Method for preparing hydroxylated butyl rubber with high conversion rate and hydroxylated butyl rubber prepared by method

Abstract

The invention discloses a method for preparing hydroxylated butyl rubber with a high conversion rate and the hydroxylated butyl rubber prepared by the method, and relates to the technical field of rubber.The method comprises the steps that butyl rubber and an epoxidation reagent are subjected to an epoxidation reaction in an organic solvent, after epoxidized butyl rubber is obtained, an acid reagent is added for a ring-opening reaction, and the epoxidized butyl rubber is obtained. And carrying out post-treatment to obtain the hydroxylated butyl rubber. According to the method for preparing the hydroxylated butyl rubber with the high conversion rate, hydroxyl is obtained through an epoxidation-acid ring opening route, the content of the hydroxyl can be increased to a great extent, and the stability of the hydroxyl in the product is ensured; according to the present invention, the epoxidation conversion rate and the hydroxylation conversion rate are substantially improved by blending different amounts and types of the organic solvent and the acid reagent, such that the hydroxylated butyl rubber with the high conversion rate is prepared, the compatibility and the gas tightness are substantially improved, and the experiment process has characteristics of simple process, low environmental pollution and easy production.

Description

Technical Field

[0001] The present invention relates to the technical field of rubber. Further, it relates to a method for preparing hydroxylated butyl rubber with high conversion rate and the hydroxylated butyl rubber obtained by this method. Background Art

[0002] Butyl rubber (IIR) is a copolymer obtained by cationic polymerization of isobutene and isoprene. It has a low degree of unsaturation, only 0.5% - 3.3%. The molecular chain consists of densely arranged side methyl groups and a highly saturated main chain. This structure endows butyl rubber with excellent performance characteristics: due to the restriction of the thermal movement of macromolecules, its gas permeability is the lowest among all hydrocarbon rubbers, that is, it has the best airtightness; its extremely low degree of unsaturation makes its heat resistance and oxidation resistance superior to other general rubbers, and it has excellent heat aging resistance; with a small amount of double bonds, it has good characteristics of absorbing vibration and impact energy. In a wide temperature range (-30 - 50°C), the rebound characteristic of butyl rubber is not more than 20%, which indicates that the ability of butyl rubber to absorb mechanical properties is superior to other rubbers, and it can be applied to fields such as tires, airtight products, shock-absorbing materials, and special rubber gloves. However, butyl rubber also has problems such as slow vulcanization speed, single vulcanization method, and poor compatibility with other rubbers.

[0003] After the halogenation modification of butyl rubber, both the vulcanization speed and airtightness are improved, and the compatibility and co-vulcanization performance with other rubbers are significantly improved, and the adhesion is also significantly improved. Halogenated butyl rubber (XIIR) mainly includes chlorinated butyl rubber (CIIR) and brominated butyl rubber (BIIR), which are mainly products of the substitution reaction of butyl rubber with chlorine or bromine. Due to its excellent performance characteristics, halogenated butyl rubber is widely used in fields such as tire inner liners and pharmaceutical stoppers. However, strong corrosive halogens are used in the preparation process of halogenated butyl rubber, and hydrogen halide is generated at the same time, which has a corrosive effect on equipment, and halogen compounds will have harmful effects on the human body and the environment.

[0004] Epoxidation modification is a common modification method for unsaturated rubbers containing carbon-carbon double bonds. After converting the carbon-carbon double bonds into epoxy functional groups, the polarity of the macromolecular chain is enhanced, and the compatibility and vulcanization speed of the modified rubber are improved. For example, Song Weixiao. Epoxidation Modification and Application Research of Natural Rubber [D]. Beijing University of Chemical Technology, 2022. Epoxidized natural rubber (ENR) was obtained by epoxidizing the double bonds on the main chain of natural rubber (NR). The introduced epoxy bonds endow ENR with polarity and reactivity, and at the same time improve its oil resistance, airtightness, adhesiveness, and wear resistance and other properties.

