Damping rubber film and preparation method thereof

Abstract

According to the preparation method disclosed by the invention, the damping rubber composition is dissolved by utilizing a solvent method, preforming is performed by adopting a tape casting technology, and hot-pressing vulcanization is performed in a vulcanizing machine, so that the damping rubber film with stable damping performance is obtained. The damping loss factor of the obtained damping rubber film is kept to be 0.5 or above at the temperature of-25 DEG C to 70 DEG C.

Description

Technical Field

[0001] The present invention relates to a damping rubber film and a preparation method thereof. Background Art

[0002] With the rapid development of modern industry, reducing vibration and noise has become an important issue in various fields. Vibration not only reduces operation precision, affects product quality, but may also shorten product life or endanger safety. The application of damping materials can consume the energy of mechanical waves, thereby reducing the harm caused by mechanical waves. In particular, in the fields of precision instrument protection, electronic components, and optical systems, high-damping materials play a key role in vibration control and energy absorption. Therefore, researching and mastering vibration control technology and developing damping material products (such as shock-absorbing rubber) suitable for industrial development have become major technical issues faced by the development of various fields.

[0003] The elastomer materials commonly used in shock-absorbing rubber mainly include the following: natural rubber (NR), styrene-butadiene rubber (SBR), cis-butadiene rubber (BR), nitrile-butadiene rubber (NBR), chloroprene rubber (CR), ethylene-propylene rubber (EPDM), butyl rubber (IIR), etc. Considering the influence of elastomer materials on shock-absorbing characteristics from the rubber formula, in addition to the selection of rubber components, it is also necessary to select appropriate vulcanizing agents, fillers (such as carbon black, silica), and additives, etc.

[0004] Among them, the vulcanization process has a long and mature history. During the processing and vulcanization process, harmful sulfur-containing compound gases will be generated. In addition, after the rubber product reaches the end of its life, it cannot be treated by high-temperature incineration because the sulfur element in it will definitely turn into harmful gases or toxic residues. Adjusting the vulcanization system, increasing the type and content of fillers, and introducing additives such as antioxidants can significantly improve the fatigue life of rubber. The use of high-performance vulcanizing agents can shorten the vulcanization time, reduce the dosage of vulcanizing agents, and increase the crosslinking density, thereby enhancing the anti-fatigue performance.

[0005] Generally speaking, environmental factors such as temperature, humidity, and oxygen content will all affect the fatigue performance of rubber. In a high-temperature environment, the movement of rubber molecular chains intensifies, which easily leads to stress relaxation and aging; low temperature makes the rubber harden, the toughness decreases, and it is easy to brittle fracture. So far, various studies have been carried out to reduce vibration in the fields of precision instrument protection, electronic components, and optical systems. However, with the continuous development of the industrial field, in addition to daily use, there are more complex application scenarios such as the seabed, high altitude, and fire sites. The research on the shock-absorbing characteristics of shock-absorbing rubber in extreme working environments is still not perfect.

[0006] In addition, the adaptability of traditional blocky or thick rubber materials is limited. High-damping materials in film form can be more flexibly adhered to or laminated on various structural surfaces to achieve precise control of vibration and noise. However, existing processes are mostly limited to calendering or molding, and it is impossible to balance thickness uniformity and high-damping characteristics.

[0007] For example, Patent Document 1 relates to the field of vibration damping technology for electric generators. By improving the formula and preparation method, the prepared product has excellent mechanical properties and is wear-resistant and aging-resistant. The vibration damping pad for the electric generator is made of the following raw materials in parts by weight: 50-60 parts of nitrile rubber, 40-50 parts of polyurethane rubber, 2-3 parts of stearic acid, 2-3 parts of dioctyl adipate, 4-6 parts of zinc oxide, 1-2 parts of glass fiber, 8-12 parts of calcined clay, 8-12 parts of microcrystalline cellulose, 8-12 parts of white carbon black, 2-4 parts of vulcanizing agent, 3-5 parts of palm wax, 2-5 parts of microcrystalline wax, and 2-4 parts of anti-aging agent. The physical properties such as tensile properties and hardness of the products prepared in Examples 1-8 and Comparative Examples 1-2 were evaluated under the condition of hot air aging at 150°C. However, the damping characteristics at low temperature environments were not evaluated. In addition, based on the relatively single use environment of the electric engine, this patent document did not consider the impact of low temperature extreme environments on the vibration damping pad. At the same time, the vibration damping pad for the electric generator obtained in this patent document is difficult to meet the special requirements such as thinning and lightening of vibration damping components in precision components such as electronic components.

