Rubber material for colored pneumatic sealing element and preparation method of rubber material

Abstract

The invention discloses a rubber material for a colored pneumatic sealing element and a preparation method of the rubber material, and belongs to the technical field of rubber, and the rubber material comprises 95-98 parts of nitrile rubber, 20-40 parts of white carbon black, 40-60 parts of nano silicon dioxide with the surface grafted with a silane coupling agent, 5-10 parts of zinc oxide, 1-3 parts of stearic acid, 4-6 parts of the silane coupling agent, 1-3 parts of an anti-aging agent, 1-3 parts of a processing aid and 0.5-1 part of sulfur. The invention relates to a high-temperature-resistant paint which is prepared from the following components in parts by weight: 0.8-1.2 parts of an accelerator TBzTD, 1.0-1.5 parts of an accelerator CZ, 0.5-1.0 part of a vulcanization accelerator, 0.3-1.0 part of an organic tin complex and 5-15 parts of titanate modified pigment. The organic pigment is subjected to surface functionalization treatment by adopting a titanate coupling agent, and alkoxy in a molecular structure of the organic pigment and hydroxyl on the surface of the pigment are subjected to dehydration condensation reaction to form stable chemical bonds. The chemical bonding effect converts polar groups on the surface of the pigment into organophilic groups, so that the compatibility of the pigment and a nitrile rubber matrix is remarkably enhanced, and migration of pigment molecules to the surface of rubber in a high-temperature environment is fundamentally inhibited.

Description

Technical Field

[0001] The present invention relates to the field of rubber technology, in particular to a rubber material for a colored pneumatic seal and a preparation method thereof. Background Art

[0002] Organic pigments commonly used in colored rubber seals (such as phthalocyanines and quinacridones) can migrate or fade over time due to ultraviolet light, high temperatures, or exposure to chemical media (such as oil mist and solvents). For example, if uncoated organic pigments are used in nitrile rubber (NBR) seals, the pigment molecules may migrate to the surface at high temperatures, resulting in uneven color or ineffective marking. Inorganic pigments (such as titanium dioxide and red iron oxide) have good migration resistance, but poor dispersibility can lead to color differences. Furthermore, some lead-containing pigments (such as chrome yellow) react with vulcanizing agents to form black lead sulfide, which affects the appearance.

[0003] Based on this, the present invention designs a colored rubber material for pneumatic seals and a preparation method thereof to solve the above problems. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, the present invention provides a colored rubber material for pneumatic seals, which comprises the following components in parts by mass:

[0005] 95-98 parts of nitrile rubber, 20-40 parts of white carbon black, 40-60 parts of nano-silica with surface grafted silane coupling agent, 5-10 parts of zinc oxide, 1-3 parts of stearic acid, 4-6 parts of silane coupling agent, 1-3 parts of antioxidant, 1-3 parts of processing aid, 0.5-1 part of sulfur, 0.8-1.2 parts of accelerator TBzTD, 1.0-1.5 parts of accelerator CZ, 0.5-1.0 parts of vulcanization accelerator, 0.3-1.0 parts of organic tin complex, 5-15 parts of titanate modified pigment;

[0006] The organic tin complex is one of dibutyltin dimercaptoacetate, dibutyltin dilaurate or dioctyltin maleate.

[0007] A method for preparing the rubber material for a colored pneumatic seal comprises the following steps:

[0008] S1: Activation of the organotin complex: mixing the organotin complex with a silane coupling agent, adding the mixture to a toluene solvent, heating and stirring under nitrogen protection, and removing the toluene by distillation under reduced pressure to obtain a silylated organotin complex;

[0009] S2: Pigment surface functionalization: dispersing the organic pigment in an alkaline aqueous solution, adding a titanate coupling agent, ultrasonicating, centrifuging and separating the precipitate, washing with ethanol, and drying to obtain a titanate-modified pigment;

[0010] S3: Complex chemical bonding. Mix the silylated organotin complex with the titanate-modified pigment, add them to the N-methylpyrrolidone solvent, add the catalyst tetrabutylammonium bromide, raise the temperature and stir for reaction, centrifuge to separate the precipitate, wash it successively with acetone and deionized water, and dry to obtain the organotin pigment.

[0011] S4: Synergistic compounding of the organotin pigment. Premix the above-prepared organotin-pigment complex with nano-silica grafted with a silane coupling agent on the surface, add them to the N-methylpyrrolidone solvent, ultrasonically disperse to form a uniform suspension, and spray-dry the suspension to obtain organotin pigment-nano-silica synergistically coated particles.