[0005] Wu Jun, Cui Baichuan, Wang Yan, et al. Synthesis and Characterization of Epoxidized Butyl Rubber [J]. Acta Polymerica Sinica, 2022, 53(02): 185-192. Epoxidized isobutylene-isoprene rubber (EIIR) with an epoxide degree of about 99% was synthesized by directly epoxidizing IIR using meta-chloroperoxybenzoic acid (mCPBA) as the epoxidizing agent. Chinese Patent CN113336877A discloses the preparation of epoxy-functionalized butyl rubber by in-situ epoxidation, and the crosslinking of EIIR was achieved by reacting maleic anhydride (MAH) with epoxy groups to form ester bonds. Due to the increase in intermolecular forces, the airtightness of EIIR has been greatly improved compared with IIR. In addition, the introduction of polar groups can also enhance the interaction with fillers. However, it was found that EIIR has poor stability, and the epoxy groups synthesized during acidic conditions or post-treatment heating further undergo ring-opening side reactions to form hydroxylated butyl rubber (HyIIR).

[0006] Chinese Patent CN115850877A discloses a preparation method and application of high-performance hydroxylated butyl rubber. The hydroxylated butyl rubber is mixed uniformly with reinforcing agents, vulcanizing agents, and vulcanization activators, and then vulcanized under high temperature and high pressure conditions to obtain high-performance hydroxylated butyl rubber with excellent airtightness and fatigue resistance. This is because the glass transition temperature (Tg) of hydroxylated butyl rubber is high, and HyIIR is very similar in structure to BIIR. It not only has the excellent airtightness, good compatibility, fast vulcanization speed, and good compatibility of brominated butyl rubber, but also the hydroxyl groups can form hydrogen bonds, further improving its airtightness on this basis.

[0007] However, there are few reports on how to prepare hydroxylated butyl rubber with high conversion rate. Ge Lun. Preparation and Properties of Hydroxyl-functionalized Rubber in the Chain [D]. Qingdao University of Science and Technology, 2022. Functionalized butyl rubber with different hydroxyl contents was prepared using tetrahydrofuran as a solvent, but the hydroxyl conversion rate in this method is very low; Chinese Patent CN109153738A discloses the conversion of epoxy functional groups on EIIR to allyl alcohol structures under high temperature and acidic conditions. However, since this reaction is a solid-phase reaction, in the absence of a solvent, it is prone to uneven dispersion, and the presence of a large amount of acid at high temperature will cause further crosslinking of the prepared rubber. Summary of the Invention

[0008] To solve the problems existing in the prior art, the present invention provides a method for preparing hydroxylated butyl rubber with high conversion rate and the hydroxylated butyl rubber prepared by this method. The present invention obtains hydroxyl groups through an epoxidation-acid ring-opening route, which can greatly increase the content of hydroxyl groups and ensure the stability of hydroxyl groups in the product.

[0009] One of the objectives of the present invention is to provide a method for preparing hydroxylated butyl rubber with high conversion rate.

[0010] The method for preparing hydroxylated butyl rubber according to the present invention includes:

[0011] Epoxidizing butyl rubber with an epoxidizing agent in an organic solvent to obtain epoxidized butyl rubber, then adding an acidic reagent for ring-opening reaction, and obtaining the hydroxylated butyl rubber after post-treatment.

[0012] Preferably,

[0013] The epoxidizing agent is a water-soluble epoxidizing agent or a water-insoluble epoxidizing agent;

[0014] Preferably,

[0015] The water-soluble epoxidizing agent is at least one of peroxy acid, a mixture of hydrogen peroxide and an acidic solution. When the water-soluble epoxidizing agent is a mixture of hydrogen peroxide and an acidic solution, an appropriate amount of acid can be added as a catalyst to accelerate the epoxidation reaction rate, such as dilute sulfuric acid, etc.; and / or,

[0016] The water-insoluble water-soluble epoxidizing agent is at least one of m-chloroperoxybenzoic acid, peracetic acid, and peroxybenzoic acid.

