Low-modulus rubber material and preparation method thereof

Abstract

The invention belongs to the technical field of vulcanized rubber materials, and particularly relates to a low-modulus rubber material and a preparation method thereof. The low-modulus rubber material provided by the invention is prepared from the following raw materials in parts by weight: 70 to 100 parts of chloroprene rubber, 0 to 30 parts of nitrile rubber, 0.5 to 2 parts of stearic acid, 1 to 3 parts of anti-aging agent, 5 to 20 parts of carbon black, 2 to 10 parts of special reinforcing filler, 2 to 10 parts of plasticizer, 10 to 20 parts of vulcanizing agent and 0.5 to 2 parts of accelerant, the special reinforcing filler is a surface modified nano filler. The use amount of each component is limited, and the components are matched with one another to obtain the low-modulus and high-damping rubber material.

Description

Technical Field

[0001] This invention belongs to the field of vulcanized rubber materials technology, specifically relating to a low-modulus rubber material and its preparation method. Background Technology

[0002] Damping materials are functional materials that absorb and partially convert mechanical energy, acoustic energy, and other forms of energy into heat energy for dissipation. They are generally used in the manufacture of various vibration damping devices. Rubber materials, including nitrile rubber, butyl rubber, silicone rubber, styrene-butadiene rubber, and natural rubber, exhibit excellent damping properties due to their unique viscoelasticity. Rubber-based vibration damping and noise reduction products are widely used in various fields. In this field, various methods are often employed to further improve the damping performance of rubber, such as blending, organic or inorganic small molecule hybridization, interpenetrating polymer networks, block or graft tools, etc. Rubber damping materials can not only significantly reduce mechanical noise and vibration, improving work efficiency, but also contribute to improved product quality.

[0003] However, with the increasing demands for vibration reduction and noise reduction in modern building vibration damping, precision instruments and equipment, mechanical engineering, and high-end equipment manufacturing, ordinary rubber damping materials can no longer meet practical needs. This field requires an extremely soft, yet effective, low-modulus rubber damping material that can dissipate vibration energy, suitable for scenarios requiring isolation of large-amplitude, low-frequency vibrations. However, high damping in rubber requires difficult molecular chain movement and generates significant frictional heat; while low modulus requires free molecular chain movement and easy deformation. Low modulus and high damping are contradictory at the molecular chain movement level. Summary of the Invention

[0004] The purpose of this invention is to provide a low-modulus rubber material and its preparation method. This invention limits the amount of each component and obtains a low-modulus, high-damping rubber material through the interaction between the components.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A low-modulus rubber material, by weight, comprises the following raw materials: The composition includes 70-100 parts of chloroprene rubber, 0-30 parts of nitrile rubber, 0.5-2 parts of stearic acid, 1-3 parts of antioxidant, 5-20 parts of carbon black, 2-10 parts of special reinforcing filler, 2-10 parts of plasticizer, 10-20 parts of vulcanizing agent, and 0.5-2 parts of accelerator; the special reinforcing filler is a surface-modified nanofiller.

[0006] Preferably, the surface-modified nanofiller is a polymer- or surfactant-coated nanofiller; the nanofiller in the surface-modified nanofiller is a single-walled carbon nanotube or nano-calcium carbonate.

[0007] Preferably, the acrylonitrile content in the nitrile rubber is 25~30wt%.

[0008] Preferably, the plasticizer includes one or more of aromatic oils, dioctyl phthalate, and dioctyl sebacate; the vulcanizing agent includes one or more of zinc oxide, magnesium oxide, and lead tetroxide.

[0009] This invention provides a method for preparing the low-modulus rubber material described above, comprising the following steps: The raw materials are mixed according to the mass fractions to obtain the rubber compound; The rubber compound is vulcanized to obtain the low-modulus rubber material.

[0010] Preferably, the vulcanization temperature is 80~120℃ and the time is 3~10h.

[0011] Preferably, the process before vulcanization further includes: pre-treating the rubber compound to obtain a rubber sheet; placing the rubber sheet between the capsule and the inner wall of the steel tube; the steel tube is a hollow steel tube, and the capsule is placed inside the hollow steel tube.

[0012] Preferably, the pretreatment is calendering; the film thickness is 2-3 mm and the number of layers is 5-8.

[0013] Preferably, the pressure between the capsule and the inner wall of the steel tube is less than 0.1 MPa.

