CN110305251B

CN110305251B - Polyisoprene oligomer, branched modifier and preparation method of branched rare earth isoprene rubber

Info

Publication number: CN110305251B
Application number: CN201810231313.6A
Authority: CN
Inventors: 孙伟; 赵姜维; 徐林; 李建成; 邵明波; 唐正伟
Original assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Current assignee: Sinopec Beijing Research Institute of Chemical Industry; China Petroleum and Chemical Corp
Priority date: 2018-03-20
Filing date: 2018-03-20
Publication date: 2021-12-31
Anticipated expiration: 2038-03-20
Also published as: CN110305251A

Abstract

The invention relates to the field of polyisoprene branching agents, and discloses a preparation method of a polyisoprene oligomer, a branching modifier and a branched rare earth isoprene rubber. The polyisoprene oligomer has the number average molecular weight of 3000-30000, and the oligomer has the structure that the content of cis 1,4 structural units is 65-75 wt%, the content of trans 1,4 structural units is 18-28 wt%, and the content of 3,4 structural units is 6-12 wt%. The polyisoprene oligomer provided by the invention can be prepared into a branched modifier by the method provided by the invention, the preparation process is simple, and water or ethanol is not required to be used as a terminator; the branched rare earth isoprene rubber is further used for preparing the branched rare earth isoprene rubber, so that the dynamic viscosity of the polymer can be effectively reduced, and the later processing of the polymer is facilitated.

Description

Polyisoprene oligomer, branched modifier and preparation method of branched rare earth isoprene rubber

Technical Field

The invention relates to the field of polyisoprene branching agents, in particular to a preparation method of a polyisoprene oligomer, a branching modifier and a branched rare earth isoprene rubber.

Background

The isoprene rubber has a structure and performance similar to those of natural rubber, is a universal synthetic rubber with excellent comprehensive performance, and is mainly used for producing tires. In recent years, rare earth isoprene rubber has high wet skid resistance and low rolling resistance, and the wear resistance can still keep a good level, so that the rare earth isoprene rubber attracts much attention in tire enterprises in the world.

However, the problems of high molecular weight, high linearity, narrow molecular weight distribution, high solution viscosity in the polymerization process, poor processability and the like of isoprene rubber prepared by polymerizing isoprene under the catalysis of rare earth limit the industrial popularization of the isoprene rubber. The chemical 'cutting' of the branched and grafted structure of the synthetic rubber is an effective method for controlling the viscosity of polymer solution and the strength and elasticity effect of polymer processing, and can also improve the compatibility when the synthetic rubber is used together with other rubber.

A new branched Mooney butadiene rubber variety 1280(BR) provided by Goodyear corporation has a series of excellent processing characteristics and physical and mechanical properties which are comparable to those of other butadiene rubbers. The Korean brocade lake company utilizes dialkyl zinc as a regulator, realizes the control of the branching degree of the nickel-based cis-1, 4-polybutadiene on the basis of not influencing the 1, 4-structure content, and has good processing performance and physical performance. The Michelin company adds Lewis acid to prepare branched polyisoprene at the later stage of polymerization reaction for preparing polyisoprene by rare earth neodymium catalysis. This reflects that branched modification of rubber is a hot spot in the development of new varieties of rubber at present.

CN200610083360.8 adopts molybdenum series or lithium series catalyst to prepare liquid polybutadiene, then butadiene and liquid polybutadiene are copolymerized under the molybdenum series catalyst system to prepare the high vinyl polybutadiene rubber. The specified graft copolymers can be prepared by copolymerization with other ethylenic monomers due to the presence of terminal or in-chain double bonds in the polybutadiene macromonomer. Compared with other existing graft polymers prepared by other methods, the method has the advantages that the length of the branched chain can be controlled during the preparation of the liquid polymer, the distribution is uniform, the homopolymer content is low, and the product quality is high. However, the liquid polybutadiene prepared by the patent needs to be obtained by steps of ethanol termination, precipitation, washing, drying and the like, and then the liquid polybutadiene is dissolved for use. The route is lengthy and cumbersome. Furthermore, in the above series of operations, it is inevitable that water, oxygen and residual polar solvent will affect the subsequent polymerization activity.

Disclosure of Invention

The invention aims to solve the problems of the existing preparation process of branching agents for isoprene rubber, and provides a polyisoprene oligomer, a branching modifier and a preparation method of branched rare earth isoprene rubber.

In order to achieve the above object, a first aspect of the present invention provides a polyisoprene oligomer, wherein the number average molecular weight of the oligomer is 3000 to 30000, and the oligomer has a structure in which the content of cis 1,4 structural units is 65 to 75 wt%, the content of trans 1,4 structural units is 18 to 28 wt%, and the content of 3,4 structural units is 6 to 12 wt%.

Preferably, the oligomer has a number average molecular weight of 4500-28000, and the oligomer has a structure in which the content of cis 1,4 structural units is 67-71 wt%, the content of trans 1,4 structural units is 19-26 wt%, and the content of 3,4 structural units is 7-11 wt%.

In a second aspect, the present invention provides a branching modifier, which is prepared by the following method:

oligomerizing isoprene in an oligomerization solvent in the presence of an inert atmosphere and an alkyllithium initiator to obtain a polyisoprene oligomer of the present invention;

and mixing the polyisoprene oligomer with aluminum alkyl to obtain the branching modifier.