[0017] Preferably,

[0018] The acidic solution is at least one of formic acid and trifluoroperacetic acid; and / or,

[0019] The molar ratio of the hydrogen peroxide to the acidic solution is (1 - 10):1, preferably (2 - 8):1, more preferably (3 - 6):1.

[0020] Preferably,

[0021] The epoxy degree of the epoxidized butyl rubber is 10 - 100%, preferably 30 - 100%, more preferably 50 - 100%.

[0022] Preferably,

[0023] The organic solvent is at least one of n-hexane, toluene, xylene, dichloromethane, chloroform, cyclohexane, hexane, pentane, and heptane; and / or,

[0024] The acidic reagent is at least one of concentrated sulfuric acid, concentrated hydrochloric acid, and concentrated phosphoric acid. Preferably, the concentration of the acidic reagent is 30 - 99%, preferably 32 - 40%, more preferably 36 - 38%.

[0025] Preferably,

[0026] The molar ratio of the epoxidizing agent to the double bonds in the butyl rubber is (0.5 to 20):1, preferably (1 to 15):1;

[0027] The molar ratio of the acidic agent to the double bonds in the butyl rubber is (0.05 to 80):1, preferably (0.05 to 50):1, more preferably (0.1 to 30):1;

[0028] The mass ratio of the organic solvent to the butyl rubber is (1 to 20):1, preferably (5 to 18):1, more preferably (10 to 15):1.

[0029] Preferably,

[0030] The reaction temperature of the epoxidation reaction is 0 - 100 °C, preferably 0 - 80 °C, more preferably 0 - 60 °C, and / or the reaction time is 5 - 180 minutes, preferably 5 - 120 minutes, more preferably 5 - 60 minutes; and / or,

[0031] The reaction temperature of the ring-opening reaction is 0 - 90 °C, preferably 0 - 70 °C, more preferably 0 - 50 °C, and / or the reaction time is 5 - 150 minutes, preferably 5 - 120 minutes, more preferably 5 - 60 minutes.

[0032] Preferably, the post-treatment includes:

[0033] Washing off the acidic agent, adding a stabilizer, flocculating, and drying;

[0034] Preferably,

[0035] The mass ratio of the stabilizer to the butyl rubber is (0.001 to 10):1, preferably (0.001 to 5):1, more preferably (0.001 to 1):1.

[0036] Preferably,

[0037] The stabilizer is at least one of basic hydrotalcite, stearate, epoxidized soybean oil, and magnesium oxide.

[0038] Specifically, the following scheme can be adopted:

[0039] The raw material used in the present invention is butyl rubber, which reacts under certain temperature, solvent, and epoxidizing agent to obtain epoxidized butyl rubber, and then an acidic agent is added to carry out a ring-opening reaction on the epoxy group to obtain a hydroxyl group. By adjusting the reaction conditions, modified butyl rubber with different hydroxyl contents can be prepared.

[0040] Specifically, it includes the following steps:

[0041] (1) Sol: Dissolve butyl rubber in an organic solvent to form a solution with a certain concentration. Among them, the organic solvent used is required to be able to dissolve butyl rubber well, including at least one of n - hexane, toluene, xylene, dichloromethane, chloroform, cyclohexane, hexane, pentane, and heptane;

[0042] (2) Epoxidation reaction: Add an epoxidizing reagent to the dissolved rubber solution to carry out an epoxidation reaction, oxidize the carbon - carbon double bond into an epoxy group, and obtain epoxidized butyl rubber. Among them, the epoxidizing reagents used are divided into water - soluble reagents (heterogeneous system) and water - insoluble reagents (homogeneous system). The water - soluble reagents include at least one of peroxyacid and hydrogen peroxide / acidic solution system, and the water - insoluble reagents include at least one of m - chloroperoxybenzoic acid, peracetic acid, and peroxybenzoic acid;

[0043] (3) Ring - opening reaction: Add an acidic reagent to the epoxidized butyl rubber solution to cause the epoxy group to undergo a ring - opening reaction to generate hydroxylated butyl rubber;

[0044] (4) Post - treatment: Wash with water or alkali to remove the acidic reagent, add a stabilizer and then flocculate and dry to obtain hydroxylated butyl rubber.

