Foamed rubber containing reclaimed materials as well as preparation method and application of foamed rubber

Abstract

The invention provides foamed rubber containing reclaimed materials as well as a preparation method and application of the foamed rubber. The reclaimed material-containing foamed rubber is prepared from the following raw materials in parts by weight: 60 to 70 parts of solid nitrile rubber, 30 to 50 parts of regenerated nitrile rubber, 10 to 20 parts of ethylene-vinyl acetate copolymer, 5 to 10 parts of styrene-ethylene-butylene-styrene block copolymer, 5 to 10 parts of liquid nitrile rubber, 10 to 20 parts of carbon black, 6 to 10 parts of foaming agent and 2.5 to 4 parts of vulcanizing agent. The foamed rubber provided by the invention has the advantages of favorable formability, lower density, uniform foam pores, low raw rubber consumption, lower cost, low material density, high weather resistance, short vulcanization time, high strength and simple production process, and is suitable for large-scale production.

Description

Technical Field

[0001] The invention belongs to the technical field of foam rubber, and particularly relates to foam rubber containing recycled materials, a preparation method and application thereof. Background Art

[0002] In the acoustics industry, foam materials are favored by many customers in the industry due to their advantages such as low density, high sensitivity, good sound damping, and good sound quality and timbre. Nitrile rubber foam folding ring is a closed-cell structure material formed by adding a certain amount of foaming agent to nitrile rubber (NBR). This type of material combines the inherent properties of nitrile rubber and the versatility of the foam structure. It also has the advantages of rubber's resistance to aging and fatigue, as well as the low density and high sensitivity of the foam material. The existing technology often uses NBR or NBR / PVC (polyvinyl chloride) as a matrix to prepare foam materials. The problem with this technology is that when using NBR alone for foaming, the melt fluidity is poor, the vulcanization process is complex, the processing difficulty is high, the bubble size and finished product density are generally difficult to control, and the cost and energy consumption are high. However, NBR / PVC blended foaming will introduce halogen groups, which cannot pass some EU standards and has limited application scenarios.

[0003] CN105037851A discloses a closed-cell secondary foaming material using styrene-butadiene rubber, natural rubber, and nitrile rubber, and a preparation method thereof. The closed-cell secondary foaming material using styrene-butadiene rubber, natural rubber, and nitrile rubber maintains the good elasticity, wear resistance, crack resistance, and wet-slip resistance of the styrene-butadiene rubber, increases its resilience, elongation, tensile strength, and tear strength by adding natural rubber, and improves its oil resistance by adding nitrile rubber. The material can be used for a long time in air at 120°C or in oil at 150°C, becoming an indispensable elastic material in the automotive, aviation, petroleum, and copying industries. The preparation method of the closed-cell secondary foaming material using styrene-butadiene rubber, natural rubber, and nitrile rubber adds a separate mastication and calendering and static process for the two rubber materials, and adopts a new process of primary vulcanization and secondary foaming. The preparation method is simple and easy, suitable for large-scale quantitative production, and highly practical.

[0004] CN107474299A discloses a nitrile rubber foamed using a paste system and its preparation method. This method uses cyclopentane and polybutadiene to prepare nitrile rubber powder into a viscous paste. The paste is then foamed at low temperatures to form a foam with uniform micropores. Further high-temperature vulcanization cross-links the foamed nitrile rubber into a foam with good strength. By pre-foaming at low temperatures, this method overcomes the drawback of simultaneous foaming and cross-linking under high-temperature melting, which makes it difficult to form uniform and stable pores. This method provides an excellent technical approach for foaming elastic materials such as rubber.

