Oil-resistant TPV (thermoplastic vulcanizate) material and preparation method thereof

Abstract

The invention provides an oil-resistant TPV material and a preparation method thereof, and belongs to the technical field of resin synthesis. The oil-resistant TPV material comprises the following components in parts by weight: 30-50 parts of PA (polyamide); 40 to 60 parts of NBR (nitrile butadiene rubber); 5-7 parts of a composite vulcanizing agent; 10-15 parts of a plasticizer; 1-2 parts of stearic acid; 10-20 parts of light calcium carbonate; 1-2 parts of an anti-aging agent; according to the invention, a mixture of trimethylolpropane trimethacrylate and 2, 5-dimethyl-2, 5-bis (tert-butylperoxy) hexane is used as a composite vulcanizing agent, and a mixture of dibutoxyethyl adipate and acetyl tri-n-butyl citrate is used as a plasticizer; and by controlling the mass ratio of the composite vulcanizing agent to the plasticizer, the oil resistance, compressive deformation and aging resistance of the rubber can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of resin synthesis, and in particular relates to an oil-resistant TPV material and a preparation method thereof. Background Art

[0002] Thermoplastic vulcanizate (TPV) is a new type of thermoplastic elastomer made through dynamic vulcanization technology, with a high content of cross-linked rubber particles as the dispersed phase and a small amount of thermoplastic resin as the continuous phase. The dispersed rubber phase in TPV imparts excellent elasticity, while the continuous plastic phase allows for melt processing at high temperatures. This effectively avoids the high energy consumption, recycling difficulties, and environmental pollution associated with traditional thermoset rubber processing. With the growing adoption of the concept of "green chemistry," TPV, as a new "green" elastomer, is widely used in the automotive, construction, aerospace, and medical fields. It is beginning to replace traditional thermoset rubber and is rapidly developing towards specialized functionalities.

[0003] TPV is typically prepared through melt blending. Unlike conventional direct melt blending of rubber, the rubber phase undergoes simultaneous crosslinking during blending, resulting in a complex process involving fragmentation, melting, and crosslinking. To achieve crosslinking of the rubber phase and ultimately produce TPV, TPV preparation processes include chemical crosslinking dynamic vulcanization and electronically induced dynamic vulcanization.

[0004] Chinese patent CN116496580A discloses an oil-resistant TPV material and its preparation method. The material is prepared using the following components in parts by weight: 5-25 parts PP resin, 30-50 parts EPDM rubber, 10-30 parts TPU, 15-40 parts TPEE, 0.3-1.5 parts vulcanizer, 0.5-1.0 parts vulcanization accelerator, 310 parts (preferably 510 parts) compatibilizer, and 1.0-4.2 parts additive. The TPU has a hardness of 60-95 Shore A, and the TPEE has a hardness of 28-40 Shore D. The TPV material provided by this invention exhibits excellent oil resistance while also offering good mechanical properties and other comprehensive performance characteristics.

[0005] Chinese patent CN113831612A discloses an oil-resistant TPV composition and its preparation method. The oil-resistant TPV composition comprises the following raw materials in parts by weight: 30-40 parts injection-molding-grade nylon; 40-70 parts nitrile rubber; 8-15 parts compatibilizer; 0.5-1.0 parts stabilizer; 4-6.5 parts composite vulcanizer; 10-20 parts trioctyl trimellitate; 1.0-1.5 parts stearic acid; 10-20 parts precipitated silica; and 0.5-2 parts antioxidant. This invention utilizes a one-step, high-temperature granulation process to prepare the TPV composition, reducing the thermal history of PA and NBR, significantly reducing the degree of material degradation, and improving the performance of the TPV. Furthermore, it enables PA and ABS-g-MAH powders to achieve a good pre-dispersion effect without undergoing a high-temperature thermal cycle, thereby improving the processing stability, oil resistance, and performance of the TPV product.

[0006] However, the existing PA+NBR type TPV materials have high requirements for screw extrusion equipment due to the high requirements of the dynamic vulcanization process of NBR, and the aging resistance and compression deformation of the obtained TPV materials cannot meet the needs well. Therefore, it is necessary to develop a TPV material and its preparation method that not only has good oil resistance but also has high aging resistance and low compression deformation. Summary of the Invention

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: An oil-resistant TPV material comprises the following components in parts by weight: PA 30-50 parts; NBR 40-60 parts; 5-7 parts of composite vulcanizing agent; 10-15 parts of plasticizer; 1-2 parts of stearic acid; 10-20 parts of light calcium carbonate; 1-2 parts of antioxidant.