[0008] In addition, for example, Patent Document 2 relates to an elastomeric composition having acoustic attenuation characteristics. This one-component thermosetting reactive composition is composed of a liquid rubber having reactive ethylenic double bonds, a solid rubber as required, and a sulfur-based vulcanization system, and has a high acoustic dynamic loss coefficient in a wide range of use temperatures, about +10°C to +40°C, in a vulcanized state. These compositions can be used as acoustic attenuation adhesives, sealing or coating materials. However, in this patent document, when the elastomeric composition is used as a coating, it is formed on the surface of the component by spraying or extrusion and heated to form a coating, which is difficult to meet the process requirements of electronic components such as chips. And only the acoustic wave attenuation value (d-combi) is concerned, and the impact of low temperature extreme environments on the vibration damping effect is not concerned either.

[0009] It can be seen that commonly used rubber materials at present are difficult to balance high-damping performance within a wide temperature range at the same time, resulting in an inability to achieve stable vibration damping effects in extreme environments, such as a wide operating temperature range (e.g., high temperature up to 70°C and low temperature down to -25°C). And in the prior art, the technical problem that it is difficult to balance uniformity and high-damping characteristics in a wide temperature range when rubber materials are made into films for use in precision components has not been studied. Therefore, designing and preparing a high-damping rubber film that can maintain a damping loss factor greater than 0.5 and has excellent uniformity in the range of -25°C to 70°C has become an urgent problem to be solved in this field.

[0010] Prior art documents

[0011] Patent document 1: CN 108794834 B

[0012] Patent document 2: JP-Tokuhyo 10-509755 Summary of the invention

[0013] Technical problems to be solved by the invention

[0014] As described above, in the technologies disclosed in the above patent documents, the stable vibration damping effect in a wide working temperature range (such as high temperature up to 70°C and low temperature down to -25°C) is not considered, and the uniformity when the damping material is made into a film is not concerned. Therefore, the technical problem to be solved by the present invention is that the present invention aims to provide a damping rubber film with uniform thickness and appropriate thickness that is difficult to obtain by traditional preparation processes and has a stable vibration damping effect in a wide working temperature range including extreme environments.

[0015] Solutions for solving the technical problems

[0016] In view of the above technical problems, the inventors of the present application have continuously conducted painstaking research and finally proposed a preparation method for obtaining a damping rubber film with stable damping performance by dissolving a damping rubber composition using a solvent method, preforming by a casting technique, and performing hot press vulcanization in a vulcanizer. The obtained damping rubber film maintains a damping loss factor of more than 0.5 at -25°C to 70°C.

[0017] That is, the present invention relates to the following technical solutions.

[0018] The present invention provides a method for preparing a damping rubber film, including the following steps:

[0019] Step of preparing a rubber solution: Dissolve a damping rubber composition with nitrile rubber as the main rubber component in a solvent to form a rubber solution;

[0020] Preforming step: Coat and dry the rubber solution by a casting method to form a preformed rubber film with a thickness of 0.05 - 0.3 mm;

[0021] Hot press vulcanization step: Perform hot press vulcanization on the preformed rubber film at 120 - 200°C and 3 - 15 MPa,

[0022] The damping rubber composition further includes a vulcanizing agent, a plasticizer, a reinforcing filler, and an anti-aging agent,

[0023] The content of acrylonitrile (ACN) in the nitrile rubber is more than 30% and 60% or less by percentage, and the Mooney viscosity of the nitrile rubber is more than 60 and 120 or less,

[0024] The vulcanizing agent is selected from one or more of sulfur, organic peroxides, quinone oxime compounds, and resin vulcanizing agents.

[0025] The plasticizer is selected from one or more of ester plasticizers and petroleum resins. The ester plasticizer is an ester formed by a polycarboxylic acid having two or more carboxyl groups and an alcohol having 1 to 20 carbon atoms.

[0026] According to an embodiment of the present invention, the content of the rubber component in the damping rubber composition is 40-90% by weight.

[0027] According to an embodiment of the present invention, the content of the vulcanizing agent in the damping rubber composition is 1-30 parts by weight based on 100 parts by weight of the rubber component.

[0028] According to an embodiment of the present invention, the content of the plasticizer in the damping rubber composition is 1-20 parts by weight based on 100 parts by weight of the rubber component.

[0029] According to an embodiment of the present invention, the content of the reinforcing filler in the damping rubber composition is 1-50 parts by weight based on 100 parts by weight of the rubber component.

[0030] According to an embodiment of the present invention, the content of the anti-aging agent in the damping rubber composition is 10-60 parts by weight based on 100 parts by weight of the rubber component.

[0031] According to an embodiment of the present invention, the reinforcing filler is an inorganic reinforcing filler, and the particle size of the inorganic reinforcing filler is 1-100 microns.

