A temperature and moisture resistant expanded rubber composition and a method for producing the same

Abstract

The present application relates to the technical field of rubber material, in particular to a temperature and humidity resistant swelling rubber composition and a preparation method thereof.The present application provides a temperature and humidity resistant swelling rubber composition, which comprises, in terms of weight fraction, 100 parts of main material rubber, 2-10 parts of antioxidant, 20-35 parts of carbon black, 8-15 parts of foaming agent, 10-18 parts of vulcanizing agent, 6-15 parts of protective wax and 2-6 parts of filler; wherein the filler is carbon nanotube and nano calcium carbonate.The temperature and humidity resistant swelling rubber composition provided by the present application has excellent temperature and humidity resistance, and after being placed in an environment of 60 DEG C and 95% RH for 2 weeks, the viscosity and swelling rate of the material can remain basically unchanged, thereby guaranteeing good filling effect in subsequent use.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rubber materials, in particular to a temperature and humidity resistant expanded rubber composition and a preparation method thereof. BACKGROUND

[0002] Both the expanded rubber block and the expanded rubber tape belong to expanded rubber products, which have the characteristics of volume expansion through physical or chemical action, so as to realize the sealing and filling of spaces such as gaps or holes. According to the expansion mechanism, they are mainly divided into water-swelling type, heat-swelling type and chemical-swelling type, among which the water-swelling type and the heat-swelling type are more widely used in engineering sealing field. However, the traditional expanded rubber products are prone to self-vulcanization during storage, especially in high temperature and high humidity environment, which leads to the decrease of product adhesion and expansion rate, even unable to foam, and thus unable to play a good filling effect.

[0003] Therefore, it is urgent to develop an expanded rubber composition with excellent heat resistance and humidity resistance, so that it can be stored stably under high temperature and high humidity conditions and still have good filling effect when used later. SUMMARY

[0004] In view of this, the present application provides a temperature and humidity resistant expanded rubber composition and a preparation method thereof. The expanded rubber composition has excellent temperature and humidity resistance. The adhesion and expansion rate of the material can remain unchanged after being placed in an environment of 60℃ and 95%RH for 2 weeks, ensuring good filling effect when used later.

[0005] The technical scheme of the present application is as follows:

[0006] The present application provides a temperature and humidity resistant expanded rubber composition, which comprises, in terms of weight fraction: 100 parts of main material rubber, 2-10 parts of antioxidant, 20-35 parts of carbon black, 8-15 parts of foaming agent, 10-18 parts of vulcanizing agent, 6-15 parts of protective wax and 2-6 parts of filler; wherein the filler is carbon nanotube and nano calcium carbonate.

[0007] The application introduces anti-aging agents, carbon black, foaming agents, vulcanizing agents, protective waxes and fillers as fillers into the rubber matrix by optimizing the base formula of the rubber composition, wherein the anti-aging agents can improve the temperature and humidity resistance of the rubber composition system, the carbon black can not only ensure the strength of the rubber, but also improve the fluidity of the composition and ensure good dispersion performance of each component; the foaming agent can ensure the expansion effect of the rubber composition; the addition of the vulcanizing agent can cross-link the main material rubber molecular chains in the rubber composition to form a network structure, thereby providing the obtained expanded rubber product with basic mechanical properties; the protective wax can form a protective film on the surface of the expanded rubber composition to avoid the erosion of moisture in the environment on the expanded rubber composition. In addition, carbon nanotubes and nano calcium carbonate are added as fillers, the carbon nanotubes have good mechanical strength and heat resistance, and can be inserted between the gaps of the main material rubber molecular chains; when the temperature and humidity of the environment where the expanded rubber composition is located increase, the carbon nanotubes can effectively hinder the migration of the rubber molecular chains, thereby avoiding the premature vulcanization of the expanded rubber composition due to the influence of the environment and losing adhesion, and ensuring that it does not affect subsequent use; at the same time, nano calcium carbonate is also added, in actual use, the expanded rubber composition is expanded by heating, at this time, the nano calcium carbonate is dispersed in the gaps of the rubber matrix to promote the sliding of the rubber polymer molecular chains and ensure that the expanded rubber composition has good expansion rate.

[0008] Preferably, the mass ratio of the carbon nanotubes to the nano calcium carbonate is 1:0.2-0.6; and the aspect ratio of the carbon nanotubes is 8-12.

[0009] The mass ratio of the carbon nanotubes to the nano calcium carbonate can not only avoid premature vulcanization of the expanded rubber composition in a humid and hot environment, but also ensure that it has good expansion rate.