[0005] CN101215391A discloses a method for preparing a CPE-modified nitrile rubber foam material that is environmentally friendly, low-cost, and widely applicable. The method comprises the following steps: adding 100 parts of nitrile rubber to 100 parts of chlorinated polyethylene, 1 to 5 parts of a vulcanizing agent, 1 to 3 parts of an accelerator, 5 to 15 parts of a main foaming agent, and 1 to 8 parts of a composite regulating foaming agent, by weight, and heating at 100 to 190° C. for 10 to 100 minutes to obtain a modified nitrile rubber (NBR) foam material. The advantages of the modified method are: significantly improving the ozone resistance and heat aging resistance of the NBR foam material; improving the flame retardancy, wear resistance, and tensile strength of the NBR foam material; significantly reducing the product cost of the NBR foam material while maintaining good production processability; having better environmental friendliness; the resulting modified NBR foam material has good physical properties and cell stability; and the process is simple and easy to control.

[0006] However, the above solutions also fail to solve the defects of the prior art. Therefore, how to provide a foam rubber with good foaming performance, good processing performance, low finished product density and environmental protection has become a problem to be solved urgently. Summary of the Invention

[0007] In response to the shortcomings of the prior art, the present invention provides a foamed rubber containing recycled materials, a preparation method thereof, and applications thereof. The foamed rubber provided by the present invention has good moldability, a relatively low density, and uniform pores, thereby reducing the use of raw rubber and lowering costs. The material has low density, high weather resistance, a short vulcanization time, high strength, and a simple production process, making it suitable for large-scale production.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a foam rubber containing recycled materials, wherein the raw materials for preparing the foam rubber containing recycled materials include, by weight, 60-70 parts of solid nitrile rubber, 30-50 parts of recycled nitrile rubber, 10-20 parts of ethylene-vinyl acetate copolymer (EVA), 5-10 parts of styrene-ethylene-butylene-styrene block copolymer (SEBS), 5-10 parts of liquid nitrile rubber, 10-20 parts of carbon black, 6-10 parts of foaming agent and 2.5-4 parts of vulcanizing agent.

[0010] Among them, the number of parts of solid nitrile rubber can be 60 parts, 61 parts, 62 parts, 63 parts, 64 parts, 65 parts, 66 parts, 67 parts, 68 parts, 69 parts or 70 parts, etc., the number of recycled nitrile rubber can be 30 parts, 32 parts, 34 parts, 36 parts, 38 parts, 40 parts, 42 parts, 44 parts, 46 parts, 48 ​​parts or 50 parts, etc., the number of parts of ethylene-vinyl acetate copolymer can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts or 20 parts, etc., the number of styrene-ethylene-butylene-styrene block copolymer can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts or 20 parts, etc. The number of parts of the material can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts, etc., the number of parts of liquid nitrile rubber can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts or 10 parts, etc., the number of parts of carbon black can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts or 20 parts, etc., the number of parts of the foaming agent can be 6 parts, 7 parts, 8 parts, 9 parts or 10 parts, etc., the number of parts of the vulcanizing agent can be 2.5 parts, 3 parts, 3.5 parts or 4 parts, etc., but are not limited to the values ​​listed above, and other values ​​not listed within the above numerical range are equally applicable.

[0011] The above-mentioned foamed rubber is compounded with solid nitrile rubber, recycled nitrile rubber, ethylene-vinyl acetate copolymer, styrene-ethylene-butylene-styrene block copolymer and liquid nitrile rubber, and the synergistic effect not only reduces the use of raw rubber, increases the proportion of recycled materials and saves costs, but also reduces the vulcanization energy required for foaming, making the bubbles more uniform, greatly reducing the difficulty of foaming, significantly reducing the material density, and improving weather resistance. It also improves processing fluidity and reduces permanent deformation. It has the advantages of good molding performance, low density, high strength, halogen-free, energy saving and environmental protection, and is suitable for large-scale production.

[0012] Preferably, the acrylonitrile content in the solid nitrile rubber and the liquid nitrile rubber is independently 24-33%, for example, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32% or 33%, etc., but is not limited to the values ​​listed above. Other values ​​not listed within the above numerical range are also applicable.