[0032] According to an embodiment of the present invention, hot press vulcanization is carried out for 15 to 30 minutes under the conditions of a vulcanization temperature of 150-180°C and a pressure of 5-10 MPa.

[0033] According to an embodiment of the present invention, in the process of coating and drying the rubber solution by the casting method, the drying temperature is below 80°C.

[0034] The present invention provides a film obtained by the preparation method described above. The obtained film maintains a damping loss factor of 0.5 or more at -25°C to 70°C.

[0035] Advantages of the Invention

[0036] According to the technical solution of the present invention, after preforming the rubber film and then vulcanizing it, a uniform damping rubber film that can provide a stable vibration damping effect in a wide working temperature range including extreme environments can be provided. Further, a uniform preformed rubber film with a thickness of 0.05-0.3 mm can be prepared by using the casting process to meet the fine vibration damping requirements. The combination of the casting film-forming and vulcanization processes can achieve continuous or batch operation on existing industrial equipment, improving production efficiency. Detailed Embodiments

[0037] The present invention is further described below by way of example, but it is to be understood that these specific examples will not limit the scope of the present invention in any way. It should be noted that, unless otherwise specified, the raw materials used in the following examples are commercially available products, and their quality meets national standards. In the present invention, when not specifically specified, content refers to weight percentage or weight ratio.

[0038] [Damping rubber composition]

[0039] The damping rubber composition of the present invention is a rubber composition with nitrile rubber (NBR) as the main rubber component, containing 1-30 parts by weight of a vulcanizing agent, 1-20 parts by weight of a plasticizer, 1-50 parts by weight of a reinforcing filler and 10-60 parts by weight of an anti-aging agent relative to 100 parts by weight of the rubber component. The acrylonitrile (ACN) content of the nitrile rubber is greater than 30% and less than 60%, and the Mooney viscosity is greater than 60 and less than 120. The vulcanizing agent is selected from one or more of sulfur, organic peroxide, quinone oxime compound and resin vulcanizing agent, and the plasticizer is selected from one or more of ester plasticizer, petroleum resin and the like. The ester plasticizer is an ester formed by a polycarboxylic acid having two or more carboxyl groups and an alcohol having 1 to 20 carbon atoms.

[0040] <Rubber ingredients>

[0041] The damping mechanism of rubber products is the energy dissipation caused by the internal friction between molecules when the molecular chain moves under the action of alternating stress. Nitrile rubber (NBR) has a large tanδ and better damping performance because it contains more side methyl groups and polar side groups, and is widely used in vibration reduction materials. However, in general, the damping factor of a single rubber is very small, the glass transition temperature (Tg) range is narrow, and the effective damping temperature range is narrow. Therefore, it is difficult to prepare high-performance damping materials using only a single rubber, and it is usually necessary to improve the damping performance of the material by blending other rubber materials.

[0042] The present invention has obtained a damping rubber film by blending acrylonitrile-butadiene rubber as the main rubber component with a specific vulcanizing agent, and coordinating a damping rubber composition of components such as a specific anti-aging agent, which can achieve excellent damping performance within a wide temperature range, which is a surprising effect in the art. In the present invention, using acrylonitrile-butadiene rubber as the main rubber component means that the content of acrylonitrile-butadiene rubber in the rubber component is more than 50% by weight, preferably more than 60%, more preferably more than 65%, more preferably more than 80% or more than 90%. In the most preferred embodiment of the present application, the rubber component is only composed of acrylonitrile-butadiene rubber.

[0043] Nitrile rubber is a copolymer formed by the polymerization of acrylonitrile and butadiene monomers. The acrylonitrile content in nitrile rubber affects the polarity, chain flexibility, intermolecular interaction force, and the content of double bonds in the molecular chain of nitrile rubber. The acrylonitrile (ACN) content of the nitrile rubber used in the present invention is greater than 30% and 60% or less (by weight percentage), preferably 31% or more and 50% or less, and most preferably 45% or less.

[0044] By using the nitrile rubber with the specified acrylonitrile content of the present invention, good processability can be achieved, and excellent cold resistance can be maintained. The damping loss factor of the damping rubber material can still be maintained in a cold environment as low as -25°C.

[0045] The Mooney viscosity of the nitrile rubber of the present invention is greater than 60 and 120 or less, preferably 72 or more and 105 or less, and most preferably 100 or less.

[0046] By using the nitrile rubber with the specified Mooney viscosity of the present invention, good film-forming properties can be achieved, the texture is uniform, and it can be applied to a wider range of application scenarios. And excellent heat resistance and cold resistance are maintained.

