Easily vulcanized butyl rubber and preparation method thereof

Abstract

The invention relates to the technical field of chemical engineering, and discloses easily vulcanized butyl rubber and a preparation method thereof. Traditional butyl rubber is poor in vulcanization performance. According to the easily vulcanized butyl rubber provided by the invention, an epoxy group and a hydroxyl group are simultaneously introduced into the butyl rubber, the molar ratio of the hydroxyl group to the epoxy group is controlled to be (0.4-1.0): 1, the molar content of the hydroxyl group in a molecular chain of the butyl rubber is 0.5-1.4%, and the molar content of the epoxy group is 1.1-2.5%; cross-linking sites in a molecular chain of the butyl rubber and the vulcanization speed of the butyl rubber are improved. And due to the introduction of hydroxyl, the butyl rubber can have the properties of high epoxidation degree and low glass transition temperature at the same time, so that the easily vulcanized butyl rubber has better mechanical properties, shows excellent low-temperature flexibility and crack resistance, and is excellent in air tightness.

Description

Technical Field

[0001] The present invention relates to the field of chemical engineering technology, and particularly to an easily vulcanizable butyl rubber and a preparation method thereof. Background Art

[0002] Butyl rubber (IIR) is a highly saturated linear polymer material, which is a copolymer obtained by cationic polymerization of isobutene and a small amount of isoprene. Due to the low content of carbon-carbon double bonds in butyl rubber, its disadvantages are very obvious. For example, it is difficult to vulcanize, difficult to bond, has poor compatibility with general diene rubbers, and is difficult to co-vulcanize with other rubbers. The characteristic that butyl rubber is difficult to vulcanize will lead to a decline in the performance of some butyl rubber products, such as airtightness.

[0003] In order to improve the performance of butyl rubber, researchers usually modify it. Represented by halogenated butyl rubber and epoxidized butyl rubber, after halogenation or epoxidation modification, butyl rubber will not only generate additional crosslinking sites, but also increase the reactivity of double bonds. Compared with ordinary butyl rubber, the vulcanization rate of the above-mentioned modified butyl rubber is accelerated, the intermolecular force is increased, and the airtightness of the products based on the modified butyl rubber is greatly improved. However, in the current epoxidation modification method, the obtained modified butyl rubber has a low degree of epoxidation; while the modification method of introducing halogen has high toxicity and is not environmentally friendly.

[0004] In the prior art, for example, Chinese Patent with the publication number CN113336877A discloses a preparation method of epoxidized butyl rubber. In this patent, a composite emulsion or emulsion is used as the dispersion system, and in the dispersion system, the raw material butyl rubber reacts with hydrogen peroxide / organic acid, then the rubber solution is washed with a low-concentration alkali solution, and then the rubber solution is flocculated with ethanol or steam-stripped with boiling water, and finally an epoxidized butyl rubber is prepared. However, in the method of this patent, ideally, after hydrogen peroxide is added to the reaction system, it only reacts with the organic acid to generate an epoxidizing reagent, and then these epoxidizing reagents immediately react with the butyl rubber to epoxidize the butyl rubber. Therefore, the epoxidation method of butyl rubber in this patent is limited by the reaction rate and reaction degree of hydrogen peroxide and organic acid, and further limited by the concentration and activity of hydrogen peroxide. In this system, as the reaction proceeds and the reaction degree deepens, the concentration and activity of hydrogen peroxide will greatly decrease, ultimately resulting in insufficient epoxidation degree of the product and insufficient improvement of the airtightness of butyl rubber. Summary of the Invention

[0005] In order to solve the technical problems of the difficulty in vulcanizing butyl rubber and the insufficient airtightness of its products, the present invention provides an easily vulcanizable butyl rubber and a preparation method thereof.

[0006] The specific technical solution of the present invention is as follows: In a first aspect, the present invention provides an easily vulcanizable butyl rubber, wherein the butyl rubber molecular chain contains both hydroxyl groups and epoxy groups, and the molar ratio of hydroxyl groups to epoxy groups is 0.4 to 1.0:1.