[0013] Preferably, the Mooney viscosity of the solid nitrile rubber is 30-60, such as 30, 35, 40, 45, 50, 55 or 60, but is not limited to the above-listed values. Other values ​​not listed within the above numerical range are also applicable.

[0014] Preferably, the Mooney viscosity of the liquid nitrile rubber is 10,000-50,000, for example, 10,000, 15,000, 20,000, 25,000, 30,000, 35,000, 40,000, 45,000 or 50,000, etc., but is not limited to the values ​​listed above, and other values ​​not listed within the above numerical range are also applicable.

[0015] Preferably, the Mooney viscosity of the regenerated nitrile rubber is 40-50, for example, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49 or 50, but is not limited to the above-listed values. Other values ​​not listed within the above numerical range are also applicable, and the ash content is less than 10%.

[0016] Preferably, the vinyl acetate content in the ethylene-vinyl acetate copolymer is 25-30%, for example, 25%, 26%, 27%, 28%, 29% or 30%, etc., but is not limited to the values ​​listed above. Other values ​​not listed within the above numerical range are also applicable.

[0017] Preferably, the styrene content in the styrene-ethylene-butylene-styrene block copolymer is less than 20%, and the Shore hardness is 25-60, for example, 25, 30, 35, 40, 45, 50, 55 or 60, etc., but is not limited to the values ​​listed above. Other values ​​not listed within the above numerical range are also applicable.

[0018] Preferably, the foaming agent comprises any one of azodicarbonamide (AC), oxybisbenzenesulfonylhydrazide (OBSH) or urea, or a combination of at least two thereof, preferably a combination of azodicarbonamide, oxybisbenzenesulfonylhydrazide and urea.

[0019] Preferably, the vulcanizing agent includes sulfur, accelerator DM and accelerator TMTD.

[0020] Preferably, the raw materials for preparing the foamed rubber containing recycled materials also include 0.5-2 parts of release agent in parts by weight, such as 0.5 parts, 1 part, 1.5 parts or 2 parts, etc., but are not limited to the values ​​listed above. Other values ​​not listed within the above numerical range are also applicable.

[0021] Preferably, the release agent comprises zinc stearate and / or calcium stearate.

[0022] Preferably, the raw materials for preparing the foamed rubber containing recycled materials also include 1-3 parts of antioxidants in parts by weight, such as 1 part, 1.5 parts, 2 parts, 2.5 parts or 3 parts, but are not limited to the values ​​listed above. Other values ​​not listed within the above numerical range are also applicable.

[0023] Preferably, the antioxidant includes antioxidant 4020 and / or antioxidant RD.

[0024] The above-mentioned specific reagents and parameter control can effectively improve the performance of the product.

[0025] In a second aspect, the present invention provides a method for preparing the foamed rubber containing recycled materials as described above, the preparation method comprising the following steps:

[0026] Solid nitrile rubber, recycled nitrile rubber, ethylene-vinyl acetate copolymer, styrene-ethylene-butylene-styrene block copolymer, liquid nitrile rubber and carbon black are mixed and stirred, then mixed with a foaming agent and a vulcanizing agent and milled, and the foamed rubber containing recycled materials is obtained after vulcanization.

[0027] Preferably, the mixing and stirring further includes mixing with a release agent and an antioxidant.

[0028] In a third aspect, the present invention further provides the use of the foamed rubber containing recycled materials as described above in the preparation of loudspeakers.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The invention provides a foamed rubber containing recycled materials. The foamed rubber is compounded by solid nitrile rubber, recycled nitrile rubber, ethylene-vinyl acetate copolymer, styrene-ethylene-butylene-styrene block copolymer and liquid nitrile rubber. The synergistic effect reduces the use of raw rubber, increases the proportion of recycled materials and saves costs, and can also reduce the vulcanization energy required for foaming, making the cells more uniform. The foaming difficulty is greatly reduced, the material density is significantly reduced, the weather resistance is improved, the processing fluidity is improved, and the permanent deformation is reduced. The foamed rubber has the advantages of good molding performance, low density, high strength, halogen-free, energy-saving and environmental protection, and is suitable for large-scale production. DETAILED DESCRIPTION

[0031] In order to further illustrate the technical means and effects adopted by the present invention, the technical solutions of the present invention are further described below in conjunction with the preferred embodiments of the present invention, but the present invention is not limited to the scope of the embodiments.