[0045] The second object of the present invention is to provide a hydroxylated butyl rubber prepared by a method for preparing hydroxylated butyl rubber with a high conversion rate.

[0046] In the present invention, the carbon - carbon double bond in the isoprene unit of butyl rubber is first epoxidized, and the epoxy group is then catalytically rearranged under the action of an acid to obtain an allyl alcohol structure. Therefore, in terms of structure, HyIIR not only retains the polyisobutylene unit in IIR and does not damage the good airtightness characteristic of IIR itself, but also introduces a polar group, hydroxyl. On the basis of further improving airtightness, oil resistance, and compatibility, it brings a new cross - linking method. Compared with EIIR, HyIIR has a high - saturation main chain and rich side groups, endowing it with better aging resistance, and its structure is more stable and easier to store. This hydroxylated butyl rubber with a high conversion rate can be widely used in aspects such as tires, sealing gaskets, and pressure - buffering materials due to its excellent compatibility and airtightness. The present invention realizes the hydroxylation of butyl rubber, and the hydroxyl conversion rate is very high, improving the airtightness, compatibility, fatigue resistance, flexing performance, and mechanical properties of butyl rubber. It is a rubber with great prospects and application markets.

[0047] The method for preparing hydroxylated butyl rubber with high conversion rate provided by the present invention obtains hydroxyl groups through an epoxidation-acid ring-opening route. This method can greatly increase the content of hydroxyl groups and ensure the stability of hydroxyl groups in the product. By adjusting the dosage and types of different organic solvents and acidic reagents, both the conversion rates of epoxidation and hydroxylation are greatly improved, thereby preparing hydroxylated butyl rubber with high conversion rate, and both the compatibility and airtightness are greatly improved. The experimental process has simple technology, little environmental pollution, and is easy to produce. Description of the Drawings

[0048] Figure 1 It is the NMR diagram of the epoxidized butyl rubber prepared in Example 2;

[0049] Figure 2 It is the NMR diagram of the hydroxylated butyl rubber prepared in Example 2;

[0050] Figure 1 There is no characteristic peak of double bond (at 5.07 ppm shift), and the peak at 2.73 ppm shift represents the characteristic peak of epoxy group, indicating that the double bond in butyl rubber is successfully epoxidized;

[0051] Figure 2 The characteristic peak of epoxy group disappears in it, and the peaks at 4.0 ppm, 5.0 ppm, and 5.25 ppm shifts represent the characteristic peaks of hydroxyl groups, proving that the epoxy group is successfully hydroxylated. Detailed Embodiments

[0052] The present invention will be specifically described below in conjunction with specific drawings and embodiments. It is necessary to point out here that the following embodiments are only for further illustration of the present invention and cannot be understood as limiting the protection scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention still fall within the protection scope of the present invention.