[0007] Conventional butyl rubber has poor vulcanization performance. The easily vulcanizable butyl rubber provided by the present invention improves the crosslinking sites in the butyl rubber molecular chain by introducing epoxy groups and hydroxyl groups simultaneously into the butyl rubber. And due to the introduction of hydroxyl groups, the degree of epoxidation in the butyl rubber can be increased. Due to the polarity and compatibility of hydroxyl groups, in the simultaneous modification of butyl rubber by hydroxyl groups and epoxy groups, by controlling the molar ratio of hydroxyl groups to epoxy groups to be 0.4 to 1.0:1, the easily vulcanizable butyl rubber can have better mechanical properties and exhibit excellent low-temperature flexibility and crack resistance.

[0008] As a preference of the above-mentioned butyl rubber, the molar content of the hydroxyl groups is 0.5 to 1.4%, and the molar content of the epoxy groups is 1.1 to 2.5%.

[0009] As a preference of the above-mentioned butyl rubber, the glass transition temperature (Tg) of the butyl rubber is -45°C to -35°C.

[0010] By introducing hydroxyl groups and epoxy groups simultaneously onto the butyl rubber, the vulcanization rate of the butyl rubber can be increased on the premise of ensuring a relatively low glass transition temperature. Specifically, by making "the molar content of hydroxyl groups on the butyl rubber molecular chain is 0.5 to 1.4%, the molar content of epoxy groups is 1.1 to 2.5%, and the molar ratio of hydroxyl groups to epoxy groups is 0.4 to 1.0:1", the vulcanization time T90 of the butyl rubber can be shortened by 30 to 50% compared with the vulcanization time of traditional halogenated butyl rubber, and the glass transition temperature of the butyl rubber can be optimized to -45°C to -35°C.

[0011] Tg is the temperature critical point at which the material changes from the high elastic state to the glassy state. The lower the Tg of the butyl rubber, the better the flexibility and elasticity of the butyl rubber in a low-temperature environment, and brittle cracking can be avoided.

[0012] As a preference of the above-mentioned butyl rubber, the hydroxyl groups are formed by selectively oxidizing the double bonds in isoprene units, and the hydroxyl distribution index (HDI) ≥ 0.85.

[0013] The hydroxyl groups in the molecular chain of the modified butyl rubber are evenly distributed, which is beneficial to improving the vulcanization rate of the butyl rubber and, moreover, improving the airtightness of the sealing products based on this butyl rubber.

[0014] In a second aspect, the present invention provides a preparation method for an easily vulcanizable butyl rubber, comprising the following steps: Step 1: Dissolve the butyl rubber in a solvent, add an aqueous peracetic acid solution, and react at 25 to 35°C for 2 to 5 hours; Step 2: Add m-chloroperbenzoic acid (mCPBA) and trifluoroacetic acid to the product obtained in Step 1, and react at 0-5°C for 6-12 hours; Step 3: Add sodium bicarbonate solution to neutralize the product obtained in Step 2, then wash with water, and dry to obtain the vulcanizable butyl rubber.

[0015] In the present invention, peracetic acid in Step 1 preferentially oxidizes the double bond to form a hydroxyl group. In this step, the reaction temperature needs to be controlled at 25-35°C. If the temperature is too high, it is easy to cause the molecular chain to break, resulting in the peroxidation of butyl rubber and a decrease in performance; if the temperature is too low, the hydroxyl group content in the molecular chain will be too low, resulting in a decrease in the degree of epoxidation in Step 2. Forming more hydroxyl groups in the butyl rubber molecular chain in Step 1 is beneficial to the epoxidation of butyl rubber in Step 2.

[0016] In the present invention, m-chloroperbenzoic acid in Step 2 selectively epoxidizes the remaining double bonds at low temperature, so that the molar content of the hydroxyl group in the final product is 0.5-1.4%, the molar content of the epoxy group is 1.1-2.5%, and the molar ratio of the hydroxyl group to the epoxy group is 0.4-1.0:1. The reaction in Step 2 is carried out at a lower temperature, at 0-5°C, so trifluoroacetic acid needs to be added to promote the reaction, but the reaction temperature in Step 2 cannot be increased to promote the reaction, because too high a reaction temperature is likely to cause side reactions of epoxy ring opening. If the reaction temperature in Step 2 is too low, it will be difficult to epoxidize butyl rubber.