[0032] The raw materials used in the following examples, their parameters and sources are as follows:

[0033] (1) Solid nitrile rubber

[0034] N2845: Mooney viscosity 45, acrylonitrile mass percentage 28%, purchased from Nandi Company;

[0035] N2865: Mooney viscosity 65, acrylonitrile mass percentage 28%, purchased from Nandi Corporation;

[0036] N3345: Mooney viscosity of 45, acrylonitrile content of 33% by mass, purchased from Nandi Company.

[0037] (2) Block recycled nitrile rubber

[0038] ZH-RNBR-40A: Mooney viscosity 44, ash content 5.5% by mass, purchased from Jiangsu Zhonghong Environmental Protection Technology Co., Ltd.

[0039] ZH-RNBR-45A: Mooney viscosity 46, ash content 5.9% by mass, purchased from Jiangsu Zhonghong Environmental Protection Technology Co., Ltd.

[0040] ZH-RNBR-50A: Mooney viscosity of 49, ash content of 4.3% by mass, purchased from Jiangsu Zhonghong Environmental Protection Technology Co., Ltd.

[0041] (3) Ethylene-vinyl acetate copolymer

[0042] Elvax210W: VA content 28%, melt index 400g / 10min, purchased from DuPont, USA;

[0043] Elvax240W: VA content 28%, melt index 25g / 10min, purchased from DuPont, USA;

[0044] Elvax250W: VA content 28%, melt index 6g / 10min, purchased from DuPont Company, USA.

[0045] (4) SEBS (styrene-ethylene-butylene-styrene block copolymer)

[0046] YH-501: 15% styrene content, 30-50 Shore A hardness, purchased from Baling Petrochemical Company;

[0047] YH-502: 18% styrene content, 40-60 Shore A hardness, purchased from Baling Petrochemical Company;

[0048] YH-503: styrene content 15%, hardness 25-45 Shore A, purchased from Baling Petrochemical Company.

[0049] (5) Antiaging agent

[0050] RD: purchased from Zhedong Rubber Additives Co., Ltd.;

[0051] 4020: Purchased from Zhejiang East Rubber Additives Co., Ltd.

[0052] (6) Accelerator

[0053] DM: purchased from Zhedong Rubber Additives Co., Ltd.;

[0054] TMTD: purchased from Zhedong Rubber Additives Co., Ltd.

[0055] Example 1

[0056] This embodiment provides a low-density, easily moldable foam rubber for a speaker containing recycled materials, which includes, by weight: 60 parts of nitrile rubber, 30 parts of recycled nitrile rubber, 10 parts of EVA, 5 parts of SEBS, 5 parts of liquid nitrile rubber, 10 parts of carbon black N550, 0.5 parts of a mixed internal release agent, 1 part of an antioxidant mixture, 6 parts of a foaming system, 1.0 part of sulfur, 1.0 part of an accelerator DM, and 0.5 part of TMTD.

[0057] The NBR is Nandi nitrile rubber N2845, and the mass percentage of acrylonitrile is 28%.

[0058] The block-shaped recycled nitrile rubber is ZH-RNBR-40A from Zhonghong Environmental Protection Technology Co., Ltd.

[0059] The ethylene-vinyl acetate copolymer is Elvax 210W from DuPont Company of the United States, with a vinyl acetate weight percentage of 28%, a melt flow rate of 400 g / 10 min, and a glass transition temperature of 60°C.