[0008] The PA is PA powder (nylon powder); The NBR is a mixture of medium acrylonitrile butadiene rubber and high acrylonitrile butadiene rubber, the acrylonitrile content in the medium acrylonitrile butadiene rubber is 30-40%, and the acrylonitrile content in the high acrylonitrile butadiene rubber is 40-50%.

[0009] The mass ratio of the medium acrylonitrile butadiene rubber to the high acrylonitrile butadiene rubber is 3-5:1, preferably 4:1.

[0010] The NBR used in the present invention is a mixture of medium acrylonitrile butadiene rubber and high acrylonitrile butadiene rubber. The medium acrylonitrile butadiene rubber has excellent mechanical properties and processability, while the high acrylonitrile butadiene rubber has stronger resistance to non-polar oils or solvents, but its mechanical properties will be reduced. During the implementation of the present invention, the medium acrylonitrile butadiene rubber and the high acrylonitrile butadiene rubber are mixed and the mass ratio of the two is controlled to be 3-5:1, which can significantly improve the mechanical properties and oil resistance of the TPV material.

[0011] The composite vulcanizing agent is a mixture of trimethylolpropane trimethacrylate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, with a mass ratio of 1:5-10; Preferably, the composite vulcanizing agent is a mixture of trimethylolpropane trimethacrylate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, with a mass ratio of 1:6-9; More preferably, the composite vulcanizing agent is a mixture of trimethylolpropane trimethacrylate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, with a mass ratio of 1:8.

[0012] The present invention uses a mixture of trimethylolpropane trimethacrylate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane as a composite vulcanizing agent, and by controlling the mass ratio of the two, the crosslinking effect between PA and NBR can be significantly improved, so that the crosslinking network of PA and NBR is denser and the ability to resist external deformation is improved, thereby significantly increasing the tensile strength. During vulcanization, trimethylolpropane trimethacrylate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane have a reinforcing effect on the rubber, thereby improving the mechanical properties of the rubber. In addition, the addition of trimethylolpropane trimethacrylate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane can effectively increase the degree of vulcanization, increase the crosslinking density of the rubber material, control the slippage of the rubber molecular chains to a large extent, effectively prevent the slippage behavior of the rubber molecular chains during compression deformation, thereby maintaining a high molecular chain recovery ability, and further significantly improving the compression deformation of the rubber.

[0013] The plasticizer is a mixture of dibutoxyethyl adipate and acetyl tri-n-butyl citrate, with a mass ratio of 3-5:1, preferably 3:1.

[0014] The present invention uses a mixture of dibutoxyethyl adipate and acetyl tri-n-butyl citrate as a plasticizer. The addition of the two can form a cross-linking structure between rubber molecules, thereby improving the stability of the rubber.

[0015] As some preferred embodiments, the mass ratio of the composite vulcanizing agent to the plasticizer is 1:1.5-3; preferably 1:2.5.

[0016] During the implementation of the present invention, the oil resistance, compression deformation and aging resistance of the rubber can be improved by controlling the mass ratio of the composite vulcanizer and the plasticizer. It is speculated that the reason is that the plasticizer plays a lubricating role between the rubber molecular chains, causing the molecular chains to slip relatively. The addition of the composite vulcanizer can increase the cross-linking density, making the cross-linking network denser and improving the ability to resist deformation due to external forces. Controlling the mass ratio of the two can enable better mixing and cross-linking between the rubbers, thereby improving the comprehensive performance of the rubber.

[0017] The antioxidant is antioxidant 4010.

[0018] The present invention also provides a method for preparing the above-mentioned oil-resistant TPV material, comprising the following steps: (1) PA, NBR, composite vulcanizing agent, plasticizer, stearic acid, light calcium carbonate and antioxidant are added to an internal mixer and kneaded uniformly at room temperature. The uniformly kneaded rubber blocks are then granulated using a single-screw granulator at 50°C to obtain composite granules. (2) The composite particles are dynamically vulcanized and granulated in a twin-screw extruder with an aspect ratio of 50 to obtain the oil-resistant TPV material.

[0019] In step (2), the temperature of the melt homogenization section of the dynamic vulcanization of the twin-screw extruder is 210°C, the temperature of the dynamic vulcanization section is 220°C, and the temperature of the extrusion molding section is 210°C.

[0020] Compared with the prior art, the present invention has the following beneficial effects: (1) The NBR used in the present invention is a mixture of medium acrylonitrile butadiene rubber and high acrylonitrile butadiene rubber, wherein the medium acrylonitrile butadiene rubber has excellent mechanical properties and processability, and the high acrylonitrile butadiene rubber has stronger resistance to non-polar oils or solvents, but its mechanical properties will be reduced. During the implementation of the present invention, the medium acrylonitrile butadiene rubber and the high acrylonitrile butadiene rubber are mixed and the mass ratio of the two is controlled to be 3-5:1, which can significantly improve the mechanical properties and oil resistance of the TPV material.