[0014] Preferably, the method for preparing the rubber compound includes the following steps: Chloroprene rubber and nitrile rubber are plasticized to obtain a plasticized rubber matrix; The plasticized rubber matrix is ​​mixed with antioxidant, carbon black, special reinforcing filler, stearic acid and plasticizer, and then mixed and discharged to obtain the mixed rubber compound. The intensively mixed rubber compound is then blended with a vulcanizing agent and an accelerator to obtain the rubber compound.

[0015] This invention provides a low-modulus rubber material, comprising the following raw materials by weight: 70-100 parts chloroprene rubber, 0-30 parts nitrile rubber, 0.5-2 parts stearic acid, 1-3 parts antioxidant, 5-20 parts carbon black, 2-10 parts special reinforcing filler, 2-10 parts plasticizer, 10-20 parts vulcanizing agent, and 0.5-2 parts accelerator; the special reinforcing filler is a surface-modified nanofiller. The special reinforcing filler used in this invention is mainly used to improve the compression set of rubber materials. By limiting the raw material composition and dosage, this invention forms a reversible "weakly bonded" network between the special reinforcing filler and the rubber molecular chain, thereby perfectly balancing the low modulus and high damping properties of rubber, successfully obtaining a low-modulus, high-damping rubber material with chloroprene rubber as the main component, thus meeting the demanding application requirements such as building vibration isolation and precision engineering.

[0016] This invention provides a method for preparing the low-modulus rubber material, comprising the following steps: mixing raw materials according to mass parts to obtain a rubber compound; and vulcanizing the rubber compound to obtain the low-modulus rubber material. The preparation method provided by this invention is simple to operate and operates under mild conditions. Furthermore, this invention limits the vulcanization conditions for the low-modulus rubber material, allowing it to be vulcanized within a medium-low temperature range of 80~120℃, thus solving the problem of scorching at high temperatures in chloroprene rubber and facilitating the preparation of low-modulus rubber materials. Attached Figure Description

[0017] Figure 1 This is a schematic flowchart of the vulcanization method for low-modulus rubber materials in an embodiment of the present invention. Detailed Implementation

[0018] This invention provides a low-modulus rubber material, comprising the following raw materials by weight: The composition includes 70-100 parts of chloroprene rubber, 0-30 parts of nitrile rubber, 0.5-2 parts of stearic acid, 1-3 parts of antioxidant, 5-20 parts of carbon black, 2-10 parts of special reinforcing filler, 2-10 parts of plasticizer, 10-20 parts of vulcanizing agent, and 0.5-2 parts of accelerator; the special reinforcing filler is a surface-modified nanofiller.

[0019] In this invention, unless otherwise specified, all raw materials / components used in the preparation are commercially available products well known to those skilled in the art.

[0020] By weight, the raw materials of the low-modulus rubber material of the present invention include 70-100 parts of chloroprene rubber and 0-30 parts of nitrile rubber; specifically, the chloroprene rubber can be 70, 80, 90, or 100 parts; and the nitrile rubber can be 0, 10, 20, or 30 parts. In one embodiment of the present invention, the total mass fraction of the chloroprene rubber and nitrile rubber is 100 parts; the chloroprene rubber includes CR12, CR21, CR23, or CR32 series; and the acrylonitrile content in the nitrile rubber is 25-30 wt%. The chloroprene rubber is the main body and foundation of the rubber material, determining its basic properties such as mechanical strength, damping performance, aging resistance, flame retardancy, water resistance, and adhesion. The nitrile rubber has good damping performance, and its use in combination with chloroprene rubber helps to broaden the effective damping temperature range of the material, further improving its damping performance.

[0021] Based on the mass fraction of the chloroprene rubber, the raw material of the low-modulus rubber material of the present invention includes 0.5 to 2 parts of stearic acid, specifically 1 part. As one embodiment of the present invention, the stearic acid can be used as an activator of the vulcanization system, as well as a lubricant and processing aid, effectively reducing internal friction between rubber molecular chains, improving processing performance, and enhancing the dispersibility of reinforcing fillers.

[0022] Based on the mass fraction of the chloroprene rubber, the raw material of the low-modulus rubber material of the present invention includes 1 to 3 parts of antioxidant, specifically 2 parts or 2.5 parts. As one embodiment of the present invention, the antioxidant includes an amine antioxidant; the antioxidant can delay the degradation and aging of rubber caused by heat, oxygen, ozone, ultraviolet radiation, etc., and extend the service life of the low-modulus rubber material.

