Medium-high molecular weight high-activity polyisobutene and preparation method thereof

Abstract

The invention provides medium-high molecular weight high-activity polyisobutene and a preparation method thereof, and the preparation method comprises the following steps: mixing hydrogen peroxide and a butyl rubber solution, and reacting for 0.5-20 hours at 20-80 DEG C under the catalytic action of a catalyst to obtain epoxidized butyl rubber; dissolving epoxidized butyl rubber to obtain an epoxidized butyl rubber solution; adding an oxidative cracking reagent into the epoxidized butyl rubber solution, and reacting at 0-80 DEG C for 0.5-20 hours to obtain a polyisobutylene solution; the medium-high molecular weight high-activity polyisobutene has the characteristics of high molecular weight, narrow distribution and higher end group activity, and can be applied to the application fields of traditional high-activity polyisobutene such as additives of lubricating oil, fuel oil, rubber and the like; and the product can be used as a sealing material, a waterproof water-retaining agent, a rubber and plastic modifier and the like, can meet wider application requirements, and has good industrial application value.

Description

Technical Field

[0001] The present invention relates to the field of fine polymer chemicals and their manufacture, and particularly to a medium- to high-molecular-weight highly active polyisobutene having a carbonyl group, a hydroxyl group, or a carboxyl group at the chain end and a preparation method thereof. Background Art

[0002] Conventional highly active polyisobutene (HRPIB) refers to polyisobutene in which the content of terminal α-olefin structure accounts for more than 70%, and is mostly used as an additive for lubricating oil, fuel oil, rubber, etc., a drag reducer for oilfield fracturing fluid, wire rope oil, waterproof explosive, rocket propellant, ashless dispersant, and plasticizer, water retention agent, etc.

[0003] In the past, HRPIB could only be obtained through the cationic polymerization of isobutene and the chain transfer reaction during the polymerization process. Since there are two ways to remove β-hydrogen when the active chain transfers to the monomer chain, polyisobutene with terminal α-olefin and β-olefin will be formed respectively. Among them, polyisobutene with terminal α-olefin has higher reactivity in addition, substitution and other reactions; while polyisobutene with terminal β-olefin has almost no active reaction due to steric hindrance and charge effect. Therefore, the industrial community often regards the content of α-olefin as an important quality index of HRPIB, and has developed various chemical modification methods such as oxidation, aminolysis, copolymerization and addition to convert terminal vinyl groups into carboxyl groups, amino groups, ester groups, etc. for various applications.

[0004] In addition, in traditional HRPIB, the chain transfer reaction of the active chain is used to introduce active groups. Although cationic polymerization is indeed prone to chain transfer reaction, it is precisely this chain transfer reaction that makes it difficult to increase the molecular weight of the polymerization product. Therefore, the number-average molecular weight of HRPIB specified by the industry is between 900 and 2,500 g / mol, and the molecular weight distribution index ≤ 2.5. Of course, in order to broaden the application field, some research and development have increased the number-average molecular weight to 5,000 g / mol or even higher, and the PDI has been reduced to less than 2.0. For example, CN108026202A discloses a technology for obtaining hydroxyl-functionalized polyisobutene by ozonation and reduction treatment of polyisobutene, butyl rubber or their mixture. However, this technology cannot control the molecular weight of PIB by the amount of ozone introduced, and the obtained PIB has no residual isoprene units.

[0005] In other words, the currently available highly active polyisobutene has the problem that it is difficult to increase the molecular weight. Summary of the Invention

[0006] The object of the present invention is to provide a medium- to high-molecular-weight highly active polyisobutene and a preparation method thereof, which can introduce a carbonyl group, a hydroxyl group or a carboxyl group at the end of the medium- to high-molecular-weight highly active polyisobutene to increase the molecular weight of the highly active polyisobutene.