[0021] (2) The present invention uses a mixture of trimethylolpropane trimethacrylate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane as a composite vulcanizing agent, and by controlling the mass ratio of the two, the crosslinking effect between PA and NBR can be significantly improved, making the crosslinking network of PA and NBR denser and improving the ability to resist external deformation, so that its tensile strength is significantly increased, and during vulcanization, trimethylolpropane trimethacrylate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane will have a reinforcing effect on the rubber, thereby improving the mechanical properties of the rubber; in addition, the addition of trimethylolpropane trimethacrylate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane can effectively increase the degree of vulcanization, increase the crosslinking density of the rubber, control the slip of the rubber molecular chain to a large extent, effectively prevent the slip behavior of the rubber molecular chain during compression deformation, thereby maintaining a high molecular chain recovery ability, and further significantly improving the compression deformation of the rubber.

[0022] (3) The present invention uses a mixture of dibutoxyethyl adipate and acetyl tri-n-butyl citrate as a plasticizer. The addition of the two can form a cross-linked structure between rubber molecules, thereby improving the stability of the rubber.

[0023] (4) During the implementation of the present invention, the oil resistance, compression deformation and aging resistance of the rubber can be improved by controlling the mass ratio of the composite vulcanizer and the plasticizer. It is speculated that the reason is that the plasticizer plays a lubricating role between the rubber molecular chains, causing the molecular chains to slip relative to each other. The addition of the composite vulcanizer can increase the cross-linking density, making the cross-linking network denser and improving the ability to resist deformation due to external forces. Controlling the mass ratio of the two can make the rubbers better mixed and cross-linked, thereby improving the comprehensive performance of the rubber. DETAILED DESCRIPTION

[0024] The following non-limiting examples are provided to enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way. The following are merely illustrative of the scope of the present invention, and those skilled in the art may make various changes and modifications to the present invention based on the disclosed content, which should also fall within the scope of the present invention.

[0025] When numerical ranges are given in the examples, it should be understood that, unless otherwise specified herein, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the invention belongs.

[0026] The present invention is further described below by way of specific examples. Unless otherwise specified, the various chemical reagents used in the examples of the present invention were obtained through conventional commercial channels.

[0027] Example 1 An oil-resistant TPV material and a preparation method thereof, comprising the following components in parts by weight: PA 30 parts; Medium acrylonitrile NBR (acrylonitrile content is 33%) 30 parts; High acrylonitrile NBR (acrylonitrile content is 45%) 10 parts; 1 part of trimethylolpropane trimethacrylate; 5 parts of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; 8 parts of dibutoxyethyl adipate; 2 parts of acetyl tri-n-butyl citrate; 1 part of stearic acid; 10 parts of light calcium carbonate; 1 part of antioxidant 4010.

[0028] The preparation method is: (1) PA, medium acrylonitrile NBR, high acrylonitrile NBR, trimethylolpropane trimethacrylate, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, dibutoxyethyl adipate, acetyl tri-n-butyl citrate, stearic acid, light calcium carbonate and antioxidant 4010 were added to an internal mixer and kneaded uniformly at room temperature. The kneaded rubber blocks were then granulated at 50°C using a single-screw granulator to obtain composite particles. (2) The composite particles are dynamically vulcanized and granulated in a twin-screw extruder with an aspect ratio of 50 to obtain the oil-resistant TPV material.

[0029] In step (2), the temperature of the melt homogenization section of the dynamic vulcanization of the twin-screw extruder is 210°C, the temperature of the dynamic vulcanization section is 220°C, and the temperature of the extrusion molding section is 210°C.

[0030] Example 2 An oil-resistant TPV material and a preparation method thereof, comprising the following components in parts by weight: PA 50 parts; Medium acrylonitrile NBR (acrylonitrile content is 33%) 50 parts; High acrylonitrile NBR (acrylonitrile content is 45%) 10 parts; 0.7 parts of trimethylolpropane trimethacrylate; 6.3 parts of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; 12.5 parts of dibutoxyethyl adipate; 2.5 parts of acetyl tri-n-butyl citrate; 3 parts of stearic acid; 20 parts of light calcium carbonate; 2 parts of antioxidant 4010.