[0012] S5: First stage of mixing. Put nitrile rubber, zinc oxide, stearic acid, antioxidant, and processing aids into a Banbury mixer, add silica and organotin pigment-nano-silica synergistically coated particles for mixing, discharge the rubber and clean the Banbury mixer chamber, re-put the rubber material, add sulfur in batches, and mix to obtain Mixing Compound A.

[0013] S6: Second stage of mixing. Add Mixing Compound A to an open mill, add accelerator TBzTD, accelerator CZ, and vulcanization accelerator TETD in sequence, take off the sheet and cool to obtain the finished rubber material.

[0014] Further, S1 is specifically as follows: Mix the organotin complex with the silane coupling agent, add them to the toluene solvent, and the solvent dosage is 5-8 times the mass of the organotin complex. Under nitrogen protection, maintain an inert atmosphere with a nitrogen flow rate of 10-15 L / min, raise the temperature to 80-90 °C, stir for reaction at 600-800 rpm for 1-2 h, after the reaction ends, carry out vacuum distillation at 50-60 °C for 30-40 min to remove toluene, and obtain the silylated organotin complex.

[0015] Further, S2 is specifically as follows: Disperse the organic pigment in an alkaline aqueous solution with pH = 8-9, add the titanate coupling agent, and the mass of the titanate is 1%-3% of the mass of the pigment. At 50-60 °C, perform ultrasonic treatment at a frequency of 40-50 kHz for 30-40 min, centrifuge at a centrifuge speed of 4000-5000 rpm and a centrifugation time of 10-15 min to separate the precipitate, wash it with ethanol at a centrifugation speed of 3000-4000 rpm and a centrifugation time of 5-8 min, wash it with ethanol 3-5 times, and the mass of ethanol each time is 3 times the mass of the precipitate. Finally, dry it in a vacuum drying oven at 60-75 °C for 2-4 h to obtain the titanate-modified pigment.

[0016] Further, S3 specifically involves mixing the silylated organotin complex with the titanate-modified pigment, adding it to the N-methylpyrrolidone solvent. The solvent dosage is 4 - 6 times the total solid content. 0.1 - 0.3 parts of the catalyst tetrabutylammonium bromide is added, and the temperature is raised to 100 - 110 °C. Stirring reaction is carried out at 1000 - 1200 rpm for 3 - 5 h. After the reaction is completed, the precipitate is separated at a centrifuge speed of 6000 - 7000 rpm for 20 - 30 min, and washed 2 - 4 times successively with acetone at a centrifuge speed of 3000 - 4000 rpm for 5 - 7 min and deionized water at a centrifuge speed of 4000 - 5000 rpm for 10 - 15 min, and dried in a vacuum drying oven at 80 - 85 °C and a vacuum degree of -0.1 MPa for 4 - 6 h to obtain the organotin pigment.

[0017] Further, S4 specifically involves premixing the organotin-pigment complex prepared above with the nano-silica grafted with a surface silane coupling agent, adding it to the N-methylpyrrolidone solvent. The solvent mass is 3 - 5 times the total solid content. At 60 - 80 °C, ultrasonic dispersion is carried out at a frequency of 40 - 50 kHz and a power of 200 - 300 W for 20 - 30 min to form a uniform suspension. The suspension is spray-dried with an inlet temperature of 120 - 140 °C, an outlet temperature of 60 - 80 °C, and an atomization pressure of 0.2 - 0.4 MPa to obtain the organotin pigment-nano-silica co-coated particles.

[0018] Further, the particle size of the nano-silica grafted with the surface silane coupling agent is 20 - 50 nm.

[0019] Further, S5 specifically involves putting nitrile rubber, zinc oxide, stearic acid, antioxidant, and processing aid into the internal mixer. The internal mixer speed is set at 40 - 60 rpm, and mixing is carried out for 40 - 60 s. Then, silica and the organotin pigment-nano-silica co-coated particles are added, and the internal mixer speed is adjusted to 50 - 70 rpm, and mixing is carried out for 80 - 100 s. The discharged rubber is removed and the internal mixer chamber is cleaned. The rubber compound is recharged, the internal mixer speed is adjusted to 20 - 30 rpm, and sulfur is added in three portions, and mixing is carried out for 50 - 70 s to obtain the A mixed rubber.