[0007] It should be noted that both polyisobutene and butyl rubber are products of the cationic polymerization of isobutene. Among them, the molecular weight of butyl rubber is larger than that of polybutene. And in order to endow it with good vulcanization (crosslinking) performance, 1-5 mol% of isoprene is introduced during the cationic polymerization of isobutene, which embeds some C=C double bonds in the molecular chain of butyl rubber. The chemical formula of butyl rubber is as follows:

[0008]

[0009] Based on the fact that the molecular weight of butyl rubber is larger and there are carbon-carbon double bonds embedded in its molecular chain, the research team of this application thought of epoxidizing the carbon-carbon double bonds of butyl rubber and then carrying out cleavage. In this way, while reducing the molecular weight, carbonyl groups can be introduced at the ends of the molecular chain; half of them are aldehyde groups, and the other half are ketone groups. By regulating the epoxidation rate or cleavage rate of butyl rubber or selecting butyl rubber with a lower isoprene content, the molecular weight can be controlled within the medium-high range. Since both terminal aldehyde groups and terminal ketone groups have the activities of nucleophilic addition, oxidation and reduction reactions, especially the aldehyde group is more easily converted into carboxyl, oxime, amine, and ester groups than vinyl group, the product is medium-high molecular weight active polyisobutene. Based on this route, this scheme proposes a new preparation method for medium-high molecular weight and high-activity polyisobutene. The preparation method of this medium-high molecular weight and high-activity polyisobutene includes the following steps:

[0010] To achieve the above object, this technical scheme provides a preparation method for medium-high molecular weight and high-activity polyisobutene, including the following steps:

[0011] Mix hydrogen peroxide and butyl rubber solution and react at 20-80 °C for 0.5-20 h under the catalysis of a catalyst to obtain epoxidized butyl rubber, where the molar ratio of hydrogen peroxide to isoprene units in butyl rubber is 0.01-20:1;

[0012] Dissolve the epoxidized butyl rubber to obtain an epoxidized butyl rubber solution; add an oxidative cleavage reagent to the epoxidized butyl rubber solution and react at 0-80 °C for 0.5-20 h to obtain a polyisobutene solution, where the molar ratio of the oxidative cleavage reagent to the epoxy groups in the epoxidized butyl rubber solution is 1-4:1;

[0013] Filter the polyisobutene solution and vacuum dry it to remove the solvent to obtain medium-high molecular weight and high-activity polyisobutene.

[0014] The number-average molecular weight Mn of the medium-high molecular weight and high-activity polyisobutene prepared by this scheme is between 6,000 and 100,000 g / mol, and the molecular weight distribution index PDI < 1.8.

[0015] Furthermore, dissolve butyl rubber in a first organic solvent to obtain a butyl rubber solution.

[0016] In some embodiments, the concentration of the butyl rubber solution in this solution is 10-100 g / L. The advantage of this is that the butyl rubber can be fully dissolved, and the viscosity of the system can be effectively reduced, enabling the reaction to proceed fully.

[0017] In some embodiments, the first organic solvent is a mixture composed of one or more of dichlorinated or trichlorinated methane or ethane, straight-chain alkanes with 4-6 carbon atoms, isoparaffins or naphthenes.

[0018] In this solution, hydrogen peroxide is used as an epoxidizing agent to epoxidize butyl rubber. Under the catalytic action of a catalyst, the C═C double bonds in the main chain of the butyl rubber molecules are epoxidized, and the conversion rate of the double bonds is 1-100%. It should be noted that the molecular weight and isoprene unit content of high-molecular-weight and high-activity polyisobutene in the product can be adjusted by controlling the epoxidation rate of butyl rubber. Generally speaking, the higher the epoxidation rate of butyl rubber, the higher the cracking rate of epoxidized butyl rubber, and the smaller the molecular weight and the lower the isoprene unit content of high-molecular-weight and high-activity polyisobutene.

[0019] In some embodiments, hydrogen peroxide and the butyl rubber solution are mixed and, under the catalytic action of a catalyst, reacted at 20-80 °C for 0.5-20 h to obtain a reaction solution. The reaction solution is cooled and centrifuged to obtain a supernatant. Methanol is added to the supernatant to obtain a precipitate, and the precipitate is dried under vacuum to obtain epoxidized butyl rubber.

[0020] In some embodiments, the catalyst is a quaternary ammonium salt of phosphotungstic heteropolyacid.