[0031] The preparation method is: (1) PA, medium acrylonitrile NBR, high acrylonitrile NBR, trimethylolpropane trimethacrylate, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, dibutoxyethyl adipate, acetyl tri-n-butyl citrate, stearic acid, light calcium carbonate and antioxidant 4010 were added to an internal mixer and kneaded uniformly at room temperature. The kneaded rubber blocks were then granulated at 50°C using a single-screw granulator to obtain composite particles. (2) The composite particles are dynamically vulcanized and granulated in a twin-screw extruder with an aspect ratio of 50 to obtain the oil-resistant TPV material.

[0032] In step (2), the temperature of the melt homogenization section of the dynamic vulcanization of the twin-screw extruder is 210°C, the temperature of the dynamic vulcanization section is 220°C, and the temperature of the extrusion molding section is 210°C.

[0033] Example 3 An oil-resistant TPV material and a preparation method thereof, comprising the following components in parts by weight: PA 45 copies; Medium acrylonitrile NBR (acrylonitrile content is 33%) 40 parts; High acrylonitrile NBR (acrylonitrile content is 45%) 10 parts; 0.6 parts of trimethylolpropane trimethacrylate; 4.8 parts of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; 10.2 parts of dibutoxyethyl adipate; 3.3 parts of acetyl tri-n-butyl citrate; 1.8 parts of stearic acid; 16.2 parts of light calcium carbonate; 1.5 parts of antioxidant 4010.

[0034] The preparation method is: (1) PA, medium acrylonitrile NBR, high acrylonitrile NBR, trimethylolpropane trimethacrylate, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, dibutoxyethyl adipate, acetyl tri-n-butyl citrate, stearic acid, light calcium carbonate and antioxidant 4010 were added to an internal mixer and kneaded uniformly at room temperature. The kneaded rubber blocks were then granulated at 50°C using a single-screw granulator to obtain composite particles. (2) The composite particles are dynamically vulcanized and granulated in a twin-screw extruder with an aspect ratio of 50 to obtain the oil-resistant TPV material.

[0035] In step (2), the temperature of the melt homogenization section of the dynamic vulcanization of the twin-screw extruder is 210°C, the temperature of the dynamic vulcanization section is 220°C, and the temperature of the extrusion molding section is 210°C.

[0036] Comparative Example 1 The difference from Example 3 is that the plasticizer is replaced by triethylene glycol diisooctanoate, that is: PA 45 copies; Medium acrylonitrile NBR (acrylonitrile content is 33%) 40 parts; High acrylonitrile NBR (acrylonitrile content is 45%) 10 parts; 0.6 parts of trimethylolpropane trimethacrylate; 4.8 parts of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; 15.5 parts of triethylene glycol diethyl octanoate; 1.8 parts of stearic acid; 16.2 parts of light calcium carbonate; 1.5 parts of antioxidant 4010.

[0037] The rest is the same as Example 3.

[0038] Comparative Example 2 The difference from Example 3 is that the mass ratio of the composite vulcanizing agent to the plasticizer is 1:1, that is: The components are as follows in parts by weight: PA 45 copies; Medium acrylonitrile NBR (acrylonitrile content is 33%) 40 parts; High acrylonitrile NBR (acrylonitrile content is 45%) 10 parts; 1.2 parts of trimethylolpropane trimethacrylate; 9.4 parts of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; 7.9 parts of dibutoxyethyl adipate; 2.7 parts of acetyl tri-n-butyl citrate; 1.8 parts of stearic acid; 16.2 parts of light calcium carbonate; 1.5 parts of antioxidant 4010.

[0039] The rest is the same as Example 3.

[0040] Comparative Example 3 The difference from Example 3 is that the mass ratio of the composite vulcanizing agent to the plasticizer is 1:4, that is: The components are as follows in parts by weight: PA 45 copies; Medium acrylonitrile NBR (acrylonitrile content is 33%) 40 parts; High acrylonitrile NBR (acrylonitrile content is 45%) 10 parts; 0.5 parts of trimethylolpropane trimethacrylate; 3.8 parts of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane; 12.7 parts of dibutoxyethyl adipate; 4.2 parts of acetyl tri-n-butyl citrate; 1.8 parts of stearic acid; 16.2 parts of light calcium carbonate; 1.5 parts of antioxidant 4010.

[0041] The rest is the same as Example 3.

[0042] Effect test: 1. Oil resistance According to GB / T 1690-2010, the sample was placed in 93# gasoline and immersed at 100℃ for 72 h, and its mass change rate was measured.

[0043] 2. Compression permanent deformation performance Tested in accordance with GB / T1683-2018.

