CN108794830B

CN108794830B - Rubber composition, vulcanized rubber, and preparation method and application thereof

Info

Publication number: CN108794830B
Application number: CN201710287673.3A
Authority: CN
Inventors: 赵青松; 解希铭; 王丽丽; 郑方远; 姜科; 王丽静; 唐功庆
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Priority date: 2017-04-27
Filing date: 2017-04-27
Publication date: 2021-07-02
Anticipated expiration: 2037-04-27
Also published as: CN108794830A

Abstract

The invention relates to the field of rubber, in particular to a rubber composition, a preparation method of vulcanized rubber, the vulcanized rubber prepared by the method and application of the vulcanized rubber. The rubber composition contains polar rubber and a polarity reinforcing agent, wherein the polar rubber is composed of polar structural units and nonpolar structural units, the content of the polar structural units is 25-45 wt%, and the cohesive energy density of the polar rubber is 300-400J/cm-³(ii) a The surface of the polar reinforcing agent has the polar group density of 0.1-10 groups/nm²To do so byThe content of the polar rubber is 100 parts by weight, and the content of the polar reinforcing agent is 10-50 parts by weight. The vulcanized rubber provided by the invention has good mechanical properties, compression deformation resistance, ageing resistance and oil resistance.

Description

Rubber composition, vulcanized rubber, and preparation method and application thereof

Technical Field

The invention relates to the field of rubber, in particular to a rubber composition, a preparation method of vulcanized rubber, the vulcanized rubber prepared by the method and application of the vulcanized rubber.

Background

Rubber sealing parts are often used in environments such as high temperature, fuel oil and extremely harsh fluids, and vulcanized rubber is required to have good oil resistance, aging resistance and small compression set. However, in the conventional rubber products, a combination of a nonpolar rubber and a nonpolar reinforcing agent is often used, for example, butadiene rubber and carbon black, and the oil resistance of the rubber products obtained by the combination is not satisfactory. Therefore, in order to make the rubber product more suitable for rubber sealing parts, it is very important to study how to further improve the oil resistance and maintain good mechanical properties and aging resistance.

Disclosure of Invention

The invention aims to overcome the defects of poor mechanical property, oil resistance and aging resistance of the existing vulcanized rubber, and provides a rubber composition, a preparation method of the vulcanized rubber, the vulcanized rubber prepared by the method and application of the vulcanized rubber. The vulcanized rubber provided by the invention has good mechanical properties, compression deformation resistance, ageing resistance and oil resistance.

The inventor of the invention finds that the dispersion capability of the reinforcing agent in the rubber can be obviously enhanced and the mechanical property of the obtained rubber can be obviously improved by specifically selecting the polar rubber and the polar reinforcing agent and mutually matching the polar rubber and the polar reinforcing agent according to a certain proportion; the enhancement of polarity increases the cohesive force of the obtained rubber, and the aging resistance and the deformation resistance of the obtained rubber are also improved; meanwhile, the oil resistance of the obtained rubber is also obviously improved. According to a preferred embodiment of the present invention, the mechanical properties, compression set resistance, aging resistance and oil resistance of the resulting rubber can be further improved by specifically selecting other components and their contents in the rubber composition.

The first aspect of the invention provides a rubber composition, wherein the rubber composition contains polar rubber and a polarity reinforcing agent, the polar rubber is composed of polar structural units and non-polar structural units, the content of the polar structural units is 25-45 wt%, and the cohesive energy density of the polar rubber is 300-400J/cm³(ii) a The surface of the polar reinforcing agent has the polar group density of 0.1-10 groups/nm²The content of the polarity reinforcing agent is 10-50 parts by weight based on 100 parts by weight of the content of the polarity rubber.

In a second aspect, the present invention provides a method for producing a vulcanized rubber, wherein the method comprises mixing the rubber composition of the present invention to obtain a mix, and then vulcanizing the mix.

In a third aspect, the invention provides a vulcanizate prepared according to the method of the invention.

In a fourth aspect, the invention provides the use of the vulcanized rubber of the invention in the manufacture of a rubber sealing component.

By using the rubber composition disclosed by the invention, the comprehensive performance of the mechanical property, the compression deformation resistance, the ageing resistance and the oil resistance of the obtained vulcanized rubber is obviously improved compared with that of the conventional vulcanized rubber.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

FIG. 1 shows the vulcanization characteristics of H1-H3 mixtures obtained in the examples and DH1 mixtures obtained in the comparative examples.

FIG. 2 is a plot of the storage shear modulus G' -frequency of the H1-H3 rubber mixtures obtained in the examples and of the DH1 rubber mixtures obtained in the comparative examples as determined by the rubber processing Analyzer RPA.

FIG. 3 shows the storage shear modulus G' -strain curves of the H1-H3 rubber mixtures from the examples and of the DH1 rubber mixtures from the comparative examples, measured with a rubber processing Analyzer RPA.

FIG. 4 is a graph showing the storage shear modulus G' -strain curves of S1-S3 obtained in examples and DS1 vulcanizate obtained in comparative example as measured by rubber processing Analyzer RPA.

FIG. 5 is a plot of storage shear modulus G' -frequency for S1-S3 from the examples and DS1 vulcanizate from the comparative example as determined by rubber processing Analyzer RPA.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The first aspect of the present invention provides a rubber composition comprising a polar rubber and a polarity-enhancing agent, wherein the polar rubber is composed of a polar structural unit and a non-polar structural unitWherein the content of the polar structural unit is 25-45 wt%, and the cohesive energy density of the polar rubber is 300-400J/cm³(ii) a The surface of the polar reinforcing agent has the polar group density of 0.1-10 groups/nm²The content of the polarity reinforcing agent is 10-50 parts by weight based on 100 parts by weight of the content of the polarity rubber.

