A kind of damping rubber and preparation method thereof

Abstract

The present application provides a damping glue and a preparation method thereof, the damping glue is based on 10 parts by weight of nitrile rubber, and also includes the following raw materials in parts by weight: 5-15 parts of epoxy resin, 2.4-7.2 parts of water, 0.7-2.1 parts of curing agent, and 30-100 parts of solvent; the solvent includes a first solvent and a second solvent, and the weight ratio of the first solvent to the second solvent is 0.8-1.5:1; the first solvent includes a carboxylic acid ester solvent; the second solvent includes one or more of propylene glycol butyl ether, propylene glycol methyl ether, ethylene glycol butyl ether acetate, dipropylene glycol methyl ether, diethylene glycol ethyl ether acetate, and propylene glycol methyl ether acetate. Water is introduced into the damping glue provided by the present application, which improves the solubility of the curing agent in the damping glue system, avoids the problem of curing agent sedimentation during long-term storage and application of the damping glue, and ensures the strength of the damping glue layer finally obtained.

Description

Technical Field

[0001] The present application relates to the field of polymer materials, and in particular to a damping adhesive and a preparation method thereof. Background Art

[0002] The damping steel plate made by compounding damping rubber and steel plate has been widely used in the fields of automobile, machinery, aerospace, etc. due to its excellent vibration reduction and noise reduction effect. At present, the industry mostly adopts the method of mixing rubber and curing agent together and then dissolving them with epoxy resin in organic solvent to prepare damping rubber, but the materials in the obtained damping rubber are not mixed evenly, especially the curing agent. The curing agent is not completely dissolved in the system and is very easy to precipitate during storage and application, resulting in a low curing agent content in the local glue solution, which reduces the curing degree of the epoxy resin in the system, and further affects the strength of the final damping rubber layer. Summary of the invention

[0003] In view of this, the present application provides a damping glue and a preparation method thereof. Water is introduced into the damping glue system, which improves the solubility of the curing agent in the damping glue system, avoids the problem of curing agent sedimentation during long-term storage and application of the damping glue, and ensures the strength of the final damping glue layer.

[0004] Specifically, the first aspect of the present application provides a damping glue, which is based on 10 parts by weight of nitrile rubber, and also includes the following raw materials in parts by weight: 5-15 parts of epoxy resin, 2.4-7.2 parts of water, 0.7-2.1 parts of curing agent, and 30-100 parts of solvent; the solvent includes a first solvent and a second solvent, and the weight ratio of the first solvent to the second solvent is 0.8-1.5:1; the first solvent includes a carboxylic acid ester solvent; the second solvent includes one or more of propylene glycol butyl ether, propylene glycol methyl ether, ethylene glycol butyl ether acetate, dipropylene glycol methyl ether, diethylene glycol ethyl ether acetate, and propylene glycol methyl ether acetate.

[0005] The damping glue provided in the first aspect of the present application also contains water on the basis of an organic solvent. Generally, in a damping glue system mainly composed of organic components, the curing agent adapted to the epoxy resin contained in the system has a strong polarity and is not easily soluble in an organic solvent, and water is a good solvent for the above-mentioned curing agent. Therefore, by introducing a water component, the solubility of the curing agent in the system can be increased, which effectively solves the problem that the curing agent is prone to sedimentation during the storage and application of the damping glue, so that the curing agent can be evenly distributed in the glue liquid, thereby ensuring the strength of the damping glue layer finally obtained. At the same time, water can be mutually soluble in the first solvent and the second solvent mixed system defined in the present application, which not only ensures the dissolution of the curing agent, but also does not affect the inherent physical and chemical properties of the damping glue (such as the viscosity of the damping glue, and the vibration reduction and noise reduction performance of the damping glue layer finally obtained). In addition, water is a medium-boiling point substance in the damping glue system, and its presence will not affect the subsequent curing process conditions of the damping glue. However, too much water may affect the stability of the damping glue, which is not conducive to the storage and application of the damping glue. If the water content in the system is too little, it will affect the dissolution of the curing agent, causing the precipitation of the curing agent, and affecting the strength of the damping glue layer obtained in the end. Therefore, the appropriate water content is the key to the damping glue of this application to exert its effect.