[0020] Further, S6 specifically involves adding the A mixed rubber to the open mill. The roll temperature is set at 50 - 60 °C, the roll gap is adjusted to 1 - 2 mm, and accelerator TBzTD, accelerator CZ, and vulcanization accelerator TETD are added in sequence. After mixing for 60 - 90 s, the roll gap is adjusted to 3 - 5 mm, and the sheet is taken out and cooled to obtain the finished rubber compound.

[0021] The beneficial effects of the present invention compared with the prior art are as follows:

[0022] 1. The present invention uses a titanate coupling agent to perform surface functionalization treatment on organic pigments. The alkoxy groups in its molecular structure undergo dehydration condensation reactions with the hydroxyl groups on the pigment surface to form stable chemical bonds. This chemical bonding converts the polar groups on the pigment surface into organophilic groups, significantly enhancing the compatibility between the pigment and the nitrile rubber matrix, and fundamentally inhibiting the migration of pigment molecules to the rubber surface under high-temperature environments. Experiments show that the pigments modified with titanate remain stable under high-temperature environments, effectively solving the problem of uneven color caused by the migration of traditional organic pigments.

[0023] 2. The silanized organotin complex of the present invention forms a chemical bond bridging structure through the condensation reaction of its siloxy groups with the active sites on the surface of the titanate-modified pigments. This chemical bonding not only enhances the interfacial bonding strength between the pigment and the rubber, but more importantly, the organotin groups capture the free radicals generated during the rubber vulcanization process through coordination, inhibiting the degradation of pigment molecules caused by thermal-oxidative aging. At the same time, the long-chain alkyl groups in the organotin complex are inserted between the rubber molecular chains to form a physical entanglement network, further preventing the Brownian motion of pigment molecules, and significantly improving the color retention of the seal in harsh environments.

[0024] 3. The surface-grafted silane coupling agent-modified nano-silica of the present invention and the organotin-pigment complex form a three-dimensional coating network through hydrogen bonds and van der Waals forces. This coating structure has a dual function: on the one hand, the high specific surface area of nano-SiO2 effectively disperses pigment aggregates, significantly improving color uniformity; on the other hand, the SiO2 particles act as a physical barrier to block the direct erosion of pigment molecules by ultraviolet rays and chemical media. At the same time, the silanol groups on its surface form secondary bonds with the rubber molecular chains, enhancing the interfacial bonding force, thereby improving the weather resistance and chemical corrosion resistance of the seal.

[0025] 4. Through the chemical matching design of the organotin-pigment complex and the vulcanizing agent, the present invention effectively alleviates the problem of the reaction between traditional lead-containing pigments and sulfur to form black lead sulfide. The silanized organotin complex not only acts as a coupling agent to promote the interfacial bonding between the filler and the rubber during the vulcanization process, but also participates in the vulcanization crosslinking reaction through its organic groups, increasing the density of the vulcanization network. This not only avoids color difference problems, but also synchronously optimizes the mechanical properties of the seal, achieving the coordinated improvement of color stability and mechanical strength. Detailed Embodiments

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0027] Example 1: This example provides a rubber material for a colored pneumatic seal. By mass fraction, it includes the following components:

[0028] 95 parts of nitrile rubber, 20 parts of white carbon black, 40 parts of nano-silica with surface-grafted silane coupling agent, 5 parts of zinc oxide, 1 part of stearic acid, 4 parts of silane coupling agent, 1 part of anti-aging agent, 1 part of processing aid, 0.5 part of sulfur, 0.8 part of accelerator TBzTD, 1.0 part of accelerator CZ, 0.5 part of vulcanization accelerator, 0.3 part of organotin complex, and 5 parts of titanate-modified pigment;

[0029] The organotin complex is one of dibutyltin dimercaptoacetate, dibutyltin dilaurate, or dioctyltin maleate.