[0017] As a preference of the above preparation method, the molar ratio of peracetic acid to m-chloroperbenzoic acid is 1:0.8-1.5.

[0018] As a preference of the above preparation method, in the reaction system of Step 1, the concentration of peracetic acid is 10-20 wt%.

[0019] As a preference of the above preparation method, in Step 1, the reaction is carried out in three-stage gradient heating: the first stage is to keep the temperature at 25°C for 1 hour, the second stage is to keep the temperature at 30°C for 2 hours, and the third stage is to keep the temperature at 35°C for 1 hour.

[0020] By three-stage gradient heating, the epoxy group content in the obtained butyl rubber can be the highest, and the hydroxyl group content is in the range of 0.5-1.4 mol%. By introducing an appropriate content of hydroxyl groups into the butyl rubber molecular chain with a higher degree of epoxidation, the butyl rubber product finally exhibits the lowest glass transition temperature and excellent airtightness.

[0021] As a preference of the above preparation method, in Step 1, the solvent is tetrahydrofuran.

[0022] Preferably, in the reaction process of step 2, ultraviolet light irradiation is used to assist epoxidation, and the wavelength of the ultraviolet light is 365 nm and the power is 50-100 W.

[0023] In a third aspect, the present invention provides an application of the easy-to-vulcanize butyl rubber in the preparation of sealing products. For example, applications in tire inner liners and seals.

[0024] Since the easy-to-vulcanize butyl rubber provided by the present invention has a low glass transition temperature Tg, good resilience can also be achieved at low temperatures, which greatly broadens the application temperature and application scenarios of the sealing products based on the butyl rubber of the present invention. For example, when driving in cold regions, the tires based on the butyl rubber of the present invention can maintain good grip; the sealing products based on the butyl rubber of the present invention, such as the sealing strips of cold chain equipment, can withstand long-term low temperatures without failure.

[0025] Compared with the prior art, the present invention has the following technical effects: (1) The vulcanization performance of traditional butyl rubber is poor. The easy-to-vulcanize butyl rubber provided by the present invention improves the crosslinking sites in the butyl rubber molecular chain and the vulcanization speed of the butyl rubber by simultaneously introducing epoxy groups and hydroxyl groups into the butyl rubber, controlling the molar ratio of hydroxyl groups to epoxy groups to be 0.4-1.0:1, and making the molar content of hydroxyl groups in the butyl rubber molecular chain be 0.5-1.4% and the molar content of epoxy groups be 1.1-2.5%. And due to the introduction of hydroxyl groups, the butyl rubber can have the properties of high epoxidation degree and low glass transition temperature at the same time, making the easy-to-vulcanize butyl rubber have excellent mechanical properties, excellent low-temperature flexibility and crack resistance, and excellent airtightness.

[0026] (2) The present invention realizes the preparation of easy-to-vulcanize butyl rubber by the method of preferentially introducing hydroxyl groups and then introducing epoxy groups. In the method of the present invention, due to the preferential introduction of hydroxyl groups, the epoxidation degree in the butyl rubber in the second step can be increased; and through the regulation of the introduction of hydroxyl groups, the optimization regulation of the epoxidation degree can be realized, and further the optimization of the vulcanization speed of the butyl rubber and the airtightness of its products can be realized. Detailed Embodiments

[0027] The present invention will be further described below in conjunction with embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are usually only a part of the embodiments of the present invention, rather than all of the embodiments. Therefore, all other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention shall fall within the scope of protection of the present invention.

[0028] In the following examples, the weight-average molecular weight of the butyl rubber raw material used is 350,000, and the degree of unsaturation is 3.0%.

[0029] In the following examples, the hydroxyl content was tested by near-infrared spectroscopy (NIRS), and the epoxy group was tested by nuclear magnetic resonance hydrogen spectroscopy ( 1 1H-NMR).

