Butyl inner tube rubber composition with ultralow air permeability coefficient and preparation method of butyl inner tube rubber composition

Abstract

The invention relates to the technical field of tire rubber manufacturing, and discloses a butyl inner tube rubber composition with an ultralow air permeability coefficient and a preparation method thereof. The superfine washed kaolin and the dicyclopentadiene hydrogenated resin are added into the rubber composition, do not affect the excellent elasticity of traditional butyl rubber and can synergistically improve the air tightness of the butyl inner tube rubber composition, so that the situation that the gas permeability of a butyl inner tube is increased under the conditions of high temperature, complex road conditions and long-term use is avoided, and the service life of the butyl inner tube is prolonged. And the risk of tire burst caused by low tire pressure due to the increase of the gas permeability of the butyl inner tire is reduced. The invention provides a solution for improving the long-acting sealing performance of the butyl inner tube of the heavy-duty vehicle, and has obvious economic benefit and environmental protection value.

Description

Technical Field

[0001] The present invention relates to the technical field of tire rubber manufacturing, and more specifically, to an ultra-low air permeability butyl inner tube rubber composition and a preparation method thereof. Background Art

[0002] With the popularization of the concept of green travel, the market demand for transportation tools such as electric trucks and buses continues to grow. The sealing performance of the butyl rubber inner tube, which is the core component, directly affects the user experience and product competitiveness. Although traditional butyl inner tube rubber has good airtightness (the air permeability coefficient is as low as 4×E -14 cm 3 ·cm / (cm 2 ·s·Pa), there are still technical bottlenecks in the increase of gas permeability under high temperature, complex road conditions and long-term use scenarios. Because the compactness of the butyl rubber molecular chain will deform with temperature fluctuations, resulting in the expansion of the microporous structure. These problems lead to the monthly average air pressure loss rate of existing products under the working conditions of 23°C to 70°C being generally higher than 15%, forcing users to frequently replenish air, which not only reduces the riding efficiency but also causes energy waste. In recent years, the industry has tried to improve airtightness by increasing the rubber layer thickness or adding a barrier coating, but such methods significantly increase the product weight (about 25%-40% increase) and affect the dynamic balance performance of the tire.

[0003] Chinese Invention Patent (Publication No.: CN113549253B, Publication Date: February 24, 2023) discloses a silica-reinforced tread rubber composition with a low porosity and its mixing method and application. Using petroleum resin to replace rubber processing oil equivalently reduces the porosity of the tread semi-finished product; the flaky inorganic filler used has a large aspect ratio, which can extend the gas penetration channel and reduce the formation of bubbles, improving the porosity of the tread semi-finished product. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention provides an ultra-low air permeability butyl inner tube rubber composition and a preparation method thereof, which can effectively inhibit the diffusion and migration of gas molecules in the butyl rubber matrix while maintaining the excellent elasticity of traditional butyl rubber, and improve the airtightness of the butyl inner tube rubber composition.

[0005] To achieve the above object, the present invention adopts the following technical solutions: An ultra-low air permeability butyl inner tube rubber composition, wherein the rubber composition is prepared by mixing the following components of raw materials based on 100 parts by weight of raw rubber: 100 parts of rubber matrix, 30-70 parts of carbon black, 5-25 parts of ultra-fine washed kaolin, 1-5 parts of tackifying resin, 5 - 10 parts of dicyclopentadiene hydrogenated resin, 0.5 - 2.5 parts of sulfur, 1 - 3 parts of accelerator, 5 - 20 parts of naphthenic oil; The rubber matrix includes butyl rubber.

[0006] Preferably, the rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber: 100 parts of rubber matrix, 50 - 60 parts of carbon black, 8 - 12 parts of ultra - fine washed kaolin, 0.2 - 2 parts of antioxidant, 1 - 4 parts of microcrystalline wax, 1 - 5 parts of tackifying resin, 5 - 10 parts of dicyclopentadiene hydrogenated resin, 0.5 - 2.5 parts of sulfur, 1 - 3 parts of accelerator, 5 - 10 parts of naphthenic oil.

[0007] Preferably, the specific surface area of the ultra - fine washed kaolin is 10 - 20 m -2 / kg, and the median diameter D50 is 0.1 - 0.2 μm.

[0008] More preferably, the specific surface area of the ultra - fine washed kaolin is 17.7 m -2 / kg, and the median diameter D50 is 0.15 μm.

[0009] Preferably, the weight - average molecular weight Mw of the dicyclopentadiene hydrogenated resin is 600 - 900 g / mol, the softening point is 100 - 140 °C, and the aromaticity is 0 - 20%.

