Composition containing nitrile rubber, manufacturing process and application thereof

Abstract

The invention belongs to the technical field of rubber materials, and particularly relates to a composition containing nitrile rubber, a manufacturing process and application of the composition. The nitrile rubber composition comprises nitrile rubber, modified polyformaldehyde, nano calcium carbonate, nano silicon dioxide, epoxidized soybean oil, triisooctyl trimellitate, diisobutyl peroxide, ammonium polyphosphate, an anti-aging agent and carbon black N880, and the ammonium polyphosphate and the anti-aging agent are added, so that the anti-aging performance of the nitrile rubber composition is remarkably improved; and mass production is carried out in our company.

Description

Technical Field

[0001] The invention belongs to the technical field of rubber materials, and in particular relates to a composition containing nitrile rubber, a manufacturing process and an application thereof. Background Art

[0002] Nitrile rubber (NBR) is a copolymer formed by the polymerization of acrylonitrile and butadiene monomers. The acrylonitrile content in nitrile rubber is 42%-46%, 36%-41%, 31%-35%, 25%-30%, and 18%-24%. The higher the acrylonitrile content, the better the oil resistance, but the cold resistance decreases accordingly. Due to the excellent performance of nitrile rubber, it is widely used in the manufacture of various oil-resistant rubber products, such as O-rings, gaskets, hoses, fuel tank linings, printing rollers, oil tank linings, insulating floor boards, oil-resistant soles, hard rubber parts, fabric coatings, pipe thread protective layers, pump impellers, wire sheaths, adhesives, food packaging films, rubber gloves and other fields.

[0003] The disadvantages of nitrile rubber are: it is not resistant to ozone, aromatic, halogenated hydrocarbons, ketones, ester solvents, and has poor low temperature resistance. In addition, its elasticity is slightly low.

[0004] Chinese patent CN 112795063 discloses an environmentally friendly n-pentane-resistant rubber composition, which comprises nitrile rubber, carbon black N774, softener DPHP, zinc oxide ZNO, stearate SA, antioxidant RD, antioxidant 4010, vulcanizing agent S-80H, accelerator CZ and accelerator TT, which improves the n-pentane resistance of the rubber material and is suitable for use as a processing material for gas stove seals, but its anti-aging performance is poor.

[0005] Chinese patent CN 112852033 discloses a high-pressure and low-temperature resistant rubber composition, which is made of the following raw materials in parts by weight: 80-120 parts of nitrile rubber, 45-65 parts of a reinforcing agent (a mixture of carbon black N550, carbon black N774 and white carbon black 255 in a weight ratio of 30-50:30-40:4-6), 10-20 parts of a softener (dioctyl adipate), 7.5-11.5 parts of a compounding agent (a mixture of zinc oxide ZNO, stearate SA antioxidant RD and antioxidant 4010 in a weight ratio of 4-6:0.5-1.5:1-3:1-2), and 3-4 parts of a vulcanization accelerator (a mixture of vulcanizing agent S-80H, accelerator CZ and accelerator TT in a weight ratio of 0.5-1.5:1-1.5:1-1.5). This material is safe and environmentally friendly, but its anti-aging performance is difficult to ensure.

[0006] In summary, as time goes by, the molecules of nitrile rubber are prone to aging and their anti-aging properties are affected, which is a huge disadvantage in practical applications. The current preparation process and combination have major defects. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a nitrile rubber composition material with excellent performance and excellent anti-aging performance.

[0008] Specifically, the technical solution of the present invention is as follows:

[0009] The invention provides a nitrile rubber composition, which comprises nitrile rubber, modified polyoxymethylene, nano calcium carbonate, nano silicon dioxide, epoxy soybean oil, tri-isooctyl trimellitate, diisobutyl peroxide, ammonium polyphosphate, an anti-aging agent and carbon black N880.

[0010] A nitrile rubber composition, wherein the components are calculated by weight ratio as follows:

[0011] 100 parts of nitrile rubber, 6 parts of modified polyoxymethylene, 6 parts of nano calcium carbonate, 3 parts of nano silicon dioxide, 17.8 parts of epoxy soybean oil, 2.7 parts of triisooctyl trimellitate, 2.5 parts of diisobutyl peroxide, 1.5 parts of ammonium polyphosphate, 7 parts of antioxidant, and 40 parts of carbon black N880.