[0021] Furthermore, the epoxidized butyl rubber is dissolved in a second organic solvent to obtain an epoxidized butyl rubber solution.

[0022] In some embodiments, the second organic solvent is a mixture composed of one or more of tetrahydrofuran, dichlorinated or trichlorinated methane or ethane, straight-chain alkanes with 4-6 carbon atoms, isoparaffins or naphthenes.

[0023] In some embodiments, the concentration of the epoxidized butyl rubber solution is 15-150 g / L. The advantage of this is that the yield of the obtained active polyisobutene can be increased, thereby improving the preparation efficiency. On the other hand, due to the presence of epoxy groups in the epoxidized butyl rubber solution, the polarity of the rubber becomes higher, and the solvent content can be correspondingly reduced.

[0024] In some embodiments, periodic acid is selected as the oxidative cleavage reagent in this solution. The periodic acid in this solution cleaves epoxidized butyl rubber to obtain a polyisobutylene solution, and the number-average molecular weight of the polyisobutylene in the polyisobutylene solution is between 6,000 and 100,000 g / mol and the chain ends are carbonyl groups. It should be noted that the molecular weight and isoprene unit content of high-molecular-weight and high-activity polyisobutylene in the product can be adjusted by controlling the cleavage rate of epoxidized butyl rubber. Generally speaking, the higher the cleavage rate of epoxidized butyl rubber, the smaller the molecular weight and the lower the isoprene unit content of medium- and high-molecular-weight and high-activity polyisobutylene.

[0025] It should be noted that if no treatment is done, the chain ends of medium- and high-molecular-weight and high-activity polyisobutylene are carbonyl groups, one end is an aldehyde group and the other end is a ketone group.

[0026] Furthermore, if medium- and high-molecular-weight and high-activity polyisobutylene with hydroxyl groups at the chain ends is needed, before filtering the polyisobutylene solution, it further includes the step of adding a reducing agent to the polyisobutylene solution and reacting it at 0-80 °C for 0.5-20 h, where the molar ratio of the reducing agent to the carbonyl group of the polyisobutylene in the polyisobutylene solution is 0.5-10:1.

[0027] In some embodiments, sodium borohydride or red aluminum is selected as the reducing agent. The reducing agent converts the carbonyl group at the end of the polyisobutylene into a hydroxyl group, and then through subsequent filtration, rotary evaporation and vacuum drying, medium- and high-molecular-weight and high-activity polyisobutylene with hydroxyl groups at the chain ends can be obtained.

[0028] Furthermore, if medium- and high-molecular-weight and high-activity polyisobutylene with carboxyl groups at the chain ends is needed, before filtering the polyisobutylene solution, it further includes the step of adding an oxidizing agent to the polyisobutylene solution and reacting it at 0-80 °C for 0.5-20 h, where the molar ratio of the oxidizing agent to the carbonyl group of the polyisobutylene in the polyisobutylene solution is 0.5-10:1.

[0029] In some embodiments, any one or combination of Jones reagent, dichromate, permanganate is selected as the oxidizing agent. The oxidizing agent converts the carbonyl group at the end of the polyisobutylene into a carboxyl group, and then through subsequent filtration, rotary evaporation and vacuum drying, medium- and high-molecular-weight and high-activity polyisobutylene with carboxyl groups at the chain ends can be obtained.

[0030] Furthermore, filter the solid residues of the catalyst and oxidative cleavage agent in the polyisobutylene solution, and remove the solvent by rotary evaporation and vacuum drying to obtain medium- and high-molecular-weight and high-activity polyisobutylene.

[0031] This solution also provides medium- and high-molecular-weight and high-activity polyisobutylene prepared according to the above preparation method of medium- and high-molecular-weight and high-activity polyisobutylene, with a number-average molecular weight Mn between 6,000 and 100,000 g / mol and a molecular weight distribution index PDI < 1.8.

[0032] In some embodiments, more than 95% of the terminals of medium and high molecular weight high-activity polyisobutene are carbonyl groups, or hydroxyl groups or carboxyl groups.