[0060] Styrene-ethylene-butylene-styrene copolymer (SEBS) is YH-501 produced by Baling Petrochemical, with a styrene content of 15% and a hardness of 30-50 Shore A.

[0061] The liquid nitrile rubber is LNBR-24 from Lanzhou Petrochemical.

[0062] The mixed internal mold release agent is prepared by mixing zinc stearate and calcium stearate in a mass ratio of 3:1.

[0063] The mixed antioxidant is a mixture of antioxidant 4020 and antioxidant RD in a mass ratio of 2:1.

[0064] The foaming system is made by mixing AC / OBSH / urea in a weight ratio of 2:3:1.

[0065] The preparation method of the low-density, easily moldable speaker foam rubber containing recycled materials provided in this embodiment is as follows:

[0066] Step 1: One-stage blending. Put NBR, recycled NBR, EVA, and SEBS into an internal mixer, add LNBR, carbon black, antioxidant, release agent and other small ingredients, maintain 100℃ and stir at 40r / min for 7 minutes;

[0067] Step 2: Low-temperature mixing. Quickly cool to 40°C with cold water, add sulfur, accelerator DM, TMTD and foaming system, stir at 40 rpm for 3 minutes, and remove from the internal mixer;

[0068] Step three: open the sheet. On the open mill, left and right cutter turn over three times, 0.5mm triangle bag 5 times, adjust the roll gap to 4mm and take out the sheet;

[0069] Step four: curing. The rubber obtained after step three is cured at 180℃ to obtain the low-density easy-to-mold foam rubber containing recycled materials for loudspeaker.

[0070] Example 2

[0071] The example provides a low-density easy-to-mold foam rubber containing recycled materials for loudspeaker, which comprises, by weight parts: nitrile rubber 65 parts, recycled nitrile rubber 40 parts, EVA 15 parts, SEBS 7.5 parts, liquid nitrile rubber 7.5 parts, carbon black N550 15 parts, mixed internal release agent 1 part, antioxidant mixture 2 parts, foaming system 8 parts, sulfur 1.0 part, accelerator DM 1.5 parts, TMTD 1 part.

[0072] NBR is N2865, the mass percentage of acrylonitrile is 28%.

[0073] The block-shaped recycled nitrile rubber is ZH-RNBR-45A of Zhonghong Environmental Technology Co., Ltd.

[0074] Ethylene-vinyl acetate copolymer is Elvax240W of DuPont, the weight percentage of vinyl acetate is 28%, and the melt flow rate is 25g / 10min.

[0075] Styrene-ethylene-butylene-styrene copolymer (SEBS) is YH-502 of Balin Petrochemical, the styrene content is 18%, and the hardness is 40-60 shore A.

[0076] Liquid nitrile rubber is LNBR-24 of Lanzhou Petrochemical.

[0077] The mixed internal release agent is a mixture of zinc stearate and calcium stearate in a mass ratio of 3:1.

[0078] The mixed antioxidant is a mixture of antioxidant 4020 and antioxidant RD in a mass ratio of 2:1.

[0079] The foaming system is a mixture of AC / OBSH / urea in a weight ratio of 2:3:1.

[0080] The example provides a preparation method of the low-density easy-to-mold foam rubber containing recycled materials for loudspeaker, as follows:

[0081] Step one: one-stage blending. Put NBR, recycled NBR, EVA, SEBS into the internal mixer, add LNBR, carbon black, antioxidant, release agent, etc. small materials, keep 100℃ with 40r / min stirring for 7min;

[0082] Step two: low temperature mixing. Cool down to 40℃ quickly with cold water, add sulfur, accelerator DM, TMTD and foaming system, stir for 3 min at 40 r / min, then take out from the internal mixer;

[0083] Step three: open mill sheet. Cut the knife on the open mill three times, 0.5 mm triangle bag 5 times, adjust the roll gap to 4 mm to sheet;

[0084] Step four: vulcanization molding. The rubber obtained after step three is vulcanized and molded at 180℃ to obtain the low-density easy-to-mold foamed rubber containing recycled materials for loudspeaker.