According to the rubber composition of the present invention, the polar structural unit content in the polar rubber can achieve better aging resistance, oil resistance and mechanical properties when the content satisfies the above range, and in order to further optimize the properties, the polar structural unit content in the polar rubber is preferably 30 to 45% by weight, more preferably 35 to 40% by weight.

In the present invention, the polarity degree of the polar rubber is characterized by Cohesive Energy Density (CED), which is the energy required for vaporizing the condensate per unit volume, and since the polymer cannot be vaporized, the cohesive energy density cannot be directly measured, and can only be estimated by the dissolving capacity in different solvents, and the main method is the maximum swelling ratio method (applicable to vulcanized rubber) or the maximum intrinsic viscosity method. When the cohesive energy density of the polar rubber meets the requirement of 300-400J/cm³The range of (A) can realize better aging resistance, oil resistance and mechanical property, and in order to further optimize the performance, the range of (A) is more preferably 350-³. Taking nitrile rubber as an example, the process of testing cohesive energy density by the maximum intrinsic viscosity method is as follows: the mixture solvent obtained by looking up data and mixing the toluene and the dimethyl malonate in a certain proportion is a good solvent of the nitrile rubber, and the solubility parameter delta of the toluene₁＝18.2(J/cm³)^0.5Solubility parameter delta of dimethyl malonate₂＝21.1(J/cm³)^0.5It was found experimentally that at a certain temperature the two solvents are mixed in a certain ratio (volume fraction v of toluene)₁0.655, volume fraction v of dimethyl malonate₂0.345) and the polymer solution obtained by dissolving the nitrile rubber in the mixture has a higher intrinsic viscosity than the solution obtained by dissolving the nitrile rubber in the solvent mixed in other proportion, the formula for calculating the Cohesive Energy Density (CED) of the nitrile rubber is givenThe following were used: CED ═ δ₁v₁+δ₂v₂)²＝(18.2×0.655+21.1×0.345)²J/cm³＝369J/cm³。

According to the rubber composition, the polar rubber is composed of a polar structural unit and a non-polar structural unit, wherein the polar structural unit is preferably a structural unit formed by opening double bonds of a mono-olefin compound and/or a conjugated diene compound with one or more of a nitrile group, a carboxylic acid group, a carboxylic ester group and a halogen group; more preferably, the polar structural unit is a structural unit formed by opening a double bond of a monoolefin compound and/or a conjugated diene compound containing 2-10 carbon atoms and one or more of a nitrile group, a carboxylic acid group, a carboxylic ester group and a halogen group; further preferably, the polar structural unit is a structural unit formed by one or more of acrylonitrile, acrylic acid, methyl acrylate and chloroprene through double bond opening. By selecting the preferable polar structural unit, the cohesive force among rubber molecules can be realized, and the dissolving and plasticizing effects of the light-reducing oil on the rubber can be realized, so that the oil resistance of the rubber is improved; meanwhile, the cohesion among rubber molecules is increased, and the high temperature resistance and aging resistance of the rubber can be improved, so that the rubber sealing component is more suitable for being used in environments of high temperature, fuel oil and the like.

According to the rubber composition of the present invention, the selection of the nonpolar structural unit is not particularly limited, and may be a nonpolar structural unit used in a rubber variety which is conventional in the art. In a preferred case, the nonpolar structural unit is a structural unit formed by one or more of ethylene, propylene, butadiene, styrene and isoprene through double bond opening; the preferable nonpolar structural unit can be better matched with the polar structural unit, and has better flexibility in a molecular chain, so that the rubber has good processing performance.

According to the rubber composition of the present invention, the polar rubber may be a saturated or unsaturated rubber. Preferably, the polar rubber is selected from one or more of nitrile rubber, hydrogenated nitrile rubber, acrylate rubber and neoprene rubber; the hydrogenation saturation of the hydrogenated nitrile rubber is preferably 80-99.9%, and within the range, the rubber molecule saturation is improved, the double bonds in a molecular chain are fewer, and the aging performance is also improved.

According to the rubber composition of the present invention, the content ratio of the polar rubber to the polar reinforcing agent can achieve better aging resistance, oil resistance and mechanical properties when the above ranges are satisfied, and for further optimization of the properties, the content of the polar reinforcing agent is preferably 25 to 45 parts by weight, more preferably 35 to 40 parts by weight, based on 100 parts by weight of the polar rubber.

In the present invention, the degree of polarity of the polarity-enhancing agent is characterized by the polar group density of the surface of the polarity-enhancing agent when the polar group density of the surface of the polarity-enhancing agent satisfies the above-mentioned 0.1 to 10 groups/nm²The range of (2) can realize better aging resistance, oil resistance and mechanical property, and in order to further optimize the performance, the density of polar groups on the surface of the polar reinforcing agent is preferably 1-6 groups/nm²More preferably 2 to 5 groups/nm². The polar group density is obtained by measuring the polar group content by a titration method described in the paper "determination of hydroxyl content of silicon in black carbon by vapor phase method" (Pioneer Prof., et al, organosilicon fluorine information, 2007 (1): 28-31) and calculating by a formula given in the paper.

According to the rubber composition of the present invention, the polar group contained on the polarity-enhancing agent is preferably selected from one or more of a hydroxyl group, a carboxyl group and an epoxy group, wherein the hydroxyl group is more preferably a silicon hydroxyl group (Si — OH).

According to the rubber composition of the present invention, the matrix of the polarity enhancer is preferably selected from one or more of carbon, metal oxide, non-metal oxide, carbonate and silicate, more preferably from one or more of carbon, silica and zinc oxide.