Preferably, the alkyl lithium is of the formula R¹A compound represented by Li, wherein R¹Is C₁～C₆Alkyl groups of (a); preferably, the alkyl lithium is n-butyl lithium.

Preferably, the molar ratio of the alkyl lithium to isoprene, calculated as Li, is (2X 10)^-3～2×10^-2):1, preferably (2.5X 10)^-3～1.5×10^-2)：1。

Preferably, the aluminum alkyl is of the formula AlR² ₃A compound of formula (I) wherein R²Is C₁～C₆Preferably, the alkyl aluminum is triisobutylaluminum.

Preferably, the molar ratio of the alkyl aluminum to the alkyl lithium is (1-2): 1, preferably (1.05-1.5): 1, calculated as Al and calculated as Li.

Preferably, the oligomeric solvent is C₅～C₁₀The oligomerization temperature of the saturated alkane is 10-70 ℃, the oligomerization pressure is 0.1-0.4 MPa, and the oligomerization time is 1-10 h; preferably, the oligomerization temperature is 25-65 ℃, the oligomerization pressure is 0.15-0.35 MPa, and the oligomerization time is 3-7 h.

The third aspect of the invention provides a preparation method of branched rare earth isoprene rubber, which comprises the following steps:

isoprene monomer and the branching modifier are polymerized in a polymerization solvent in the presence of an inert atmosphere and a rare earth polymerization catalyst.

Preferably, the concentration of the isoprene monomer in the polymerization solvent is 8 to 20 wt%; the branched modifier contains polyisoprene oligomer, and the polyisoprene oligomer accounts for 0.5-7 wt% of the isoprene monomer; the rare earth polymerization catalyst contains neodymium element, and the molar ratio of the rare earth polymerization catalyst to the isoprene monomer is (0.6 multiplied by 10) in terms of Nd^-4～5×10^-4)：1。

Preferably, the polymerization temperature is 0-70 ℃, the polymerization pressure is 0.1-0.4 MPa, and the polymerization time is 1-10 h.

Preferably, the rare earth polymerization catalyst contains neodymium carboxylate, an alkyl aluminum compound and a halide; the molar ratio of the alkyl aluminum compound to the neodymium carboxylate in terms of Al and Nd is (10-80): 1; the molar ratio of the halide to the neodymium carboxylate in terms of Nd is (1-6): 1.

preferably, the neodymium carboxylate is neodymium carboxylate with 7-14 carbon atoms, and the alkyl aluminum compound is of the general formula AlR³ ₃And/or AlHR⁴ ₂A compound of formula (I), R³、R⁴Are each independently C₁～C₆Alkyl groups of (a); the halide is of the general formula AlR⁵ ₂A compound represented by Cl, R⁵Is C₁～C₆Alkyl group of (1).

Through the technical scheme, the polyisoprene oligomer provided by the invention can be prepared into the branched modifier through the method provided by the invention, the preparation process is simple, and water or ethanol is not required to be used as a terminator; the branched modifier is further used for preparing branched rare earth isoprene rubber, can effectively reduce the dynamic viscosity of the prepared polymer, and is beneficial to the later processing of the polymer.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The first aspect of the invention provides a polyisoprene oligomer, wherein the number average molecular weight of the oligomer is 3000-30000, the content of cis 1,4 structural units in the oligomer structure is 65-75 wt%, the content of trans 1,4 structural units in the oligomer structure is 18-28 wt%, and the content of 3,4 structural units in the oligomer structure is 6-12 wt%.

In the present invention, the number average molecular weight of the oligomer may be determined byAnd (3) Gel Permeation Chromatography (GPC) characterization. Structural units of the oligomer are represented by¹H NMR characterization was performed using AVANCE II 400, manufactured by Bruker, Switzerland. The respective contents of the cis 1,4 structural unit, the trans 1,4 structural unit and the 3,4 structural unit in the oligomer are obtained¹And H NMR spectrum, measuring the area of the characteristic peak and determining by calculation.

In the invention, the variety of the alkyl lithium is wide in the optional range, and the alkyl lithium commonly used in the field can achieve the aim of the invention. Preferably, the alkyl lithium is of the formula R¹A compound represented by Li, wherein R¹Is C₁～C₆Alkyl group of (1). Specifically, the alkyl lithium may be selected from one or more of methyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, and tert-butyl lithium, and preferably, the alkyl lithium is n-butyl lithium.

In the present invention, the amount of the alkyllithium may be not particularly limited and may be appropriately selected depending on the molecular weight of the intended oligomer. Preferably, the molar ratio of the alkyl lithium to isoprene, calculated as Li, is (2X 10)^-3～2×10^-2):1, preferably (2.5X 10)^-3～1.5×10^-2)：1。

In the invention, the variety of the alkyl aluminum is wide in the optional range, and the aim of the invention can be achieved. Preferably, the aluminum alkyl is of the formula AlR² ₃A compound of formula (I) wherein R²Is C₁～C₆Preferably, the alkyl aluminum is triisobutylaluminum.

In the present invention, the aluminum alkyl is added after the oligomerization reaction is completed, for mixing with the polyisoprene oligomer. As the amount of the aluminum alkyl is increased, a large amount of inactive coordination complex can be formed, and the rate of the lithium-based catalytic polymerization reaction can be greatly reduced, so that the polymerization activity is finally lost. Preferably, the molar ratio of the alkyl aluminum to the alkyl lithium is (1-2): 1, preferably (1.05-1.5): 1, calculated as Al and calculated as Li.