[0047] In the present invention, in the damping rubber composition obtained by hot press vulcanization crosslinking, the rubber component is 40 - 90% by weight percentage, preferably 45 - 80%, and more preferably 48 - 70%.

[0048] <Vulcanizing agent>

[0049] A vulcanizing agent is a substance that can cause rubber to vulcanize (crosslink). It is divided into two major categories: inorganic and organic. Inorganic vulcanizing agents include sulfur, sulfur monochloride, selenium, tellurium, etc. Organic vulcanizing agents include organic peroxides (such as benzoyl peroxide), quinone oxime compounds, resin vulcanizing agents, etc. Among them, inorganic vulcanizing agents containing excessive elemental sulfur and sulfur-containing compounds have the disadvantage of polluting the environment such as harmful gas emissions.

[0050] The vulcanizing agent used in the present invention is selected from one or more of sulfur, organic peroxides, quinone oxime compounds, resin vulcanizing agents, etc. Preferably, the vulcanizing agent contains resin vulcanizing agents. By forming C-C bonds and ether bonds with relatively high thermal stability for crosslinking, the heat resistance and other properties of the vulcanized rubber can be improved.

[0051] Among them, in the vulcanization process of nitrile rubber, the peroxide vulcanization system can obtain a rubber compound with low compression set, fast vulcanization speed, and heat air aging resistance. The present invention can use common peroxide vulcanizing agents, such as alkyl peroxides, diacyl peroxides (benzoyl peroxide (BPO)), and peroxy esters. Specific peroxide vulcanizing agents such as dicumyl peroxide (DCP), 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, etc.

[0052] When used as a vulcanizing agent for quinone oxime compounds in vulcanizing nitrile rubber, better physical and mechanical properties can be obtained, especially better heat aging resistance. Specifically, p-benzoquinone dioxime etc. can be used.

[0053] As the resin-based vulcanizing agent, one or more of phenolic resin-based vulcanizing agents are preferred, and one or more of phenol formaldehyde resins are further preferred. As the phenol formaldehyde resin, unsubstituted phenol formaldehyde resin, alkyl-substituted phenol formaldehyde resin (alkyl having 1-15 carbon atoms), etc. can be cited. The alkyl as the substituent of the alkyl-substituted phenol formaldehyde resin can be 1-3, and the alkyl can be substituted by halogen (alkyl having 1-15 carbon atoms). As the resin-based vulcanizing agent, better physical and mechanical properties can be obtained, especially better heat aging resistance. The film vulcanized by the resin-based vulcanizing agent of the present invention can achieve good film-forming property and uniform texture.

[0054] For the dosage of the vulcanizing agent in the damping rubber composition of the present invention, it is 1-30 parts by weight, preferably 2-28 parts by weight, more preferably 5-27 parts by weight, and most preferably 10-25 parts by weight based on 100 parts by weight of the rubber component.

[0055] <Plasticizer>

[0056] The use of the plasticizer can significantly improve the mixing performance of NBR during the processing and the forming performances such as calendering, extrusion, injection molding, etc., and the plasticizer can improve the polymer processing performance and tensile performance; reduce the viscosity, lower the hardness and modulus, increase the fluidity, improve the cold resistance, etc. The plasticizer used in the present invention is selected from one or more of ester plasticizers, petroleum resins, etc. By adding the plasticizer, the intermolecular force of NBR can be weakened, thereby reducing the Tg of the rubber, facilitating the casting of the damping rubber composition into a rubber film with uniform thickness, and at the same time cooperating with the vulcanizing agent to endow NBR with higher elasticity, lower heat generation, and improved cold resistance.

[0057] The ester plasticizer is preferably selected from one or more of esters formed by polycarboxylic acids having two or more carboxyl groups and alcohols having 1-20 carbon atoms.

[0058] The ester plasticizer can include ester plasticizers formed by phthalic acid and alcohols having 1-20 carbon atoms and fatty acid esters formed by fatty acids having two or more carboxyl groups and alcohols having 1-20 carbon atoms, etc.

[0059] The phthalate plasticizer has excellent compatibility and plasticizing effect. The phthalate plasticizer is one or more selected from dibutyl phthalate (DBP), dioctyl phthalate, etc. The fatty acid ester plasticizer is one or more selected from dioctyl adipate, diisooctyl sebacate, di-n-hexyl sebacate, di-n-butyl sebacate, etc.

[0060] Petroleum resin has good plasticizing effect and processing performance, and can improve the hardness, wear resistance and weather resistance of products.

[0061] Regarding the dosage of the plasticizer in the damping rubber composition of the present invention, based on 100 parts by weight of the rubber component, it is 1-20 parts by weight, preferably 5-18 parts by weight, more preferably 6-15 parts by weight.