According to a preferred embodiment of the rubber composition of the present invention, the polarity enhancer is selected from one or more of graphene, graphene oxide and white carbon black. More preferably, the polarity enhancer is a combination of two polarity enhancers, and more preferably a combination of white carbon black and graphene oxide. According to a preferred embodiment of the present invention, the polarity enhancer is white carbon black or a mixture of white carbon black and graphene oxide, the content of the white carbon black is 20 to 40 parts by weight, and the content of the graphene oxide is 0 to 20 parts by weight, based on 100 parts by weight of the polar rubber; according to a more preferred embodiment of the present invention, the polarity enhancer is a mixture of white carbon black and graphene oxide, the white carbon black is 20 to 35 parts by weight, and the graphene oxide is 0.01 to 10 parts by weight, based on 100 parts by weight of the polar rubber. And the total content of the white carbon black and the graphene oxide satisfies 10 to 50 parts by weight, preferably 25 to 45 parts by weight, and more preferably 35 to 40 parts by weight, based on 100 parts by weight of the polar rubber.

According to the rubber composition disclosed by the invention, the white carbon black, the graphene and the graphene oxide can be white carbon black, graphene and graphene oxide which are conventional in the field, and can be obtained commercially. The inventor of the invention finds that the surface of the white carbon black contains polar groups such as silicon hydroxyl, epoxy and the like, and can generate stronger interaction with the polar groups (such as nitrile groups of nitrile rubber), so as to promote the dispersion of the white carbon black in a rubber matrix. The graphene and graphene oxide base has a layered carbon atom layer structure, contains polar groups such as hydroxyl, epoxy, carboxyl and the like on the surface, and can be well dispersed in a polar rubber matrix, so that a high-efficiency reinforcing effect is exerted; the white carbon black is easy to self-aggregate, and the addition of the layered reinforcing agents such as graphene, graphene oxide and the like and the blocking of the layered reinforcing agents among the white carbon black particles reduce the self-aggregation of the white carbon black particles to a certain extent, so that the dispersion of the white carbon black in rubber groups is improved.

The rubber composition according to the invention may also contain the types of auxiliaries conventionally added in the art. Preferably, the rubber composition further comprises a coupling agent, an anti-aging agent, a vulcanizing agent, a vulcanization activator, a vulcanization accelerator and a plasticizer, wherein the coupling agent is contained in an amount of 1 to 5 parts by weight, the anti-aging agent is contained in an amount of 1 to 5 parts by weight, the vulcanizing agent is contained in an amount of 3 to 9 parts by weight, the vulcanization accelerator is contained in an amount of 1 to 4 parts by weight, the vulcanization activator is contained in an amount of 2 to 4 parts by weight and the plasticizer is contained in an amount of 1 to 5 parts by weight, based on 100 parts by weight of the polar rubber.

According to the rubber composition of the present invention, the content of the coupling agent is preferably 1 to 3 parts by weight, more preferably 1 to 2 parts by weight, based on 100 parts by weight of the polar rubber.

According to the rubber composition of the present invention, the coupling agent preferably has R- (SiX)₁X₂X₃)_mA silane coupling agent of the structure, wherein R is an aliphatic or aromatic hydrocarbon group containing one or more of a vinyl group, an epoxy group, an amino group, a methacryloyloxy group, a mercapto group, a 3-propionylthio-1-propyl group and a polysulfide bond, and X is₁、X₂And X₃Identical or different, independently selected from methoxy, ethoxy and chlorine, m ═ 1 or 2.

According to the rubber composition of the present invention, preferably, the coupling agent is selected from one or more of vinyltris (β -methoxyethoxy) silane, bis- [ γ - (triethoxysilyl) propyl ] tetrasulfide, γ -mercaptopropyltriethoxysilane, bis (triethoxypropylsilane) disulfide and 3-propionylthio-1-propyl-trimethoxysilane.

In the shearing field of rubber melt of an internal mixer, at a proper temperature of 145-150 ℃, sulfydryl or polysulfide bond of the coupling agent has higher reaction activity, generates free radicals to attack carbon-carbon double bonds on rubber molecules to form covalent bonds to be connected to the rubber molecules, and simultaneously, SiX in the coupling agent₁X₂X₃The groups can react with hydroxyl, epoxy, carboxyl and other polar groups on the surface of reinforcing agents such as white carbon black, graphene and the like to form covalent bonds connected to the surface of the reinforcing agents, and the two reactions of the coupling agent enable rubber molecules and polar reinforcing agent molecules to be connected through chemical bonds, so that the combination of the rubber molecules and the polar reinforcing agents is promoted, the polar reinforcing agents are more easily dispersed in a rubber matrix, and the reaction formula is as follows (the reaction formula is only shown in the specification)For illustration):

Rubber—C＝C+R—(SiX₁X₂X₃)_m+X—Filler→Rubber—Filler；

wherein the X group represents a polar group on the surface of the polarity enhancer; rubber-C ═ C denotes rubber molecules, X-filler denotes polar reinforcing agent molecules.

According to the rubber composition of the present invention, it is preferable that the antioxidant is contained in an amount of 1 to 2 parts by weight based on 100 parts by weight of the polar rubber.

According to the rubber composition of the present invention, preferably, the antioxidant is selected from one or more of quinoline antioxidants, benzimidazole antioxidants and amine antioxidants; the quinoline antioxidant can be 2,2, 4-trimethyl-1, 2-dihydroquinoline polymer, the benzimidazole antioxidant can be 2-mercaptobenzimidazole zinc salt, and the amine antioxidant can be one or more selected from N- (1, 3-dimethylbutyl) -N '-phenyl-p-phenylenediamine, N-cumyl-N' -phenyl-p-phenylenediamine and N-phenyl-2-naphthylamine.