[0030] In the following examples, the test of the vulcanization time T90 was as follows: 100 g of rubber compound was taken, 12 g of sulfur, 3 g of accelerator TMTD, 30 g of carbon black, and 10 g of zinc oxide were added, mixed evenly, and kneaded to prepare a kneaded rubber. In a rotorless vulcanization instrument, the vulcanization curve of the rubber compound was tested by vulcanizing the kneaded rubber at a vulcanization temperature of 160 °C and a pressure of 15 MPa, and the time required to reach 90% crosslinking degree (T90) was recorded.

[0031] In the following examples, the permeability coefficient of vulcanized butyl rubber was tested according to GB1038-2000 to characterize the airtightness of butyl rubber.

[0032] In the following examples, the glass transition temperature of vulcanized butyl rubber was tested by differential scanning calorimetry (DSC).

[0033] Example 1 A butyl rubber containing both hydroxyl and epoxy groups was provided, and the preparation steps were as follows: Step 1: 100 g of butyl rubber raw material was added to 150 mL of tetrahydrofuran, and an aqueous solution of peracetic acid with a concentration of 0.2 mol / L was added, and stirred to obtain a homogeneous mixed system. Among them, the concentration of peracetic acid in the mixed system was 15 wt%. The temperature of the mixed system was adjusted to 30 °C and reacted at 30 °C for 4 hours. Step 2: m-Chloroperbenzoic acid and trifluoroacetic acid were added to the rubber solution obtained in Step 1, and stirred and mixed evenly. Among them, the molar ratio of m-chloroperbenzoic acid added to the molar ratio of peracetic acid added was 1.2:1, and trifluoroacetic acid was used as a catalyst, and the added amount was 1 g. After mixing evenly, it was reacted in an ice bath (0 °C) for 10 hours, and ultraviolet light irradiation was used to assist epoxidation during the reaction. The wavelength of the ultraviolet light was 365 nm and the power was 100 W. Step 3: The product obtained in Step 2 was added with sodium bicarbonate solution to neutralize to pH 7.2, then washed with water, and the butyl rubber containing both hydroxyl and epoxy groups was obtained after removing the residual solvent by supercritical CO2 fluid extraction technology. The conditions for supercritical CO2 fluid extraction were a temperature of 40 °C, a pressure of 10 MPa, and a time of 1 hour. Among them, the hydroxyl group was formed by selectively oxidizing the double bond in the isoprene unit, and the hydroxyl distribution index (HDI) ≥ 0.85.

[0034] Example 2 Provide a butyl rubber containing both hydroxyl groups and epoxy groups, and the preparation steps are as follows: Step 1: Add 100 g of butyl rubber raw material into 150 mL of tetrahydrofuran, and add an aqueous solution of peracetic acid with a concentration of 0.2 mol / L. Stir to obtain a homogeneous mixed system, wherein the concentration of peracetic acid in the mixed system is 10 wt%. Adjust the temperature of the mixed system to 25 °C and react at 25 °C for 5 hours.

[0035] Step 2: Add m-chloroperbenzoic acid and trifluoroacetic acid to the rubber solution obtained from the reaction in Step 1, and stir to mix evenly. Among them, the molar ratio of m-chloroperbenzoic acid added to the molar amount of peracetic acid added is 0.8:1, and the amount of trifluoroacetic acid added is 1 g. After mixing evenly, react at 5 °C for 6 hours, and use ultraviolet light irradiation to assist epoxidation during the reaction. The wavelength of the ultraviolet light is 365 nm and the power is 100 W.

[0036] Step 3: Add sodium bicarbonate solution to the product obtained from the reaction in Step 2 to neutralize to pH 7.2, then wash with water, and use supercritical CO2 fluid extraction technology to remove the residual solvent to obtain butyl rubber containing both hydroxyl groups and epoxy groups. The conditions for supercritical CO2 fluid extraction are a temperature of 40 °C, a pressure of 10 MPa, and a time of 1 hour. Among them, the hydroxyl groups are formed by selectively oxidizing the double bonds in isoprene units, and the hydroxyl distribution index (HDI) ≥ 0.85.