[0062] <Reinforcing filler>

[0063] The reinforcing filler is closely related to the damping coefficient and modulus of nitrile rubber. The internal friction between the macromolecular chain segments and the filler, and between the fillers during the deformation process will change the damping performance of the vulcanizate. The morphology such as the particle size of the filler will affect the damping performance.

[0064] The reinforcing filler of the present invention is preferably an inorganic reinforcing filler, and the inorganic reinforcing filler is one or more selected from clay, calcium carbonate, magnesium carbonate, alumina, talc powder, mica powder, graphite, carbon black and white carbon black. Among them, for example, hard clay is inexpensive and has a significant reinforcing effect. Hydrated alumina in alumina is an excellent reinforcing filler for the heat-resistant formula of nitrile rubber.

[0065] Among them, white carbon black, that is, amorphous silica, is a white and non-toxic fine powder, which has excellent properties such as porosity, high dispersion, light weight, good chemical stability and high temperature resistance. White carbon black is an effective reinforcing filler for NBR and can effectively improve the tensile strength and tear strength of the vulcanizate. However, it is generally considered that using carbon black and white carbon black to reinforce NBR will also affect its heat resistance, and the present invention breaks through such technical understanding.

[0066] The particle size of the inorganic reinforcing filler of the present invention is 1-100 microns, preferably 1-80 microns, more preferably 1-60 microns

[0067] Regarding the dosage of the reinforcing filler in the damping rubber composition of the present invention, based on 100 parts by weight of the rubber component, it is 1-50 parts by weight, preferably 5-40 parts by weight, more preferably 8-30 parts by weight.

[0068] <Antioxidant>

[0069] During the use of NBR, due to changes in factors such as heat, oxygen, light, and water in the environment, it is prone to thermal-oxidative aging, resulting in a decline in mechanical properties and physicochemical properties, and affecting the service performance of products. When rubber ages, its molecular chains will continuously degrade and crosslink. When the decomposition rate is too high, the molecular weight of the rubber will decrease, the product will become sticky, and the strength will decrease; conversely, the surface will harden and lose elasticity. By adding anti-aging agents to the rubber, aging can be delayed.

[0070] The anti-aging agents used in this application are selected from one or more of phenols, poly-dihydroquinolines, amines, and imidazoles.

[0071] Among them, preferably one or more of hindered phenols, bisphenol hindered phenols, triphenol hindered phenols, hydroquinones, poly-dihydroquinolines, diphenylamine, p-phenylenediamine, mercaptobenzothiazole and its salts.

[0072] As specific anti-aging agents, examples can include hindered phenol AO60, hindered phenol AO-70, hindered phenol AO-80, bisphenol hindered phenol 2246, triphenol type hindered phenol 3114, 3125, 330, 2,2,4-trimethyl-1,2-dihydroquinoline polymer (RD), N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (4020), N-cyclohexyl-N'-phenyl-p-phenylenediamine (4010), 2-mercaptobenzothiazole (MB), 2-mercaptobenzothiazole zinc salt (MBZ), etc., one or more of them.

[0073] Regarding the dosage of the anti-aging agent in the damping rubber composition of the present invention, based on 100 parts by weight of the rubber component, it is 10-60 parts by weight, preferably 20-60 parts by weight, more preferably 25-55 parts by weight, and most preferably 30-55 parts by weight.

[0074] <Other Additives>

[0075] In the damping rubber composition of the present invention, lubricants, vulcanization accelerators, tackifiers and other conventional additives in the art can be added as needed. Regarding the dosage of other additives in the damping rubber composition of the present invention, based on 100 parts by weight of the rubber component, it is 0-20 parts by weight, preferably 0.1-10 parts by weight, more preferably 0.5-5 parts by weight.

[0076] [Manufacturing Method of Damping Rubber Film]

[0077] The preparation method of the damping rubber film of the present invention includes the processes of preparing a rubber solution, preforming, and hot pressing and vulcanizing, so as to obtain a film with a damping loss factor of 0.5 or more at -25°C - 70°C. The damping rubber film of the present invention can be easily cut, or further coated or laminated, etc.

[0078] <Preparation Process of Rubber Solution>

[0079] Cut each component of the damping rubber composition with nitrile rubber as the main rubber component into pieces with an equivalent projected area diameter of 0.5 - 2 cm, and then add them to a solvent to form a uniform rubber solution.

[0080] As the solvent of the present invention, as long as it can be uniformly mixed with each component of the damping rubber composition to form a rubber solution and can volatilize quickly during the casting process, one or more of organic solvents are preferred, and more preferably one or more selected from toluene, methyl ethyl ketone, cyclohexanone, etc. The viscosity of the rubber solution can be adjusted according to the film thickness and equipment requirements.