The rubber composition of the invention can effectively improve the aging resistance through the mutual matching of the polar rubber and the polar reinforcing agent. The rubber obtained by the invention has more excellent aging resistance by adding the preferred antioxidant.

According to the rubber composition, a specific vulcanization compounding system of a vulcanizing agent, a vulcanization accelerator and a vulcanization activator is selected, so that the rubber compound has better vulcanization characteristic, and the vulcanized rubber has better mechanical property.

According to the rubber composition of the present invention, more preferably, the vulcanizing agent is contained in an amount of 5 to 8 parts by weight, the vulcanization accelerator is contained in an amount of 1 to 2 parts by weight, and the vulcanization activator is contained in an amount of 2.2 to 3.5 parts by weight, based on 100 parts by weight of the polar rubber.

According to the rubber composition of the present invention, the vulcanizing agent may be one or more selected from sulfur-based vulcanizing agents and peroxide-based vulcanizing agents, preferably a peroxide-based vulcanizing agent. Wherein, the sulfur vulcanizing agent can be insoluble sulfur; the peroxide-based vulcanizing agent is preferably one or more selected from di-tert-butyl peroxide, dibenzoyl peroxide, dicumyl peroxide and the like. By using the above-mentioned preferred peroxide-based vulcanizing agent, a vulcanized rubber obtained from the rubber composition of the present invention can have a good heat resistance.

According to the rubber composition of the present invention, the vulcanization accelerator is preferably selected from one or more of thiazole accelerators and sulfenamide accelerators, wherein the thiazole accelerators may be 2-mercaptobenzothiazole and/or 2, 2' -dibenzothiazyl disulfide, and the sulfenamide accelerators may be selected from one or more of N-tert-butyl-2-benzothiazylsulfenamide, N-tert-butyl-bis (2-benzothiazyl) sulfenimide, N-cyclohexyl-2-benzothiazylsulfenamide and N-cyclohexyl-2-benzothiazylsulfenamide. More preferably, the vulcanization accelerator is selected from one or more of 2-mercaptobenzothiazole, 2' -dibenzothiazyl disulfide and N-cyclohexyl-2-benzothiazylsulfenamide. By using the preferable vulcanization accelerator, the crosslinking reaction between rubber and a vulcanizing agent can be greatly promoted, the vulcanization speed is increased, the vulcanization temperature is reduced, the vulcanization time is shortened, the consumption of the vulcanizing agent is reduced, and the physical and mechanical properties and the aging resistance of vulcanized rubber are improved.

According to the rubber composition of the present invention, the vulcanization activator may be selected from one or more of inorganic activators and organic activators; wherein, the inorganic active agent is preferably zinc oxide (one or more of indirect zinc oxide, direct zinc oxide and active zinc oxide can be included), and the organic active agent is preferably one or more selected from stearic acid, lauric acid and caprylic acid. According to a preferred embodiment of the present invention, the vulcanization activator is a combination of an inorganic activator and an organic activator, and preferably, the organic activator is contained in an amount of 0.2 to 0.4 parts by weight and the inorganic activator is contained in an amount of 2 to 3 parts by weight, based on 100 parts by weight of the polar rubber. By using the above-mentioned preferred vulcanization activators, the vulcanization time can be effectively shortened.

According to the rubber composition of the present invention, the plasticizer is preferably contained in an amount of 1 to 4 parts by weight, more preferably 1 to 3.8 parts by weight, based on 100 parts by weight of the polar rubber.

According to the rubber composition of the present invention, the plasticizer may be one or more selected from the group consisting of petroleum-based plasticizers, fatty oil-based plasticizers, synthetic plasticizers, and the like. Wherein, the petroleum plasticizer can be naphthenic oil and/or aromatic oil; the fatty oil-based plasticizer may be selected from one or more of glycerin, soybean oil, oleic acid, and zinc stearate; the synthetic plasticizer may be selected from one or more of ethylene glycol, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl adipate, and epoxidized soybean oil.

According to the rubber composition of the present invention, preferably, the plasticizer is selected from one or more of ethylene glycol, diethyl phthalate, dioctyl adipate and epoxidized soybean oil. The plasticizer can increase the distance between rubber molecular chains, properly reduce intermolecular acting force, generate a lubricating effect, and ensure that the molecular chains are easy to slide, thereby improving the processability of the rubber compound under the condition of not influencing the dispersion of the reinforcing agent. By using the above-mentioned preferred plasticizer, the above-mentioned plasticizing effect can be more favorably achieved by blending with other components in the rubber composition of the present application, and the plasticizer is more easily absorbed by rubber, has good compatibility, is resistant to extraction, and is less likely to volatilize.

According to the rubber composition of the present invention, other conventional auxiliaries may be contained in the rubber composition, for example, a colorant may be further added. The content of the colorant may be 1 to 6 parts by weight based on 100 parts by weight of the polar rubber.

According to the rubber composition of the invention, preferably, the colorant is a combination of titanium dioxide and zinc oxide, wherein the zinc oxide can be used as a vulcanization activator and a colorant in the rubber composition, and the titanium dioxide is only used as a colorant and has no reinforcing or vulcanization accelerating effect. Preferably, the content of the titanium dioxide is 1 to 4 parts by weight, more preferably 1 to 3.5 parts by weight, and the content of the zinc oxide is 1 to 4 parts by weight, more preferably 2 to 3 parts by weight, based on 100 parts by weight of the polar rubber. When zinc oxide is used in the vulcanization activator, the content of the zinc oxide is the content of the zinc oxide in the vulcanization activator. When a colorant is contained, the resulting rubber is lighter in color and suitable for use as a light-colored rubber article.

According to the method, the mixing process comprises two modes of open mixing and banburying.

According to the method of the invention, the mixing can be carried out by an open mixing mode, wherein the open mixing mode comprises the step of mixing all the components of the rubber composition in an open mixer at the temperature of 20-50 ℃ for 5-30 min.