In the present invention, the oligomerization reaction is carried out for the purpose of obtaining the polyisoprene oligomer of the present invention. Preferably, the oligomeric solvent is C₅～C₁₀The oligomerization temperature of the saturated alkane is 10-70 ℃, the oligomerization pressure is 0.1-0.4 MPa, and the oligomerization time is 1-10 h; preferably, the oligomerization temperature is 25-65 ℃, the oligomerization pressure is 0.15-0.35 MPa, and the oligomerization time is 3-7 h.

In the present invention, the oligomerization solvent may be selected from at least one of hexane, cyclohexane, methylcyclopentane, n-heptane and n-octane. The concentration of isoprene in the oligomerization solvent may be 8 to 20 wt%.

In the present invention, the inert atmosphere may be an oxygen-free condition, such as a nitrogen atmosphere.

In the invention, the preparation process of the branched modifier can be specifically as follows:

vacuumizing a plurality of polymerization bottles, baking at high temperature, and filling high-purity nitrogen into the polymerization bottles for repeating the steps for three times; the oligomeric solvent, isoprene, was added in the same amount to multiple polymerization flasks.

One of the polymerization bottles is taken as a miscellaneous bottle, 4-vinylpyridine is added as an indicator, and lithium alkyl (Li for short) is adopted to calibrate the amount of impurities in the oligomeric solvent and isoprene.

The initiator alkyllithium was added to the other polymerization bottles in a metered amount, minus the corresponding amount of the catalyst, and then the oligomerization of isoprene was carried out under the above-described oligomerization conditions.

And (3) after the reaction is finished, adding alkyl aluminum (Al for short) into a polymerization bottle to obtain the branching modifier containing the polyisoprene oligomer.

The branched modifier provided by the invention is prepared by the method, contains the polyisoprene oligomer with the defined structure and a defined amount of aluminum alkyl, can be used for preparing branched rare earth isoprene rubber, has reduced dynamic viscosity, and is beneficial to the post processing of the polymer.

The present invention also provides a method for preparing the polyisoprene oligomer, which comprises the following steps: the isoprene in the oligomerization solvent is oligomerized in the presence of an alkyl lithium initiator under an inert atmosphere. Wherein the conditions are as described above.

In the present invention, preferably, the concentration of the isoprene monomer in the polymerization solvent may be 8 to 20 wt%.

In the present invention, preferably, the branched modifier comprises the polyisoprene oligomer of the invention, wherein the polyisoprene oligomer is 0.5 to 7 wt% of the isoprene monomer; preferably 3 to 5% by weight.

In the invention, the polymerization temperature is preferably 0-70 ℃, the polymerization pressure is preferably 0.1-0.4 MPa, and the polymerization time is preferably 1-10 h. Preferably, the polymerization temperature is 5-65 ℃, the polymerization pressure is 0.15-0.35 MPa, and the polymerization time is 2-6 h.

In the present invention, the polymerization solvent may be C₅～C₁₀And/or C₅～C₁₀More preferably, the polymerization solvent is selected from one or more of n-pentane, isopentane, n-hexane, cyclohexane, n-heptane and n-octane.

In the present invention, the polymerization reaction may be carried out in an inert atmosphere in order to overcome oxygen inhibition. The inert gas atmosphere may be maintained by introducing an inert gas into the polymerization reaction system. The inert atmosphere may be, for example, nitrogen.

In the present invention, after the completion of the polymerization reaction, the termination reaction may be carried out by adding a terminator to activateThe polymer chain is deactivated, so that the polymerization reaction is terminated. The kind and amount of the terminator are not particularly limited as long as the terminator is capable of inactivating the living polymer chains. In general, the terminating agent may be water, C₁～C₆Aliphatic alcohol of (1), C₄～C₁₂And an aryl polyol, which is a compound produced by substituting at least two of the hydrogen atoms on the benzene ring with hydroxyl groups. Preferably, the terminating agent is one or more of water, methanol, ethanol, isopropanol and 2, 6-di-tert-butylhydroquinone.

In the present invention, the amount of the terminator is not particularly limited as long as the amount of the terminator is capable of deactivating the active species in the polymerization product, and thus, it is not described herein again.

In the invention, after finishing the termination reaction, the polymer solution is precipitated, washed and dried to obtain the branched rare earth isoprene rubber.

In the present invention, the kind of the rare earth polymerization catalyst used in the polymerization reaction is not particularly limited, and various rare earth catalysts conventionally used for isoprene rubber may be used. For example, the rare earth polymerization catalyst may contain rare earth organic carboxylates, aluminum alkyls and/or aluminum alkyl hydrides, halogen-containing compounds, and polymers obtained by polymerizing conjugated dienes. As another example, the rare earth polymerization catalyst can contain neodymium carboxylates, alkyl aluminum compounds, and halides. Preferably, the rare earth polymerization catalyst contains neodymium carboxylate, an alkyl aluminum compound, and a halide.

In the present invention, it is preferable that the molar ratio of the alkyl aluminum compound in terms of Al to the neodymium carboxylate in terms of Nd is (10 to 80): 1, preferably (20-50): 1; the molar ratio of the halide to the neodymium carboxylate in terms of Nd is (1-6): 1, preferably (2-4): 1.

in the present invention, the kind of the neodymium carboxylate can be selected widely, and the neodymium carboxylate commonly used in the art can achieve the purpose of the present invention. Preferably, the neodymium carboxylate is neodymium carboxylate with 7-14 carbon atoms, and preferably, the neodymium carboxylate can be selected from one or more of neodymium naphthenate, neodymium n-octoate, neodymium iso-octoate, neodymium neodecanoate and neodymium n-decanoate.