[0030] A preparation method of the rubber material for a colored pneumatic seal described above includes the following steps:

[0031] S1: Activation of the organotin complex. Mix the organotin complex with the silane coupling agent, add it to toluene solvent, and the solvent dosage is 5 times the mass of the organotin complex. Under nitrogen protection, maintain an inert atmosphere with a nitrogen flow rate of 10 L / min, heat up to 80 °C, stir and react at 600 rpm for 1 h. After the reaction, carry out vacuum distillation at a vacuum degree of -0.08 MPa and 50 °C for 30 min to remove toluene, and obtain the silylated organotin complex;

[0032] S2: Surface functionalization of the pigment. Disperse the organic pigment (phthalocyanine blue) in an alkaline aqueous solution with pH = 8, add the titanate coupling agent, and the mass of the titanate is 1% of the mass of the pigment. At 50 °C, carry out ultrasonic treatment at a frequency of 40 kHz for 30 min, separate the precipitate with a centrifuge at a rotation speed of 4000 rpm and a centrifugation time of 10 min, wash it with ethanol at a centrifugation speed of 3000 rpm and a centrifugation time of 5 min for 3 times, and each time the mass of ethanol is 3 times the mass of the precipitate. Finally, dry it in a vacuum drying oven at 60 °C and a vacuum degree of -0.09 MPa for 2 h to obtain the titanate-modified pigment;

[0033] S3: Chemical bonding of the composite. Mix the silylated organotin complex with the titanate-modified pigment, add it to N-methylpyrrolidone solvent, and the solvent dosage is 4 times the total solid content. Add 0.1 part of catalyst tetrabutylammonium bromide, heat up to 100 °C, stir and react at 1000 rpm for 3 h. After the reaction is completed, separate the precipitate with a centrifuge at a rotation speed of 6000 rpm and a centrifugation time of 20 min, wash it 2 times each with acetone at a centrifugation speed of 3000 rpm and a time of 5 min and deionized water at a centrifugation speed of 4000 rpm and a time of 10 min, and dry it in a vacuum drying oven at 80 °C and a vacuum degree of -0.1 MPa for 4 h to obtain the organotin pigment;

[0034] S4: Co - blending of organotin pigments. Premix the prepared organotin - pigment complex with nano - silica grafted with surface silane coupling agent, add it to N - methyl - 2 - pyrrolidone (NMP) solvent. The mass of the solvent is 3 times the total solid content. At 60 °C, ultrasonic dispersion is carried out at a frequency of 40 kHz and a power of 200 W for 20 min to form a uniform suspension. Spray - dry the suspension, with an inlet temperature of 120 °C, an outlet temperature of 60 °C, and an atomization pressure of 0.2 MPa to obtain organotin pigment - nano - silica co - coated particles;

[0035] The particle size of the nano - silica grafted with surface silane coupling agent is 20 nm;

[0036] S5: First stage of mixing. Put nitrile rubber, zinc oxide, stearic acid, antioxidant, processing aid into a mixer. Set the mixer speed at 40 rpm and mix for 40 s. Then add silica white and organotin pigment - nano - silica co - coated particles. Adjust the mixer speed to 50 rpm and mix for 80 s. Stop when the temperature rises to 145 °C during the mixing process. Discharge the rubber and clean the mixing chamber. Re - put the rubber material, adjust the mixer speed to 20 rpm, and add sulfur in three portions. Mix for 50 s until the rubber temperature reaches 155 °C to obtain Mixing Compound A;

[0037] S6: Second stage of mixing. Add Mixing Compound A to an open mill. Set the roll temperature at 50 °C and the roll gap at 1 mm. Add accelerator TBzTD, accelerator CZ, and vulcanization accelerator TETD in sequence. Thin - pass 4 times. Let the rubber stand for 10 s and remix after each thin - pass. After mixing for 60 s, adjust the roll gap to 3 mm, take off the sheet and cool to obtain the finished rubber material.

[0038] Example 2: This example provides a rubber material for a colored pneumatic seal. By mass, it includes the following components:

[0039] 98 parts of nitrile rubber, 40 parts of silica white, 60 parts of nano - silica grafted with surface silane coupling agent, 10 parts of zinc oxide, 3 parts of stearic acid, 6 parts of silane coupling agent, 3 parts of antioxidant, 3 parts of processing aid, 1 part of sulfur, 1.2 parts of accelerator TBzTD, 1.5 parts of accelerator CZ, 1.0 part of vulcanization accelerator, 1.0 part of organotin complex, 15 parts of titanate - modified pigment;

[0040] The organotin complex is one of dibutyltin dimercaptoacetate, dibutyltin dilaurate, or dioctyltin maleate.