[0010] Further preferably, the mass ratio of the carbon nanotubes to the nano calcium carbonate is 1:0.4; and the aspect ratio of the carbon nanotubes is 8-10.

[0011] Preferably, the main material rubber is at least one selected from the group consisting of styrene butadiene rubber, nitrile rubber, butyl rubber, ethylene propylene rubber, chlorohydrin rubber, acrylate rubber and silicone rubber.

[0012] The application selects the above main material which is not easy to cross-link and vulcanize in a high temperature and high humidity environment to ensure that the obtained expanded rubber composition does not lose adhesion in a high temperature and high humidity environment.

[0013] Preferably, the anti-aging agent is at least one selected from the group consisting of phenolic anti-aging agents, amine anti-aging agents and heterocyclic anti-aging agents.

[0014] The above anti-aging agent has good temperature and humidity resistance, and its single use or multiple use can improve the temperature and humidity resistance of the formula system.

[0015] Further preferably, the phenolic antioxidant can be antioxidant 1010 or antioxidant 1076, the amine antioxidant can be antioxidant 4020 or antioxidant 4010, and the heterocyclic antioxidant can be antioxidant MB or antioxidant RD.

[0016] Preferably, the carbon black has a particle size of 10-30 nm and 80-100 nm.

[0017] Further preferably, the carbon black can be carbon black 110, carbon black 220 or carbon black 330.

[0018] Preferably, the mass ratio of the carbon black with a particle size of 10-30 nm to the carbon black with a particle size of 80-100 nm is 1:2-4.

[0019] The present application ensures good dispersion performance while ensuring the strength of the rubber compound by adding carbon black with different particle sizes.

[0020] Preferably, the blowing agent is a mixture of organic blowing agent and microsphere blowing agent with a mass ratio of 1:0.2-0.8.

[0021] The microsphere blowing agent is a blowing agent that can rapidly expand and increase in volume to tens of times its own size after heating, and has the advantages of stable performance, non-flammability, non-pollution, non-toxicity, non-odor, non-corrosion to the mold, and no dyeing to the product. The present application selects a blowing agent with a higher decomposition temperature, which can avoid premature decomposition of the blowing agent due to temperature changes during the storage of the expanded composition. The use of organic blowing agent and microsphere blowing agent together can not only improve the stability of the expanded composition during storage, but also provide good expansion rate and expansion effect.

[0022] Further preferably, the organic blowing agent can be azodicarbonamide, p-toluene hydrazine, or dinitrosopentamethylene tetramine.

[0023] Preferably, the vulcanizing agent is selected from one or more of thiazoles, sulfenamides and guanidine vulcanizing agents.

[0024] The above-mentioned vulcanizing agent belongs to a slow vulcanization system, which can slow down the vulcanization speed and avoid the early scorching phenomenon of the expanded rubber composition.

[0025] Further preferably, the vulcanizing agent can be any one of 2-mercaptobenzothiazole, diphenyl disulfide, N,N-diisopropyl-2-benzothiazole sulfenamide, di-o-tolyl guanidine or o-tolyl biguanide.

[0026] Preferably, the protective wax contains 22.0 wt%-35.0 wt% of C20-C23, 10.0 wt%-15.0 wt% of C24-C26, 30.0 wt%-40.0 wt% of C27-C30, and 25.0 wt%-35.0 wt% of C31-C35.

[0027] This invention selects protective waxes / wax-like materials with varying solubility in rubber. Utilizing the blooming properties of waxes, a protective film is formed on the surface of the expanded rubber composition, preventing moisture erosion of the rubber compound. By employing protective waxes with different carbon numbers, their solubility and migration are balanced, thereby enhancing their protective effect.

[0028] The present invention also provides a method for preparing the above-mentioned temperature and moisture resistant swelling rubber composition, the steps of which include:

[0029] Add the main material rubber to a two-mill and plasticize it at a low temperature of 55-70℃ for 10-15 minutes, then raise the temperature to 90-105℃ and plasticize it for 20-30 minutes to obtain the plasticized main material rubber.

[0030] The antioxidant, carbon black, foaming agent, vulcanizing agent, protective wax and filler are added to the plasticized main material rubber and mixed thoroughly at a temperature below 50°C to obtain the temperature and moisture resistant expansion rubber composition.