In the present invention, the kind of the aluminum alkyl compound can be selected from a wide range, and the aluminum alkyl commonly used in the art can achieve the object of the present invention. The alkyl aluminum compound is of the general formula AlR³ ₃And/or AlHR⁴ ₂A compound of formula (I), R³、R⁴Are each independently C₁～C₆Alkyl groups of (a); preferably, the alkyl aluminum compound is triisobutylaluminum and/or diisobutylaluminum hydride.

In the present invention, the kind of the halide is widely selected, and the halide commonly used in the art can achieve the object of the present invention. The halide is of the general formula AlR⁵ ₂A compound represented by Cl, R⁵Is C₁～C₆Alkyl group of (1). Preferably the halide is one or more of diethylaluminum monochloride, ethylaluminum sesquichloride and diisobutylaluminum monochloride.

In the present invention, the amount of the rare earth polymerization catalyst used may be appropriately selected according to the molecular weight of the intended branched rare earth isoprene rubber. Preferably, the rare earth polymerization catalyst contains neodymium element, and the molar ratio of the rare earth polymerization catalyst to the isoprene monomer in terms of Nd is (0.6X 10)^-4～5×10^-4):1, preferably (1X 10)^-4～4×10^-4)：1。

In the present invention, an aged liquid of the rare earth polymerization catalyst may be used. Can be prepared by the following method:

any two components of neodymium carboxylate, alkyl aluminum compound and halide are contacted in an organic solvent and subjected to a first aging, and then the remaining other component is added and subjected to a second aging.

In the present invention, the organic solvent can be selected from a wide range, for example, saturated aliphatic hydrocarbons and alicyclic hydrocarbons; preferably selected from C₅～C₁₀Linear alkane of (1) and C₅～C₁₀Cycloalkane of (a); more preferably selected from the group consisting of n-pentane, isopentane, n-hexane, cyclohexane, n-heptane and n-octaneOne or more of alkanes.

In the present invention, the conditions of the first aging and the second aging are well known to those skilled in the art, and it is sufficient that the components in the rare earth catalyst are sufficiently mixed and reacted, and further the isoprene is catalyzed and polymerized to obtain polyisoprene with the above properties, but in order to eliminate or reduce the influence of the components in the air on the aging process, the first aging and the second aging are preferably performed in an inert atmosphere. The inert atmosphere refers to any gas or gas mixture which does not chemically react with the reactants and products, such as one or more of nitrogen and a gas from group zero of the periodic table of elements. The first aging condition generally comprises a temperature of 30-60 ℃ and a time of 10-60 min, and the second aging condition generally comprises a temperature of 10-30 ℃ and a time of 1-48 h.

The present invention will be described in detail below by way of examples.

The following are the test characterization methods in the examples and comparative examples.

The dynamic viscosity measuring method of the glue solution comprises the following steps: the polymerization product was made into a 2g/100ml solution using cyclohexane as a solvent, and the torque α of the solution at different rotational speeds (. gamma.) was measured at 25. + -. 0.2 ℃ using a rotational viscometer. Calculating the dynamic viscosity eta of the glue sample according to the following formula: τ is α × Z, η is τ/Ds, Z is a rotation angle constant, τ is shear stress, Ds is a shear rate;

characterizing the polyisoprene by Gel Permeation Chromatography (GPC) for weight average molecular weight (Mw) and molecular weight distribution (Mw/Mn), and preparing standard curves with polystyrene standards;

microstructure of polymer¹H NMR characterization was performed using AVANCE II 400, manufactured by Bruker, Switzerland.

Selecting a formant with a chemical shift delta of 1.61ppm as-CH in trans-1, 4-polyisoprene₃Analysis of peaks and-CH in 3, 4-Polyisoprene₃Analyzing a peak, and recording the peak area as Q;

selecting a resonance peak with a chemical shift delta of 1.68ppm as-CH in cis-1, 4-polyisoprene₃The peak area is recorded asP；

Selecting a formant with a chemical shift δ of 4.68-4.76ppm as ═ CH in 3, 4-polyisoprene₂Analyzing a peak, and recording the peak area as N;

a resonance peak with a chemical shift delta of 5.12ppm was selected as a CH-analyzed peak in cis-1, 4-polyisoprene and trans-1, 4-polyisoprene isoprene rubber, and the peak area was M. Then:

cis 1, 4-structure% ═ P/(P + Q). times.100%

Trans 1, 4-structure% ═ 2M/(2M + N) × 100% P/(P + Q) × 100%

3, 4-structure% ═ N/(2M + N) × 100%.

Examples A1-A3

Marking 4 polymerization bottles as A0, A1, A2 and A3, vacuumizing, baking at high temperature, filling high-purity nitrogen, and repeating the steps for three times;

the same amount of hexane and isoprene (isoprene content 0.10g isoprene/mL hexane, Ip for short) was added to each polymerization flask. Taking a polymerization bottle A0 as a impurity killing bottle, adding 4-vinylpyridine as an indicator, and calibrating the amount of impurities in the solution by nBuLi to obtain the impurity killing amount.

