, and magnesium carbonate.
The rubber composition according to claim 1, wherein the crosslinking agent comprises at least one of a peroxide crosslinking agent and sulfur, and the peroxide crosslinking agent is di-tert-butyl peroxide. , dicumyl peroxide, tert-butyl cumyl peroxide, 1,1-di-tert-butyl peroxide-3,3,5-trimethylcyclohexane, 2,5-dimethyl -2,5-di(tert-butylperoxy)hexane, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexyne-3, bis(tert-butylperoxyperoxide) Of phenyl, 2,5-dimethyl-2,5-bis(benzoyl peroxy)hexane, tert-butyl peroxybenzoate, t-butylperoxy-2-ethylhexyl carbonate At least one.
The rubber composition according to claim 1, wherein the rubber composition further comprises an auxiliary component based on 100 parts by weight of the rubber base, the auxiliary component comprising: 0.2 to 12 parts of a co-crosslinking agent, plasticized 1 to 5 parts of the agent, 2 to 10 parts of the metal oxide, and 0 to 3 parts of the vulcanization accelerator.
The rubber composition according to claim 5, wherein the co-crosslinking agent comprises triallyl cyanurate, triallyl isocyanurate, ethylene glycol dimethacrylate , triethylene glycol dimethacrylate, triallyl trimellitate, trimethylolpropane trimethacrylate, N,N'-m-phenylene bismaleimide, N,N'- At least one of bis-indenyl acetonide, 1,2-polybutadiene, a metal salt of an unsaturated carboxylic acid, and sulfur.
A rubber composition according to claim 5, wherein the plasticizer is pine tar, motor oil, naphthenic oil, paraffin oil, coumarone, RX-80, stearic acid, paraffin, liquid At least one of polyisobutylene.
The rubber composition according to claim 5, wherein the metal oxide is at least one of zinc oxide, magnesium oxide, and calcium oxide.
The rubber composition according to claim 5, wherein the vulcanization accelerator comprises 2-thiol benzothiazole, dibenzothiazole disulfide, tetramethylthiuram monosulfide, and tetrasulfide disulfide. Kethiram, tetraethylthiuram disulfide, N-cyclohexyl-2-benzothiazolyl sulfenamide, N,N-dicyclohexyl-2-phenylthiazolyl sulfenamide, bismaleyl At least one of an imine and an ethylene thiourea.
The rubber composition according to claim 1, wherein the selected ethylene-propylene rubber and ethylene propylene diene rubber have a Mooney viscosity ML (1+4) of 40 to 80 at 125 ° C and an ethylene content of 45. %~70%.
A method of processing the rubber composition according to any one of claims 1 to 10, characterized in that the processing method comprises the steps of:

(1) Rubber kneading: setting the temperature of the internal mixer and the rotation speed of the rotor, firstly adding the rubber composition other than the crosslinking system to the internal mixer for mixing by weight, and then adding the crosslinking system to be kneaded. After uniformly discharging, the mixture is obtained, the rubber mixture is thinned on the open mill, and then the film is left to be vulcanized, wherein the crosslinking system contains a crosslinking agent, and may further comprise a crosslinking agent and a vulcanization accelerator. At least one of them;

(2) Vulcanization: The rubber compound is filled into the cavity of the mold, and after being vulcanized by vulcanization on a flat vulcanizer, the vulcanized rubber is obtained by demolding.
A seal for a capacitor, characterized in that the seal for a capacitor comprises the rubber composition component according to any one of claims 1 to 10.