[0006] In the present application, the second solvent can dissolve nitrile rubber and can be miscible with water, so that the curing agent can be well dissolved in the system without sedimentation. When the damping glue has a solvent that satisfies this condition, it is still possible to cause the dissolved curing agent to settle during the storage and application of the damping glue, for example, acetone and tetrahydrofuran. The second solvent defined in the present application includes one or more of propylene glycol butyl ether, propylene glycol methyl ether, ethylene glycol butyl ether acetate, dipropylene glycol methyl ether, diethylene glycol ethyl ether acetate, and propylene glycol methyl ether acetate. These solvents are all ether alcohol solvents, and ether alcohol substances contain both oleophilic ether bonds and hydrophilic hydroxyls, wherein hydroxyls are easy to interact with the amino groups in the above-mentioned curing agent to form intermolecular hydrogen bonds, improve the sufficient solubility and compatibility of the curing agent in the system, so that the damping glue can be placed for a long time without sedimentation.

[0007] In some embodiments of the present application, the weight portion of the second solvent is 12-56 parts. At this time, the damping glue system containing the second solvent of this weight portion can better ensure the solubility of the curing agent and the nitrile rubber, thereby ensuring the stability and viscosity of the damping glue, which is beneficial to the subsequent sizing process. In addition, the second solvent is a high-boiling point solvent in the system, and its evaporation rate is slower than that of medium-boiling point solvents such as water. An appropriate amount of the second solvent can avoid the problem that the damping glue cannot be completely dried within a specific time, thereby ensuring the strength of the damping glue layer finally obtained.

[0008] In the present application, the first solvent is a good solvent for acrylonitrile-butadiene rubber. In some embodiments, the first solvent comprises one or both of ethyl acetate and butyl acetate. The above two solvents can be mutually soluble in a small amount of water present in the system while playing a good role in dissolving acrylonitrile-butadiene rubber, and have good comprehensive properties.

[0009] In some embodiments of the present application, the weight portion of the first solvent is 13-60 parts. A certain amount of the first solvent can ensure that the nitrile rubber is fully dissolved in the system, and will not reduce the content of the core raw materials (such as rubber, epoxy resin) in the system, and ensure the vibration reduction and noise reduction function and adhesion of the damping rubber layer formed by the damping rubber.

[0010] In the embodiment of the present application, the curing agent is a latent curing agent for curing epoxy resin, including one or more of dicyandiamide compounds, adipic acid dihydrazide, and imidazole compounds. Exemplarily, the imidazole curing agent may include one or more of imidazole, 2-methylimidazole, and 2-ethylimidazole. The above-mentioned latent curing agent has a good curing effect and is soluble in water.

[0011] In some embodiments of the present application, the weight ratio of the water to the curing agent is 1-10: 1. An appropriate amount of water can ensure that the curing agent is fully dissolved in the system and is conducive to maintaining the stability of the damping glue.

[0012] In the embodiment of the present application, the curing agent further includes a curing accelerator, and the curing accelerator includes an organic urea compound. The organic urea compound is used in combination with the above-mentioned dicyandiamide compound, adipic acid dihydrazide or imidazole compound to reduce the curing temperature of the damping adhesive. Exemplarily, the organic urea compound may include organic urea curing accelerators of brands such as Omicure U-24, U-24M, U-35, U-40 and U-52.

[0013] In the embodiment of the present application, the weight ratio of the epoxy resin to the curing agent is 2-20:1. Preferably, the mass of the curing accelerator does not exceed 100% of the mass of the curing agent, for example, 12.5-100%. The appropriate amount of curing agent and curing accelerator can ensure that the epoxy resin in the system is completely cured while making the epoxy resin have a suitable curing speed, which is conducive to the application of the damping glue.

[0014] In the embodiment of the present application, the epoxy resin is an epoxy resin commonly used in the art, and illustratively, may include but is not limited to one or more of bisphenol A epoxy resin, brominated bisphenol A epoxy resin, bisphenol F epoxy resin or novolac epoxy resin.

