阅读说明：本技术 一种端亚氨基官能化大分子支化剂制备双峰分布星形支化丁基橡胶的淤浆聚合方法 (Slurry polymerization method for preparing bimodal distribution star-shaped branched butyl rubber by using terminal imino functionalized macromolecular branching agent ) 是由 伍一波 黄珊 商育伟 李树新 郭文莉 于 2019-11-22 设计创作，主要内容包括：本发明属于丁基橡胶制备技术领域的一种端亚氨基官能化大分子支化剂制备双峰分布星形支化丁基橡胶的淤浆聚合方法。该淤浆聚合方法包括合成端亚氨基官能化大分子支化剂和合成带有氨基的星形支化丁基橡胶两个步骤,采用活性阴离子聚合技术制备苯乙烯及其衍生物与异戊二烯的共聚物,并用席夫碱封端得到含亚氨基的支化剂大分子。将支化剂溶于氯甲烷中加入至丁基橡胶淤浆聚合釜中,作为阳离子聚合的接枝剂和淤浆稳定剂制备具有双峰分布的星形支化丁基橡胶；有更低的门尼应力松弛、特性黏度,具有更好的加工性能；封端时引入的亚氨基可增加支化剂极性,有利于炭黑在丁基橡胶基体中分散,改善丁基橡胶与炭黑相容性,体系能量降低。(The invention belongs to the technical field of butyl rubber preparation, and relates to a slurry polymerization method for preparing bimodal distribution star-shaped branched butyl rubber by using an imino-terminated functionalized macromolecular branching agent. The slurry polymerization method comprises two steps of synthesizing an imino-functionalized macromolecular branching agent and synthesizing star-branched butyl rubber with amino, a copolymer of styrene and derivatives thereof and isoprene is prepared by adopting a living anion polymerization technology, and the imino-containing branching agent macromolecules are obtained by using Schiff bases for end capping. Dissolving a branching agent in methyl chloride, adding the solution into a butyl rubber slurry polymerization kettle, and preparing star-shaped branched butyl rubber with bimodal distribution as a grafting agent and a slurry stabilizer for cationic polymerization; the Mooney stress relaxation and the intrinsic viscosity are lower, and the processing performance is better; the imino group introduced during the end sealing can increase the polarity of the branching agent, is beneficial to the dispersion of carbon black in a butyl rubber matrix, improves the compatibility of the butyl rubber and the carbon black and reduces the system energy.)

1. A slurry polymerization process for the preparation of bimodal distribution star branched butyl rubber from an imino-terminated functionalized macromolecular branching agent, comprising the specific experimental steps of:

step 1, synthesis of a terminal imino-functionalized macromolecular branching agent:

step 2, synthesizing star-shaped branched butyl rubber with amino groups:

wherein X is H, CH₃、C(CH₃)₃Or Cl; the solvent selected in the synthesis process is a nonpolar solvent, and mainly comprises one or more of n-hexane, cyclohexane, pentane, cyclopentane, isopentane, n-heptane, octane and isooctane; the initiator is an alkyl monolithium compound RLi, wherein R is a linear or branched chain alkyl, cycloalkyl or aryl containing 1-12 carbon atoms, and n-butyllithium and tert-butyllithium are specifically selected; the end capping agent is Schiff base (Schiff base) with a structural formula of R₁R₂C＝NR₃Wherein R is₁、R₂、R₃Is alkyl, aryl or alkoxy; or one of benzaldehyde aniline, benzaldehyde p-methylaniline and p-N, N-dimethylaminobenzoic acid aniline is selected.

2. The slurry polymerization process of claim 1, wherein the experimental steps are:

(1) adding a solvent, styrene and derivatives thereof, Tetramethylethylenediamine (TMEDA) and an initiator into a polymerization bottle under anhydrous and anaerobic conditions, shaking up and sealing, reacting at 20-50 ℃ for 3-5 hours, adding isoprene, reacting at 20-50 ℃ for 3-6 hours, adding Schiff base with the same amount as the initiator, reacting at 50-60 ℃ for 30min, adding a polymerization solvent and a terminator methanol after the reaction is finished, repeatedly dissolving and flocculating, washing off unreacted end-capping reagent, and drying in a vacuum drying oven at 30 ℃ for later use;

(2) dissolving a prepared branching agent sample, adding the sample, isobutene and isoprene into a polymerization kettle, reducing the temperature to below-85 ℃, adding a prepared initiator, adding methanol within 1min after the reaction starts, stopping, and carrying out vacuum drying on the sample to obtain the star-shaped branched butyl rubber with bimodal distribution; the synthesized star-branched butyl rubber has a number average molecular weight of 1.17 × 10⁵～33.1×10⁵Weight average molecular weight of 3.26X 10⁵～1.56×10⁶The molecular weight distribution is 1.8-3.4; the content of the synthesized star-shaped branched butyl rubber polymer region is 3-15%, and the molecular weight of the polymer region is 5.91 multiplied by 10⁵～8.82×10⁶And the average arm number is 4-12.