[0010] Further preferably, the weight - average molecular weight Mw of the dicyclopentadiene hydrogenated resin is 600 - 700 g / mol, the softening point is 120 °C, and the aromaticity is 0%.

[0011] Preferably, the rubber matrix further includes one or more of ethylene - propylene rubber, halogenated butyl rubber, and modified chlorosulfonated polyethylene.

[0012] Preferably, the carbon black is one or more of N134, N234, N220, N330, N550, N660, N666, N774.

[0013] More preferably, the carbon black is N330 and / or N666. When the carbon black is a mixture of N330 and N666, the addition amount of N330 is 20 - 30 parts, and the addition amount of N666 is 30 - 40 parts.

[0014] Preferably, the tackifying resin is one or more of C5 petroleum resin, C9 petroleum resin, and C5 / C9 copolymerized petroleum resin.

[0015] More preferably, the tackifying resin is C5 petroleum resin.

[0016] Preferably, the accelerator is one or more of tetramethylthiuram disulfide, 2-mercaptobenzothiazole, zinc diethyldithiocarbamate, tetrabenzylthiuram disulfide, and zinc dibenzyldithiocarbamate. More preferably, the accelerator is one or more of tetramethylthiuram disulfide, 2-mercaptobenzothiazole, and zinc diethyldithiocarbamate.

[0017] Furthermore, the present invention also provides a method for preparing the rubber composition, comprising the following steps: 1) First-stage mixing: Mix using a tangential type internal mixer; add the rubber matrix, carbon black, and fine materials other than the vulcanizing agent and naphthenic oil, press the upper ram, and hold for 30-40 seconds; raise the upper ram, press the upper ram to heat the rubber compound to 130-150 °C, and add naphthenic oil; press the upper ram and hold for 30-40 seconds; raise the upper ram, press the upper ram to heat the rubber compound to 170-175 °C; raise the upper ram, discharge the rubber and press it into sheets, and cool to room temperature to obtain the first-stage masterbatch; 2) Second-stage mixing: Mix using a tangential type internal mixer; add the first-stage masterbatch, press the upper ram, and hold for 20-30 seconds; raise the upper ram, press the upper ram to heat the rubber compound to 140-150 °C; raise the upper ram, press the upper ram to heat the rubber compound to 170-175 °C; raise the upper ram, discharge the rubber and press it into sheets, and cool to room temperature to obtain the second-stage masterbatch; 3) Final mixing: Mix using a tangential type internal mixer; add the second-stage masterbatch, sulfur, and accelerator; press the upper ram and hold for 10-20 seconds; raise the upper ram, press the upper ram and hold for 20-25 seconds; raise the upper ram, press the upper ram to heat the rubber compound to 95-105 °C; raise the upper ram, discharge the rubber and press it into sheets.

[0018] The beneficial effects of the present invention are as follows: The present invention designs a butyl inner tube rubber composition, and ultrafine washed kaolin and dicyclopentadiene hydrogenated resin are added to the composition. The two can synergistically improve the airtightness of the butyl inner tube rubber composition, thereby avoiding the increase in gas permeability of the butyl inner tube under high temperature, complex road conditions, and long-term use scenarios, and reducing the risk of tire pressure becoming low and tire bursting due to the increase in gas permeability of the butyl inner tube. The present invention provides a solution for improving the long-term sealing performance of butyl inner tubes for heavy-duty vehicles, and has significant economic benefits and environmental protection value. Detailed Embodiments

[0019] Combined with the embodiments of the present invention, the technical solutions in the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0020] The rubber composition formulations of the examples, comparative examples, and reference examples are shown in Table 1.

[0021] Table 1 Rubber Composition Formulations Reference ratio Comparative example 1 Comparative example 2 Comparative example 3 Example 1 Example 2 Example 3 Butyl rubber 100 100 100 100 100 100 100 N330 20 20 20　 20 20 20 20 N666 50 50 35 35 35 37 33 Ultra-fine washed kaolin / / 10 / 10 8 12 Flaky inorganic filler TNK / / / 10 / / / Antioxidant 4020 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Microcrystalline wax 1.0 1.0 1.0 1.0 1.0 1.0 1.0 C5 petroleum resin 3.0 3.0 3.0 3.0 3.0 3.0 3.0 Zinc oxide 5.0 5.0 5.0 5.0 5.0 5.0 5.0 Stearic acid 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Naphthenic oil 19.0 12.0 12.0 8.0 8.0 10.0 15.0 Dicyclopentadiene hydrogenated resin / 8.0 / / 8.0 10.0 5.0 Resin SYLVATRAXX4401 / / / 8.0 / / / Sulfur 2.1 2.1 2.1 2.1 2.1 2.1 2.1 Accelerator TDTM 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Accelerator M 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Accelerator EZ 0.25 0.25 0.25 0.25 0.25 0.25 0.25 Raw material sources: Ultra-fine washed kaolin: NC75, specific surface area is 17.7 m -2 / kg, median diameter D50 is 0.15 μm, Nuochen (Tianjin) Material Technology Co., Ltd.; Flaky inorganic filler TNK: Jiangsu Qixiang Chemical Products; Dicyclopentadiene hydrogenated resin: PR-120, weight average molecular weight Mw is 600 - 700 g / mol, softening point is 120 °C, aromaticity is 0%, ExxonMobil; Resin SYLVATRAXX 4401, a product of Kraton Chemical Co., Ltd.