[0023] Based on the mass fraction of the chloroprene rubber, the raw material of the low-modulus rubber material of the present invention includes 5 to 20 parts of carbon black, specifically 12 parts, 15 parts, or 20 parts. As one embodiment of the present invention, the carbon black includes carbon black N234, carbon black N774, or carbon black N990; the carbon black, by binding with rubber molecules, improves the tensile stress and tear strength of the material and reduces costs.

[0024] Based on the mass fraction of the chloroprene rubber, the raw material of the low-modulus rubber material of the present invention includes 2 to 10 parts of special reinforcing filler, specifically 2 parts, 4 parts, 6 parts, or 8 parts. In one embodiment of the present invention, the special reinforcing filler is a surface-modified nanofiller; the surface-modified nanofiller is a polymer- or surfactant-coated nanofiller; the nanofiller in the surface-modified nanofiller is a single-walled carbon nanotube or nano-calcium carbonate; the polymer includes polyurethane prepolymer or liquid rubber, and the surfactant includes stearic acid; the purpose of surface modification of the nanofiller in the present invention is to improve the dispersibility of the nanofiller in the rubber, reduce its surface energy, and prevent agglomeration; the special reinforcing filler is mainly used to improve the compression set of the rubber material.

[0025] Based on the mass fraction of the chloroprene rubber, the raw materials of the low-modulus rubber material of the present invention include 2 to 10 parts of plasticizer, specifically 3 parts, 5 parts, 8 parts, or 10 parts. As one embodiment of the present invention, the plasticizer includes one or more of aromatic oils, dioctyl phthalate (DOP), and dioctyl sebacate (DOS); the plasticizer can improve the processing performance of the rubber, and simultaneously improve the low-temperature performance and flexibility of the rubber.

[0026] Based on the mass fraction of the chloroprene rubber, the raw materials of the low-modulus rubber material of the present invention include 10-20 parts of vulcanizing agent, specifically 12 parts, 15 parts, or 18 parts. In one embodiment of the present invention, the vulcanizing agent includes one or more of zinc oxide, magnesium oxide, and lead tetroxide; the vulcanizing agent can provide cross-linking bonds, enabling linear polymer chains to form a three-dimensional network structure through chemical cross-linking, thereby making the rubber a highly elastic material, which is the core of the rubber's usability.

[0027] Based on the mass fraction of the chloroprene rubber, the raw material of the low-modulus rubber material of the present invention includes 0.5 to 2 parts of accelerator, specifically 0.5 parts, 1 part, or 2 parts. In one embodiment of the present invention, the accelerator includes a thiourea accelerator; the accelerator can lower the vulcanization temperature, accelerate the vulcanization speed, and reduce the amount of vulcanizing agent used; it can also improve the compression set and resilience of the rubber material.

[0028] This invention, by limiting the raw material composition and dosage, forms a reversible "weak bond" network between the special reinforcing filler and the rubber molecular chain, thereby perfectly balancing the two properties of low modulus and high damping of rubber, and successfully obtaining a low modulus and high damping rubber material with chloroprene rubber as the main body, thus meeting the demanding application requirements such as building vibration isolation and precision engineering.

[0029] This invention provides a method for preparing the low-modulus rubber material described above, comprising the following steps: The raw materials are mixed according to the mass fractions to obtain the rubber compound; The rubber compound is vulcanized to obtain the low-modulus rubber material.

[0030] This invention involves mixing raw materials according to parts by mass to obtain a rubber compound. As one embodiment of this invention, the preparation method of the rubber compound includes the following steps: Chloroprene rubber and nitrile rubber are plasticized to obtain a plasticized rubber matrix; The plasticized rubber matrix is ​​mixed with antioxidant, carbon black, special reinforcing filler, stearic acid and plasticizer, and then mixed and discharged to obtain the mixed rubber compound. The intensively mixed rubber compound is then blended with a vulcanizing agent and an accelerator to obtain the rubber compound.

[0031] This invention involves plasticizing chloroprene rubber and nitrile rubber to obtain a plasticized rubber matrix. In one embodiment, the plasticizing temperature can be 40-60°C, specifically 50°C, and the time can be 5-8 minutes; the plasticizing is performed in a two-roll mill; after plasticizing, the resulting rubber compound is allowed to stand for 12 hours.