3. The slurry polymerization process of claim 1, wherein the initiator is formulated by: and adding a certain amount of saturated dichloromethane solution of water into the trichlorotriethylaluminum, adding 10-50 mL of dehydrated dichloromethane for dilution, and aging at room temperature for 10-30 min.

4. The slurry polymerization process of claim 1, wherein the amount of polystyrene and derivatives thereof is 40-80 wt% of the copolymer, the amount of 3,4 structures in the polyisoprene is 10-80 wt%, the end capping efficiency of the end capping agent is 70%, and the molecular weight of the branching agent is 5 x 10³～9.2×10⁴。

5. The slurry polymerization method for preparing the bimodal distribution star-branched butyl rubber by using the terminal imino-functionalized macromolecular branching agent according to claim 1, wherein the polymerization time of styrene and derivatives thereof in the synthesis of the terminal imino-functionalized macromolecular branching agent is 1-4 h, the polymerization time of isoprene is 2-6 h, and the reaction time of adding the end-capping agent is 20-60 min; the reaction temperature in the process of the polystyrene and the derivatives thereof and the polyisoprene is 20-50 ℃, and the reaction rate can be accelerated by raising the temperature; when the Schiff base is used for end capping, the reaction temperature is 50-60 ℃.

6. A slurry polymerization process for the preparation of bimodal distribution star-branched butyl rubber from a terminal imino-functionalized macromolecular branching agent according to claim 1, wherein the star-branched butyl rubber is synthesized using from 0.2% to 3% of the branching agent, the branching agent acting simultaneously as a slurry stabilizer and wherein the higher the proportion of polystyrene and its derivatives, the better the slurry stability; after the slurry stabilizer is added, the continuous polymerization time is prolonged from 30-40 h to 40-80 h.

7. The slurry polymerization process for the preparation of bimodal distribution star-branched butyl rubber from a terminal imino-functionalized macromolecular branching agent according to claim 1, wherein the diluent used is methyl chloride; the polymerization solvent for dissolving the branching agent during polymerization is chloromethane, dichloromethane, trichloromethane, carbon tetrachloride, 1, 2-dichloroethane, chlorobutane, chloropentane, 2-chloropropane, chlorocyclopentane, chlorocyclohexane, toluene and homologs thereof, and all the solvents are polar solvents; the main initiator is water, 2-chloro-2, 4, 4-trimethylpentane, HCl, BrH, HF and HClO₄、HClSO₃、H₂SO₄、H₃PO₄One of (1); the coinitiator is BeCl₂、ZnCl₂、CdCl₂、HgCl₂、BF₃、BCl₃、AlCl₃、Al₂Et₃Cl₃、AlEt₂Cl、AlBr₃、RAl₃、R_nAlX_n-3、SnCl₄、TiCl₄、TiBr₄、ZrCl₄、VCl₄、WCl₅、FeCl₃One or a mixture of several of them; wherein R represents a C1-C8 alkane, X represents a halogen atom, and n represents 0 to 3An integer number.

8. The slurry polymerization process for the preparation of bimodal distribution star-branched butyl rubber from a terminal imino-functionalized macromolecular branching agent according to claim 1, wherein the total concentration of monomeric isobutylene and isoprene in the synthesis of the star-branched butyl rubber is 10-30 wt%, preferably 30%, of the reaction system; the monomer isoprene accounts for 2-6 wt% of the total monomer.

9. The slurry polymerization process for the preparation of bimodal distribution star-branched butyl rubber from a terminal imino-functionalized macromolecular branching agent of claim 1, wherein the star-branched butyl rubber is synthesized at a reaction temperature of-60 ℃ to-100 ℃ and wherein decreasing the reaction temperature increases the molecular weight.