[0081] The amount of the solvent is 0.5 - 5 times, preferably 0.7 - 4 times, the total weight of the rubber damping composition.

[0082] For uniform mixing, conventional mixing methods such as stirring can be used. There is no special regulation for the mixing temperature, preferably 20 - 60 °C, more preferably 25 - 50 °C.

[0083] According to needs, a viscosity regulator can be further added. The type of the viscosity regulator is not particularly limited, and examples include polyethylene oxide (PEO), sodium polyacrylate (PNaAA), etc.

[0084] <Casting and Film Forming Process>

[0085] On a casting device (such as a casting machine), uniformly coat the rubber solution on the surface of the substrate to initially form a wet film.

[0086] By means of constant-temperature drying, uniform heating-up or stepwise heating, the drying temperature is below 80 °C, preferably at a temperature of 30 - 80 °C, to volatilize the solvent in the wet film, so as to ensure that the solvent is fully volatilized and avoid premature cross-linking of the material during drying. A preformed rubber film is obtained, and the thickness can be controlled in the range of 0.05 - 0.3 mm.

[0087] <Pressurized Vulcanization Process>

[0088] Place the preformed rubber film in a vulcanizer, and perform hot press vulcanization under the conditions of a vulcanization temperature of 120 - 200 °C, a pressure of 3 - 15 MPa, and a time of 10 - 40 minutes. The vulcanization temperature is the basic condition for the rubber to undergo vulcanization reaction. A high vulcanization temperature results in a fast vulcanization speed and high production efficiency. On the contrary, the vulcanization speed is slow and the production efficiency is low. If the temperature is higher than 200 °C, the high-temperature rubber molecular chains will crack, resulting in the phenomenon of vulcanization reversion. If the temperature is lower than 120 °C, the vulcanization reaction efficiency will decrease. The above vulcanization temperature is preferably 130 - 180 °C, more preferably 140 - 170 °C. The pressure is preferably 4 - 12 MPa, more preferably 6 - 9 MPa. The vulcanization time is preferably 15 - 30 minutes, more preferably 15 - 25 minutes.

[0089] After vulcanization, a damping rubber film with a stable cross-linked structure is formed. The damping rubber film of the present invention maintains a damping loss factor of more than 0.5 at -25°C to 70°C. The damping rubber film according to the present invention can achieve a stable vibration damping effect in a wide working temperature range including extreme environments and has a uniform texture.

[0090] Examples

[0091] Hereinafter, the present invention will be described more specifically by way of examples and comparative examples, but the present invention is not limited to these examples.

[0092] <Nitrile rubber>

[0093] Nitrile rubber 1: (NBR3308, acrylonitrile content 32% - 35%, Mooney viscosity 75 - 85, manufacturer: Lanzhou Chemical Industry Corporation)

[0094] Nitrile rubber 2 (NBR3606, acrylonitrile content 36% - 40%, Mooney viscosity 65 - 80, manufacturer: Lanzhou Chemical Industry Corporation)

[0095] Nitrile rubber 3: (NBR1704 acrylonitrile content 17 - 20%, Mooney viscosity 40 - 65, manufacturer: Lanzhou Chemical Industry Corporation)

[0096] Nitrile rubber 4: (trade name Russian 2665, acrylonitrile content 27% - 30%, Mooney viscosity 60 - 70)

[0097] <Vulcanizing agent>

[0098] Sulfur (powder, Luoyang Tianzhidao New Material Technology Co., Ltd.)

[0099] Dicumyl peroxide (DCP, Xiangyun Chemical Industry)

[0100] Resin vulcanizing agent 1: (phenolic resin, Hebei Zetian Chemical Industry Co., Ltd.)

[0101] Resin vulcanizing agent 2: (SP1045, Lianhui Chemical Industry)

[0102] <Plasticizer>

[0103] DMP (dimethyl phthalate, Shanghai Huafutai Chemical Industry Co., Ltd.)

[0104] DBP: (dibutyl phthalate, Shandong Yousuo Chemical Technology Co., Ltd.)

[0105] DOS: (dioctyl sebacate, Tianyuan Aviation Materials (Yingkou) Technology Co., Ltd.)

[0106] <Reinforcing filler>

[0107] Silica 1 (particle size: 48 microns, Shanghai Puni Industry Co., Ltd.)

[0108] Silica 2 (particle size: 1.6 microns, Hengtai Plasticizing Raw Material Co., Ltd.)

[0109] Silica 3 (particle size: 0.5 microns, Jinan Delan Chemical Co., Ltd.)