[0031] The preparation method provided by the present invention firstly involves low-temperature plasticizing and high-temperature plasticizing of the main rubber material. The full plasticizing of the main rubber material enables it to achieve greater plasticity, thereby reducing the Mooney viscosity of the main rubber material and making it easier to mix evenly with other fillers. Then, the antioxidant, carbon black, foaming agent, vulcanizing agent, protective wax and filler are added to the plasticized main rubber material and fully mixed at a lower temperature to ensure that the various materials are fully mixed and evenly dispersed.

[0032] The present invention also provides an expanding rubber block or expanding rubber tape, which is prepared from the above-mentioned temperature and moisture resistant expanding rubber composition or the temperature and moisture resistant expanding rubber composition prepared according to the above-mentioned preparation method as raw materials.

[0033] In practical applications, the expanded rubber blocks or tapes are subjected to electrophoretic baking, during which the expanded rubber blocks / tapes achieve cross-linking, vulcanization, expansion, and foaming.

[0034] Compared to existing technologies, the advantages of this invention are as follows: By specifically selecting the formulation, this invention significantly improves the temperature and humidity resistance of the expanded rubber composition and its structural stability during the expansion process. Testing of its temperature and humidity resistance shows that the expanded rubber composition can be stored at 60℃ and 95%RH for two weeks without changes in viscosity or expansion ratio, solving the practical problem that existing expanded rubbers are prone to large-scale production and storage due to environmental changes. For production departments, this allows for the production of larger quantities of rubber material (i.e., expanded rubber composition) at once, reducing production waste, and preventing the material from becoming unusable due to prolonged storage, thus saving production costs. Secondly, products extruded from this material can be stocked, enabling timely fulfillment of customer needs. Thirdly, when this expanded rubber composition is stored as a traded product in the customer's warehouse, it will not suffer from insufficient viscosity or reduced expansion rate due to harsh storage conditions, ensuring product quality, improving customer satisfaction, and reducing losses for manufacturers due to customer returns and exchanges. This has significant practical and economic value. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0036] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the meaning consistent with their meaning in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined.

[0037] Unless otherwise specified, the equipment, apparatus, reagents, and raw materials used in the following embodiments and comparative examples of this invention are all commercially available products in the art.

[0038] Currently, expanded rubber blocks / tapes are manufactured by suppliers (i.e., non-vulcanized rubber compositions) and shipped to the client's warehouse. The client then picks up the goods according to the production schedule. In actual use, the client lays the product on sheet metal and then undergoes electrophoretic baking, during which the expanded rubber blocks / tapes achieve cross-linking, vulcanization, expansion, and foaming. However, the client's warehouse is a conventional warehouse with a relatively harsh storage environment. The temperature and humidity are greatly affected by the weather, especially in summer when the temperature and humidity inside the warehouse are very high, which is not conducive to the storage of expanded rubber blocks / tapes (expanded rubber blocks / tapes are best stored in a dry environment at 23℃). Under such conditions, the expanded rubber blocks / tapes are prone to self-vulcanization, causing the product to lose its tackiness during storage. When used, it adheres poorly to the sheet metal and is prone to falling off. At the same time, it reduces the product's expansion rate or even prevents it from foaming, resulting in the inability to fill cavities.

[0039] The temperature and humidity resistant expanding rubber composition provided by this invention can be placed in an environment of 60°C and 95%RH for 2 weeks without changing its viscosity and expansion rate, thus solving the practical problem that existing expanding rubbers are difficult to mass-produce and store in advance due to environmental changes.

[0040] Example 1

[0041] This embodiment provides a temperature and moisture resistant expansion rubber composition, which, by weight, comprises: 100 parts of main rubber (50 parts of styrene-butadiene rubber, 20 parts of butyl rubber, and 30 parts of chlorohydrin rubber), 6 parts of antioxidant (3 parts of antioxidant 1010 and 3 parts of antioxidant 4020), 28 parts of carbon black (8 parts of carbon black with a particle size of 10-30 nm and 20 parts of carbon black with a particle size of 80-100 nm), 12 parts of foaming agent (8 parts of azodicarbonamide and 4 parts of microsphere foaming agent), 15 parts of vulcanizing agent (2-mercaptobenzothiazole), 11 parts of protective wax, and 4 parts of filler (3 parts of carbon nanotubes with an aspect ratio of 8-10 and 1 part of nano-calcium carbonate).