[0037] Example 3 Provide a butyl rubber containing both hydroxyl groups and epoxy groups, and the preparation steps are as follows: Step 1: Add 100 g of butyl rubber raw material into 150 mL of tetrahydrofuran, and add an aqueous solution of peracetic acid with a concentration of 0.2 mol / L. Stir to obtain a homogeneous mixed system, wherein the concentration of peracetic acid in the mixed system is 20 wt%. Adjust the temperature of the mixed system to 35 °C and react at 35 °C for 2 hours.

[0038] Step 2: Add m-chloroperbenzoic acid and trifluoroacetic acid to the rubber solution obtained from the reaction in Step 1, and stir to mix evenly. Among them, the molar ratio of m-chloroperbenzoic acid added to the molar amount of peracetic acid added is 1.5:1, and the amount of trifluoroacetic acid added is 1 g. After mixing evenly, react at 2 °C for 12 hours, and use ultraviolet light irradiation to assist epoxidation during the reaction. The wavelength of the ultraviolet light is 365 nm and the power is 50 W.

[0039] Step 3: Add sodium bicarbonate solution to the product obtained in Step 2 to neutralize it to pH 6.5, then wash it with water, and remove the residual solvent by supercritical CO2 fluid extraction technology to obtain butyl rubber containing both hydroxyl and epoxy groups. The conditions for supercritical CO2 fluid extraction are a temperature of 40 °C, a pressure of 10 MPa, and a time of 1 hour. Among them, the hydroxyl group is formed by selectively oxidizing the double bond in the isoprene unit, and the hydroxyl distribution index (HDI) ≥ 0.85.

[0040] Example 4 Provide a butyl rubber containing both hydroxyl and epoxy groups, and the preparation steps are as follows: Step 1: Add 100 g of butyl rubber raw material to 150 mL of tetrahydrofuran, add an aqueous solution of peracetic acid with a concentration of 0.2 mol / L, stir to obtain a homogeneous mixed system, and make the concentration of peracetic acid in the mixed system 15 wt%. Then heat the mixed system in three stages with a gradient: the first stage is to keep it at 25 °C for 1 hour, the second stage is to keep it at 30 °C for 2 hours, and the third stage is to keep it at 35 °C for 1 hour. After the third stage ends, the reaction ends.

[0041] Step 2: Add m-chloroperbenzoic acid and trifluoroacetic acid to the glue solution obtained in Step 1, stir and mix evenly. Among them, the molar ratio of m-chloroperbenzoic acid added to the molar ratio of peracetic acid added is 1.2:1, and the amount of trifluoroacetic acid added is 1 g. After mixing evenly, react in an ice bath (0 °C) for 10 hours, and use ultraviolet light irradiation to assist epoxidation during the reaction. The wavelength of the ultraviolet light is 365 nm and the power is 100 W.

[0042] Step 3: Add sodium bicarbonate solution to the product obtained in Step 2 to neutralize it to pH 7.8, then wash it with water, and remove the residual solvent by supercritical CO2 fluid extraction technology to obtain butyl rubber containing both hydroxyl and epoxy groups. The conditions for supercritical CO2 fluid extraction are a temperature of 40 °C, a pressure of 10 MPa, and a time of 1 hour. Among them, the hydroxyl group is formed by selectively oxidizing the double bond in the isoprene unit, and the hydroxyl distribution index (HDI) ≥ 0.85.

[0043] Example 5 Provide a butyl rubber containing both hydroxyl and epoxy groups, and the preparation steps are as follows: Step 1: Add 100 g of butyl rubber raw material to 150 mL of tetrahydrofuran, add an aqueous solution of peracetic acid with a concentration of 0.2 mol / L, stir to obtain a homogeneous mixed system, and make the concentration of peracetic acid in the mixed system 15 wt%. Adjust the temperature of the mixed system to 25 °C and react at 25 °C for 4 hours.

[0044] Step 2: Add meta-chloroperoxybenzoic acid and trifluoroacetic acid to the glue solution obtained in Step 1, stir and mix evenly. Among them, the molar ratio of the added meta-chloroperoxybenzoic acid to the added peracetic acid is 1.2:1, and the added amount of trifluoroacetic acid is 1 g. After mixing evenly, react in an ice bath (0 °C) for 10 hours. During the reaction process, ultraviolet light irradiation is used to assist epoxidation, and the wavelength of the ultraviolet light is 365 nm and the power is 100 W.