Technical Field

The invention belongs to the technical field of preparation of butyl rubber, and particularly relates to a slurry polymerization method for preparing bimodal distribution star-shaped branched butyl rubber by using an imino-terminated functionalized macromolecular branching agent; in particular to a method for preparing bimodal distribution star-shaped branched butyl rubber by a slurry polymerization method by taking imino functionalized macromolecules as branching agents; namely a preparation method for synthesizing star-shaped branched butyl rubber by using diblock terminal imino copolymer of styrene and derivatives thereof and isoprene as a branching agent and a slurry stabilizer.

Background

Butyl rubber is polymerized from isobutene and a small amount of isoprene, and is the only industrial product of the existing cationic polymerization. The molecular chain unsaturation degree of the butyl rubber is extremely low, about 0.5 to 3.3 percent (mol), which is far lower than that of the natural rubber, but the molecular chain unsaturation degree is enough to form a cross-linked network structure, and because of the high saturation structure, the butyl rubber has excellent aging resistance, low air permeability and air tightness which is 20 times that of the natural rubber; excellent shock-absorbing performance, good weather resistance and ozone resistance, thus being widely used for manufacturing medical bottle stoppers, rubber gloves and high-quality radial tires. The butyl rubber and the ethylene propylene diene monomer rubber have better heat resistance when being blended, and the durability and the storage life are better than those of a natural rubber inner tube.

Although butyl rubber has many advantages, the molecular structure is arranged closely, and has huge methyl group, which causes the stress relaxation to be slow in processing, the energy consumption is high, the processing performance is poor, in order to solve the problem, star-shaped branched butyl rubber is researched, and the star-shaped branched butyl rubber is a bimodal polymer which is composed of a graft structure with high molecular mass and a linear component with low molecular mass, has excellent viscoelasticity, has faster stress relaxation compared with the linear butyl rubber, and has lower energy consumption in processing.

In the process of preparing the star-branched butyl rubber, the key to the successful preparation of the star-branched butyl rubber is the synthesis of an effective branching agent. Researchers have conducted many studies on star-type branching systems using divinylbenzene as a branching agent. The system using divinylbenzene as a branching agent is easy to synthesize star-branched butyl rubber, can be used for researching the synthesis rule research and the structure characterization method research of the star-branched structure, but is not suitable for industrial application according to the current research result because the gel content is very high along with the increase of the molecular weight of the polymer. A large number of double bonds exist in an isoprene section in poly (styrene-isoprene), and a polyisobutylene chain segment is formed in the polymerization process of butyl rubber to attack the double bonds in the polyisoprene section to form a highly branched structure. The isoprene connecting segment formed by anionic polymerization has two microstructures of a 1, 4 structure and a 3,4 structure, the isoprene of the 3,4 structure is polymerized into a 1, 1-substituted vinyl polymer, the steric hindrance of a substituent group is small, the polarization degree is increased, and the double bond on the main chain of the 3, 4-structured polyisoprene is easily attacked by the polyisobutyl chain segment. Therefore, the polarity regulator such as amine or tetrahydrofuran is used for regulating the microstructure of polyisoprene to be mainly 3,4 structure, so that the grafting efficiency of the branching agent can be improved, and the average arm number and the macromolecular content of branched macromolecules can be increased.

The slurry polymerization is adopted in the industrial production of butyl rubber in China, the slurry polymerization has high conversion rate and is more economical compared with solution polymerization slurry polymerization, but in the slurry polymerization process, products are easy to agglomerate and block polymerization equipment, and a slurry stabilizer is added into a polymerization system to prevent agglomeration, prolong continuous polymerization time and improve energy efficiency.

Carbon black is the most widely applied reinforcing filler in rubber, butyl rubber has high molecular chain saturation degree, no polar group, poor compatibility with carbon black during processing, obvious payne effect, obviously reduced mechanical property and high processing energy consumption, and imino is introduced into a branching agent to enhance the molecular chain polarity of the butyl rubber, improve the compatibility of the butyl rubber and the reinforcing filler and also reduce the processing energy consumption.

Up to now, no report has been published on the synthesis of star-branched butyl rubber by using imino-terminated styrene and its derivatives and 3,4 structure-based isoprene diblock copolymer as branching agent and slurry stabilizer, which can improve the processability of butyl rubber, prolong the polymerization period and improve the compatibility of butyl rubber and carbon black. The synthesized star-shaped branched butyl rubber with double peak distribution is suitable for being used as the components of tire inner liners, inner tubes and sealing elements.