[0012] In a preferred embodiment of the present invention, the anti-aging agent is a mixture of tributylthiourea and tri-n-butyl acetyl citrate, and the ratio of tributylthiourea to tri-n-butyl acetyl citrate is 5:2 by weight. Other ratios of anti-aging agent combinations have been found to significantly reduce hardness, elongation at break, tensile strength, and permanent deformation, especially in aging resistance experiments, where the performance is reduced by more than 10%.

[0013] In a preferred embodiment of the present invention, the nitrile rubber is a mixture of nitrile rubber 1052 and nitrile rubber 7030. Calculated by weight, the ratio of nitrile rubber 1052 to nitrile rubber 7030 is 3:1.

[0014] In a preferred embodiment of the present invention, the preparation method of the modified polyformaldehyde is: 80 parts by weight of polyformaldehyde, 10 parts by weight of ethylene terpolymer, 8 parts by weight of aluminate coupling agent and 5 parts by weight of dioctyl phthalate are mixed uniformly in a mixer, and the mixture is kneaded uniformly at a temperature of 170° C. using a double-roll mixer to obtain; without adding the modified polyformaldehyde, the ozone resistance of the nitrile rubber composition is reduced, and the anti-aging performance cannot achieve the technical effect described in the present invention. The inventor believes that the modified polyformaldehyde and the anti-aging agent play a synergistic role to improve the performance of the nitrile rubber composition.

[0015] The process of the nitrile rubber composition, the manufacturing process comprises the following steps:

[0016] 1) Anti-aging agent treatment solution: dissolve tri-n-butyl acetyl citrate in an organic solvent, add tributyl thiourea, and concentrate by rotary evaporation in a water bath to obtain an anti-aging agent treatment solution;

[0017] 2) Rubber compounding: melt-mix nitrile rubber, modified polyoxymethylene, nano-calcium carbonate, nano-silicon dioxide, epoxy soybean oil, tri-ethylhexyl trimellitate, diisobutyl peroxide, and carbon black N880 at 205°C, put into a raw material box, mix, extrude, and form;

[0018] 3) Water-insulated cooling: cooling the rubber semi-finished product formed in step (2);

[0019] 4) Secondary processing: adding ammonium polyphosphate and the anti-aging agent treatment solution obtained in step (1) into the cooled rubber semi-finished product in step (3), mixing evenly, extruding, and molding;

[0020] 5) Secondary cooling: Cool the mixture from step (4) and collect the finished product.

[0021] The organic solvent is selected from 75% or more ethanol aqueous solution.

[0022] The cooling temperature of step (3) is 80-90°C, and the cooling temperature of step (5) is 25-45°C.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The nitrile rubber composition of the present invention selects the ingredients and the optimal ratio, adds ammonium polyphosphate and an antioxidant (tri-n-butyl acetyl citrate and tributyl thiourea), and optimizes the manufacturing process, including the pretreatment process of the antioxidant and the processing and cooling processes, thereby significantly improving the ozone resistance and anti-aging performance of the nitrile rubber composition. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 : Comparison results of ozone resistance test hardness (°) of Examples 1-5.

[0026] Figure 2 : Comparison results of the elongation at break (%) in the ozone resistance test of Examples 1-5.

[0027] Figure 3 : Comparative results of tensile strength (%) of ozone resistance test of Examples 1-5.

[0028] Figure 4 : Comparison results of permanent deformation rate (%) of ozone resistance test of Examples 1-5.

[0029] Figure 5 : Comparison results of hardness (°) of high temperature aging test of Examples 1-5.

[0030] Figure 6 : Comparison results of the elongation at break (%) of the high temperature aging test of Examples 1-5.

[0031] Figure 7 : Comparison results of tensile strength (%) of high temperature aging test of Examples 1-5.