[0085] Example 3

[0086] The example provides a low-density easy-to-mold foamed rubber containing recycled materials for loudspeaker, which comprises, by weight parts: nitrile rubber 70 parts, reclaimed nitrile rubber 50 parts, EVA 20 parts, SEBS 10 parts, liquid nitrile rubber 10 parts, carbon black N550 20 parts, mixed internal release agent 2 parts, antioxidant mixture 3 parts, foaming system 10 parts, sulfur 1.2 parts, accelerator DM 1.5 parts, TMTD 1.3 parts.

[0087] NBR is N3345, the mass percentage of acrylonitrile is 33%.

[0088] The block-shaped reclaimed nitrile rubber is ZH-RNBR-50A of Zhonghong Environmental Technology Co., Ltd.

[0089] Ethylene-vinyl acetate copolymer is Elvax250W of DuPont, the weight percentage of vinyl acetate is 28%, and the melt flow rate is 6 g / 10 min.

[0090] Styrene-ethylene-butylene-styrene copolymer (SEBS) is YH-503 of Balin Petrochemical, the styrene content is 15%, and the hardness is 25-45 Shore A.

[0091] Liquid nitrile rubber is LNBR-24 of Lanzhou Petrochemical.

[0092] The mixed internal release agent is a mixture of zinc stearate and calcium stearate in a mass ratio of 3:1.

[0093] The mixed antioxidant is a mixture of antioxidant 4020 and antioxidant RD in a mass ratio of 2:1.

[0094] The foaming system is a mixture of AC / OBSH / urea in a weight ratio of 2:3:1.

[0095] The example provides a preparation method of the low-density easy-to-mold foamed rubber containing recycled materials for loudspeaker, which comprises the following steps:

[0096] Step 1: One-stage blending. Put NBR, recycled NBR, EVA, and SEBS into an internal mixer, add LNBR, carbon black, antioxidant, release agent and other small ingredients, maintain 100℃ and stir at 40r / min for 7 minutes;

[0097] Step 2: Low-temperature mixing. Quickly cool to 40°C with cold water, add sulfur, accelerator DM, TMTD and foaming system, stir at 40 rpm for 3 minutes, and remove from the internal mixer;

[0098] Step 3: Open the mill to remove the sheet. On the open mill, turn the left and right cutters over the sheet three times each, make 0.5mm triangle packs five times, and adjust the roller distance to 4mm to remove the sheet.

[0099] Step 4: Vulcanization molding: The rubber compound obtained after step 3 is vulcanized and molded at 180° C. to obtain the low-density and easily moldable foam rubber for speakers containing recycled materials.

[0100] Example 4

[0101] This embodiment provides a low-density, easily moldable foam rubber for speakers containing recycled materials. The difference from Example 1 is that in the foam rubber component for speakers containing low-density, easily moldable speakers containing recycled materials provided in Example 4, the weight percentage of vinyl acetate in the ethylene-vinyl acetate copolymer is 21% (purchased from DuPont Company, USA). The other components are the same as those in Example 1, and the corresponding preparation method is also the same as that in Example 1.

[0102] Example 5

[0103] This embodiment provides a low-density, easily moldable foam rubber for speakers containing recycled materials. The difference from Example 1 is that in the foam rubber component for speakers containing low-density, easily moldable speakers containing recycled materials provided in Example 5, the weight percentage of vinyl acetate in the ethylene-vinyl acetate copolymer is 35% (purchased from DuPont Company, USA), and the other components are the same as those in Example 1, and the corresponding preparation method is also the same as that in Example 1.