[0015] The second aspect of the present application provides a method for preparing a damping adhesive, comprising the following steps:

[0016] Adding the nitrile rubber into the first solvent and stirring until it is completely dissolved to obtain a rubber solution;

[0017] Mixing the curing agent with water and the second solvent, and stirring until the curing agent is completely dissolved to obtain a curing agent solution;

[0018] The rubber dissolving liquid, the curing agent dissolving liquid and the epoxy resin are mixed and stirred evenly to obtain the damping glue. The damping glue comprises the following raw materials in parts by weight: 10 parts of nitrile rubber, 5-15 parts of epoxy resin, 2.4-7.2 parts of water, 0.7-2.1 parts of curing agent, and 30-100 parts of solvent; the solvent comprises a first solvent and a second solvent in a weight ratio of 0.8-1.5:1; the first solvent is a carboxylic acid ester solvent; the second solvent comprises one or more of propylene glycol butyl ether, propylene glycol methyl ether, ethylene glycol butyl ether acetate, dipropylene glycol methyl ether, diethylene glycol ethyl ether acetate, and propylene glycol methyl ether acetate.

[0019] The preparation method provided in the second aspect of the present application divides the dissolution of rubber and curing agent into two independent steps, and the process is relatively simple, the production efficiency is high, and it is suitable for large-scale industrial production. At the same time, the curing agent can be stably dissolved in the second solvent and water, and the obtained curing agent solution and rubber solution can also be mutually soluble, which increases the dissolution of the curing agent while also ensuring the inherent physical and chemical properties of the damping rubber, and effectively solves the problem that conventional damping rubber is prone to sedimentation during long-term storage and application.

[0020] In the embodiment of the present application, before adding the nitrile rubber to the first solvent, the nitrile rubber is also pretreated, specifically including: plasticizing the nitrile rubber and then cutting it into pieces. Among them, plasticizing can improve the solubility of the nitrile rubber raw material in the solvent, shorten the preparation time of the rubber solution, and reduce its viscosity, thereby making it easier to coat the damping rubber on the surface of the substrate to be coated with the damping rubber, and can enhance the adhesion of the damping rubber solution to the substrate. Cutting the nitrile rubber into pieces of suitable size can accelerate its dissolution in the solvent and shorten the processing cycle.

[0021] Preferably, the temperature of the plasticizing is 60° C.-70° C. The appropriate temperature can accelerate the plasticizing process of the rubber.

[0022] At this time, the nitrile rubber is first plasticized and then dissolved, wherein the curing agent does not participate in the plasticizing process of the nitrile rubber, and there is no need to adjust the plasticizing process parameters according to the properties of the curing agent, making the plasticizing process of the nitrile rubber simpler and the process easier to control. DETAILED DESCRIPTION

[0023] The embodiments of the present application are further described below with reference to a plurality of embodiments.

[0024] Example 1

[0025] The nitrile rubber was milled for 5 minutes on a double-roll mill, and then shredded. 10 parts by weight of the rubber was mixed with 30 parts by weight of ethyl acetate to obtain a rubber solution.

[0026] 0.6 parts by weight of dicyandiamide, 0.15 parts by weight of Omicure U-24M, 20 parts by weight of propylene glycol methyl ether acetate, and 2.5 parts by weight of water were mixed and stirred until dissolved to prepare a curing agent solution;

[0027] The rubber solution, curing agent solution and 5.5 parts by weight of epoxy resin were mixed and stirred evenly, and the damping glue was obtained after filtering. The glue was yellow and transparent (slightly foggy).

[0028] Example 2

[0029] The nitrile rubber was milled for 5 minutes on a double-roll mill, and then shredded. 10 parts by weight of the rubber was mixed with 30 parts by weight of ethyl acetate to obtain a rubber solution.

[0030] 0.6 parts by weight of dicyandiamide, 0.15 parts by weight of Omicure U-24M, 20 parts by weight of propylene glycol methyl ether acetate, and 3.75 parts by weight of water were mixed and stirred until dissolved to prepare a curing agent solution;

[0031] The rubber solution, curing agent solution and 5.5 parts by weight of epoxy resin were mixed and stirred evenly, and the damping glue was obtained after filtering. The glue was yellow and transparent (slightly foggy).

[0032] Example 3

[0033] The nitrile rubber was milled for 5 minutes on a double-roll mill, and then shredded. 10 parts by weight of the rubber was mixed with 30 parts by weight of ethyl acetate to obtain a rubber solution.