[0110] <Anti-aging agent>

[0111] Hindered phenol AO60 (Shanghai Kayin Chemical)

[0112] Bisphenol hindered phenol 2246 (Guangzhou Yuanda)

[0113] Triphenolic hindered phenol 3114 (Shanghai Boyer Chemical Co., Ltd.)

[0114] 2,2,4-Trimethyl-1,2-dihydroquinoline polymer (RD) (Shandong Yousuo Chemical Technology Co., Ltd.)

[0115] 2-Mercaptobenzimidazole (MB) (Zhejiang Huangyan Zhedong Rubber Auxiliary Co., Ltd.)

[0116] N-(1,3-Dimethylbutyl)-N'-phenyl-p-phenylenediamine (4020) (Shijiazhuang Anhui Chemical Technology Co., Ltd.)

[0117] N-Cyclohexyl-N'-phenyl-p-phenylenediamine (4010) (Shandong Yousuo Chemical Technology Co., Ltd.)

[0118] <Measurement method>

[0119] <Measurement of damping factor>

[0120] In the characterization of the damping performance of elastomers, the tangent value tanδ of the phase angle δ (also known as the mechanical loss angle) of the strain lagging behind the stress is generally used as the damping factor to describe the internal friction of the material. The internal friction of the elastomer material can be expressed as:

[0121]

[0122] Where: E″ represents the loss modulus and E′ represents the storage modulus.

[0123] The present invention uses a MAK-04 type viscoelastic spectrometer produced by Metravib Company of France. The vertical load is applied to 50 N, and the displacement and load are zeroed. Then the vibration frequency is preloaded to 125 Hz, and the excitation amplitude is ±50 μm. Except for pre-forming the glue solution in a specified fixture, a damping rubber film with specified dimensions of 15 mm in length, 3 mm in width, and 2 mm in thickness is obtained as a sample according to the preparation method of the example or comparative example, and the damping factor is measured. The dynamic testing machine uses the single-point testing method and automatically records SampleThe damping loss factor (tanδ). Reference can be made to GJB981-1990.

[0124] <Appearance evaluation>

[0125] Smooth surface, no bubbles: 〇

[0126] Fine lines or small bubbles on the surface: Δ

[0127] Obvious cracking or other conditions on the surface: ×

[0128] Example 1

[0129] Prepare each raw material according to the formula shown in Table 1. Prepare 100 g of nitrile rubber, 2 g of sulfur, 20 g of resin curing agent 1, 10 g of DMP, 15 g of silica 1, 45 g of AO60, and 5 g of antioxidant 4010.

[0130] In the process of preparing the rubber solution, cut the materials into small pieces about 2 cm in size, and add the materials to toluene at a ratio of 5 parts of toluene per part of the damping rubber composition, and stir at room temperature for 60 - 90 minutes until a uniform rubber solution is formed.

[0131] In the preforming process, on a casting machine, uniformly coat the rubber solution on the surface of the substrate to initially form a wet film. Volatilize the solvent in the wet film by drying at a constant temperature of 80 °C to obtain a preformed rubber film with a thickness of 0.12 mm.

[0132] In the hot pressing and curing process, after placing the rubber film in a curing machine, hot press and cure it at 160 °C and 5 MPa for 15 minutes.

[0133] Use the aforementioned measurement method to measure the damping factor. The results show that the obtained damping rubber film has a loss factor of 0.52 or more in the range of -25 °C to 70 °C. Appearance evaluation: smooth surface, no bubbles: 〇

[0134] Examples 2 - 4

[0135] Except for preparing each raw material by adjusting the formula according to Table 1 (100 g of nitrile rubber, and other components are weighed according to the weight ratio or weight percentage shown in the table), prepare the rubber solution, preform, and hot press and cure in the same manner as in Example 1, and conduct the tests in the same way. The results are shown in Table 1.

[0136] Comparative Examples 1 - 4

[0137] Except for preparing each raw material by adjusting the formula according to Table 1 (100 g of nitrile rubber, and other components are weighed according to the weight ratio or weight percentage shown in the table), prepare the rubber solution, preform, and hot press and cure according to the mixing method of Example 1 and conduct the tests in the same way. The results are shown in Table 1.

[0138] Comparative Example 5

[0139] Except that the drying temperature in the preforming process of Example 1 was set to be dried at a constant temperature of 130 °C to volatilize the solvent in the wet film, each raw material was prepared according to the same formula as in Example 1, the glue solution, preforming and hot press vulcanization were prepared by the same method, and the tests were carried out in the same way. The results are shown in Table 1 as follows.