[0041] A preparation method of the rubber material for the colored pneumatic seal includes the following steps:

[0042] S1: Activation of organotin complex. Mix the organotin complex with a silane coupling agent, add it to toluene solvent, and the solvent dosage is 8 times the mass of the organotin complex. Under nitrogen protection, maintain an inert atmosphere with a nitrogen flow rate of 15 L / min, heat up to 90 °C, stir and react at 800 rpm for 2 h. After the reaction, carry out vacuum distillation at a vacuum degree of -0.08 MPa and 60 °C for 40 min to remove toluene, and obtain a silylated organotin complex;

[0043] S2: Surface functionalization of pigment. Disperse the organic pigment (quinacridone red) in an alkaline aqueous solution with pH = 9, add a titanate coupling agent, and the mass of the titanate is 3% of the mass of the pigment. At 60 °C, carry out ultrasonic treatment at a frequency of 50 kHz for 40 min, separate the precipitate with a centrifuge at a rotational speed of 5000 rpm and a centrifugation time of 15 min, wash it with ethanol at a centrifugal rotational speed of 4000 rpm and a centrifugation time of 8 min, wash it 5 times, and the mass of ethanol each time is 3 times the mass of the precipitate. Finally, dry it in a vacuum drying oven at 75 °C and a vacuum degree of -0.09 MPa for 4 h to obtain a titanate-modified pigment;

[0044] S3: Chemical bonding of the composite. Mix the silylated organotin complex with the titanate-modified pigment, add it to N-methylpyrrolidone solvent, and the solvent dosage is 6 times the total solid content. Add 0.3 parts of the catalyst tetrabutylammonium bromide, heat up to 110 °C, stir and react at 1200 rpm for 5 h. After the reaction is completed, separate the precipitate with a centrifuge at a rotational speed of 7000 rpm and a centrifugation time of 30 min, wash it 4 times successively with acetone at a centrifugal rotational speed of 4000 rpm and a time of 7 min and deionized water at a centrifugal rotational speed of 5000 rpm and a time of 15 min, and dry it in a vacuum drying oven at 85 °C and a vacuum degree of -0.1 MPa for 6 h to obtain an organotin pigment;

[0045] S4: Co-synergistic blending of the organotin pigment. Premix the organotin-pigment composite prepared above with nano-silica grafted with a silane coupling agent on the surface, add it to N-methylpyrrolidone (NMP) solvent, and the solvent mass is 5 times the total solid content. At 80 °C, carry out ultrasonic dispersion at a frequency of 50 kHz and a power of 300 W for 30 min to form a uniform suspension. Spray-dry the suspension, with an inlet temperature of 140 °C, an outlet temperature of 80 °C, and an atomization pressure of 0.4 MPa to obtain organotin pigment-nano-silica co-coated particles;

[0046] The particle size of the nano-silica grafted with a silane coupling agent on the surface is 50 nm;

[0047] S5: The first stage of mixing. Put nitrile rubber, zinc oxide, stearic acid, anti-aging agent, and processing aid into a Banbury mixer. Set the rotation speed of the Banbury mixer at 60 rpm and mix for 60 s. Then add silica and organotin pigment-nano silica co-coated particles. Adjust the rotation speed of the Banbury mixer to 70 rpm and mix for 100 s. Stop when the temperature rises to 145 °C during the mixing process. Discharge the rubber and clean the mixing chamber. Re-put the rubber compound, adjust the rotation speed of the Banbury mixer to 30 rpm, and add sulfur in three portions, mixing for 70 s until the temperature of the rubber compound reaches 155 °C to obtain Mixing Compound A;

[0048] S6: The second stage of mixing. Put Mixing Compound A into an open mill. Set the roll temperature at 60 °C and adjust the roll gap to 2 mm. Sequentially add accelerator TBzTD, accelerator CZ, and vulcanization accelerator TETD. Thin pass 4 times, and let the rubber compound stand for 10 s and remix after each thin pass. After mixing for 90 s, adjust the roll gap to 5 mm, take off the sheet and cool it to obtain the finished rubber compound.

[0049] Example 3: This example provides a rubber material for a colored pneumatic seal. By mass, it includes the following components:

[0050] 96 parts of nitrile rubber, 37 parts of silica, 56 parts of nano silica grafted with surface silane coupling agent, 8 parts of zinc oxide, 2 parts of stearic acid, 5 parts of silane coupling agent, 2 parts of anti-aging agent, 2.5 parts of processing aid, 0.8 parts of sulfur, 1.1 parts of accelerator TBzTD, 1.3 parts of accelerator CZ, 0.9 parts of vulcanization accelerator, 0.6 parts of organotin complex, and 12 parts of titanate-modified pigment;

[0051] The organotin complex is one of dibutyltin dimercaptoacetate, dibutyltin dilaurate, or dioctyltin maleate.