[0022] The preparation method of the rubber composition is as follows: 1) First-stage mixing: Use a tangential type internal mixer for mixing; add the rubber matrix, carbon black, and fine materials other than the vulcanizing agent and naphthenic oil, press the upper ram, and keep for 30 - 40 seconds; raise the upper ram, press the upper ram to heat the rubber compound to 130 - 150 °C, and add naphthenic oil; press the upper ram and keep for 30 - 40 seconds; raise the upper ram, press the upper ram to heat the rubber compound to 170 - 175 °C; raise the upper ram, discharge the rubber and press it into sheets, and cool to room temperature to make the first-stage masterbatch; 2) Second-stage mixing: Use a tangential type internal mixer for mixing; add the first-stage masterbatch, press the upper ram, and keep for 20 - 30 seconds; raise the upper ram, press the upper ram to heat the rubber compound to 140 - 150 °C; raise the upper ram, press the upper ram to heat the rubber compound to 170 - 175 °C; raise the upper ram, discharge the rubber and press it into sheets, and cool to room temperature to make the second-stage masterbatch; 3) Final mixing: Use a tangential type internal mixer for mixing; add the second-stage masterbatch, sulfur, and accelerator; press the upper ram and keep for 10 - 20 seconds; raise the upper ram, press the upper ram and keep for 20 - 25 seconds; raise the upper ram, press the upper ram to heat the rubber compound to 95 - 105 °C; raise the upper ram, discharge the rubber and press it into sheets.

[0023] Using a differential pressure method gas permeation instrument, test the gas permeability coefficient (cm 3 ·cm / (cm2 ·s·Pa)), the proportional performance was set at 100% to process the data of the comparative examples and the examples. The lower the value (the higher the value, the lower the air permeability coefficient), the better the airtight performance of the rubber compound. The test results are shown in Table 2.

[0024] Table 2 Air Permeability Coefficient of Rubber Composition Reference ratio Comparative example 1 Comparative example 2 Comparative example 3 Example 1 Example 2 Example 3 Permeability coefficient at 23°C 100 141.88 167.27 169.20 174.70 170.83 172.62 Elongation at break % (23°C) 636.15 643.09 671.76 632.56 659.33 664.84 674.57 Permeability coefficient at 50°C 100 106.24 113.31 126.49 161.95 157.39 152.50 Permeability coefficient at 70°C 100 129.33 135.18 131.53 179.63 175.33 162.41 From the reference ratio and Comparative Example 1, it can be seen that replacing part of the processing oil with dicyclopentadiene hydrogenated resin can improve the airtightness of the inner tube rubber composition; from the reference ratio and Comparative Example 2, it can be seen that replacing part of the carbon black with ultrafine water-washed kaolin can further improve the airtightness of the inner tube rubber composition. From Example 1, the reference ratio, and Comparative Examples 1 and 2, it can be seen that ultrafine water-washed kaolin and dicyclopentadiene hydrogenated resin can synergistically improve the airtightness of the inner tube rubber composition. At the same time, from Example 1 and Comparative Example 3, it can also be seen that ultrafine water-washed kaolin and dicyclopentadiene hydrogenated resin have a better effect on improving airtightness, are more suitable for butyl inner tubes, and do not affect the excellent elasticity of traditional butyl rubber.

[0025] The above is the description of the embodiments of the present invention. Through the above description of the disclosed embodiments, those skilled in the art can implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the broadest scope consistent with the principles and novel points disclosed herein.

Claims

1. An ultra-low air permeability butyl inner tube rubber composition, characterized in that, The rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber: 100 parts of rubber matrix, 30 - 70 parts of carbon black, 5 - 25 parts of ultra-fine washed kaolin, 1 - 5 parts of tackifying resin, 5 - 10 parts of dicyclopentadiene hydrogenated resin, 0.5 - 2.5 parts of sulfur, 1 - 3 parts of accelerator, 5 - 20 parts of naphthenic oil; The rubber matrix includes butyl rubber.