[0053] The raw materials used in the embodiments of the present invention are all commercially available products, and the specific information is as shown in Table 1 below:

[0054] Table 1

[0055]

[0056] Example 1

[0057] Weigh 30 g of IIR and dissolve it in 60 g of n-hexane. Place it in a three-necked flask and heat it up to 55 °C. Add 1.48 g of formic acid and stir for 5 min. Add 1 g of dilute sulfuric acid with a mass concentration of 30% to the reaction flask and stir for 5 min. Weigh 12.86 g of hydrogen peroxide (the molar ratio of hydrogen peroxide, formic acid to the double bond in IIR is 20:5:2), and add it dropwise within 15 min. After the dropwise addition of hydrogen peroxide is completed, react at 55 °C for 2 h to complete epoxidation, obtaining epoxidized butyl rubber. Add 26.9 g of concentrated hydrochloric acid with a mass fraction of 30% (the molar ratio of concentrated hydrochloric acid to the double bond in IIR is 30:1), and react at 55 °C for 10 min to complete hydroxylation. Wash the reacted rubber solution once with alkali and twice with water to remove acidic reagents. Then add 0.5% of epoxidized soybean oil based on the mass of IIR and 1% of calcium stearate based on the mass of IIR to the rubber solution. Finally, carry out flocculation with boiling water. The flocculated rubber sample is dried in an oven at 50 °C for 2 h to obtain hydroxylated butyl rubber.

[0058] The epoxy degree of the epoxidized butyl rubber prepared above was detected by nuclear magnetic resonance to be 100%, and the hydroxyl conversion rate of the hydroxylated butyl rubber was 50%.

[0059] According to GBT12137-2002, the permeation coefficient of the above-mentioned hydroxylated butyl rubber was obtained by airtightness test as 3.829×10 -14 .

[0060] Example 2

[0061] Weigh 30 g of IIR and dissolve it in 270 g of dichloromethane. Place it in a three-necked flask and solvate it at room temperature. Add 2 g of m-chloroperbenzoic acid (the molar ratio of m-chloroperbenzoic acid to the double bond in IIR is 1.3:1), and react at room temperature for 1 h to complete epoxidation, obtaining epoxidized butyl rubber. Add 1.8 g of concentrated hydrochloric acid with a mass fraction of 37% (the molar ratio of concentrated hydrochloric acid to the double bond in IIR is 2:1), and react for 10 min to complete hydroxylation. Wash the reacted rubber solution once with alkali and twice with water to remove acidic reagents. Then add 0.3% of epoxidized soybean oil based on the mass of IIR and 1% of calcium stearate based on the mass of IIR to the rubber solution. Finally, carry out flocculation with boiling water. The flocculated rubber sample is dried in an oven at 50 °C for 2 h to obtain hydroxylated butyl rubber.

[0062] The epoxy degree of the epoxidized butyl rubber prepared above was detected by nuclear magnetic resonance to be 100%, and the hydroxyl conversion rate of the hydroxylated butyl rubber was 80%.

[0063] According to GBT12137-2002, the permeation coefficient of the above-mentioned hydroxylated butyl rubber was obtained by airtightness test as 1.616×10 -14 .

[0064] Example 3

[0065] Weigh 30 g of IIR and dissolve it fully in 450 g of toluene. Place it in a three-necked flask and solubilize it at room temperature. Add 23 g of m-chloroperoxybenzoic acid (the molar ratio of m-chloroperoxybenzoic acid to the double bonds in IIR is 15:1) dropwise into the polymer solution. React at 30 °C for 2 h to complete epoxidation and obtain epoxidized butyl rubber. Add 0.1 g of concentrated hydrochloric acid with a mass fraction of 45% (the molar ratio of concentrated hydrochloric acid to the double bonds in IIR is 0.1:1), and react for 0.5 h to complete hydroxylation. Wash the reacted rubber solution once with alkali and twice with water to remove acidic reagents. Then add 1% of the mass of IIR of epoxidized soybean oil and 1% of the mass of IIR of calcium stearate to the rubber solution. Finally, carry out flocculation with boiling water. Dry the flocculated rubber sample in an oven at 50 °C for 2 h to obtain hydroxylated butyl rubber.

[0066] Using nuclear magnetic resonance method, the epoxy degree of the epoxidized butyl rubber prepared above is 100%, and the hydroxyl conversion rate of the hydroxylated butyl rubber is 60%.