[0140] The compositions of the damping rubber compositions of Examples 1-4 and Comparative Examples 1-5 and the measurement results of the obtained damping rubber films are shown in Table 1 below. The composition units of each component are all parts by weight or weight percentage.

[0141]

[0142]

[0143]

[0144] Example 5

[0145] The damping rubber composition was formulated according to the ratio of Example 2 above. The material was cut into small pieces about 1.5 cm in size. The high damping rubber composition was mixed with a mixed solvent of methyl ethyl ketone and cyclohexanone in a weight ratio of 1:1 and stirred at room temperature for 60-90 minutes until a uniform glue solution was formed.

[0146] In the preforming process, on a casting machine, the glue solution was evenly coated on the surface of the substrate to initially form a wet film. The temperature was raised to 80 °C at a heating rate of 30 °C / min to avoid premature vulcanization of the rubber and volatilize the solvent in the wet film to obtain a preformed glue film with a thickness of about 0.1 mm.

[0147] In the hot press vulcanization process, after the glue film was placed in a vulcanizer, it was hot press vulcanized at 150 °C and 8 MPa for 20 minutes to obtain a damping rubber film. The results showed that the loss factor of the obtained film was above 0.51 in the range of -25 °C to 70 °C. The appearance evaluation showed that the surface was smooth and there were no bubbles: 〇.

[0148] As described above, it is only a preferred embodiment of the present invention, and it does not impose any form of limitation on the present invention; any person skilled in the art can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the scope of the technical solution of the present invention, or modify it into an equivalent embodiment with equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of protection of the technical solution of the present invention.

[0149] Industrial Application

[0150] The manufacturing method of the damping rubber film described in the present invention and the film obtained by this method can be applied to the protection of electronic components, vibration prevention of precision instrument parts, vibration prevention of optical systems, etc. Its preparation process flow is simple, and only a small amount of modification to the existing production line is required to realize industrial production, which has significant economic benefits and popularization value.

Claims

1. Preparation method of damping rubber film, comprising the following processes: Process of preparing rubber solution: Dissolve a damping rubber composition with nitrile rubber as the main rubber component in a solvent to form a rubber solution; Pre-forming process: Coating and drying the rubber solution by casting method to form a pre-formed rubber film with a thickness of 0.05 - 0.3 mm; Hot pressing and vulcanizing process: Conduct hot pressing and vulcanization on the pre-formed rubber film at 120 - 200 °C and 3 - 15 MPa; The damping rubber composition further comprises a vulcanizing agent, a plasticizer, a reinforcing filler and an anti-aging agent; The content of acrylonitrile (ACN) in the nitrile rubber is more than 30% and 60% or less by percentage, and the Mooney viscosity of the nitrile rubber is more than 60 and 120 or less; The vulcanizing agent is selected from one or more of sulfur, organic peroxides, quinone oxime compounds, resin-based vulcanizing agents; The plasticizer is selected from one or more of ester plasticizers, petroleum resins, and the ester plasticizer is an ester formed by a polycarboxylic acid with two or more carboxyl groups and an alcohol with 1 - 20 carbon atoms; 2. The preparation method according to claim 1, wherein, The content of the rubber component in the damping rubber composition is 40 - 90% by weight percentage; 3. The preparation method according to claim 1 or 2, wherein The content of the vulcanizing agent in the damping rubber composition is 1 - 30 parts by weight based on 100 parts by weight of the rubber component; 4. The preparation method according to claim 1 or 2, wherein The content of the plasticizer in the damping rubber composition is 1 - 20 parts by weight based on 100 parts by weight of the rubber component; 5. The preparation method according to claim 1 or 2, wherein, The content of the reinforcing filler in the damping rubber composition is 1 - 50 parts by weight based on 100 parts by weight of the rubber component; 6. The preparation method according to claim 1 or 2, wherein The content of the anti-aging agent in the damping rubber composition is 10 - 60 parts by weight based on 100 parts by weight of the rubber component; 7. The preparation method according to claim 1 or 2, wherein, The reinforcing filler is an inorganic reinforcing filler, and the particle size of the inorganic reinforcing filler is 1 - 100 microns; 8. The preparation method according to claim 1 or 2, wherein, Conduct hot pressing and vulcanization for 15 - 30 minutes under the conditions of a vulcanization temperature of 150 - 180 °C and a pressure of 5 - 10 MPa; 9. The preparation method according to claim 1 or 2, wherein in the process of coating and drying the rubber solution by casting method, the drying temperature is 80 °C or below; 10. The film obtained by the preparation method according to any one of claims 1 - 9, and the obtained film maintains a damping loss factor of 0.5 or more at - 25 °C - 70 °C.

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