According to the method of the present invention, preferably, the rubber composition of the present invention is mixed by banburying, and the banburying process includes: firstly, carrying out first-stage banburying on components except for a vulcanizing agent, an anti-aging agent and a vulcanization accelerator in the rubber composition, and then adding the vulcanizing agent, the anti-aging agent and the vulcanization accelerator to carry out second-stage banburying.

According to the method of the present invention, the feeding manner of the first banburying can be divided into a batch feeding manner and a one-time feeding manner. Preferably, the addition is carried out by a batch addition method in which the polar rubber, the polar reinforcing agent and the coupling agent are added in the first batch, and after kneading at a temperature of 140-. Wherein, the adding mode of the first batch is preferably as follows: one half of the polar rubber is added first, then the polar reinforcing agent and the coupling agent are added, and finally the other half of the polar rubber is added.

According to the process of the invention, in the first banburying stage, the temperature of mixing is preferably strictly controlled so that it is not higher than 150 ℃ after the addition of the second batch. By controlling the temperature, the premature crosslinking of the rubber caused by the coupling agent at an overhigh temperature is avoided, gel or crosslinking points are generated in the rubber, the subsequent processing processes such as second-stage banburying, vulcanization and the like are influenced, and the adverse effect on the service performance of the rubber is simultaneously generated.

According to the process of the invention, the initial temperature of the first stage of internal mixing is preferably from 50 to 80 ℃.

According to the method of the invention, preferably, after the first stage of banburying and before the second stage of banburying, the rubber compound obtained in the first stage of banburying is passed through an open mill once with a roll gap of 4-8mm, and then left at room temperature for 2-24 h.

According to the method of the present invention, the process of the second banburying stage is not particularly limited, and for example, the process comprises the following steps: setting the initial temperature to be 30-50 ℃, adding the materials, and then mixing, wherein the mixing end point is that the temperature of the rubber material reaches 110 ℃ or the time reaches 5 min.

According to the process of the invention, the process of vulcanization comprises: vulcanizing the mixed rubber obtained by mixing for 5-30min under the pressure of 3-4MPa and the temperature of 140-180 ℃.

In a third aspect, the invention provides a vulcanizate prepared according to the method of the invention. The vulcanized rubber has good aging resistance, oil resistance and mechanical property, and is particularly suitable for manufacturing rubber sealing parts.

The present invention will be described in detail below by way of examples.

The raw materials used in the following examples and comparative examples are as follows:

polybutadiene-acrylonitrile rubber (nitrile rubber for short) NBR: the designation NBR2665, manufactured by Russian Boolean, Mooney viscosity ML (1+4min, 100 ℃) is 65 + -3; wherein the acrylonitrile structure content is 28 wt%; volatile matter is less than or equal to 0.8 weight percent, and total ash is less than or equal to 0.5 weight percent; cohesive energy density is 372J/cm³(the same applies hereinafter, measured by the maximum intrinsic viscosity method).

Polybutadiene-acrylonitrile rubber: the NBR4165, manufactured by Russian Boolean, has a bound acrylonitrile structure content of 41% by weight and a Mooney viscosity ML (1+4min, 100 ℃) of 65; the cohesive energy density is 398J/cm³。

Hydrogenated nitrile rubber (HNBR for short): the product was designated Zetpol2010, manufactured by Ralskian corporation, having a bound acrylonitrile structure content of 36% by weight, a Mooney viscosity center ML (1+4min, 100 ℃ C.) of 85, and a density of 0.95g/cm³Iodine value of 11mg/100mg and hydrogenation saturation of 96 percent; the cohesive energy density is 385J/cm³。

Polychloroprene rubber (neoprene for short): the product is the brand CR2322, produced by Chongqing longevity chemical industry, and has moderate crystallization rate, non-pollution type antioxidant, Mooney viscosity ML (1+4min, 100 ℃) of 45-55; the cohesive energy density is 368J/cm³。

Silane coupling agent: two brand coupling agents, purchased from Nanjing eosin photochemical Mill. The first brand Si69, the effective component is bi- [ gamma- (triethoxy silicon) propyl ] -tetrasulfide; the second trade name is KH580, the active ingredient is gamma-mercaptopropyltriethoxysilane.

Industrial reference carbon black 8 #: manufactured by the de gusa company; the polar group density of the surface is 1 group/nm²(surface polar group Density the same applies hereinafter) the content of polar groups was determined by the titration method described in the paper "determination of content of silicon hydroxyl groups in fumed white carbon black" (Pioneer Prof., et al, organosilicon fluorine information, 2007 (1): 28-31) and calculated by the formula given in the paper).

White carbon black: brand 165GR, manufactured by Rodiya, Qingdao; the polar group density of the surface is 6 groups/nm²。

And (3) graphene oxide: the C, H, O element content is more than 98.35 atom% produced by Sichuan Jinlu group Limited company; the polar group density of the surface is 3 groups/nm²。

Other ingredients were purchased from chemical company, Ikka, Beijing, in chemical purity.

Example H1

(1) Rubber compositions were prepared, and the components and parts by weight of the rubber compositions are shown in Table 1.

(2) And (2) carrying out internal mixing on the obtained rubber composition, wherein the internal mixing comprises a first-stage internal mixing and a second-stage internal mixing, and specifically comprises the following steps:

first-stage banburying: setting the initial temperature of the internal mixer at 60 +/-3 ℃, closing the discharge port, fixing the rotor and lifting the upper top bolt. The first charge was carried out according to the composition shown in table 1: adding half of the polar rubber, adding the polar reinforcing agent and the coupling agent, and finally adding the other half of the polar rubber; the mixture was kneaded at 148 ℃ for 5 minutes. Then, the upper ram was raised, a second batch of material was added according to the ingredients shown in table 1, the inlet of the internal mixer and the top of the upper ram were cleaned, and the upper ram was lowered; controlling the temperature not to be higher than 150 ℃ (fluctuating between 140 ℃ and 150 ℃), and mixing for 3 minutes.