[0104] Example 6

[0105] This embodiment provides a low-density, easily moldable foam rubber for speakers containing recycled materials. The difference from Example 1 is that in the foam rubber component for speakers containing low-density, easily moldable speakers containing recycled materials provided in Example 6, the weight percentage of styrene in the styrene-ethylene-butylene-styrene block copolymer is 25% (purchased from Baling Petrochemical Company), and the other components are the same as those in Example 1, and the corresponding preparation method is also the same as that in Example 1.

[0106] Comparative Example 1

[0107] This comparative example provides a low-density, easily moldable foam rubber containing recycled materials for use in loudspeakers. The difference from Example 1 is that the low-density, easily moldable foam rubber containing recycled materials provided in Example 1 does not contain recycled nitrile rubber, and the reduced portion is proportionally distributed to nitrile rubber, EVA, SEBS and liquid nitrile rubber. The other components are the same as those in Example 1, and the corresponding preparation method is also the same as that in Example 1.

[0108] Comparative Example 2

[0109] This comparative example provides a low-density, easily moldable foam rubber containing recycled materials for use in loudspeakers. The difference from Example 1 is that the low-density, easily moldable foam rubber containing recycled materials provided in Comparative Example 2 does not contain EVA, and the reduced portion is proportionally distributed to nitrile rubber, recycled nitrile rubber, SEBS and liquid nitrile rubber. The other components are the same as those in Example 1, and the corresponding preparation method is also the same as that in Example 1.

[0110] Comparative Example 3

[0111] This comparative example provides a low-density, easily moldable foam rubber containing recycled materials for use in loudspeakers. The difference from Example 1 is that the low-density, easily moldable foam rubber containing recycled materials provided in Comparative Example 3 does not contain SEBS, and the reduced portion is proportionally distributed to nitrile rubber, EVA, recycled nitrile rubber and liquid nitrile rubber. The other components are the same as those in Example 1, and the corresponding preparation method is also the same as that in Example 1.

[0112] Comparative Example 4

[0113] This comparative example provides a low-density, easily moldable foam rubber for speakers containing recycled materials. The difference from Example 1 is that the low-density, easily moldable foam rubber for speakers containing recycled materials provided in Comparative Example 4 does not contain liquid nitrile rubber, and the reduced portion is proportionally distributed to nitrile rubber, EVA, SEBS and recycled nitrile rubber. The other components are the same as those in Example 1, and the corresponding preparation method is also the same as that in Example 1.

[0114] Effect test

[0115] (1) Sample density: The water immersion weighing method (calculating the density by measuring the mass difference between the sample in air and water) was used to characterize the density of the low-density, easy-to-form speaker foam rubber containing recycled material provided in the above example. The test results are shown in Table 1.

[0116] (2) Tensile strength / elongation at break: The test was conducted according to the method specified in the national standard GB / T528-2009. The test results are shown in Table 1.

[0117] (3) Rubber compression set test: The test was conducted in accordance with the method specified in GB / T7759.1-2015. The test medium was hot air, the temperature was 70°C, the test time was 3 days, and the initial compression rate of the compression set was 15%. The test results are shown in Table 1.

[0118] (4) Peel strength: The test was conducted according to the method specified in GB / T 7760-2003, with a peel angle of 90°, a tensile speed of 50±5 mm / min, and a sample thickness of 2 mm. The test results are shown in Table 1.

[0119] (5) Vulcanization property test: The test was carried out according to the method specified in GB / T 16584-1996 at a test temperature of 180°C. The test results are shown in Table 1.

[0120] Table 1

[0121]

[0122] As can be seen from Table 1, compared with the comparative example, the vulcanization rate of the low-density, easy-to-form speaker foam rubber containing recycled materials provided in the embodiment is improved, and the density is significantly reduced, indicating that the technical solution of the present invention can not only shorten the vulcanization time, but also reduce the difficulty of foaming and further reduce the density; compared with Comparative Example 2, the mechanical properties and compression set of the embodiment are significantly improved, and the density is reduced, indicating that EVA can make the rubber-plastic blend system easier to foam, the internal cell size and number are significantly improved, and it can also provide good mechanical properties and resistance to compression set; SEBS and LNBR can both be used as interfacial compatibilizers to reduce phase separation and improve the compatibility of the blend, which is reflected in the further improvement of mechanical properties and compression set; the compounding of the various components synergistically improves the performance of the product. In addition, the vulcanization rate of the thin products of the embodiment is relatively fast and the molding appearance is good, indicating that this patented technology can be used for large-scale continuous production with high efficiency.