[0032] Figure 8 : Comparison results of permanent deformation rate (%) of high temperature aging test of Examples 1-5. DETAILED DESCRIPTION

[0033] In order to make the purpose and technical solution of the present invention clearer, the present invention is further described below in conjunction with embodiments, but the protection scope of the present invention is not limited to these embodiments, and the embodiments are only used to explain the present invention. It should be understood by those skilled in the art that any changes or equivalent substitutions that do not deviate from the concept of the present invention are included in the protection scope of the present invention.

[0034] Example 1 Nitrile rubber composition and its manufacturing process

[0035] Ingredients:

[0036]

[0037]

[0038] Manufacturing process:

[0039] 1) Anti-aging agent treatment solution: dissolve tri-n-butyl acetyl citrate in an ethanol aqueous solution of more than 75%, add tributyl thiourea, and concentrate by rotary evaporation in a water bath to obtain an anti-aging agent treatment solution;

[0040] 2) Rubber compounding: melt-mix nitrile rubber, modified polyoxymethylene, nano-calcium carbonate, nano-silicon dioxide, epoxy soybean oil, tri-ethylhexyl trimellitate, diisobutyl peroxide, and carbon black N880 at 205°C, put into a raw material box, mix, extrude, and form;

[0041] 3) Water-insulated cooling: Cooling the rubber semi-finished product formed in step (2) at 85° C.

[0042] 4) Secondary processing: adding ammonium polyphosphate and the anti-aging agent treatment solution obtained in step (1) into the cooled rubber semi-finished product in step (3), mixing evenly, extruding, and molding;

[0043] 5) Secondary cooling: Cool the mixture from step (4) to 35°C and collect the finished product.

[0044] Example 2 Nitrile rubber composition and its manufacturing process

[0045] Ingredients:

[0046]

[0047]

[0048] The manufacturing process is the same as described in Example 1.

[0049] Example 3 Nitrile rubber composition and its manufacturing process Ingredients list:

[0050]

[0051] The manufacturing process is the same as described in Example 1.

[0052] Example 4 Nitrile rubber composition and its manufacturing process Ingredients list:

[0053]

[0054]

[0055] The manufacturing process is the same as described in Example 1.

[0056] Example 5 Nitrile rubber composition and its manufacturing process

[0057] Ingredients:

[0058]

[0059] The manufacturing process is the same as described in Example 1.

[0060] Verification Example

[0061] 1. Comprehensive performance evaluation of the compositions of Examples 1-4

[0062] 1. Ozone resistance test

[0063] The test is carried out in accordance with GB / T7762-2014 static tensile test for ozone crack resistance of vulcanized rubber or thermoplastic rubber.

[0064] Sample size: The length and width of the standard strip sample are 20cm and the thickness is 1.0cm.

[0065] Ozone concentration: (50±5)×10 -8 ; Temperature: 40C ± 2℃.

[0066] Test method: After placing the sample in an ozone test chamber for 72 hours, check the tensile strength, elongation at break, hardness and permanent deformation of the sample.

[0067] After 72 hours of ozone test, the tensile strength, elongation at break, hardness and permanent deformation rate of the samples were used as the scoring standards. Each embodiment took 5 equilibrium experiments and finally used Graphad Prism 9.0 for statistical analysis. Figure 1-4 .

[0068] Figure 1 : Comparison results of hardness (°) of ozone resistance test of Examples 1-5. It can be seen that there is a significant difference (P<0.05) between Examples 1-2 and Examples 3-5.

[0069] Figure 2 : Comparison results of the elongation at break (%) of the ozone resistance test of Examples 1-5. It can be seen that there is no significant difference between Example 1 and Examples 2-5 (P>0.05).

[0070] Figure 3 : Comparison results of tensile strength (%) of ozone resistance test of Examples 1-5. It can be seen that there is a significant difference (P<0.05) between Example 1 and Examples 3 and 5.

[0071] Figure 4 : Comparison results of permanent deformation rate (%) of ozone resistance test of Examples 1-5. It can be seen that there is a significant difference (P<0.05) between Example 1 and Examples 2, 3, and 5.