[0032] After obtaining the plasticized rubber matrix, the present invention mixes and kneads the plasticized rubber matrix with an antioxidant, carbon black, a special reinforcing filler, stearic acid, and a plasticizer, and then discharges the mixture to obtain a kneaded rubber compound. In one embodiment of the present invention, the mixing and kneading are carried out in a kneading machine; the mixing and kneading temperature can be 95~105℃, specifically 100℃, and the kneading time for a single kneading cycle is 1~4 minutes; specifically, when the antioxidant, carbon black, and special reinforcing filler are added, the kneading time for a single kneading cycle can be 2~4 minutes, specifically 3 minutes; when the stearic acid and plasticizer are added, the kneading time for a single kneading cycle can be 1~3 minutes, specifically 2 minutes; the discharge temperature is 80~100℃, specifically 90℃; after discharge, the resulting rubber compound is further cooled to room temperature (25℃±2℃).

[0033] After obtaining the internally mixed rubber compound, the present invention further mixes the internally mixed rubber compound with a vulcanizing agent and an accelerator to obtain the rubber compound. In one embodiment of the present invention, the mixing is carried out in a two-roll mill at a temperature of 40-50°C, specifically 45°C, for a time of 3-8 minutes, specifically 6 minutes. The mixing process further includes: sequentially cutting and rolling the compound on both sides, sheeting, and cooling; the cutting and rolling is performed 6 times.

[0034] After obtaining the rubber compound, the present invention vulcanizes the rubber compound to obtain the low-modulus rubber material. In one embodiment of the present invention, the vulcanization temperature is 80-120°C, and the time is 3-10 hours. Before vulcanization, the method further includes: pre-treating the rubber compound to obtain a rubber sheet; placing the rubber sheet between a capsule and the inner wall of a steel tube; the steel tube is a hollow steel tube, and the capsule is placed inside the hollow steel tube. In one embodiment of the present invention, the pretreatment is calendering; the film thickness is 2-3 mm, and the number of layers is 5-8; the capsule is a water-filled capsule; the preferred method for placing the film between the capsule and the inner wall of the steel pipe is as follows: the film is laid layer by layer on the inner wall of the steel pipe, ensuring that the surface of each layer of film is flat and completely adhered; the water-filled capsule is placed on the film, and another part of the film is laid layer by layer on the surface of the capsule, and the capsule is inflated and pressurized to ensure that the surface of the laid film is flat until the capsule, film, and inner wall of the steel pipe are tightly adhered; the pressure between the capsule and the inner wall of the steel pipe is less than 0.1 MPa.

[0035] Figure 1 This is a schematic flowchart of the vulcanization method for low-modulus rubber materials in an embodiment of the present invention. Figure 1 (1) is the calendered CR film; (2) is the CR film evenly laid on the inside of the steel pipe; (3) is the water-filled capsule placed on the film; (4) is the film evenly laid on the surface of the capsule; (5) is the capsule filled with air and pressurized to ensure that the capsule, film, and inner wall of the steel pipe are tightly attached; (6) is the capsule placed in an oven for vulcanization after being fixed with clamps. In order to further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0036] Example 1 The components in this embodiment are listed in Table 1 by mass fraction.

[0037] The preparation method of rubber compound is carried out according to the following steps: Neoprene rubber was plasticized on a two-roll mill at 50°C for 5 minutes and allowed to stand for 12 hours. The plasticized neoprene rubber was then fed into an internal mixer at 100°C. Antioxidant was added and the mixture was mixed for 3 minutes. Carbon black and special reinforcing filler were added in two batches, with each batch mixed for 3 minutes to ensure uniform dispersion of the filler. Stearic acid was added and mixed for 2 minutes. Plasticizer was added in two batches, with each batch mixed for 2 minutes to ensure uniform dispersion. The rubber was discharged at 90°C and then cooled to room temperature (25°C ± 2°C). The cooled rubber compound was fed into a two-roll mill, where vulcanizing agent and accelerator were added. The mixture was then mixed at 45°C for 6 minutes. The rubber was cut and rolled 6 times on each side, then sheeted and cooled to obtain the rubber compound.

[0038] The vulcanization method for low-modulus rubber materials is carried out according to the following steps: The obtained rubber compound was pretreated by calendering to obtain a rubber sheet (2mm thick, 5 layers). The middle part of the calendered rubber sheet was laid evenly layer by layer on the inner wall of the steel pipe, ensuring that the surface of each layer of rubber sheet was flat and completely adhered. A water-filled capsule was placed on the rubber sheet, and then the two ends of the rubber sheet were laid evenly layer by layer on the surface of the capsule. The capsule was inflated and pressurized to ensure that the surface of the laid rubber sheet was flat. After the rubber sheet was laid, pressure was continued (pressure < 0.1MPa). At this time, the capsule, rubber sheet and inner wall of the steel pipe were tightly adhered. The outside of the steel pipe was fixed with clamps. The entire system was placed in an oven at 120℃ for 3 hours for vulcanization to obtain a low-modulus rubber material.