Polymerization bottles A1, A2 and A3 were charged with a stoichiometric amount of the initiator nBuLi (Li for short), which was measured according to the Li/Ip data in Table 1. Isoprene in polymerization bottles a1, a2 and A3 was oligomerized under the oligomerization conditions shown in table 1, and triisobutylaluminum (abbreviated as Al) was added in a metered amount to polymerization bottles a1, a2 and A3 after the completion of the reaction, and the molar ratio of the metered amount of Al to the amount of Li added excluding the amount of impurities was as shown in table 1, thereby obtaining a branching modifier PIP.

The molecular weight and microstructure content of the obtained PIP are shown in table 1.

The methods of example A1, example A2, and example A3 correspond to the methods of obtaining the branching modifiers PIP from polymer bottles A1, A2, and A3, respectively, and the branching modifiers obtained are numbered PIP-1, PIP-2, PIP-3.

Comparative example A1

The procedure is as in example A2, except that triisobutylaluminum is added in such an amount that the "molar ratio of the amount of Al metered to the amount of Li (minus the amount of impurities)" is 0.8 and the "molar ratio of the amount of Al metered to the amount of Li (minus the amount of impurities)" is 1.05. The branched modifier PIP was prepared with the designation PIP-D1.

Comparative example A2

The procedure is as in example A2, except that "after the end of the reaction, an ethanolic solution containing hydrogen chloride (molar ratio of the amount of HCl to the amount of Li added, minus the amount of impurities, is 6)" is added to the polymerization flask A2 instead of "after the end of the reaction, a metered amount of triisobutylaluminum is added to the polymerization flask A2, the molar ratio of the amount of Al to the amount of Li added, minus the amount of impurities, being 1.05".

Most of the solvent of the prepared liquid polyisoprene is removed by a rotary evaporator, and the liquid polyisoprene is dried in vacuum to obtain a branching modifier PIP with the number of PIP-D2.

The molecular weight and microstructure content of the obtained liquid PIP are shown in table 1.

Preparation example 1

Preparing the rare earth polymerization catalyst.

Adding a certain amount of neodymium neodecanoate (Nd) and triisobutylaluminum (Al) into a catalyst preparation device under the protection of nitrogen, wherein Al/Nd (mol) is 30: 1; after aging at 30 ℃ for 0.5h, a certain amount of diethylaluminum monochloride (abbreviation: Cl), Cl/nd (mol) ═ 2.5: aging is continued for 1 hour at the temperature of 1 and 30 ℃.

The resulting catalyst aging solution was designated Cat-1.

Preparation example 2

Preparing the rare earth polymerization catalyst.

Adding certain amounts of neodymium neodecanoate (Nd) and triisobutylaluminum (Al) into a catalyst preparation device under the protection of nitrogen, wherein Al/Nd (mol) is 20: 1; after aging at 40 ℃ for 10min, a certain amount of diethylaluminum monochloride (abbreviation: Cl), Cl/nd (mol) ═ 4: aging is continued for 48h at 1 and 20 ℃.

The resulting catalyst aging solution was designated Cat-2.

Preparation example 3

Preparing the rare earth polymerization catalyst.

Adding certain amounts of neodymium neodecanoate (Nd) and triisobutylaluminum (Al) into a catalyst preparation device under the protection of nitrogen, wherein Al/Nd (mol) is 50: 1; after aging at 60 ℃ for 1h, a certain amount of diethylaluminum monochloride (abbreviation: Cl), Cl/nd (mol) 2: aging is continued for 35h at 1 and 10 ℃.

The prepared catalyst aging liquid is marked as Cat-3.

Example B1

In a stainless steel reaction vessel evacuated under vacuum and replaced with high-purity nitrogen three times, hexane and isoprene (the concentration of isoprene in hexane is about 13% by weight) were added, and the branching modifier PIP-1 (polyisoprene (W) contained) obtained in example A1 was added_PIP) Is isoprene (W)_Ip) 3 wt% of). Adding Cat-1(Nd/ip (mol) ═ 3.0X 10)^-4: 1) then, the mixture is reacted for 6 hours at 50 ℃ and 0.25MPa, and after the polymerization is finished, the reaction is stopped by ethanol containing 2, 6-di-tert-butyl hydroquinone (264) to obtain polymer glue solution. And precipitating, washing and drying the polymer solution to obtain the polymer.

The polymer test results are shown in table 2. Measured by rotational viscometer,. gamma. 49.81s^-1The dynamic viscosity at that time was 0.165 pas, the number average molecular weight of the polymer measured by GPC was 35.4 ten thousand, the molecular weight distribution index was 3.87, and the 1, 4-structure content of the polymerization product was 98.0%.

Example B2

In a stainless steel reaction vessel evacuated under vacuum and replaced with high-purity nitrogen three times, hexane and isoprene (the concentration of isoprene in hexane is about 13% by weight) were added, and the branching modifier PIP-2 obtained in example A2 (containing polyisoprene (W2) was added_PIP) Is isoprene (W)_Ip) 5 wt% of). Adding Cat-1(Nd/ip (mol) ═ 3.0X 10)^-4: 1) then reacting for 5h at 55 ℃ and 0.20MPa, after the polymerization is finished, using ethanol containing 2, 6-di-tert-butylhydroquinone (264) to terminate the reaction, and precipitating, washing and drying the polymer solution to obtain the polymer.

Polymer analysis tests were performed and the results are shown in Table 2.