[0045] Step 3: Add sodium bicarbonate solution to the product obtained in Step 2 to neutralize to pH 7.2, then wash with water, and use supercritical CO2 fluid extraction technology to remove the residual solvent to obtain butyl rubber containing both hydroxyl groups and epoxy groups. The conditions for supercritical CO2 fluid extraction are a temperature of 40 °C, a pressure of 10 MPa, and a time of 1 hour. Among them, the hydroxyl groups are formed by selectively oxidizing the double bonds in the isoprene units, and the hydroxyl group distribution index (HDI) ≥ 0.85.

[0046] Example 6 Provide a butyl rubber containing both hydroxyl groups and epoxy groups, and the preparation steps are as follows: Step 1: Add 100 g of butyl rubber raw material to 150 mL of tetrahydrofuran, add an aqueous solution of peracetic acid with a concentration of 0.2 mol / L, and stir to obtain a homogeneous mixed system. Among them, the concentration of peracetic acid in the mixed system is 15 wt%. Adjust the temperature of the mixed system to 35 °C and react at 35 °C for 4 hours.

[0047] Step 2: Add meta-chloroperoxybenzoic acid and trifluoroacetic acid to the glue solution obtained in Step 1, stir and mix evenly. Among them, the molar ratio of the added meta-chloroperoxybenzoic acid to the added peracetic acid is 1.2:1, and the added amount of trifluoroacetic acid is 1 g. After mixing evenly, react in an ice bath (0 °C) for 10 hours. During the reaction process, ultraviolet light irradiation is used to assist epoxidation, and the wavelength of the ultraviolet light is 365 nm and the power is 100 W.

[0048] Step 3: Add sodium bicarbonate solution to the product obtained in Step 2 to neutralize to pH 7.2, then wash with water, and use supercritical CO2 fluid extraction technology to remove the residual solvent to obtain butyl rubber containing both hydroxyl groups and epoxy groups. The conditions for supercritical CO2 fluid extraction are a temperature of 40 °C, a pressure of 10 MPa, and a time of 1 hour. Among them, the hydroxyl groups are formed by selectively oxidizing the double bonds in the isoprene units, and the hydroxyl group distribution index (HDI) ≥ 0.85.

[0049] Comparative Example 1 Provide a butyl rubber. The preparation steps are different from those of Example 1 in that: hydroxylation modification in Step 1 is not carried out. The specific steps of this comparative example are as follows: Step 1: Add 100 g of butyl rubber raw material into 150 mL of tetrahydrofuran, add m-chloroperbenzoic acid and catalyst trifluoroacetic acid, and stir to obtain a homogeneous mixed system. Among them, the concentration of m-chloroperbenzoic acid in the mixed system is 28 wt%, and the amount of trifluoroacetic acid added is 1 g. Adjust the temperature of the mixed system to 0 °C and react at 0 °C for 10 hours. During the reaction, ultraviolet light irradiation is used to assist epoxidation, and the wavelength of the ultraviolet light is 365 nm and the power is 100 W.

[0050] Step 2: Add sodium bicarbonate solution to the product obtained in Step 1 to neutralize to pH 7.2, then wash with water, and use supercritical CO2 fluid extraction technology to remove the residual solvent to obtain modified butyl rubber. The conditions for supercritical CO2 fluid extraction are temperature 40 °C, pressure 10 MPa, and time 1 hour.

[0051] Comparative Example 2 Provide a kind of butyl rubber. The preparation steps are different from those of Example 1 in that: the epoxidation modification in Step 2 is not carried out. The specific steps of this comparative example are as follows: Step 1: Add 100 g of butyl rubber raw material into 150 mL of tetrahydrofuran, add 0.2 mol / L aqueous peracetic acid solution, and stir to obtain a homogeneous mixed system. Among them, the concentration of peracetic acid in the mixed system is 15 wt%. Adjust the temperature of the mixed system to 30 °C and react at 30 °C for 4 hours.