And (3) second-stage banburying:

the initial temperature of the internal mixer was set at 40. + -. 5 ℃ and the rotation speed 77 rpm. The discharge opening is closed, the rotor is fixed, and the upper top bolt is lifted. Adding half of the rubber material obtained in the first stage of banburying, then adding the components shown in the table 1, finally adding the other half of the rubber material obtained in the first stage of banburying, and putting down the upper plug. The rubber compound was mixed and the resulting mix was discharged when mixing reached 5 min.

The obtained rubber compound was taken out of the mill, and a sheet for rubber material vulcanization characteristics was made 6mm thick, and other sheets tested were made 2.2mm thick. The resulting mix was designated as H1.

TABLE 1

Examples H2-H6

(2) The internal mixing was carried out as described in example H1. According to a specific embodiment, in the rubber material mixing stage of the second banburying, when the temperature of the rubber material reaches 110 ℃ or the time reaches 5min, the obtained rubber compound can be unloaded when one of the conditions is met.

The obtained rubber mixtures were designated as H2 to H6.

Example H7

(1) The same rubber composition as in example H1 was prepared.

(2) The internal mixing was carried out according to the step (2) of example H1, except that in the first stage internal mixing, the addition was not carried out in two portions, but the contents of the first stage internal mixing were added simultaneously.

The resulting mix was designated as H7.

Comparative example DH1

(1) Rubber compositions were prepared, and the components and parts by weight of the rubber compositions are shown in Table 2.

(2) The internal mixing was carried out in accordance with the procedure (2) of example H1, except that in the first stage internal mixing, the materials of the first stage internal mixing were not fed in two portions, but the materials fed in the first stage internal mixing and the second stage internal mixing were fed simultaneously, specifically, as shown in Table 2.

The resulting mixtures were each designated DH 1.

TABLE 2

Comparative example DH2

(1) Preparing a rubber composition, wherein the reinforcing agent adopts 30 parts by weight of industrial reference carbon black, the rubber adopts 100 parts by weight of butadiene rubber (the brand No. BR9000, produced by Beijing Yanshan division of petrochemical company Limited in China, and has no polarity), and other components and using amounts are the same as those in the example H1;

(2) the internal mixing was carried out as described in example H1.

The resulting mixtures were each designated DH 2.

Test example I

This test example I was used to test the properties of the mixtures H1 to H7 and DH1 to DH2 obtained above, as follows:

(1) characterization of processing performance in Banbury mixer processing

The rubber was mixed using a 1.5L internal mixer from America Falalel, and the temperature and mixing power changes during the first stage of mixing were recorded. The stabilized temperature (which can be measured at 500 s) and the stabilized kneading power (which can be measured at 500 s) are shown in Table 3. It is generally considered that the lower the temperature in the steady state, the better the processability, and the lower the kneading power after stabilization, the lower the energy consumption for the processing. As can be seen from Table 3, the temperature and mixing power in mixing of H1-H7 of the present invention can be achieved to a degree comparable to that of DH 1-DH 2 of the prior art, and the combination of the temperature and mixing power in mixing of H1-H3 according to the preferred embodiment of the present invention is relatively best in all examples and comparative examples.

(2) Mooney viscosity and Mooney relaxation

Mooney viscosities of the rubber mixtures were measured by a Mooney viscometer of Taiwan high-speed railway, and the measured Mooney viscosities were recorded in Table 3 under test conditions ML (1+4min, 100 ℃). It is generally accepted that within certain limits, higher Mooney viscosities of the compounds indicate stronger interaction between the rubber matrix and the filler. As can be seen from Table 3, the Mooney viscosities of H1-H7 of the present invention can be comparable to or significantly higher than those of DH 1-DH 2 or DH 1-DH 2.

(3) Vulcanization characteristic:

the vulcanization performance of the rubber compound is tested by adopting a vulcanization characteristic module of an RPA2000 rubber processing analyzer (product of American alpha company), wherein the test conditions are as follows: the results are shown in Table 4, using examples of H1-H3 and DH1, with an oscillation angle of 1 DEG, a frequency of 1.67Hz, and a temperature of 180 ℃. The maximum torque Max S 'represents the modulus of vulcanized rubber and is related to mechanical properties, and the larger the Max S', the better the mechanical properties; the minimum torque MinS 'is related to the processing performance, and within a proper range, when MinS' is larger, the processing performance is better; max S '-Min S' represents the density of the cross-linking points formed in the vulcanization process, and in a certain range, the higher the density of the cross-linking points is, the better the mechanical property is; s ' @ Min S ' and S ' @ Max S ' respectively refer to a loss torque S ' corresponding to the minimum energy storage torque Min S ' and a loss torque S ' corresponding to the maximum energy storage torque Max S ', and the loss torques S ' can also reflect the processing performance, and when S ' @ Min S ' and S ' @ Max S ' are larger in a proper range, the processing performance is better; the scorching time T'02 represents the processing safety of the rubber material; t '25 characterizes the vulcanization rate at the initial stage of vulcanization, and the shorter T' 25 indicates a faster vulcanization rate.

In addition, taking H1, H2, H3 and DH1 as examples, the vulcanization characteristic curves are plotted in FIG. 1, and as can be seen from FIG. 1, the vulcanized rubber torques Max S' of H1-H3 are higher than DH1, which shows that the vulcanized rubbers H1-H3 have better mechanical properties than DH 1. The vulcanization characteristic curves of H1-H3 have a tendency of slightly increasing torque within 7-20min, which shows that under the synergistic action of a vulcanizing agent, a vulcanization accelerator, a vulcanization activator and an anti-aging agent, the vulcanization processability of examples H1-H3 and the aging resistance of vulcanized rubbers S1-S3 are better.