[0052] A preparation method of the rubber material for a colored pneumatic seal includes the following steps:

[0053] S1: Activation of organotin complex. Mix the organotin complex with the silane coupling agent, add it into toluene solvent, and the solvent dosage is 7 times the mass of the organotin complex. Under nitrogen protection, maintain an inert atmosphere with a nitrogen flow rate of 14 L / min, heat up to 85 °C, and stir and react at 740 rpm for 1.5 h. After the reaction, carry out vacuum distillation at a vacuum degree of -0.08 MPa and 58 °C for 36 min to remove toluene to obtain a silylated organotin complex;

[0054] S2: Surface functionalization of the pigment. Disperse the organic pigment (phthalocyanine blue) in an alkaline aqueous solution with pH = 8.6, add a titanate coupling agent, where the mass of the titanate is 2.6% of the mass of the pigment. At 58 °C, perform ultrasonic treatment at a frequency of 46 kHz for 35 min. Separate the precipitate with a centrifuge at a rotational speed of 4700 rpm for 10 min. Wash with ethanol at a centrifugal rotational speed of 3400 rpm for 6 min, and wash 4 times with ethanol, with the mass of ethanol each time being 3 times the mass of the precipitate. Finally, dry in a vacuum drying oven at 72 °C and a vacuum degree of -0.09 MPa for 2.5 h to obtain the titanate-modified pigment;

[0055] S3: Chemical bonding of the complex. Mix the silylated organotin complex with the titanate-modified pigment, add it to an N-methylpyrrolidone solvent, where the solvent dosage is 5 times the total solid content. Add 0.2 parts of the catalyst tetrabutylammonium bromide, heat up to 105 °C, and stir and react at 1100 rpm for 4 h. After the reaction is completed, separate the precipitate with a centrifuge at a rotational speed of 6700 rpm for 28 min. Wash successively with acetone at a centrifugal rotational speed of 3500 rpm for 6 min and deionized water at a centrifugal rotational speed of 3500 rpm for 12 min, each for 3 times. Dry in a vacuum drying oven at 84 °C and a vacuum degree of -0.1 MPa for 3.5 h to obtain the organotin pigment;

[0056] S4: Synergistic blending of the organotin pigment. Premix the prepared organotin-pigment complex with nano-silica grafted with a silane coupling agent, add it to an N-methylpyrrolidone (NMP) solvent, where the solvent mass is 4 times the total solid content. At 72 °C, perform ultrasonic dispersion at a frequency of 46 kHz and a power of 250 W for 25 min to form a uniform suspension. Spray-dry the suspension with an inlet temperature of 135 °C, an outlet temperature of 76 °C, and an atomization pressure of 0.3 MPa to obtain organotin pigment-nano-silica synergistically coated particles;

[0057] The particle size of the nano-silica grafted with the silane coupling agent is 35 nm;

[0058] S5: First-stage mixing. Put nitrile rubber, zinc oxide, stearic acid, antioxidant, and processing aids into a mixer. Set the mixer rotational speed to 45 rpm and mix for 56 s. Add white carbon black and organotin pigment-nano-silica synergistically coated particles, adjust the mixer rotational speed to 68 rpm, and mix for 90 s. Stop when the temperature rises to 145 °C during the mixing process, discharge the rubber and clean the mixer chamber. Put the rubber compound back in, adjust the mixer rotational speed to 25 rpm, and add sulfur in three portions, mixing for 65 s until the rubber compound temperature reaches 155 °C to obtain Mixing Compound A;

[0059] S6: The second stage of mixing. Add the A mixed rubber to the open mill, set the roll temperature to 54 °C, adjust the roll gap to 1.5 mm, and sequentially add accelerator TBzTD, accelerator CZ, and vulcanization accelerator TETD. Pass the rubber sheet thinly through the rolls 4 times. After each thin pass, let the rubber compound stand for 10 s and then remix. After mixing for 80 s, adjust the roll gap to 4.3 mm, take off the sheet and cool it to obtain the finished rubber compound.

[0060] Comparative Example 1: The difference between this comparative example and Example 3 is that S2 was not carried out, and phthalocyanine blue was directly selected.