Example B3

Is vacuumizedA stainless steel autoclave was purged with high-purity nitrogen three times, followed by addition of hexane and isoprene (concentration of isoprene in hexane: about 13% by weight) respectively, and addition of the branching modifier PIP-3 obtained in example A3 (containing polyisoprene (W)_PIP) Is isoprene (W)_Ip) 4 wt% of). Adding Cat-1(Nd/ip (mol) ═ 3.0X 10)^-4: 1) then reacting for 6h at 60 ℃ and 0.30MPa, after the polymerization is finished, using ethanol containing 2, 6-di-tert-butylhydroquinone (264) to terminate the reaction, and precipitating, washing and drying the polymer solution to obtain the polymer.

Polymer analysis tests were performed and the results are shown in Table 2.

Example B4

The procedure is as in example B1, except that "the branching modifier PIP-1 (containing polyisoprene (W) obtained in example A1 is added_PIP) Is isoprene (W)_Ip) 0.5% by weight of the total amount of the branched modifier PIP-1 (containing polyisoprene (W)) obtained in example A1 was added "instead of_PIP) Is isoprene (W)_Ip) 3% by weight of (c) ". And (3) preparing a polymer.

The polymer analysis was tested and the results are shown in Table 2.

Example B5

The procedure is as in example B1, except that "the branching modifier PIP-1 (containing polyisoprene (W) obtained in example A1 is added_PIP) Is isoprene (W)_Ip) 1.5% by weight of the total amount of the branched modifier PIP-1 (containing polyisoprene (W)) obtained in example A1 was added "instead of_PIP) Is isoprene (W)_Ip) 3% by weight of (c) ". And (3) preparing a polymer.

The polymer analysis was tested and the results are shown in Table 2.

Example B6

In a stainless steel reaction vessel evacuated under vacuum and replaced with high-purity nitrogen three times, hexane and isoprene (the concentration of isoprene in hexane is about 13% by weight) were added, and the branching modifier PIP-2 obtained in example A2 (containing polyisoprene (W2) was added_PIP) Is isoprene (W)_Ip) 1 wt% of). Adding Cat-1(Nd/ip (mol) ═ 3.0X 10)^-4: 1) then reacting for 4h at 50 ℃, and after the polymerization is finished, terminating the reaction by using ethanol containing 2, 6-di-tert-butylhydroquinone (264) to obtain polymer glue solution. And precipitating, washing and drying the polymer solution to obtain the polymer.

Polymer analysis tests were performed and the results are shown in Table 2.

Example B7

The procedure is as in example B6, except that "the branching modifier PIP-2 obtained in example A2 (containing polyisoprene (W))_PIP) Is isoprene (W)_Ip) 3% by weight of) of the branched modifier PIP-2 obtained in example A2 (containing polyisoprene (W)_PIP) Is isoprene (W)_Ip) 1% by weight of (c) ". And (3) preparing a polymer.

The polymer analysis was tested and the results are shown in Table 2.

Example B8

The procedure is as in example B6, except that "the branching modifier PIP-2 obtained in example A2 (containing polyisoprene (W))_PIP) Is isoprene (W)_Ip) 7% by weight of the polymer solution was "substituted" by adding the branched modifier PIP-2 obtained in example A2 (containing polyisoprene (W)_PIP) Is isoprene (W)_Ip) 1% by weight of (c) ". And (3) preparing a polymer.

The polymer analysis was tested and the results are shown in Table 2.

Example B9

In a stainless steel reaction vessel evacuated under vacuum and replaced with high-purity nitrogen three times, hexane and isoprene (the concentration of isoprene in hexane is about 13% by weight) were added, and the branching modifier PIP-3 (polyisoprene (W) contained) obtained in example A3 was added_PIP) Is isoprene (W)_Ip) 1 wt% of). Adding Cat-1(Nd/ip (mol) ═ 3.0X 10)^-4: 1) then reacting for 4h at 50 ℃, and after the polymerization is finished, terminating the reaction by using ethanol containing 2, 6-di-tert-butylhydroquinone (264) to obtain polymer glue solution. And precipitating, washing and drying the polymer solution to obtain the polymer.

Polymer analysis tests were performed and the results are shown in Table 2.

Example B10

The procedure is as in example B9, except that "the branching modifier PIP-3 (containing polyisoprene (W) obtained in example A3 is added_PIP) Is isoprene (W)_Ip) 2% by weight of the total amount of the branched modifier PIP-3 obtained in example A3 (containing polyisoprene (W))_PIP) Is isoprene (W)_Ip) 1% by weight of (c) ". And (3) preparing a polymer.

The polymer analysis was tested and the results are shown in Table 2.

Example B11

In a stainless steel reaction vessel evacuated under vacuum and replaced with high-purity nitrogen three times, hexane and isoprene (the concentration of isoprene in hexane is about 20% by weight) were added, and the branching modifier PIP-2 obtained in example A2 (containing polyisoprene (W2) was added_PIP) Is isoprene (W)_Ip) 5 wt% of). Adding Cat-2(Nd/ip (mol) ═ 5.0X 10)^-4: 1) then reacting for 2h at 10 ℃ and 0.15MPa, after the polymerization is finished, using ethanol containing 2, 6-di-tert-butylhydroquinone (264) to terminate the reaction, and precipitating, washing and drying the polymer solution to obtain the polymer.

Polymer analysis tests were performed and the results are shown in Table 2.