[0052] Step 2: Add sodium bicarbonate solution to the product obtained in Step 1 to neutralize to pH 7.2, then wash with water, and use supercritical CO2 fluid extraction technology to remove the residual solvent to obtain modified butyl rubber. The conditions for supercritical CO2 fluid extraction are temperature 40 °C, pressure 10 MPa, and time 1 hour.

[0053] Comparative Example 3 Provide a kind of butyl rubber. The preparation steps are different from those of Example 1 in that: epoxidation modification is carried out first, and then hydroxyl modification is carried out.

[0054] The specific steps of this comparative example are as follows: Step 1: Add 100 g of butyl rubber raw material into 150 mL of tetrahydrofuran, add m-chloroperbenzoic acid and catalyst trifluoroacetic acid, and stir to obtain a homogeneous mixed system. Among them, the concentration of m-chloroperbenzoic acid in the mixed system is 28 wt%, and the amount of trifluoroacetic acid added is 1 g. Adjust the temperature of the mixed system to 0 °C and react at 0 °C for 10 hours. During the reaction, ultraviolet light irradiation is used to assist epoxidation, and the wavelength of the ultraviolet light is 365 nm and the power is 100 W.

[0055] Step 2: Add an aqueous solution of peracetic acid with a concentration of 0.2 mol / L to the glue solution obtained in Step 1 to obtain a mixed system, and stir evenly. Among them, based on the mass of the glue solution obtained in Step 1, the mass concentration of peracetic acid is 15 wt%, that is, the molar ratio of m-chloroperbenzoic acid added to the molar ratio of peracetic acid added is 1.2:1. Adjust the temperature of the mixed system to 30 °C and react at 30 °C for 4 hours.

[0056] Step 3: Add a sodium bicarbonate solution to the product obtained in Step 2 to neutralize it to pH 7.2, then wash it with water, and use supercritical CO2 fluid extraction technology to remove the residual solvent to obtain modified butyl rubber. The conditions for supercritical CO2 fluid extraction are a temperature of 40 °C, a pressure of 10 MPa, and a time of 1 hour.

[0057] Comparative Example 4 Provide a kind of butyl rubber. The preparation steps are different from those of Example 1 in that: the amount of m-chloroperbenzoic acid added in Step 2 is different. Specifically, the molar ratio of m-chloroperbenzoic acid added to the molar ratio of peracetic acid added is 0.6:1.

[0058] Comparative Example 5 Provide a kind of butyl rubber. The preparation steps are different from those of Example 1 in that: the amount of m-chloroperbenzoic acid added in Step 2 is different. Specifically, the molar ratio of m-chloroperbenzoic acid added to the molar ratio of peracetic acid added is 1.6:1.

[0059] Performance Characterization Test the following data, and the results are shown in Table 1: (1) Take the butyl rubber prepared in Examples 1 to 6 and Comparative Examples 1 to 5, and test the molar contents of hydroxyl groups and epoxy groups. The molar content of hydroxyl groups (mol%) represents the number of moles of hydroxyl groups in every 100 butyl rubber repeating units (isobutene + isoprene). The molar content of epoxy groups (mol%) represents the number of moles of epoxy groups in every 100 butyl rubber repeating units (isobutene + isoprene).

[0060] (2) Take the butyl rubber prepared in Examples 1 to 5 and Comparative Examples 1 to 5, and take the butyl rubber raw material for vulcanization, record the vulcanization time T90, and conduct the glass transition temperature (Tg) and airtightness test of the rubber.

[0061] Table 1 Data Analysis: (1) As can be seen from the data of the examples, the butyl rubber provided by the present invention has the characteristic of easy vulcanization, and the vulcanization time T90 can reach 9 minutes. Thus, it can be known that by introducing epoxy groups and hydroxyl groups into the butyl rubber simultaneously and controlling the molar ratio of hydroxyl groups to epoxy groups to be 0.4 - 1.0:1, the vulcanization speed of the butyl rubber can be increased. As shown in Comparative Example 1 and Comparative Example 2, if hydroxyl groups are not introduced or the proportion of introduced hydroxyl groups is too large, the vulcanization speed of the butyl rubber after introducing epoxy groups will be significantly reduced, and the glass transition temperature will increase significantly. In addition, in the prior art, the glass transition temperature of the butyl rubber increases significantly after introducing epoxy groups. Due to the introduction of hydroxyl groups in the present invention, the butyl rubber can have the properties of high epoxidation degree and low glass transition temperature. Especially when the molar ratio of hydroxyl groups to epoxy groups is 0.6:1, the glass transition temperature of the easy-vulcanizing butyl rubber is the lowest, showing little change compared with the raw material butyl rubber, having better mechanical properties and excellent airtightness.