[0034] 0.6 parts by weight of dicyandiamide, 0.15 parts by weight of Omicure U-24M, 20 parts by weight of propylene glycol methyl ether acetate, and 7 parts by weight of water were mixed and stirred until dissolved to prepare a curing agent solution;

[0035] The rubber solution, curing agent solution and 5.5 parts by weight of epoxy resin were mixed and stirred evenly, and the damping glue was obtained after filtering. The glue was yellow and transparent (slightly foggy).

[0036] Example 4

[0037] The nitrile rubber was milled for 5 minutes on a double-roll mill, and then shredded. 10 parts by weight of the rubber was mixed with 30 parts by weight of ethyl acetate to obtain a rubber solution.

[0038] 0.6 parts by weight of dicyandiamide, 0.15 parts by weight of Omicure U-24M, 20 parts by weight of propylene glycol methyl ether acetate, and 5.2 parts by weight of water were mixed and stirred until dissolved to prepare a curing agent solution;

[0039] The rubber solution, curing agent solution and 5.5 parts by weight of epoxy resin were mixed and stirred evenly, and the damping glue was obtained after filtering. The glue was yellow and transparent (slightly foggy).

[0040] Example 5

[0041] The nitrile rubber was milled for 5 minutes on a double-roll mill, and then shredded. 10 parts by weight of the rubber was mixed with 30 parts by weight of ethyl acetate to obtain a rubber solution.

[0042] 0.6 parts by weight of dicyandiamide, 0.15 parts by weight of Omicure U-24M, 20 parts by weight of propylene glycol methyl ether acetate, and 7.2 parts by weight of water were mixed and stirred until dissolved to prepare a curing agent solution;

[0043] The rubber solution, curing agent solution and 5.5 parts by weight of epoxy resin were mixed and stirred evenly, and the damping glue was obtained after filtering. The glue was yellow and transparent (slightly foggy).

[0044] Example 6

[0045] The nitrile rubber was milled for 5 minutes on a double-roll mill, and then shredded. 10 parts by weight of the rubber was mixed with 30 parts by weight of ethyl acetate to obtain a rubber solution.

[0046] 0.6 parts by weight of dicyandiamide, 0.15 parts by weight of Omicure U-24M, 24 parts by weight of propylene glycol methyl ether acetate, and 5.2 parts by weight of water were mixed and stirred until dissolved to prepare a curing agent solution;

[0047] The rubber solution, curing agent solution and 5.5 parts by weight of epoxy resin were mixed and stirred evenly, and the damping glue was obtained after filtering. The glue was yellow and transparent (slightly foggy).

[0048] Example 7

[0049] The nitrile rubber was milled for 5 minutes on a double-roll mill, and then shredded. 10 parts by weight of the rubber was mixed with 30 parts by weight of ethyl acetate to obtain a rubber solution.

[0050] 0.6 parts by weight of dicyandiamide, 0.15 parts by weight of Omicure U-24M, 15 parts by weight of propylene glycol methyl ether acetate, 20 parts by weight of propylene glycol butyl ether, and 5.2 parts by weight of water were mixed and stirred until dissolved to prepare a curing agent solution;

[0051] The rubber solution, curing agent solution and 5.5 parts by weight of epoxy resin were mixed and stirred evenly, and the damping glue was obtained after filtering. The glue was yellow and transparent (slightly foggy).

[0052] Example 8

[0053] The nitrile rubber was milled for 5 minutes on a double-roll mill, and then shredded. 10 parts by weight of the rubber was mixed with 18 parts by weight of ethyl acetate to obtain a rubber solution.

[0054] 0.6 parts by weight of dicyandiamide, 0.15 parts by weight of Omicure U-24M, 15 parts by weight of propylene glycol methyl ether acetate, and 5.2 parts by weight of water were mixed and stirred until dissolved to prepare a curing agent solution;

[0055] The rubber solution, curing agent solution and 5.5 parts by weight of epoxy resin were mixed and stirred evenly, and the damping glue was obtained after filtering. The glue was yellow and transparent (slightly foggy).

[0056] In order to highlight the beneficial effects of the embodiments of the present application, the following comparative examples 1-4 are provided.