[0123] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the foamed rubber containing recycled materials, its preparation method, and its application. However, the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for various raw materials in the product of the present invention, addition of auxiliary ingredients, and selection of specific methods, etc., are all within the scope of protection and disclosure of the present invention.

[0124] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0125] It should also be noted that various specific technical features described in the above detailed description are not necessarily mutually exclusive, and can be combined in any suitable manner, and the present application is not limited to any particular combination described.

Claims

1. A foamed rubber containing recycled materials, characterized in that: The raw materials for preparing the foamed rubber containing recycled materials include, by weight, 60-70 parts of solid nitrile rubber, 30-50 parts of recycled nitrile rubber, 10-20 parts of ethylene-vinyl acetate copolymer, 5-10 parts of styrene-ethylene-butylene-styrene block copolymer, 5-10 parts of liquid nitrile rubber, 10-20 parts of carbon black, 6-10 parts of foaming agent and 2.5-4 parts of vulcanizing agent.

2. The foamed rubber containing recycled materials according to claim 1, characterized in that The acrylonitrile content in the solid nitrile rubber and the liquid nitrile rubber is independently 24-33%.

3. The foamed rubber containing recycled materials according to claim 1 or 2, characterized in that: The Mooney viscosity of the solid nitrile rubber is 30-60; Preferably, the Mooney viscosity of the liquid nitrile rubber is 10,000-50,000.

4. The foamed rubber containing recycled materials according to any one of claims 1 to 3, characterized in that: The Mooney viscosity of the regenerated nitrile rubber is 40-50, and the ash content is less than 10%; Preferably, the content of vinyl acetate in the ethylene-vinyl acetate copolymer is 25-30%; Preferably, the styrene content in the styrene-ethylene-butylene-styrene block copolymer is less than 20%, and the Shore hardness is 25-60.

5. The foamed rubber containing recycled materials according to any one of claims 1 to 4, characterized in that: The foaming agent includes any one of azodicarbonamide, oxybisbenzenesulfonylhydrazine or urea or a combination of at least two thereof, preferably a combination of azodicarbonamide, oxybisbenzenesulfonylhydrazine and urea; Preferably, the vulcanizing agent includes sulfur, accelerator DM and accelerator TMTD.

6. The foamed rubber containing recycled materials according to any one of claims 1 to 5, characterized in that: The raw materials for preparing the foamed rubber containing recycled materials further include 0.5-2 parts by weight of a release agent; Preferably, the release agent comprises zinc stearate and / or calcium stearate.

7. The foamed rubber containing recycled materials according to any one of claims 1 to 6, characterized in that: The raw materials for preparing the foamed rubber containing recycled materials further include 1-3 parts of an antioxidant in parts by weight; Preferably, the antioxidant includes antioxidant 4020 and / or antioxidant RD.

8. A method for preparing foamed rubber containing recycled materials according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: Solid nitrile rubber, recycled nitrile rubber, ethylene-vinyl acetate copolymer, styrene-ethylene-butylene-styrene block copolymer, liquid nitrile rubber and carbon black are mixed and stirred, then mixed with a foaming agent and a vulcanizing agent and milled, and the foamed rubber containing recycled materials is obtained after vulcanization.

9. The preparation method according to claim 8, characterized in that The mixing and stirring also includes mixing with a release agent and an antioxidant.

10. Use of the foamed rubber containing recycled materials according to any one of claims 1 to 7 in the preparation of a loudspeaker.

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