[0072] 2. Aging resistance test

[0073] 2.1 High temperature aging test

[0074] Test method: After the nitrile rubber composition samples of Examples 1-5 and Comparative Examples 1-8 were heated at 100°C for 720 hours, the cracking, tensile strength, elongation at break, hardness and permanent deformation of the samples were checked.

[0075] After high temperature aging test, the number of cracks, tensile strength, elongation at break, hardness and permanent deformation of the samples were used as the scoring standards, and finally statistical analysis was performed using Graphad Prism 9.0. Figure 5-8 .

[0076] Figure 5 : Comparison results of hardness (°) of high temperature aging test of Examples 1-5. It can be seen that there is a significant difference (P<0.05) between Example 1 and Examples 2-5.

[0077] Figure 6 : Comparison results of elongation at break (%) of high temperature aging test of Examples 1-5. It can be seen that there is a significant difference between Example 1-2 and Example 4 (P<0.05).

[0078] Figure 7 : Comparison results of tensile strength (%) of high temperature aging test of Examples 1-5. It can be seen that there is a significant difference (P<0.05) between Example 1-2 and Example 3-4.

[0079] Figure 8 : Comparison results of permanent deformation rate (%) of high temperature aging test of Examples 1-5. It can be seen that Example 2 has significant difference (P<0.05) compared with Examples 1 and 3-5.

Claims

1. A nitrile rubber composition, characterized in that The weight ratio of the components is: 100 parts of nitrile rubber, 6 parts of modified polyoxymethylene, 6 parts of nano calcium carbonate, 3 parts of nano silicon dioxide, 17.8 parts of epoxy soybean oil, 2.7 parts of triisooctyl trimellitate, 2.5 parts of diisobutyl peroxide, 1.5 parts of ammonium polyphosphate, 7 parts of antioxidant, and 40 parts of carbon black N880.

2. The nitrile rubber composition according to claim 1 or 2, characterized in that The anti-aging agent is a mixture of tributylthiourea and tri-n-butyl acetyl citrate, and the ratio of tributylthiourea to tri-n-butyl acetyl citrate is 5:2 calculated by weight.

3. The nitrile rubber composition according to claim 1 or 2, characterized in that The nitrile rubber is a mixture of nitrile rubber 1052 and nitrile rubber 7030. Calculated by weight, the ratio of nitrile rubber 1052 to nitrile rubber 7030 is 3:

1.

4. The nitrile rubber composition according to claim 1 or 2, characterized in that The preparation method of the modified polyoxymethylene is as follows: 80 parts by weight of polyoxymethylene, 10 parts by weight of ethylene terpolymer, 8 parts by weight of aluminate coupling agent and 5 parts by weight of dioctyl phthalate are uniformly mixed in a mixer, and the mixture is uniformly kneaded at a temperature of 170° C. using a double-roll mixer to obtain the modified polyoxymethylene.

5. A process for producing the nitrile rubber composition according to any one of claims 1 to 3, characterized in that: The manufacturing process comprises the following steps: (1) Anti-aging agent treatment solution: dissolve tri-n-butyl acetyl citrate in an organic solvent, add tributyl thiourea, Concentrate by rotary evaporation in a water bath to obtain an anti-aging agent treatment solution; (2) Rubber compounding: melt-mix nitrile rubber, modified polyoxymethylene, nano-calcium carbonate, nano-silicon dioxide, epoxy soybean oil, tri-ethylhexyl trimellitate, diisobutyl peroxide, and carbon black N880 at 205°C, put into a raw material box, mix, extrude, and form; (3) Water-insulated cooling: cooling the rubber semi-finished product formed in step (2); (4) secondary processing: adding ammonium polyphosphate and the anti-aging agent treatment solution obtained in step (1) into the cooled rubber semi-finished product in step (3), mixing evenly, extruding, and molding; (5) Secondary cooling: Cool the mixture from step (4) and collect the finished product.

6. The manufacturing process according to claim 8, characterized in that: The organic solvent is selected from 75% or more ethanol aqueous solution.

7. The manufacturing process according to claim 8, characterized in that: The cooling temperature of step (3) is 80-90°C, and the cooling temperature of step (5) is 25-45°C.

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