Example B12

In a stainless steel reaction vessel evacuated under vacuum and replaced with high-purity nitrogen three times, hexane and isoprene (concentration of isoprene in hexane: about 8% by weight) were added, and the branching modifier PIP-3 obtained in example A3 (containing polyisoprene (W) was added_PIP) Is isoprene (W)_Ip) 4 wt% of). Adding Cat-3(Nd/ip (mol) ═ 0.6X 10)^-4: 1) reacting for 8h at 60 ℃ and 0.35MPa, terminating the reaction by using ethanol containing 2, 6-di-tert-butylhydroquinone (264) after the polymerization is finished, and precipitating, washing and drying the polymer solution to obtain the polymer.

Polymer analysis tests were performed and the results are shown in Table 2.

Example B13

The procedure is as in example B11, except that "the branching modifier PIP-2 (comprising poly) obtained in example A2 is addedIsoprene (W)_PIP) Is isoprene (W)_Ip) 3% by weight of) of the branched modifier PIP-2 obtained in example A2 (containing polyisoprene (W)_PIP) Is isoprene (W)_Ip) 5% by weight of (c) ". And (3) preparing a polymer.

The polymer analysis was tested and the results are shown in Table 2.

Example B14

The procedure is as in example B12, except that "the branching modifier PIP-3 (containing polyisoprene (W) obtained in example A3 is added_PIP) Is isoprene (W)_Ip) 2% by weight of the total amount of the branched modifier PIP-3 obtained in example A3 (containing polyisoprene (W))_PIP) Is isoprene (W)_Ip) 4% by weight of (c) ". And (3) preparing a polymer.

The polymer analysis was tested and the results are shown in Table 2.

Comparative example B1

In a stainless steel reaction vessel evacuated under vacuum and replaced with high-purity nitrogen three times, hexane and isoprene (the concentration of isoprene in hexane is about 13% by weight) were added, and Cat-1(Nd/ip (mol) ═ 3.0 × 10) was added^-4: 1) then reacting for 4 hours at 50 ℃, after the polymerization is finished, using ethanol containing 2, 6-di-tert-butyl hydroquinone (264) to terminate the reaction, and precipitating, washing and drying the polymer solution to obtain the polymer.

Polymer analysis tests were performed and the results are shown in Table 2.

Comparative example B2

In a stainless steel reaction vessel evacuated under vacuum and replaced with high-purity nitrogen three times, hexane and isoprene (the concentration of isoprene in hexane is about 13% by weight) were added, and the branching modifier PIP-D1 (polyisoprene (W) contained therein) obtained in comparative example A1 was added_PIP) Is isoprene (W)_Ip) 3 wt% of). Adding Cat-1(Nd/ip (mol) ═ 3.0X 10)^-4: 1) then reacting for 4 hours at 50 ℃, after the polymerization is finished, using ethanol containing 2, 6-di-tert-butyl hydroquinone (264) to terminate the reaction, and precipitating, washing and drying the polymer solution to obtain the polymer.

Polymer analysis tests were performed and the results are shown in Table 2.

Comparative example B3

In a stainless steel reaction vessel evacuated under vacuum and replaced with high-purity nitrogen three times, hexane and isoprene (the concentration of isoprene in hexane is about 13% by weight) were added, and the branching modifier PIP-D2 (polyisoprene (W) contained therein) obtained in comparative example A2 was added_PIP) Is isoprene (W)_Ip) 3 wt% of). Adding Cat-1(Nd/ip (mol) ═ 3.0X 10)^-4: 1) then reacting for 4 hours at 50 ℃, after the polymerization is finished, using ethanol containing 2, 6-di-tert-butyl hydroquinone (264) to terminate the reaction, and precipitating, washing and drying the polymer solution to obtain the polymer.

Polymer analysis tests were performed and the results are shown in Table 2.

Comparative example B4

In a stainless steel reaction vessel evacuated under vacuum and replaced with high-purity nitrogen three times, hexane and isoprene (concentration of isoprene in hexane is about 20% by weight) were added, respectively. Adding Cat-2(Nd/ip (mol) ═ 5.0X 10)^-4: 1) then reacting for 2h at 10 ℃ and 0.15MPa, after the polymerization is finished, using ethanol containing 2, 6-di-tert-butylhydroquinone (264) to terminate the reaction, and precipitating, washing and drying the polymer solution to obtain the polymer.

Polymer analysis tests were performed and the results are shown in Table 2.

Comparative example B5

In a stainless steel reaction vessel evacuated under vacuum and replaced with high-purity nitrogen three times, hexane and isoprene (concentration of isoprene in hexane is about 8% by weight) were added, respectively. Adding Cat-3(Nd/ip (mol) ═ 0.6X 10)^-4: 1) reacting for 8h at 60 ℃ and 0.35MPa, terminating the reaction by using ethanol containing 2, 6-di-tert-butylhydroquinone (264) after the polymerization is finished, and precipitating, washing and drying the polymer solution to obtain the polymer.

Polymer analysis tests were performed and the results are shown in Table 2.

TABLE 1

TABLE 2

As can be seen from the results of examples, comparative examples and Table 2, in examples B1-B3 and B7, when branched rare earth isoprene rubber is prepared by using the same catalyst Cat-1 and the same amount, and the branched modifier containing polyisoprene oligomer (branched modifier PIP of example A1-example A3) provided by the invention is added in the polymerization reaction in an amount satisfying 3-5 wt% of polyisoprene oligomer as isoprene monomer, compared with comparative examples B1-B3 (using the same catalyst Cat-1 and the same amount, but without adding the branched modifier (B1), and using the branched modifiers PIP-D1, PIP-D2), branched rare earth isoprene rubber with equivalent number average molecular weight can be synthesized, the kinetic viscosity of the prepared rare earth isoprene rubber cement can be effectively reduced, and the influence on the polymerization activity is not great, the conversion rate can reach more than 95 percent.