TABLE 4

Test items	Unit of	H1	H2	H3	DH1
						Min S'	dNm	3.78	2.97	2.42	1.17
S”@Min S'	dNm	1.89	1.78	1.62	0.79
						Max S'	dNm	23.05	24.24	24.29	13.6
S”@Max S'	dNm	0.89	1.10	1.24	0.78
						Max S'-Min S'	dNm	19.27	21.27	21.87	12.43
T'02	min	1.15	1.07	0.95	1.58
						T'25	min	1.52	1.52	1.62	1.86

As can be seen from Table 4, the vulcanized rubber torques Max S' of H1-H3 are higher than DH1, indicating that the vulcanized rubbers H1-H3 have better mechanical properties than DH 1. Comparing the density of the cross-linking points formed during vulcanization (Max S '-Min S'), the density of the cross-linking points of H1-H3 is greater than DH1, which shows that the mechanical properties of the example are better than those of the comparative example DH1, and the higher cross-linking density makes the vulcanized rubber not easy to age, so the anti-aging performance of the example is better than that of the comparative example. MinS ', S ' @ Min S ' and S ' @ Max S ' of H1-H3 are also greater than DH1, which shows that the processing performance of H1-H3 is superior to DH 1. The scorch times T'02 of H1-H3 were within the safe processing time range, indicating that the processing safety of the examples was better. T' 25 of H1-H3 is less than DH1, which shows that the vulcanization speed of H1-H3 in the initial vulcanization stage is faster than that of DH 1.

(4) Processability and mechanical properties of the rubber mixtures

An RPA2000 rubber processing analyzer (product of alpha company, USA) is adopted to carry out frequency and strain scanning tests, wherein the frequency scanning temperature is 60 ℃ and the strain is 7%, and the strain scanning temperature is 60 ℃ and the frequency is 1 Hz. The storage shear modulus G' @0.69Hz with the frequency of 0.69Hz obtained by the frequency scanning test is recorded in the table 3, and generally, the larger the parameter is, the better the stiffness of the rubber material is, and the less the compression deformation is generated; the storage shear modulus G' @ 10% of the strain obtained from the strain sweep test is recorded in Table 3, and it is generally considered that the larger this parameter is, the better the stiffness of the rubber compound is, and the less the compression deformation is generated. As can be seen from Table 3, the frequency scanning storage shear modulus G' @0.69Hz of the H1-H7 of the invention is significantly better than that of DH 1-DH 2; the strain scanning storage shear modulus G' @ 10% of the H1-H7 is also obviously better than that of DH 1-DH 2.

In addition, taking H1, H2, H3 and DH1 as examples, frequency sweep curves of the rubber compound are plotted in FIG. 2, strain sweep curves of the rubber compound are plotted in FIG. 3, and as can be seen from FIG. 2 and FIG. 3, the storage shear modulus G' of the H1-H3 rubber compound under the same frequency, strain and temperature is higher than DH1, and the higher modulus ensures that the rubber compound is not easy to generate compression deformation.

Test example II

And vulcanizing the mixed rubber H1-H7 and DH 1-DH 2 at 180 ℃ for 20min respectively to obtain vulcanized rubber which is respectively marked as S1-S7 and DS 1-DS 2. Then, an RPA2000 rubber processing analyzer (product of alpha company, USA) is adopted to carry out frequency and strain scanning tests, wherein the strain scanning temperature is 100 ℃, the frequency is 1Hz, and the frequency scanning temperature is 100 ℃, and the strain is 7%. The storage shear modulus G' @0.33Hz with the frequency of 0.33Hz obtained by the frequency scanning test is recorded in the table 3, and the larger the parameter is, the more difficult the vulcanized rubber is to generate compression deformation; the storage shear modulus G' @ 5% of the strain obtained by the strain sweep test is recorded in Table 3, and it is generally considered that the larger the parameter is, the more the vulcanized rubber is less prone to compressive deformation. As can be seen from Table 3, the frequency scanning storage shear moduli G' @0.33Hz of the S1-S7 of the invention are all significantly better than DS 1-DS 2; the strain scanning storage shear modulus G' @ 5% of the strain scanning storage device from S1 to S7 is also obviously better than DS1 to DS 2.

In addition, taking S1, S2, S3 and DS1 as examples, the strain sweep curve of the vulcanized rubber is shown in fig. 4, and the frequency sweep curve of the vulcanized rubber is shown in fig. 5, and as can be seen from fig. 4 and fig. 5, the storage shear modulus G' of the S1 to S3 rubber compound is higher than DS1 at the same frequency, strain and temperature, and the higher modulus ensures that the rubber compound is not easy to generate compression deformation.

TABLE 3

Injecting: the unit "%" of the stabilized power means the percentage of the stabilized power to the maximum mixing power of the internal mixer.

In conclusion, the rubber compound obtained by adopting the rubber composition and the vulcanization method can show more excellent processing performance, mechanical property, compression deformation resistance and ageing resistance than the comparative example in the prior art, and the obtained vulcanized rubber can have better mechanical property, compression deformation resistance and ageing resistance. And because the invention adopts polar rubber and polar reinforcing agent, the vulcanized rubber of the invention can also have better oil resistance.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A rubber composition characterized in that it comprises a polar rubber and a polar reinforcing agent, the polar rubber being composed of a polar structural unit and a nonpolar structural unit and the content of the polar structural unit being 25 to 45% by weight, the cohesive energy density of the polar rubber being 300-400J/cm³(ii) a The surface of the polar reinforcing agent has the polar group density of 0.1-10 groups/nm²The content of the polarity reinforcing agent is 10-50 parts by weight based on 100 parts by weight of the content of the polarity rubber.