[0062] (2) From the comparative analysis of Comparative Example 1, Comparative Example 3 and Example 1, it can be seen that in the present invention, peracetic acid in Step 1 preferentially oxidizes double bonds to generate a relatively high content of hydroxyl groups. And from the comparative analysis of Comparative Example 1, Comparative Example 3 and Example 1, it can be known that introducing a certain amount range of hydroxyl groups is beneficial to promoting the formation of epoxy groups in the butyl rubber in Step 2; further, by combining the introduced amounts of hydroxyl groups in each example, it is found that when the molar ratio of introduced hydroxyl groups to epoxy groups is 0.6:1, the vulcanization speed of the obtained butyl rubber is the best. If the butyl rubber molecular chain contains fewer hydroxyl groups and epoxy groups, the vulcanization performance of the butyl rubber is poor, and the airtightness is also poor. From the comparative analysis of Comparative Example 4, Comparative Example 5 and Example 1, it can be seen that the molar ratio of the amount of m-chloroperbenzoic acid added to the amount of peracetic acid added will affect the amount of introduced hydroxyl groups.

[0063] The raw materials and equipment used in the present invention, unless otherwise specified, are all common raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art.

[0064] The above are only the preferred embodiments of the present invention, and do not impose any limitations on the present invention. Any simple modifications, changes and equivalent transformations made to the above embodiments according to the technical essence of the present invention still belong to the protection scope of the technical solution of the present invention.

Claims

1. An easily vulcanized butyl rubber, characterized in that: The butyl rubber molecular chain contains both hydroxyl groups and epoxy groups, and the molar ratio of the hydroxyl groups to the epoxy groups is 0.4-1.0:

1.

2. The easily vulcanized butyl rubber according to claim 1, characterized in that: The molar content of the hydroxyl group is 0.5-1.4%, and the molar content of the epoxy group is 1.1-2.5%.

3. The easily vulcanized butyl rubber according to claim 1, characterized in that: The glass transition temperature of the butyl rubber is -45°C to -35°C.

4. A method for preparing the readily vulcanizable butyl rubber according to any one of claims 1 to 3, comprising the following steps: Step 1: dissolve butyl rubber in a solvent, add peracetic acid aqueous solution, and react at 25-35°C for 2-5 hours; Step 2: adding m-chloroperbenzoic acid and trifluoroacetic acid to the product obtained in step 1, and reacting at 0-5° C. for 6-12 hours; Step 3: Add sodium bicarbonate solution to the product obtained in step 2 for neutralization, then wash with water and dry to obtain readily vulcanizable butyl rubber.

5. The preparation method according to claim 4, characterized in that: The molar ratio of peracetic acid to meta-chloroperbenzoic acid is 1:0.8-1.

5.

6. The preparation method according to claim 4, characterized in that: In the reaction system of step 1, the concentration of peracetic acid is 10-20wt%.

7. The preparation method according to claim 4, characterized in that: The reaction in step 1 is heated in three stages: the first stage is kept at 25°C for 1 hour, the second stage is kept at 30°C for 2 hours, and the third stage is kept at 35°C for 1 hour.

8. The preparation method according to claim 4, characterized in that: In step 1, the solvent is tetrahydrofuran.

9. The preparation method according to claim 4, characterized in that: In the reaction process of step 2, ultraviolet light is used to assist epoxidation, and the wavelength of the ultraviolet light is 365nm and the power is 50-100W.

10. Use of the readily vulcanizable butyl rubber according to any one of claims 1 to 3, or the readily vulcanizable butyl rubber prepared by the preparation method according to any one of claims 4 to 9 in the preparation of sealing products.

Images