[0061] Comparative Example 2: The difference between this comparative example and Example 3 is that S3 was not carried out, that is, the titanate-modified pigment was not modified by the silanized organotin complex.

[0062] Experimental Example: The rubber material for colored pneumatic seals prepared as above was tested according to the following method:

[0063] Hardness (Shore A): GB / T 531.1 - 2008 "Rubber, vulcanized or thermoplastic - Determination of indentation hardness - Part 1: Durometer method (Shore hardness)";

[0064] Tensile strength, elongation at break, 300% modulus: GB / T 528 - 2009 "Rubber, vulcanized or thermoplastic - Determination of tensile stress - strain properties";

[0065] Color difference after aging (ΔE): GB / T 3511 - 2018 "Rubber, vulcanized or thermoplastic - Resistance to weathering: Xenon - arc lamp exposure test", and the colors before and after aging were detected according to GB / T 3979 - 2008;

[0066] The experimental results are as follows:

[0067] Project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Hardness (shore A) 73 72 71 68 69 Tensile strength (MPa) 18 17 18 16 17 Elongation at break (%) 503 500 508 497 485 300% modulus (MPa) 4.37 4.02 4.36 4.07 4.03 Color difference after aging (ΔE) 0.74 0.75 0.72 0.95 0.92

[0068] As can be seen from the above table, by modifying the organic pigment with titanate coupling agent, the color fastness of the rubber material for colored pneumatic seals can be effectively improved;

[0069] By compounding the titanate - modified pigment with the silanized organotin complex, the color fastness of the rubber material for colored pneumatic seals can be further improved.

[0070] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A rubber material for a colored pneumatic seal, characterized in that, By mass parts, it includes the following components: 95 - 98 parts of nitrile rubber, 20 - 40 parts of white carbon black, 40 - 60 parts of nano - silica with surface - grafted silane coupling agent, 5 - 10 parts of zinc oxide, 1 - 3 parts of stearic acid, 4 - 6 parts of silane coupling agent, 1 - 3 parts of anti - aging agent, 1 - 3 parts of processing aid, 0.5 - 1 part of sulfur, 0.8 - 1.2 parts of accelerator TBzTD, 1.0 - 1.5 parts of accelerator CZ, 0.5 - 1.0 part of vulcanization accelerator, 0.3 - 1.0 part of organotin complex, 5 - 15 parts of titanate - modified pigment; The organotin complex is one of dibutyltin dimercaptoacetate, dibutyltin dilaurate or dioctyltin maleate.

2. A method for preparing a colored rubber material for pneumatic seals according to claim 1, characterized in that: It includes the following steps: S1: Activation of organotin complex. Mix the organotin complex with the silane coupling agent, add it to toluene solvent. Under nitrogen protection, heat up and stir, and remove toluene by reduced - pressure distillation to obtain silanized organotin complex; S2: Surface functionalization of pigment. Disperse the organic pigment in an alkaline aqueous solution, add titanate coupling agent, perform ultrasonic treatment, centrifuge to separate the precipitate, wash with ethanol, and dry to obtain titanate - modified pigment; S3: Chemical bonding of the composite. Mix the silanized organotin complex with the titanate - modified pigment, add it to N - methylpyrrolidone solvent, add catalyst tetrabutylammonium bromide, heat up and stir for reaction, centrifuge to separate the precipitate, wash successively with acetone and deionized water, and dry to obtain organotin pigment; S4: Synergistic compounding of organotin pigment. Premix the prepared organotin - pigment composite with nano - silica with surface - grafted silane coupling agent, add it to N - methylpyrrolidone solvent, ultrasonically disperse to form a uniform suspension, and spray - dry the suspension to obtain organotin pigment - nano - silica synergistically coated particles; S5: First stage of mixing. Put nitrile rubber, zinc oxide, stearic acid, anti - aging agent, and processing aid into a mixer, add white carbon black and organotin pigment - nano - silica synergistically coated particles for mixing, discharge the rubber and clean the mixer chamber, re - input the rubber compound, add sulfur in batches, and mix to obtain Mixing Compound A; S6: Second stage of mixing. Add Mixing Compound A to an open mill, successively add accelerator TBzTD, accelerator CZ, and vulcanization accelerator TETD, take off the sheet and cool to obtain the finished rubber compound.