[0039] Example 2 The components in this embodiment are listed in Table 1 by mass. The preparation method of the rubber compound in this embodiment is the same as that in Example 1, and the vulcanization method of the low-modulus rubber material is basically the same as that in Example 1, except that the vulcanization temperature is 80°C and the vulcanization time is 10 hours.

[0040] Example 3 The components in this embodiment are listed in Table 1 by mass. The preparation method of the rubber compound in this embodiment is the same as that in Example 1, and the vulcanization method of the low-modulus rubber material is basically the same as that in Example 1, except that the vulcanization temperature is 80°C and the vulcanization time is 8 hours.

[0041] Comparative Example 1 The components of the comparative example are shown in Table 1 by mass fraction. The preparation method of the rubber compound of the comparative example is the same as that of Example 1, and the vulcanization method of the low modulus rubber material is basically the same as that of Example 1, except that the vulcanization temperature is 150°C and the vulcanization time is 30 min.

[0042] Table 1. Formulations of low-modulus rubber materials in Examples 1-3 and Comparative Example 1

[0043] Test Example 1 The physical properties of the low-modulus rubber materials prepared in Examples 1-3 and Comparative Example 1 were tested. Tensile strength and elongation at break were tested according to GB / T528, hardness according to GB / T531.1, and damping performance according to GB / T9870.1. The results are shown in Table 2.

[0044] Table 2 Physical properties of the low-modulus rubber materials of Examples 1-3 and Comparative Example 1

[0045] As shown in Table 2, the average storage modulus of the low-modulus rubber materials in Examples 1-3 is 7.8-9.7 MPa, which is lower than the average storage modulus of Comparative Example 1; the loss factor of Examples 1-3 is 0.39-0.51, which is higher than 0.33 of Comparative Example 1; indicating that the low-modulus rubber materials in Examples 1-3 of the present invention have high damping and low modulus properties.

[0046] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A low-modulus rubber material, comprising the following raw materials by weight: The composition includes 70-100 parts of chloroprene rubber, 0-30 parts of nitrile rubber, 0.5-2 parts of stearic acid, 1-3 parts of antioxidant, 5-20 parts of carbon black, 2-10 parts of special reinforcing filler, 2-10 parts of plasticizer, 10-20 parts of vulcanizing agent, and 0.5-2 parts of accelerator; the special reinforcing filler is a surface-modified nanofiller.

2. The low-modulus rubber material according to claim 1, characterized in that, The surface-modified nanofiller is a polymer- or surfactant-coated nanofiller; the nanofiller in the surface-modified nanofiller is a single-walled carbon nanotube or nano-calcium carbonate.

3. The low-modulus rubber material according to claim 1, characterized in that, The acrylonitrile content in the nitrile rubber is 25~30wt%.

4. The low-modulus rubber material according to claim 1, characterized in that, The plasticizer includes one or more of aromatic oils, dioctyl phthalate, and dioctyl sebacate; the vulcanizing agent includes one or more of zinc oxide, magnesium oxide, and lead tetroxide.

5. A method for preparing the low-modulus rubber material according to any one of claims 1 to 4, comprising the following steps: The raw materials are mixed according to the mass fractions to obtain the rubber compound; The rubber compound is vulcanized to obtain the low-modulus rubber material.

6. The preparation method according to claim 5, characterized in that, The vulcanization temperature is 80~120℃, and the time is 3~10h.

7. The preparation method according to claim 5, characterized in that, The process before vulcanization also includes: pre-treating the rubber compound to obtain a rubber sheet; placing the rubber sheet between the capsule and the inner wall of the steel tube; the steel tube is a hollow steel tube, and the capsule is placed inside the hollow steel tube.

8. The preparation method according to claim 7, characterized in that, The pretreatment is calendering; the film thickness is 2-3 mm, and the number of layers is 5-8.

9. The preparation method according to claim 7, characterized in that, The pressure between the capsule and the inner wall of the steel tube is less than 0.1 MPa.

10. The preparation method according to claim 5, characterized in that, The preparation method of the rubber compound includes the following steps: Chloroprene rubber and nitrile rubber are plasticized to obtain a plasticized rubber matrix; The plasticized rubber matrix is ​​mixed with antioxidant, carbon black, special reinforcing filler, stearic acid and plasticizer, and then mixed and discharged to obtain the mixed rubber compound. The intensively mixed rubber compound is then blended with a vulcanizing agent and an accelerator to obtain the rubber compound.

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