2. The rubber composition according to claim 1, wherein the content of the polar structural unit in the polar rubber is 30 to 45% by weight.

3. The rubber composition according to claim 2, wherein the polar rubber contains a polar structural unit in an amount of 35 to 40 wt%.

4. The rubber composition as described in claim 1, wherein the polar rubber has a cohesive energy density of 350-400J/cm³。

5. The rubber composition according to any one of claims 1 to 4, wherein the polar structural unit is a structural unit formed by opening a double bond of a monoolefin-based compound and/or a conjugated diene-based compound having one or more of a nitrile group, a carboxylic acid group, a carboxylate group and a halogen group.

6. The rubber composition according to claim 5, wherein the polar structural unit is a structural unit formed by one or more of acrylonitrile, acrylic acid, methyl acrylate and chloroprene through double bond opening.

7. The rubber composition according to claim 1, wherein the nonpolar structural unit is a structural unit formed by bonding one or more of ethylene, propylene, butadiene, styrene, and isoprene through a double bond.

8. The rubber composition according to claim 1, wherein the content of the polarity-enhancing agent is 25 to 45 parts by weight based on 100 parts by weight of the polar rubber.

9. The rubber composition according to claim 8, wherein the content of the polarity-enhancing agent is 35 to 40 parts by weight based on 100 parts by weight of the polar rubber.

10. The rubber composition according to claim 1, wherein the polar-group density of the surface of the polarity-enhancing agent is 1 to 6 groups/nm²。

11. The rubber composition according to any one of claims 1 to 4 and 10, wherein the polar group contained on the polarity-enhancing agent is selected from one or more of a hydroxyl group, a carboxyl group and an epoxy group; the matrix of the polarity enhancer is selected from one or more of carbon, metal oxide, non-metal oxide, carbonate and silicate.

12. The rubber composition according to claim 11, wherein the property enhancer is selected from one or more of graphene, graphene oxide and white carbon black.

13. The rubber composition according to claim 12, wherein the polarity enhancer is white carbon black or a mixture of white carbon black and graphene oxide, the white carbon black is 20 to 40 parts by weight, and the graphene oxide is 0 to 20 parts by weight, based on 100 parts by weight of the polarity rubber.

14. The rubber composition according to claim 12, wherein the polarity enhancer is a mixture of white carbon black and graphene oxide, the white carbon black is 20 to 35 parts by weight and the graphene oxide is 0.01 to 10 parts by weight based on 100 parts by weight of the polar rubber.

15. The rubber composition according to claim 1, further comprising a coupling agent, an antioxidant, a vulcanizing agent, a vulcanization activator, a vulcanization accelerator and a plasticizer, wherein the coupling agent is contained in an amount of 1 to 5 parts by weight, the antioxidant is contained in an amount of 1 to 5 parts by weight, the vulcanizing agent is contained in an amount of 3 to 9 parts by weight, the vulcanization accelerator is contained in an amount of 1 to 4 parts by weight, the vulcanization activator is contained in an amount of 2 to 4 parts by weight and the plasticizer is contained in an amount of 1 to 5 parts by weight, based on 100 parts by weight of the polar rubber.

16. The rubber composition of claim 15, wherein the coupling agent is R- (SiX) in the formula₁X₂X₃)_mA silane coupling agent of the structure, wherein R is an aliphatic or aromatic hydrocarbon group containing one or more of a vinyl group, an epoxy group, an amino group, a methacryloyloxy group, a mercapto group, a 3-propionylthio-1-propyl group and a polysulfide bond, and X is₁、X₂And X₃Identical or different, independently selected from methoxy, ethoxy and chlorine, m ═ 1 or 2.

17. The rubber composition of claim 16, wherein the coupling agent is selected from one or more of vinyltris (β -methoxyethoxy) silane, bis- [ γ - (triethoxysilyl) propyl ] tetrasulfide, γ -mercaptopropyltriethoxysilane, bis (triethoxypropylsilane) disulfide, and 3-propionylthio-1-propyl-trimethoxysilane.

18. A method for producing a vulcanized rubber, comprising kneading the rubber composition according to any one of claims 1 to 17 to obtain a kneaded compound, and then vulcanizing the kneaded compound.

19. The preparation method according to claim 18, wherein the rubber composition is the rubber composition according to any one of claims 15 to 18, and the mixing is performed by internal mixing, and the internal mixing comprises the following steps: firstly, carrying out first-stage banburying on components except for a vulcanizing agent, an anti-aging agent and a vulcanization accelerator in the rubber composition, and then adding the vulcanizing agent, the anti-aging agent and the vulcanization accelerator to carry out second-stage banburying.

20. The method as claimed in claim 19, wherein the first banburying step is carried out by batch feeding or one-time feeding, wherein the batch feeding is that the base rubber, the polarity enhancer and the coupling agent are fed into the first banburying step, and after mixing at a temperature of 140 ℃ and 150 ℃ for 2-10min, the rest of the components are fed into the first banburying step as a second banburying step, and mixing is continued at a temperature of not higher than 150 ℃ for 1-5 min.

21. The method as claimed in claim 20, wherein the base rubber, the polarity enhancer and the coupling agent are added in the first batch, and after kneading at a temperature of 145-150 ℃ for 3-5min, the remaining components are added as the second batch, and the kneading is continued at a temperature of 140-145 ℃ for 1-3 min.

22. A vulcanized rubber prepared by the method of any one of claims 18-21.

23. Use of the vulcanized rubber according to claim 22 for making rubber sealing parts.