[0067] According to GBT12137-2002 for airtightness test, the permeation coefficient of the above-mentioned hydroxylated butyl rubber is 2.579×10 -14 。

[0068] Example 4

[0069] Weigh 30 g of IIR and dissolve it in 170 g of dichloromethane. Place it in a three-necked flask and solubilize it at room temperature. Add 1.2 g of peracetic acid (the molar ratio of peracetic acid to the double bonds in IIR is 1.3:1), and react at room temperature for 4 h to complete epoxidation and obtain epoxidized butyl rubber. Add 1.8 g of concentrated sulfuric acid with a mass fraction of 98% (the molar ratio of concentrated sulfuric acid to the double bonds in IIR is 2:1), and react for 10 min to complete hydroxylation. Wash the reacted rubber solution once with alkali and twice with water to remove acidic reagents. Then add 0.3% of the mass of IIR of epoxidized soybean oil and 1% of the mass of IIR of calcium stearate to the rubber solution. Finally, carry out flocculation with boiling water. Dry the flocculated rubber sample in an oven at 50 °C for 2 h to obtain hydroxylated butyl rubber.

[0070] Using nuclear magnetic resonance method, the epoxy degree of the epoxidized butyl rubber prepared above is 50%, and the hydroxyl conversion rate of the hydroxylated butyl rubber is 10%.

[0071] According to GBT12137-2002 for airtightness test, the permeation coefficient of the above-mentioned hydroxylated butyl rubber is 5.923×10 -14 。

[0072] Example 5

[0073] Weigh 80 g of IIR and dissolve it fully in 320 g of n - hexane. Place it in a three - necked flask and heat it to 40 °C to form a sol. Add 5.1 g of m - chloroperoxybenzoic acid (the molar ratio of m - chloroperoxybenzoic acid to the double bonds in IIR is 1:1) to the sol and react at 50 °C for 2 h to complete epoxidation, obtaining epoxidized butyl rubber. Add 4.8 g of concentrated hydrochloric acid with a mass fraction of 37% (the molar ratio of concentrated hydrochloric acid to the double bonds in IIR is 2:1), react for 30 min to complete hydroxylation. Wash the reacted sol once with alkali and twice with water to remove acidic reagents. Then add 0.5% of epoxidized soybean oil based on the mass of IIR and 0.5% of calcium stearate based on the mass of IIR to the sol. Finally, flocculate with boiling water, and dry the flocculated rubber sample in an oven at 50 °C for 2 h to obtain hydroxylated butyl rubber.

[0074] Use nuclear magnetic resonance method to detect that the epoxy degree of the epoxidized butyl rubber prepared above is 100%, and the hydroxyl conversion rate of the hydroxylated butyl rubber is 60%.

[0075] According to GBT12137 - 2002 for airtightness test, the permeation coefficient of the above - mentioned hydroxylated butyl rubber is 2.612×10 -14 。

[0076] Example 6

[0077] Weigh 15 g of IIR and dissolve it in 135 g of dichloromethane. Place it in a three - necked flask and form a sol at room temperature. Add 0.6 g of formic acid and stir for 5 min. Add 0.5 g of dilute sulfuric acid with a mass concentration of 30% to the reaction flask and stir for 5 min. Weigh 3.3 g of hydrogen peroxide (the molar ratio of hydrogen peroxide, formic acid to the double bonds in IIR is 5:2:1) and add it dropwise within 15 min. After the dropwise addition of hydrogen peroxide, react for 1 h to complete epoxidation, obtaining epoxidized butyl rubber. Add 1.2 g of concentrated hydrochloric acid with a mass fraction of 37% (the molar ratio of concentrated hydrochloric acid to the double bonds in IIR is 2:1), react at room temperature for 10 min to complete hydroxylation. Wash the reacted sol once with alkali and twice with water to remove acidic reagents. Then add 1% of epoxidized soybean oil based on the mass of IIR and 0.5% of calcium stearate based on the mass of IIR to the sol. Finally, flocculate with boiling water, and dry the flocculated rubber sample in an oven at 50 °C for 2 h to obtain hydroxylated butyl rubber.