Disclosure of Invention

The invention aims to provide a slurry polymerization method for preparing bimodal distribution star-branched butyl rubber by using an imino-terminated functionalized macromolecular branching agent, which is characterized by comprising the following specific experimental steps:

step 1, synthesis of a terminal imino-functionalized macromolecular branching agent:

step 2, synthesizing star-shaped branched butyl rubber with amino groups:

wherein X is H, CH₃、C(CH₃)₃Or Cl; the solvent selected in the synthesis process is a nonpolar solvent, and mainly comprises one or more of n-hexane, cyclohexane, pentane, cyclopentane, isopentane, n-heptane, octane and isooctane; the initiator is an alkyl monolithium compound RLi, wherein R is a linear or branched chain alkyl, cycloalkyl or aryl containing 1-12 carbon atoms, and n-butyllithium and tert-butyllithium are specifically selected; the end capping agent is Schiff base (Schiff base) with a structural formula of R₁R₂C＝NR₃Wherein R is₁、R₂、R₃Is alkyl, aryl or alkoxy; or selecting one of benzaldehyde aniline, benzaldehyde p-methylaniline and p-N, N-dimethylaminobenzoic acid aniline;

the specific experiment of the step 1 comprises the following steps:

(1) adding a solvent, styrene and derivatives thereof, Tetramethylethylenediamine (TMEDA) and an initiator into a polymerization bottle under anhydrous and anaerobic conditions, shaking up and sealing, reacting at 20-50 ℃ for 3-5 hours, adding isoprene, reacting at 20-50 ℃ for 3-6 hours, adding Schiff base with the same amount as the initiator, reacting at 50-60 ℃ for 30min, adding a polymerization solvent and a terminator methanol after the reaction is finished, repeatedly dissolving and flocculating, washing off unreacted end-capping reagent, and drying in a vacuum drying oven at 30 ℃ for later use;

(2) dissolving a prepared branching agent sample, adding the sample, isobutene and isoprene into a polymerization kettle, reducing the temperature to below-85 ℃, adding a prepared initiator, adding methanol within 1min after the reaction starts, stopping, and carrying out vacuum drying on the sample to obtain the star-shaped branched butyl rubber with bimodal distribution; the synthesized star-branched butyl rubber has a number average molecular weight of 1.17 × 10⁵～33.1×10⁵Weight average molecular weight of 3.26X 10⁵～1.56×10⁶The molecular weight distribution is 1.8-3.4. The content of the synthesized star-shaped branched butyl rubber polymer region is 3-15%, and the molecular weight of the polymer region is 5.91 multiplied by 10⁵～8.82×10⁶And the average arm number is 4-12.

Preparing the initiator: adding a certain amount of saturated dichloromethane solution of water into trichlorotriethylaluminum, and adding 10-50 mL of water to remove waterMethylene dichlorideDiluting and aging at room temperature for 10-30 min.

In the process of synthesizing the terminal imino functionalized macromolecular branching agent, the content of the polystyrene and the derivatives thereof accounts for 40-80 wt% of the copolymer, the content of the 3,4 structures in the polyisoprene accounts for 10-80%, the end-capping efficiency of the end-capping agent is 70%, and the molecular weight of the branching agent is 5 multiplied by 10³～9.2×10⁴。

In the process of synthesizing the terminal imino group functionalized macromolecular branching agent, the polymerization time of styrene and derivatives thereof is 1-4 h, the polymerization time of isoprene is 2-6 h, and the end capping agent is added for reaction for 20-60 min. The reaction temperature of the polystyrene and the derivatives thereof and the polyisoprene is 20-50 ℃, the reaction rate can be increased by raising the temperature, and the reaction temperature is 50-60 ℃ when the Schiff base is used for end sealing.

The amount of the branching agent used in the synthesis of the star-branched butyl rubber is 0.2 to 3 percent, and the branching agent can also play a role of a slurry stabilizer, and the slurry stability is better when the proportion of the polystyrene and the derivative thereof is higher. After the slurry stabilizer is added, the continuous polymerization time is prolonged from 30-40 h to 40-80 h.