Examples B4-B6 and B8-B10 also added the branching modifier (PIP-1, PIP-2, PIP-3) of the invention when preparing branched rare earth isoprene rubber, compared with comparative examples B1-B3 using the same catalyst Cat-1 and amount, the dynamic viscosity of the prepared rare earth isoprene rubber cement liquid is effectively reduced when obtaining branched rare earth isoprene rubber with equivalent number average molecular weight.

When the Cat-2 or Cat-3 is used in examples B11-B14 and the amount is limited to the amount used in the invention for isoprene rubber synthesis, compared with comparative examples B4 and B5, the branched rare earth isoprene rubber with equivalent number average molecular weight is obtained by using the same catalyst and amount (but without adding a branching modifier), and the dynamic viscosity of the obtained rare earth isoprene rubber cement can be effectively reduced.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A branching modifier, the branching modifier being prepared according to the following process:

oligomerizing isoprene in an oligomerization solvent in the presence of an inert atmosphere and an alkyl lithium initiator to obtain a polyisoprene oligomer;

mixing the polyisoprene oligomer with alkyl aluminum to obtain the branched modifier;

the number average molecular weight of the polyisoprene oligomer is 3000-30000, the content of cis 1,4 structural units in the oligomer structure is 65-75 wt%, the content of trans 1,4 structural units in the oligomer structure is 18-28 wt%, and the content of 3,4 structural units in the oligomer structure is 6-12 wt%;

the molar ratio of the alkyl aluminum to the alkyl lithium is (1-2): 1.

2. The branched modifier of claim 1, wherein the polyisoprene oligomer has a number average molecular weight of 4500-28000, and the oligomer has a cis 1,4 structural unit content of 67-71 wt%, a trans 1,4 structural unit content of 19-26 wt%, and a3, 4 structural unit content of 7-11 wt%.

3. The branching modifier of claim 1 or 2, wherein the alkyl lithium is of the general formula R¹A compound represented by Li, wherein R¹Is C₁～C₆Alkyl group of (1).

4. The branching modifier of claim 3, wherein the alkyl lithium is n-butyl lithium.

5. The branching modifier of claim 1 or 2, wherein the molar ratio of the alkyl lithium to isoprene, in terms of Li, is (2 x 10)^-3～2×10^-2)：1。

6. The branching modifier of claim 5, wherein the molar ratio of alkyl lithium to isoprene, in terms of Li, is (2.5 x 10)^-3～1.5×10^-2)：1。

7. The branching modifier of claim 1 or 2, wherein the aluminum alkyl is of the general formula AlR² ₃A compound of formula (I) wherein R²Is C₁～C₆Alkyl group of (1).

8. The branching modifier of claim 7, wherein the aluminum alkyl is triisobutylaluminum.

9. The branching modifier according to claim 1 or 2, wherein the alkyl aluminum is calculated as Al, the alkyl lithium is calculated as Li, and the molar ratio of the alkyl aluminum to the alkyl lithium is (1.05-1.5): 1.

10. The branched modifier of claim 1 or 2, wherein the oligomeric solvent is C₅～C₁₀The oligomerization temperature of the saturated alkane is 10-70 ℃, the oligomerization pressure is 0.1-0.4 MPa, and the oligomerization time is 1-10 h.

11. The branched modifier of claim 10, wherein the oligomerization temperature is 25 to 65 ℃, the oligomerization pressure is 0.15 to 0.35MPa, and the oligomerization time is 3 to 7 hours.

12. A preparation method of branched rare earth isoprene rubber comprises the following steps:

polymerizing isoprene monomer and the branching modifier according to any one of claims 1 to 11 in a polymerization solvent in the presence of a rare earth polymerization catalyst under an inert atmosphere.

13. The production method according to claim 12, wherein the concentration of the isoprene monomer in the polymerization solvent is 8 to 20 wt%; the branched modifier contains polyisoprene oligomer, and the polyisoprene oligomer accounts for 0.5-7 wt% of the isoprene monomer; the rare earth polymerization catalyst contains neodymium element, and the molar ratio of the rare earth polymerization catalyst to the isoprene monomer is (0.6 multiplied by 10) in terms of Nd^-4～5×10^-4)：1。

14. The method according to claim 12 or 13, wherein the polymerization temperature is 0 to 70 ℃, the polymerization pressure is 0.1 to 0.4MPa, and the polymerization time is 1 to 10 hours.

15. The production method according to claim 12 or 13, wherein the rare earth polymerization catalyst contains neodymium carboxylate, an alkyl aluminum compound, and a halide; the molar ratio of the alkyl aluminum compound to the neodymium carboxylate in terms of Al and Nd is (10-80): 1; the molar ratio of the halide to the neodymium carboxylate in terms of Nd is (1-6): 1.

16. the preparation method according to claim 15, wherein the neodymium carboxylate is a neodymium carboxylate with 7-14 carbon atoms, and the alkyl aluminum compound is represented by a general formula AlR³ ₃And/or AlHR⁴ ₂A compound of formula (I), R³、R⁴Are each independently C₁～C₆Alkyl groups of (a); the halide is of the general formula AlR⁵ ₂A compound represented by Cl, R⁵Is C₁～C₆Alkyl group of (1).