[0057] Comparative Example 1

[0058] The nitrile rubber was milled on a double-roll mill for 5 minutes, and after being shredded, 10 parts by weight of the rubber was taken and mixed with 30 parts by weight of ethyl acetate to be uniformly dissolved to obtain a rubber solution;

[0059] 0.6 parts by weight of dicyandiamide, 0.15 parts by weight of Omicure U-24M, and 35 parts by weight of propylene glycol methyl ether acetate were mixed and stirred to obtain a curing agent solution;

[0060] The rubber solution, curing agent solution and 5.5 parts by weight of epoxy resin are mixed and stirred evenly, and then filtered to obtain the damping glue.

[0061] Comparative Example 2

[0062] The nitrile rubber was milled on a double-roll mill for 5 minutes, and after being shredded, 10 parts by weight of the rubber was taken and mixed with 30 parts by weight of ethyl acetate to be uniformly dissolved to obtain a rubber solution;

[0063] 0.6 parts by weight of dicyandiamide, 0.15 parts by weight of Omicure U-24M, 20 parts by weight of acetone, and 2.8 parts by weight of water were mixed and stirred until dissolved to prepare a curing agent solution;

[0064] The rubber solution, curing agent solution and 5.5 parts by weight of epoxy resin are mixed and stirred evenly, and then filtered to obtain the damping glue.

[0065] Comparative Example 3

[0066] The nitrile rubber was milled for 5 minutes on a double-roll mill, and then shredded. 10 parts by weight of the rubber was mixed with 30 parts by weight of ethyl acetate to obtain a rubber solution.

[0067] 0.6 parts by weight of dicyandiamide, 0.15 parts by weight of Omicure U-24M, 60 parts by weight of propylene glycol methyl ether acetate, and 2.5 parts by weight of water were mixed and stirred until dissolved to prepare a curing agent solution;

[0068] The rubber solution, curing agent solution and 5.5 parts by weight of epoxy resin were mixed and stirred evenly, and the damping glue was obtained after filtering. The glue was yellow and transparent (slightly foggy).

[0069] Comparative Example 4

[0070] The nitrile rubber was milled for 5 minutes on a double-roll mill, and then shredded. 10 parts by weight of the rubber was mixed with 30 parts by weight of ethyl acetate to obtain a rubber solution.

[0071] 0.6 parts by weight of dicyandiamide, 0.15 parts by weight of Omicure U-24M, 15 parts by weight of propylene glycol methyl ether acetate, and 2.5 parts by weight of water were mixed and stirred until dissolved to prepare a curing agent solution;

[0072] The rubber solution, curing agent solution and 5.5 parts by weight of epoxy resin were mixed and stirred evenly, and then filtered to obtain damping glue, which was yellow and turbid.

[0073] The glue prepared in the above Examples 1-8 and Comparative Examples 1-4 was subjected to the following performance tests:

[0074] (1) Storage time test: Seal the mixed damping glue in a 1L transparent glass bottle and place it in a static environment at 25°C. Observe the time when obvious stratification occurs with the naked eye. Take a small amount of the prepared damping glue and centrifuge it at 7000 rpm for 5 minutes in a centrifuge to conduct an accelerated stability test. Observe the stratification of the damping glue after centrifugation with the naked eye.

[0075] (2) Peel strength test: Take the upper and lower layers of the damping glue after standing for 10 days, apply them to the surface of the steel plate, bake at 110℃ for 10-15min to remove the solvent, and then laminate with another steel plate. After lamination, place at 150℃ for 1h to cure. The cured composite steel plate is subjected to peel strength test according to the method in DIN EN ISO 11339-2010 standard.

[0076] (3) Damping coefficient η test: Take the upper and lower layers of the damping glue after standing for 10 days, apply them to the surface of the steel plate, bake at 110℃ for 10-15min to remove the solvent, and then laminate with another steel plate. After lamination, place at 150℃ for 1h to cure. The cured composite steel plate is subjected to peel strength test according to the method in DIN EN ISO 11339-2010 standard.