[0033] Compared with the prior art, the technical solution of the present invention has the following characteristics and beneficial effects:

[0034] Compared with the high-activity polyisobutene prepared by the traditional isobutene cationic polymerization-chain transfer method, the high-activity polyisobutene prepared from the epoxidized butyl rubber of the present invention has the characteristics of high molecular weight, narrow distribution, and higher terminal group activity. It can not only be applied to the traditional application fields of high-activity polyisobutene such as additives for lubricating oils, fuels, and rubbers, but also be used as sealing materials, water-proofing and water-retaining agents, rubber and plastic modifiers, etc., meeting broader application requirements and having good industrial application value. Description of the Drawings

[0035] Figure 1 1H NMR spectra of the epoxidized butyl rubber prepared in Example 3 and medium and high molecular weight high-activity polyisobutene with carbonyl terminals.

[0036] Figure 2 1H NMR spectra of medium and high molecular weight high-activity polyisobutene with hydroxyl terminals prepared in Example 4.

[0037] Figure 3 1H NMR spectra of medium and high molecular weight high-activity polyisobutene with carboxyl terminals prepared in Example 6. Detailed Description of the Invention

[0038] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. 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 belong to the scope of protection of the present invention.

[0039] Polymer structure analysis: It was measured using a nuclear magnetic resonance spectrometer (Bruker AVANCE NEO-500MHz) with deuterated chloroform as the solvent.

[0040] Determination of the number average molecular weight (M n ) and the molecular weight distribution index (PDI) of the polymer: It was determined by gel permeation chromatography (Waters Alliance e2695) with tetrahydrofuran as the solvent, narrow distribution polystyrene as the standard sample, the polymer concentration of 1-10 mg / mL, and the solvent flow rate of 1 mL / min.

[0041] Example 1

[0042] Dissolve 8.00 g of butyl rubber in a mixed solution of 80 mL of 1,2-dichloroethane and 80 mL of n-hexane, and keep the temperature constant at 60 °C; after adding 0.80 g of quaternary ammonium salt of phosphotungstic heteropolyacid, slowly add hydrogen peroxide (mass fraction 27.5 wt.%) dropwise to the butyl rubber solution, and react at 60 °C for 12 h, where the molar ratio of hydrogen peroxide to isoprene units in butyl rubber is 0.25:1. After the reaction is completed, cool the reaction solution at 5 °C for 15 min, and centrifuge to obtain the supernatant. Add methanol to precipitate and dry in vacuo to obtain epoxidized butyl rubber.

[0043] Dissolve 6.00 g of the above epoxidized butyl rubber in 120 mL of tetrahydrofuran, and keep the temperature constant at 40 °C. Add periodic acid and react at 40 °C for 2 h, where the molar ratio of periodic acid to epoxy groups is 1.2:1. The reaction solution is filtered, rotary evaporated and dried in vacuo to obtain polyisobutene with carbonyl groups at the ends. The Mn of the product is 98,000 g / mol and the PDI is 1.78.

[0044] Example 2

[0045] Dissolve 8.00 g of butyl rubber in a mixed solution of 80 mL of 1,2-dichloroethane and 80 mL of cyclohexane, and keep the temperature constant at 70 °C. After adding 0.60 g of quaternary ammonium salt of phosphotungstic heteropolyacid, slowly add hydrogen peroxide (mass fraction 27.5 wt.%) dropwise to the butyl rubber solution, and react at 70 °C for 6 h, where the molar ratio of hydrogen peroxide to isoprene units in butyl rubber is 2.5:1. After the reaction is completed, cool the reaction solution at 5 °C for 15 min, and centrifuge to obtain the supernatant. Add methanol to precipitate and dry in vacuo to obtain epoxidized butyl rubber.

[0046] Dissolve 6.00 g of the above epoxidized butyl rubber in 50 mL of tetrahydrofuran and 50 ml of n-hexane, and keep the temperature constant at 40 °C. Add periodic acid and react at 40 °C for 4 h, where the molar ratio of periodic acid to epoxy groups is 2.0:1. The reaction solution is filtered, rotary evaporated and dried in vacuo to obtain polyisobutene with carbonyl groups at the ends. The M n is 75,000 g / mol and the PDI is 1.62.