The diluent is chloromethane; dissolved branch in polymerizationThe polymerization solvent of the agent is chloromethane, dichloromethane, trichloromethane, carbon tetrachloride, 1, 2-dichloroethane, chlorobutane, chloropentane, 2-chloropropane, chlorocyclopentane, chlorocyclohexane, toluene and homologues thereof, all of which are polar solvents. The main initiator can be water, 2-chloro-2, 4, 4-trimethylpentane, HCl, BrH, HF, HClO₄、HClSO₃、H₂SO₄、H₃PO₄One of (1); the coinitiator may be BeCl₂、ZnCl₂、CdCl₂、HgCl₂、BF₃、BCl₃、AlCl₃、Al₂Et₃Cl₃、AlEt₂Cl、AlBr₃、RAl₃、R_nAlX_n-3、SnCl₄、TiCl₄、TiBr₄、ZrCl₄、VCl₄、WCl₅、FeCl₃Wherein R represents C1-C8 alkane, X represents halogen atom, and n represents an integer of 0-3.

During the synthesis of star-branched butyl rubber, the total concentration of the monomers isobutene and isoprene is 10-30 wt%, preferably 30% of the reaction system. The monomer isoprene accounts for 2-6 wt% of the total monomer.

The reaction temperature for synthesizing the star-shaped branched butyl rubber is between 60 ℃ below zero and 100 ℃ below zero, and the molecular weight can be improved by reducing the reaction temperature.

The method has the beneficial effects that the imino group is introduced at the tail end of the branching agent, the molecular chain polarity of the butyl rubber is enhanced, the compatibility of the butyl rubber and the reinforcing filler is improved, and the compatibility of the butyl rubber and the carbon black is improved. The synthesized star-shaped branched butyl rubber has lower solution viscosity, higher molecular weight, better carbon black compatibility, faster stress relaxation and far lower processing energy consumption than linear butyl rubber. The N in the terminal imino group can increase the electron cloud density on the double bond of the isobutene and the isoprene, is beneficial to the attack of cation active species and the existence of electron-pushing groups, improves the condition of rare electron cloud on carbon, reduces the system energy and increases the stability of cation polymerization.

Detailed Description

The invention provides a slurry polymerization method for preparing bimodal distribution star-shaped branched butyl rubber by using a terminal imino functionalized macromolecular branching agent, wherein the grafting efficiency of the branching agent is related to the microstructure of polyisoprene, and the polyisoprene with a 3,4 structure as a main structure has better grafting effect compared with the polyisoprene with a 1,2 structure as a main structure; styrene and its derivatives in the diblock copolymer of styrene and its derivatives with isoprene act to increase the solubility of the branching agent and the slurry stabilizer; the terminal imino groups of the branching agent increase the molecular polarity and improve the compatibility of the butyl rubber with carbon black. The synthesized star-shaped branched butyl rubber has lower solution viscosity, higher molecular weight, better carbon black compatibility, faster stress relaxation and far lower processing energy consumption than linear butyl rubber.

The invention is further illustrated by the examples in order to provide a better understanding of the invention.

(1) The raw material sources are as follows:

styrene, petroleum Yanshan petrochemical company, China;

isobutylene, petroleum Yanshan petrochemical, China;

monochloromethane, China Petroleum Yanshan petrochemical Co

Isoprene, petroleum Yanshan petrochemical company, China;

cyclohexane, petroleum Yanshan petrochemical, China;

n-butyl lithium, welength technologies ltd;

trichlorotriethylaluminum, largeway technologies ltd;

n, N, N ', N' -tetramethylethylenediamine, Prodwellin technologies, Inc.;

p-N, N-dimethylaminobenzoic acid anilide, Bailingwei science and technology Co., Ltd;

dichloromethane, beijing chemical plant;

anhydrous methanol, beijing chemical plant.

(2) The analysis method comprises the following steps:

the molecular weight and molecular weight distribution of the polymer, and the data of the content of the high molecular region were measured by using a combined equipment (SEC) of differential Refractive Index (RI)/multi-angle laser Light Scattering (LS) of Wyatt. The mobile phase was THF, flow rate was 1.0mL/min, and the test temperature was 35 ℃. A chromatographic column: 500-, 103-, 104-105-, the data processing software is Wyatt ASTRA.

Microstructure of polymer by hydrogen nuclear magnetic resonance spectroscopy¹H-NMR measurement. With CDCl₃(DMSO) as solvent, TMS as internal standard, at room temperature using a Bruker Vance 400MHZ nuclear magnetic resonance apparatus¹H-NMR measurement.

The average arm number f is the molecular weight (Mw) passing through the polymer domain₁(branched)) and molecular weight (Mw) of the low molecular region₀(linear)) the average number of arms of the branched butyl rubber was calculated, i.e., f ═ Mw₁/Mw₀