[0042] Example 2

[0043] This embodiment provides a temperature and moisture resistant expansion rubber composition, which, by weight, comprises: 100 parts of main rubber (40 parts of nitrile rubber and 60 parts of ethylene propylene diene monomer rubber), 10 parts of antioxidant (4 parts of antioxidant 1076 and 6 parts of antioxidant 4010), 20 parts of carbon black (4 parts of carbon black with a particle size of 10-30 nm and 16 parts of carbon black with a particle size of 80-100 nm), 8 parts of foaming agent (5 parts of p-toluenesulfonyl hydrazine and 3 parts of microsphere foaming agent), 18 parts of vulcanizing agent (10 parts of 2-mercaptobenzothiazole and 8 parts of di-o-tolueneguanidine), 7 parts of protective wax, and 6 parts of filler (4 parts of carbon nanotubes with an aspect ratio of 10-12 and 2 parts of nano-calcium carbonate).

[0044] Example 3

[0045] This embodiment provides a temperature and moisture resistant expansion rubber composition, which, by weight, comprises: 100 parts of main rubber (20 parts of styrene-butadiene rubber, 20 parts of acrylate rubber, 20 parts of silicone rubber, and 40 parts of butyl rubber), 4 parts of antioxidant (2 parts of antioxidant 4010 and 2 parts of antioxidant MB), 35 parts of carbon black (10 parts of carbon black with a particle size of 10-30 nm and 25 parts of carbon black with a particle size of 80-100 nm), 15 parts of foaming agent (10 parts of dinitrosopentamethylenetetramine and 5 parts of microsphere foaming agent), 10 parts of vulcanizing agent (N,N-diisopropyl-2-benzothiazole sulfenamide), 14 parts of protective wax, and 2.5 parts of filler (2 parts of carbon nanotubes with an aspect ratio of 8-12 and 0.5 parts of nano-calcium carbonate).

[0046] Example 4

[0047] This embodiment provides a method for preparing the temperature and moisture resistant expansion rubber composition of Example 1. The steps include: according to the formulation of Example 1, adding the main rubber material into a two-roll mill, plasticizing at a low temperature of 62°C for 12 minutes, and then heating to 98°C and plasticizing for 25 minutes to obtain the plasticized main rubber material; adding antioxidant, carbon black, foaming agent, vulcanizing agent, protective wax and filler to the plasticized main rubber material, and mixing thoroughly at 40°C to obtain the temperature and moisture resistant expansion rubber composition.

[0048] Example 5

[0049] This embodiment provides a method for preparing the temperature and moisture resistant expansion rubber composition of Example 2. The steps include: according to the formulation of Example 2, adding the main rubber material into a two-roll mill, plasticizing at a low temperature of 56°C for 15 minutes, and then heating to 90°C and plasticizing for 30 minutes to obtain the plasticized main rubber material; adding antioxidant, carbon black, foaming agent, vulcanizing agent, protective wax and filler to the plasticized main rubber material, and mixing thoroughly at 45°C to obtain the temperature and moisture resistant expansion rubber composition.

[0050] Example 6

[0051] This embodiment provides a method for preparing the temperature and moisture resistant expansion rubber composition of Example 3. The steps include: according to the formulation of Example 3, adding the main rubber material into a two-roll mill, plasticizing at a low temperature of 70°C for 10 minutes, and then heating to 105°C and plasticizing for 20 minutes to obtain the plasticized main rubber material; adding antioxidant, carbon black, foaming agent, vulcanizing agent, protective wax and filler to the plasticized main rubber material, and mixing thoroughly at 30°C to obtain the temperature and moisture resistant expansion rubber composition.

[0052] Comparative Example 1

[0053] This comparative example provides a temperature and moisture resistant expansion rubber composition, which, by weight, comprises: 100 parts of main rubber (50 parts of styrene-butadiene rubber, 20 parts of butyl rubber, and 30 parts of chlorohydrin rubber), 6 parts of antioxidant (3 parts of antioxidant 1010 and 3 parts of antioxidant 4020), 28 parts of carbon black (8 parts of carbon black with a particle size of 10-30 nm and 20 parts of carbon black with a particle size of 80-100 nm), 12 parts of foaming agent (8 parts of azodicarbonamide and 4 parts of microsphere foaming agent), 15 parts of vulcanizing agent (2-mercaptobenzothiazole), and 11 parts of protective wax.

[0054] The difference between this comparative example and the formulation of Example 1 is that no filler was added; all other components and amounts are the same as in Example 1.

[0055] Comparative Example 2

[0056] This comparative example provides a temperature and moisture resistant expansion rubber composition, which, by weight, comprises: 100 parts of main rubber (50 parts of styrene-butadiene rubber, 20 parts of butyl rubber, and 30 parts of chlorohydrin rubber), 6 parts of antioxidant (3 parts of antioxidant 1010 and 3 parts of antioxidant 4020), 28 parts of carbon black (8 parts of carbon black with a particle size of 10-30 nm and 20 parts of carbon black with a particle size of 80-100 nm), 12 parts of foaming agent (8 parts of azodicarbonamide and 4 parts of microsphere foaming agent), 15 parts of vulcanizing agent (2-mercaptobenzothiazole), 11 parts of protective wax, and 4 parts of filler (4 parts of carbon nanotubes with an aspect ratio of 8-10).