[0047] Example 3

[0048] Dissolve 8.00 g of butyl rubber in a mixed solution of 50 mL of 1,2-dichloroethane and 50 mL of n-hexane, and keep the temperature constant at 60 °C. After adding 1.20 g of quaternary ammonium salt of phosphotungstic heteropolyacid, slowly add hydrogen peroxide (mass fraction 27.5 wt.%) dropwise to the butyl rubber solution, and react at 60 °C for 8 h, where the molar ratio of hydrogen peroxide to isoprene units in butyl rubber is 10:1. After the reaction is completed, cool the reaction solution at 5 °C for 15 min, and centrifuge to obtain the supernatant. Add methanol to precipitate and dry in vacuo to obtain epoxidized butyl rubber.

[0049] Dissolve 6.00 g of the above epoxidized butyl rubber in 150 mL of an organic solvent (50 mL of tetrahydrofuran, 50 mL of n - hexane, and 50 mL of dichloroethane), and keep the temperature constant at 50 °C. Add periodic acid and react at 50 °C for 2 h, where the molar ratio of periodic acid to epoxy groups is 2.5:1. The reaction solution is filtered, rotary evaporated, and vacuum dried to obtain polyisobutylene with carbonyl groups at the ends. The M n of the product is 9,700 g / mol, and the PDI is 1.56.

[0050] Example 4

[0051] Dissolve 4.00 g of the polyisobutylene with carbonyl groups at the ends obtained in Example 1 in 40 mL of tetrahydrofuran, and keep the temperature constant at 30 °C. Add sodium borohydride and react at 30 °C for 2 h, where the molar ratio of sodium borohydride to carbonyl groups is 4:1. The reaction solution is filtered, rotary evaporated, and vacuum dried to obtain polybutene with hydroxyl groups at the ends. The Mn of the product is 97,200 g / mol, and the PDI is 1.82.

[0052] Example 5

[0053] Dissolve 4.00 g of the polyisobutylene with carbonyl groups at the ends obtained in Example 2 in 80 mL of tetrahydrofuran, and keep the temperature constant at 40 °C. Add sodium borohydride and react at 40 °C for 2 h, where the molar ratio of sodium borohydride to carbonyl groups is 1.2:1. The reaction solution is filtered, rotary evaporated, and vacuum dried to obtain polyisobutylene with hydroxyl groups at the ends. The Mn of the product is 73,800 g / mol, and the PDI is 1.68.

[0054] Example 6

[0055] Dissolve 4.00 g of the polyisobutylene with carbonyl groups at the ends obtained in Example 3 in a mixed solution of 20 mL of acetone and 20 mL of n - hexane, and keep the temperature constant at 50 °C. Slowly add Jones reagent to the butyl rubber solution and react at 50 °C for 4 h, where the molar ratio of Jones reagent to carbonyl groups is 6:1. The reaction solution is filtered, rotary evaporated, and vacuum dried to obtain polyisobutylene with carboxyl groups at the ends. The M n of the product is 8,800 g / mol, and the PDI is 1.63.

[0056] Perform structural determination on the epoxidized butyl rubber in the preparation process of Example 3 and the medium - to - high - molecular - weight high - activity polyisobutylene with carbonyl groups at the ends obtained in Example 6, and obtain the nuclear magnetic resonance hydrogen spectra of the epoxidized butyl rubber and the medium - to - high - molecular - weight high - activity polyisobutylene with carbonyl groups at the ends as shown in Figure 1 ; perform structural determination on the medium - to - high - molecular - weight high - activity polyisobutylene with hydroxyl groups at the ends prepared in Example 4 to obtain the nuclear magnetic resonance hydrogen spectrum as shown in Figure 2 ; perform structural determination on the medium - to - high - molecular - weight high - activity polyisobutylene with carboxyl groups at the ends obtained in Example 6 to obtain the nuclear magnetic resonance hydrogen spectrum as shown inFigure 3 As shown, it can be seen that the present solution can prepare high-activity polyisobutene with medium to high molecular weight having a carbonyl group, a carboxyl group or a hydroxyl group at the chain end.