2. The butyl inner tube rubber composition with an ultra-low air permeability coefficient according to claim 1, characterized in that, The rubber composition is prepared by mixing the following raw materials based on 100 parts by weight of raw rubber: 100 parts of rubber matrix, 50 - 60 parts of carbon black, 8 - 12 parts of ultra-fine washed kaolin, 0.2 - 2 parts of anti-aging agent, 1 - 4 parts of microcrystalline wax, 1 - 5 parts of tackifying resin, 5 - 10 parts of dicyclopentadiene hydrogenated resin, 0.5 - 2.5 parts of sulfur, 1 - 3 parts of accelerator, 5 - 10 parts of naphthenic oil.

3. An ultra-low air permeability butyl inner tube rubber composition according to claim 1 or 2, characterized in that, The specific surface area of the ultra-fine washed kaolin is 10-20m -2 / kg, and the median diameter D50 is 0.1-0.2μm.

4. An ultra-low air permeability butyl inner tube rubber composition according to claim 1 or 2, characterized in that, The specific surface area of the ultra-fine washed kaolin is 17.7 m -2 / kg, and the median diameter D50 is 0.15 μm.

5. An ultra-low air permeability butyl inner tube rubber composition according to claim 1 or 2, characterized in that, The weight-average molecular weight Mw of the dicyclopentadiene hydrogenated resin is 600 - 900 g / mol, the softening point is 100 - 140 °C, and the aromaticity is 0 - 20%; preferably, the weight-average molecular weight Mw of the dicyclopentadiene hydrogenated resin is 600 - 700 g / mol, the softening point is 120 °C, and the aromaticity is 0%.

6. An ultra-low air permeability butyl inner tube rubber composition according to claim 1 or 2, characterized in that, The rubber matrix further includes one or more of ethylene-propylene rubber, halogenated butyl rubber, and modified chlorosulfonated polyethylene.

7. An ultra-low air permeability butyl inner tube rubber composition according to claim 1 or 2, characterized in that, The carbon black is one or more of N134, N234, N220, N330, N550, N660, N666, N774; preferably, the carbon black is N330 and / or N666.

8. An ultra-low air permeability butyl inner tube rubber composition according to claim 1 or 2, characterized in that The tackifying resin is one or more of C5 petroleum resin, C9 petroleum resin, and C5 / C9 copolymer type petroleum resin; preferably, the tackifying resin is C5 petroleum resin.

9. An ultra-low air permeability butyl inner tube rubber composition according to claim 1 or 2, characterized in that The accelerator is one or more of tetramethylthiuram disulfide, 2-mercaptobenzothiazole, zinc diethyldithiocarbamate, tetrabenzylthiuram disulfide, and zinc dibenzyldithiocarbamate; preferably, the accelerator is one or more of tetramethylthiuram disulfide, 2-mercaptobenzothiazole, and zinc diethyldithiocarbamate.

10. The preparation method of the rubber composition according to any one of claims 1-9, characterized in that, Including the following steps: 1) First-stage mixing: Mixing is carried out using a tangential type internal mixer; adding the rubber matrix, carbon black, and fine materials except for the vulcanizing agent and naphthenic oil, pressing the upper ram, and maintaining for 30 - 40 seconds; raising the upper ram, pressing the upper ram to heat the rubber compound to 130 - 150 °C, adding naphthenic oil; pressing the upper ram, maintaining for 30 - 40 seconds; raising the upper ram, pressing the upper ram to heat the rubber compound to 170 - 175 °C; raising the upper ram, discharging and pressing into sheets, and cooling to room temperature to form a first-stage masterbatch; 2) Second-stage mixing: Mixing is carried out using a tangential type internal mixer; adding the first-stage masterbatch, pressing the upper ram, and maintaining for 20 - 30 seconds; raising the upper ram, pressing the upper ram to heat the rubber compound to 140 - 150 °C; raising the upper ram, pressing the upper ram to heat the rubber compound to 170 - 175 °C; raising the upper ram, discharging and pressing into sheets, and cooling to room temperature to form a second-stage masterbatch; 3) Final stage mixing: Use a tangential type internal mixer for mixing; add the second-stage masterbatch, sulfur, and accelerator; lower the upper ram and hold for 10 - 20 seconds; raise the upper ram, lower the upper ram and hold for 20 - 25 seconds; lower the upper ram, lower the upper ram to raise the temperature of the rubber compound to 95 - 105 °C; raise the upper ram, discharge the rubber and roll it into sheets.