[0077] Table 1 Performance test results of damping glue obtained in the embodiments and comparative examples

[0078]

[0079] It can be seen from the data in Table 1 that the damping glue prepared in Examples 1-8 has a long storage time and good stability, and the damping glue layer obtained after curing has high peel strength and good damping effect. The damping glue prepared in Comparative Example 1 does not contain water, and Comparative Example 2 replaces water with acetone. The damping glue prepared by the above two does not contain water, and the curing agent in the system is not fully dissolved, resulting in poor stability of the damping glue, short storage time, and poor damping effect and low peel strength of the damping glue layer obtained by curing. The damping glue prepared in Comparative Example 3 contains an excess of the second solvent, and the second solvent evaporates slowly and remains in the glue layer, resulting in a decrease in the peel strength of the composite steel plate; the damping glue prepared in Comparative Example 4 contains an excess of the first solvent, resulting in the inability of the curing agent to be effectively dissolved, resulting in poor stability of the damping glue, short storage time, and poor damping effect and low peel strength of the damping glue layer obtained by curing.

[0080] As shown in the above test results, the damping glue provided in the present application has stable properties, the curing agent has high solubility in the damping glue system, the damping glue will not have the problem of curing agent sedimentation during long-term storage and application, and the damping glue layer obtained after curing has high peel strength.

[0081] The above is an exemplary embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made thereto without departing from the principles of the present application. These improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. A damping rubber, characterized in that: Based on 10 parts by weight of nitrile rubber, the invention also includes the following raw materials in parts by weight: 5-15 parts of epoxy resin, 2.4-7.2 parts of water, 0.7-2.1 parts of curing agent, and 30-100 parts of solvent; the solvent includes a first solvent and a second solvent, the weight of the first solvent is 18-60 parts, and the weight ratio of the first solvent to the second solvent is 0.8-1.5:1; the first solvent is a good solvent for nitrile rubber, and the first solvent includes a carboxylic acid ester solvent; the second solvent includes one or more of propylene glycol butyl ether, propylene glycol methyl ether, ethylene glycol butyl ether acetate, dipropylene glycol methyl ether, diethylene glycol ethyl ether acetate, and propylene glycol methyl ether acetate; The curing agent includes one or more of dicyandiamide compounds, adipic acid dihydrazide, and imidazole compounds.

2. The damping adhesive according to claim 1, characterized in that: The weight portion of the second solvent is 12-24 parts.

3. The damping adhesive according to claim 1, characterized in that: The curing agent further includes a curing accelerator, and the curing accelerator includes an organic urea compound.

4. The damping adhesive according to claim 3, characterized in that: The weight ratio of the water to the curing agent is (10 / 3-10):

1.

5. The damping adhesive according to claim 3, characterized in that: The weight ratio of the epoxy resin to the curing agent is (22 / 3-20):

1.

6. The damping adhesive according to claim 1, characterized in that: The first solvent includes one or both of ethyl acetate and butyl acetate.

7. A method for preparing a damping rubber, characterized in that: The following steps are involved: Adding the nitrile rubber into the first solvent and stirring until it is completely dissolved to obtain a rubber solution; Mixing the curing agent with water and the second solvent, and stirring until the curing agent is completely dissolved to obtain a curing agent solution; The rubber dissolving liquid, the curing agent dissolving liquid and the epoxy resin are mixed and stirred evenly to obtain a damping glue; the damping glue comprises the following raw materials in parts by weight: 10 parts of nitrile rubber, 5-15 parts of epoxy resin, 2.4-7.2 parts of water, 0.7-2.1 parts of curing agent, and 30-100 parts of solvent; the solvent comprises a first solvent and a second solvent in a weight ratio of 0.8-1.5:1, and the weight of the first solvent is 18-60 parts; the first solvent is a good solvent for nitrile rubber, and the first solvent is a carboxylic acid ester solvent; the second solvent comprises one or more of propylene glycol butyl ether, propylene glycol methyl ether, ethylene glycol butyl ether acetate, dipropylene glycol methyl ether, diethylene glycol ethyl ether acetate, and propylene glycol methyl ether acetate; The curing agent includes one or more of dicyandiamide compounds, adipic acid dihydrazide, and imidazole compounds.

8. The preparation method according to claim 7, characterized in that: Before adding the nitrile rubber into the first solvent, the nitrile rubber is pretreated, specifically including: plasticizing and shredding the nitrile rubber.

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