[0057] The above embodiments only represent several implementation manners of the present application, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A method for preparing medium-high molecular weight and highly active polyisobutylene, characterized in that: The following steps are involved: Mixing hydrogen peroxide and butyl rubber liquid and reacting them at 20 to 80° C. for 0.5 to 20 hours under the catalytic action of a catalyst to obtain epoxidized butyl rubber, wherein the molar ratio of hydrogen peroxide to the isoprene unit in the butyl rubber is 0.01 to 20:1; Dissolving epoxidized butyl rubber to obtain epoxidized butyl rubber solution; adding an oxidative cleavage agent to the epoxidized butyl rubber solution, and reacting at 0-80° C. for 0.5-20 hours to obtain a polyisobutylene solution, wherein the molar ratio of the oxidative cleavage agent to the epoxy group in the epoxidized butyl rubber solution is 1-4:1; The polyisobutylene solution is filtered and vacuum dried to remove the solvent to obtain medium-high molecular weight and highly active polyisobutylene.

2. The method for preparing medium-high molecular weight and highly active polyisobutylene according to claim 1, characterized in that: The following steps are involved: If it is necessary to obtain a medium-high molecular weight and highly active polyisobutylene with a hydroxyl group at the chain end, the method further includes the following steps before filtering the polyisobutylene solution: adding a reducing agent to the polyisobutylene solution and reacting at 0 to 80° C. for 0.5 to 20 hours, wherein the molar ratio of the reducing agent to the carbonyl group of the polyisobutylene in the polyisobutylene solution is 0.5 to 10:

1.

3. The method for preparing medium-high molecular weight and highly active polyisobutylene according to claim 1, characterized in that: The following steps are involved: If it is necessary to obtain a medium-high molecular weight and highly active polyisobutylene with a carboxyl group at the chain end, the method further includes the following steps before filtering the polyisobutylene solution: adding an oxidant to the polyisobutylene solution and reacting at 0 to 80° C. for 0.5 to 20 hours, wherein the molar ratio of the oxidant to the carbonyl group of the polyisobutylene in the polyisobutylene solution is 0.5 to 10:

1.

4. The method for preparing medium-high molecular weight and highly active polyisobutylene according to claim 1, characterized in that: The butyl rubber is dissolved in the first organic solvent to obtain a butyl rubber solution.

5. The method for preparing medium-high molecular weight and highly active polyisobutylene according to claim 1, characterized in that: The concentration of butyl rubber solution is 10-100g / L.

6. The method for preparing medium-high molecular weight and highly active polyisobutylene according to claim 1, characterized in that: The epoxidized butyl rubber is dissolved in the second organic solvent to obtain an epoxidized butyl rubber solution.

7. The method for preparing medium-high molecular weight and highly active polyisobutylene according to claim 1, characterized in that: The concentration of the epoxidized butyl rubber solution is 15-150 g / L.

8. The method for preparing medium-high molecular weight and highly active polyisobutylene according to claim 1, characterized in that: The hydrogen peroxide and butyl rubber solution are mixed and reacted at 20-80° C. for 0.5-20 hours under the catalytic action of a catalyst to obtain a reaction solution, the reaction solution is cooled and centrifuged to obtain a supernatant, methanol is added to the supernatant to obtain a precipitate, and the precipitate is vacuum dried to obtain epoxidized butyl rubber.

9. The method for preparing medium-high molecular weight and highly active polyisobutylene according to claim 1, characterized in that: The catalyst is quaternary ammonium tungstate heteropolyphosphotungstate.

10. A medium-high molecular weight and highly active polyisobutylene, characterized in that: The method for preparing the medium-high molecular weight and high activity polyisobutylene according to any one of claims 1 to 9 has a number average molecular weight Mn between 6,000 and 100,000 g / mol, a molecular weight distribution index PDI <1.8, and more than 95% of the medium-high molecular weight and high activity polyisobutylene has a carbonyl, hydroxyl or carboxyl terminal.

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