[0078] Use nuclear magnetic resonance method to detect that the epoxy degree of the epoxidized butyl rubber prepared above is 100%, and the hydroxyl conversion rate of the hydroxylated butyl rubber is 50%.

[0079] According to GBT12137 - 2002 for airtightness test, the permeation coefficient of the above - mentioned hydroxylated butyl rubber is 3.842×10 -14 。

[0080] Example 7

[0081] Weigh 30 g of IIR and dissolve it in 270 g of chloroform. Place it in a three-necked flask and solubilize it at room temperature. Add 2 g of m-chloroperbenzoic acid (the molar ratio of m-chloroperbenzoic acid to the double bonds in IIR is 1.3:1). React at 40 °C for 1 h to complete epoxidation and obtain epoxidized butyl rubber. Add 18 g of concentrated hydrochloric acid with a mass fraction of 37% (the molar ratio of concentrated hydrochloric acid to the double bonds in IIR is 20:1). React for 10 min to complete hydroxylation. Wash the reacted rubber solution once with alkali and twice with water to remove acidic reagents. Then add 0.5% of epoxidized soybean oil based on the mass of IIR and 0.5% of calcium stearate based on the mass of IIR to the rubber solution. Finally, flocculate with boiling water. Dry the flocculated rubber sample in an oven at 50 °C for 2 h to obtain hydroxylated butyl rubber.

[0082] Use nuclear magnetic resonance method to detect that the epoxy degree of the epoxidized butyl rubber prepared above is 100%, and the hydroxyl conversion rate of the hydroxylated butyl rubber is 50%.

[0083] According to GBT12137-2002 for airtightness test, the permeation coefficient of the above-mentioned hydroxylated butyl rubber is 3.867×10 -14 。

[0084] Example 8

[0085] Weigh 80 g of IIR and fully dissolve it in 453 g of n-hexane. Place it in a three-necked flask and heat it to 40 °C to solubilize it. Add 5.1 g of m-chloroperbenzoic acid to the rubber solution (the molar ratio of m-chloroperbenzoic acid to the double bonds in IIR is 1:1). React at 50 °C for 2 h to complete epoxidation and obtain epoxidized butyl rubber. Add 4.8 g of concentrated phosphoric acid with a mass fraction of 85% (the molar ratio of concentrated phosphoric acid to the double bonds in IIR is 2:1). React for 30 min to complete hydroxylation. Wash the reacted rubber solution once with alkali and twice with water to remove acidic reagents. Then add 0.5% of epoxidized soybean oil based on the mass of IIR and 0.5% of calcium stearate based on the mass of IIR to the rubber solution. Finally, flocculate with boiling water. Dry the flocculated rubber sample in an oven at 50 °C for 2 h to obtain hydroxylated butyl rubber.

[0086] Use nuclear magnetic resonance method to detect that the epoxy degree of the epoxidized butyl rubber prepared above is 100%, and the hydroxyl conversion rate of the hydroxylated butyl rubber is 20%.

[0087] According to GBT12137-2002 for airtightness test, the permeation coefficient of the above-mentioned hydroxylated butyl rubber is 5.718×10 -14 。

[0088] The present invention obtains hydroxyl groups through an epoxidation-acid ring-opening route, which can greatly increase the content of hydroxyl groups; by adjusting the dosage and types of different organic solvents and acidic reagents, the conversion rates of epoxidation and hydroxylation are both greatly improved. For example, in the epoxidation reaction, dichloromethane is used as the organic solvent, and concentrated hydrochloric acid is used as the acidic reagent in the epoxidation reaction. The hydroxyl group content obtained can be increased by 65% compared with using n-hexane as the organic solvent.