[0044] 3. Tensile strength and elongation at break The obtained oil-resistant TPV material sample was pressed into a 2 mm sheet at 240° C. to prepare a sample, and its tensile properties were tested according to GB / T528-2009.

[0045] 4. Aging resistance The hot air aging test was carried out in accordance with GB / T 3512-2014 at a temperature of 150°C for 72 h.

[0046] The test results are shown in Table 1 below.

[0047] Table 1

[0048] According to the test results in Table 1 above, it can be seen that the oil-resistant TPV materials prepared in Examples 1-3 of the present invention have good mechanical properties, and are excellent in oil resistance, aging resistance and compression permanent deformation properties.

[0049] Changing the type of plasticizer in Comparative Example 1 will affect the flexibility and bendability of the rubber to a certain extent, thereby weakening the cross-linking effect between the rubbers, and further affecting the mechanical properties of the rubber, as well as its oil resistance, aging resistance and compression set properties.

[0050] In Comparative Example 2-3, changing the mass ratio of the composite vulcanizer and the plasticizer is not within the scope of protection of the present invention and will weaken the comprehensive performance of the rubber. The presumed reason is that the plasticizer acts as a lubricant between the rubber molecular chains, causing the molecular chains to slip relative to each other. The addition of the composite vulcanizer can increase the cross-linking density, making the cross-linking network denser and improving the ability to resist deformation by external forces. Changing the mass ratio of the two will affect the mixing between the rubbers and thus affect their cross-linking, thereby reducing the comprehensive performance of the rubber.

[0051] Of course, the above contents are only preferred embodiments of the present invention and should not be considered as limiting the scope of the embodiments of the present invention. The present invention is not limited to the above examples. Equivalent changes and improvements made by ordinary technicians in this technical field within the essential scope of the present invention should all fall within the scope of the patent of the present invention.

Claims

1. An oil-resistant TPV material, characterized by: The components include the following in parts by weight: PA 30-50 parts; NBR 40-60 parts; 5-7 parts of composite vulcanizing agent; 10-15 parts of plasticizer; 1-2 parts of stearic acid; 10-20 parts of light calcium carbonate; 1-2 parts of antioxidant; The NBR is a mixture of medium acrylonitrile butadiene rubber and high acrylonitrile butadiene rubber; the acrylonitrile content in the medium acrylonitrile butadiene rubber is 30-40%, and the acrylonitrile content in the high acrylonitrile butadiene rubber is 40-50%.

2. The oil-resistant TPV material according to claim 1, characterized in that: The mass ratio of the medium acrylonitrile butadiene rubber to the high acrylonitrile butadiene rubber is 3-5:

1.

3. The oil-resistant TPV material according to claim 1, characterized in that: The mass ratio of the medium acrylonitrile butadiene rubber to the high acrylonitrile butadiene rubber is 4:

1.

4. The oil-resistant TPV material according to claim 1, characterized in that: The composite vulcanizing agent is a mixture of trimethylolpropane trimethacrylate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, with a mass ratio of 1:5-10.

5. The oil-resistant TPV material according to claim 4, characterized in that: The composite vulcanizing agent is a mixture of trimethylolpropane trimethacrylate and 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, with a mass ratio of 1:

8.

6. The oil-resistant TPV material according to claim 1, characterized in that: The plasticizer is a mixture of dibutoxyethyl adipate and acetyl tri-n-butyl citrate, with a mass ratio of 3-5:

1.

7. The oil-resistant TPV material according to claim 1, characterized in that: The plasticizer is a mixture of dibutoxyethyl adipate and acetyl tri-n-butyl citrate, with a mass ratio of 3:

1.

8. The oil-resistant TPV material according to claim 1, characterized in that: The mass ratio of the composite vulcanizing agent to the plasticizer is 1:1.5-3.

9. The oil-resistant TPV material according to claim 1, characterized in that: The mass ratio of the composite vulcanizing agent to the plasticizer is 1:2.

5.

10. The method for preparing the oil-resistant TPV material according to any one of claims 1 to 9, characterized in that: The steps include: (1) PA, NBR, composite vulcanizing agent, plasticizer, stearic acid, light calcium carbonate and antioxidant are added to an internal mixer and kneaded uniformly at room temperature. The uniformly kneaded rubber blocks are then granulated using a single-screw granulator at 50°C to obtain composite granules. (2) dynamically vulcanizing and granulating the composite particles in a twin-screw extruder with an aspect ratio of 50 to obtain the oil-resistant TPV material; In step (2), the temperature of the melt homogenization section of the dynamic vulcanization of the twin-screw extruder is 210°C, the temperature of the dynamic vulcanization section is 220°C, and the temperature of the extrusion molding section is 210°C.

Images