[0057] The difference between this comparative example and the formulation of Example 1 is that the filler is only carbon nanotubes and no nano-calcium carbonate is added. The rest of the composition and dosage are the same as those of Example 1.

[0058] Test Example

[0059] Expandable rubber blocks were prepared using the temperature- and humidity-resistant expanding rubber compositions obtained in Examples 1-3 and Comparative Examples 1-2 as raw materials. The viscosity (the blocks were laid on sheet metal and left to stand at room temperature for one week to observe detachment) and expansion rate (the expansion rate was tested after the blocks were laid on sheet metal, electrophoretically baked, and then the expansion rate was measured) of the expanded rubber blocks prepared in Examples 1-3 and Comparative Examples 1-2 were tested. Then, temperature and humidity resistance tests were conducted: Separate rubber blocks were placed simultaneously in a constant temperature and humidity phase (simulating a high-temperature and high-humidity environment) at 60°C and 95%RH for two weeks. Afterward, the viscosity and expansion rate were tested again (expansion rate (%) = (expanded volume - initial volume) / initial volume × 100%). The test results are shown in Table 1.

[0060] Table 1

[0061]

[0062] As shown in Table 1, compared with Example 1, when no carbon nanotubes or fillers are added, the viscosity and expansion rate of the obtained expanded rubber composition deteriorate significantly after being placed in a high temperature and high humidity environment for 2 weeks. This indicates that the temperature and humidity resistant expanded rubber composition provided by the present invention has good structural stability and can be stored in a high temperature and high humidity environment for 2 weeks without any change in viscosity and expansion rate.

[0063] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A heat and moisture resistant expanded rubber composition, characterized by, According to the weight parts, comprising: 100 parts of main material rubber, 2-10 parts of antioxidant, 20-35 parts of carbon black, 8-15 parts of foaming agent, 10-18 parts of vulcanizing agent, 6-15 parts of protective wax, 2-6 parts of filler; The main material rubber is selected from at least one of styrene butadiene rubber, nitrile rubber, butyl rubber, ethylene propylene rubber, chlorohydrin rubber, acrylate rubber and silicone rubber, the filler is carbon nanotube and nano calcium carbonate, and the mass ratio of the carbon nanotube to the nano calcium carbonate is 1:0.2-0.

6.

2. The heat and humidity resistant swelling rubber composition according to claim 1, wherein The aspect ratio of the carbon nanotube is 8-12.

3. The heat and humidity resistant swelling rubber composition according to claim 1, wherein The antioxidant is at least one of phenolic antioxidant, amine antioxidant and heterocyclic antioxidant.

4. The heat and humidity resistant, swelling rubber composition of claim 1, wherein, The particle size of the carbon black is 10-30 nm and 80-100 nm.

5. The heat and humidity resistant, swelling rubber composition of claim 4, wherein the at least one filler is present in an amount of 5 to 50 parts by weight. The mass ratio of the carbon black with a particle size of 10-30 nm to the carbon black with a particle size of 80-100 nm is 1:2-4.

6. The heat and humidity resistant, swelling rubber composition of claim 1, wherein, The foaming agent is a mixture of organic foaming agent and microsphere foaming agent with a mass ratio of 1:0.2-0.

8.

7. The heat and humidity resistant swelling rubber composition according to Claim 1, wherein The vulcanizing agent is selected from one or more of thiazole, sulfenamide and guanidine vulcanizing agents.

8. A process for producing the heat and moisture resistant expanded rubber composition according to any one of claims 1 to 7, characterized by the steps of Comprising: The main material rubber is added into an open mill, and plasticized at a low temperature of 55-70 DEG C for 10-15 minutes, and then plasticized at a high temperature of 90-105 DEG C for 20-30 minutes to obtain plasticized main material rubber; The antioxidant, carbon black, foaming agent, vulcanizing agent, protective wax and filler are added into the plasticized main material rubber, and mixed sufficiently below 50 DEG C to obtain the temperature and humidity resistant swelling rubber composition.

9. An intumescent mastic or tape, characterized in that, The temperature and humidity resistant swelling rubber composition prepared by the method according to claim 8 is used as raw material.

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