3. The preparation method of the rubber material for the colored pneumatic seal according to claim 2, characterized in that, Specifically for S1, mix the organotin complex with the silane coupling agent, add it to toluene solvent. The solvent dosage is 5 - 8 times the mass of the organotin complex. Under nitrogen protection, maintain an inert atmosphere with a nitrogen flow rate of 10 - 15 L / min, heat up to 80 - 90 °C, stir and react at 600 - 800 rpm for 1 - 2 h. After the reaction, perform reduced - pressure distillation at 50 - 60 °C for 30 - 40 min to remove toluene, and obtain silanized organotin complex.

4. The preparation method of the rubber material for the color pneumatic seal according to claim 2, characterized in that, Specifically, S2 is to disperse the organic pigment in an alkaline aqueous solution with pH = 8 - 9, add a titanate coupling agent, the mass of the titanate is 1% - 3% of the mass of the pigment, at 50 - 60 °C, ultrasonic treatment is carried out at a frequency of 40 - 50 kHz for 30 - 40 min, the centrifuge speed is 4000 - 5000 rpm, and the centrifugation time is 10 - 15 min to separate the precipitate. Then wash it with ethanol at a centrifugation speed of 3000 - 4000 rpm and a centrifugation time of 5 - 8 min, wash it 3 - 5 times with ethanol, and the mass of ethanol each time is 3 times the mass of the precipitate. Finally, dry it in a vacuum drying oven at 60 - 75 °C for 2 - 4 h to obtain the titanate-modified pigment.

5. The preparation method of the rubber material for the colored pneumatic seal according to claim 2, characterized in that, Specifically, S3 is to mix the silylated organotin complex with the titanate-modified pigment, add it to an N-methylpyrrolidone solvent, the solvent dosage is 4 - 6 times the total solid content, add 0.1 - 0.3 parts of the catalyst tetrabutylammonium bromide, heat up to 100 - 110 °C, stir and react at 1000 - 1200 rpm for 3 - 5 h. After the reaction is completed, separate the precipitate at a centrifuge speed of 6000 - 7000 rpm and a centrifugation time of 20 - 30 min, and wash it 2 - 4 times with acetone at a centrifugation speed of 3000 - 4000 rpm and a time of 5 - 7 min and deionized water at a centrifugation speed of 4000 - 5000 rpm and a time of 10 - 15 min respectively, and dry it in a vacuum drying oven at 80 - 85 °C and a vacuum degree of -0.1 MPa for 4 - 6 h to obtain the organotin pigment.

6. The preparation method of the rubber material for the color pneumatic seal according to claim 2, characterized in that, Specifically, S4 is to premix the above-prepared organotin-pigment complex with nano-silica grafted with a silane coupling agent, add it to an N-methylpyrrolidone solvent, the solvent mass is 3 - 5 times the total solid content, at 60 - 80 °C, ultrasonic disperse it at a frequency of 40 - 50 kHz and a power of 200 - 300 W for 20 - 30 min to form a uniform suspension, and spray-dry the suspension, with an inlet temperature of 120 - 140 °C, an outlet temperature of 60 - 80 °C, and an atomization pressure of 0.2 - 0.4 MPa to obtain the organotin pigment-nano-silica co-coated particles.

7. The preparation method of the rubber material for the colored pneumatic seal according to claim 2, characterized in that, The particle size of the nano-silica grafted with the silane coupling agent is 20 - 50 nm.

8. The preparation method of the rubber material for the color pneumatic seal according to claim 2, characterized in that, Specifically, S5 is to put nitrile rubber, zinc oxide, stearic acid, antioxidant, and processing aids into a mixer, set the mixer speed at 40 - 60 rpm, knead for 40 - 60 s, add silica and organotin pigment-nano-silica co-coated particles, adjust the mixer speed to 50 - 70 rpm, knead for 80 - 100 s, discharge the rubber and clean the mixing chamber, put the rubber material back in, adjust the mixer speed to 20 - 30 rpm, add sulfur in three portions, and knead for 50 - 70 s to obtain Mixing Compound A.

9. The preparation method of the rubber material for the colored pneumatic seal according to claim 2, characterized in that, Specifically, S6 is to add Mixing Compound A to an open mill, set the roll temperature at 50 - 60 °C, adjust the roll gap to 1 - 2 mm, add accelerator TBzTD, accelerator CZ, and vulcanization accelerator TETD in sequence, knead for 60 - 90 s, then adjust the roll gap to 3 - 5 mm, take off the sheet and cool it to obtain the finished rubber material.