[0089] When dichloromethane is used as the organic solvent in the epoxidation reaction and concentrated hydrochloric acid is used as the acid ring-opening reagent, the combination of the two can achieve the highest hydroxyl group conversion rate. Based on rubber, the mass ratio of the organic solvent to butyl rubber is 9:1, and the molar ratio of the acidic reagent to the double bonds in butyl rubber is 2:1. When m-chloroperbenzoic acid is used as the epoxidation reagent, the hydroxyl group conversion rate is the highest, the epoxy conversion rate can reach 100%, and the hydroxyl group conversion rate can reach 80%.

Claims

1. A method for preparing hydroxylated butyl rubber with high conversion rate, characterized in that the method comprises: carrying out an epoxidation reaction on butyl rubber and an epoxidizing reagent in an organic solvent to obtain epoxidized butyl rubber, then adding an acidic reagent for a ring-opening reaction, and obtaining the hydroxylated butyl rubber after post-treatment.

2. The method according to claim 1, characterized in that: the epoxidizing reagent is a water-soluble epoxidizing reagent or a water-insoluble epoxidizing reagent; preferably, the water-soluble epoxidizing reagent is at least one of peroxyacid, a mixture of hydrogen peroxide and an acidic solution; and / or, the water-insoluble epoxidizing reagent is at least one of m-chloroperoxybenzoic acid, peracetic acid, peroxybenzoic acid.

3. The method according to claim 1, characterized in that: the acidic solution is at least one of formic acid, trifluoroperacetic acid; and / or, the molar ratio of the hydrogen peroxide to the acidic solution is (1 - 10):1, preferably (2 - 8):1, more preferably (3 - 6):

1.

4. The method according to claim 1, characterized in that: the epoxy degree of the epoxidized butyl rubber is 10 - 100%, preferably 30 - 100%, more preferably 50 - 100%.

5. The method according to claim 1, characterized in that: the organic solvent is at least one of n-hexane, toluene, xylene, dichloromethane, chloroform, cyclohexane, hexane, pentane, heptane; and / or, the acidic reagent is at least one of concentrated sulfuric acid, concentrated hydrochloric acid, concentrated phosphoric acid, preferably, the concentration of the acidic reagent is 30 - 99%, preferably 32 - 40%, more preferably 36 - 38%.

6. The method according to claim 1, characterized in that: the molar ratio of the epoxidizing reagent to the double bond in the butyl rubber is (0.5 - 20):1, preferably (1 - 15):1; the molar ratio of the acidic reagent to the double bond in the butyl rubber is (0.05 - 80):1, preferably (0.05 - 50):1, more preferably (0.1 - 30):1; the mass ratio of the organic solvent to the butyl rubber is (1 - 20):1, preferably (5 - 18):1, more preferably (10 - 15):

1.

7. The method according to claim 1, characterized in that: the reaction temperature of the epoxidation reaction is 0 - 100°C, preferably 0 - 80°C, more preferably 0 - 60°C, and / or, the reaction time is 5 - 180 minutes, preferably 5 - 120 minutes, more preferably 5 - 60 minutes; and / or, the reaction temperature of the ring-opening reaction is 0 - 90°C, preferably 0 - 70°C, more preferably 0 - 50°C, and / or, the reaction time is 5 - 150 minutes, preferably 5 - 120 minutes, more preferably 5 - 60 minutes.

8. The method according to claim 1, characterized in that the post-treatment comprises: washing off the acidic reagent, adding a stabilizer, flocculating, drying; preferably, The mass ratio of the stabilizer to the butyl rubber is (0.001 to 10):1, preferably (0.001 to 5):1, more preferably (0.001 to 1):

1.

9. According to the method described in claim 1, characterized in that: the stabilizer is at least one of basic hydrotalcite, stearate, epoxidized soybean oil, and magnesium oxide.

10. A hydroxylated butyl rubber prepared by the method according to any one of claims 1-9.

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