CN115521417A - Isoolefin copolymer with wide molecular weight distribution and preparation method thereof - Google Patents
Isoolefin copolymer with wide molecular weight distribution and preparation method thereof Download PDFInfo
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Abstract
The invention relates to the field of polymer preparation, and discloses a preparation method of a wide molecular weight distribution isoolefin copolymer and the wide molecular weight distribution isoolefin copolymer prepared by the method. The method comprises the following steps: under the condition of low-temperature cationic polymerization and in the presence of a diluent, carrying out contact reaction on an initiator solution and at least one isoolefin and at least one conjugated diene; the initiator solution includes at least one carbocation providing compound, at least one lewis acid, and at least one styrene-containing macroinitiator. The isoolefin copolymer prepared by the method has high weight average molecular weight and wide molecular weight distribution, and the by-products are few and the chain transfer phenomenon is obviously reduced in the preparation process.
Description
Technical Field
The invention relates to the field of polyolefin polymerization, in particular to a preparation method of a broad molecular weight distribution isoolefin copolymer and the broad molecular weight distribution isoolefin copolymer prepared by the preparation method.
Background
The isoolefin copolymer refers to a copolymer obtained by copolymerizing a C4-C7 isoolefin monomer and other monomers, wherein the common isoolefin copolymer is butyl rubber, and the butyl rubber has good air tightness and excellent comprehensive performance and is an important raw material in the tire industry. The industrial production usually adopts slurry polymerization or solution polymerization to produce butyl rubber, but the molecular weight distribution of the obtained butyl rubber is narrow.
One of the important problems associated with the slurry polymerization process for butyl rubber production is the processability of butyl rubber. It has been found through many years that the processability of butyl rubber is actually important in relation to the molecular weight distribution, and in the production of butyl rubber, in addition to ensuring a sufficient weight average molecular weight, it is necessary to maintain a proper balance of high and low molecular weight fractions, the high molecular weight fraction being used to obtain a sufficient green strength and the low molecular weight fraction being used to ensure a certain stress relaxation rate. The comparison shows that the butyl rubber with narrow molecular weight distribution is easy to break on a mixing roll, the problem that the molecular weight distribution is widened can be solved, and the carbon black can be uniformly and finely dispersed without extreme mixing steps in the mixing process, so that the product has better physical and mechanical properties; butyl rubber with a broad molecular weight distribution also has a more stable size and shape during processing. However, the molecular weight distribution of a polymer before processing is greatly dependent on the polymerization mechanism, and the molecular weight distribution characteristics of the polymer have been determined by a definite reaction. Therefore, special methods or means are often required for the purpose of broadening the molecular weight distribution of the polymer.
CN1427851A provides a method for producing butyl rubber with wide molecular weight distribution, which adopts a mixed catalyst system to synthesize the butyl rubber under the condition of-100 ℃ to-50 ℃, wherein the mixed catalyst comprises ethyl aluminum dichloride, diethyl aluminum chloride and a small amount of aluminoxane.
US7893176B2 describes a process for controlling the molecular weight distribution of isoolefin polymers by means of additives which are oxygen molecule-containing or organic oxygen-containing compounds (e.g. alcohols, ethers, ketones, aldehydes, esters) and which also contain lewis acids, initiators, diluents, etc. The molecular weight distribution of the obtained isoolefin copolymer is higher than 2.0.
CN100523018C provides a method for preparing isoolefin polymer or copolymer, which comprises homopolymerizing or copolymerizing C4-C7 isoolefin monomer in halogenated hydrocarbon or hydrocarbon diluent under the condition of composite catalyst solution, wherein the composite catalyst solution is a reaction product of Lewis acid and additive, and the additive is selected from at least one of alcohol, phenol, amide, amine or pyridine, carboxylate and ketone. The method can adjust the molecular weight distribution of the product within a certain range by adjusting the proportion of the additive and the aluminum trichloride.
The method of adding the additive has the defects of increasing by-products of the reaction, exacerbating the chain transfer phenomenon and the like.
Disclosure of Invention
The present invention has been made to overcome the above problems occurring in the prior art, and an object of the present invention is to provide a method for preparing a broad molecular weight distribution isoolefin copolymer having a high weight average molecular weight and a broad molecular weight distribution isoolefin prepared by the method.
In order to achieve the above object, a first aspect of the present invention provides a method for preparing a broad molecular weight distribution isoolefin copolymer, comprising the steps of:
under the reaction condition of low-temperature cationic polymer and in the presence of a diluent, carrying out contact reaction on an initiator solution and at least one isoolefin and at least one conjugated diene;
the initiator solution includes at least one carbocation providing compound, at least one lewis acid, and at least one styrene-containing macroinitiator.
In a second aspect, the present invention provides a broad molecular weight distribution isoolefin copolymer prepared by the above process.
Through the technical scheme, the preparation method of the isoolefin copolymer with wide molecular weight distribution provided by the invention and the isoolefin copolymer with wide molecular weight distribution prepared by the method have the following beneficial effects:
in the preparation method of the isoolefine copolymer with wide molecular weight distribution, a macromolecular grafting agent of styrene is introduced into a common initiation system, a part of butyl rubber with a star-shaped branched structure can be obtained in the polymerization process, the part of butyl rubber has high molecular weight so that the butyl rubber has enough strength, and the butyl rubber with a linear structure can be obtained by adopting the conventional initiation system.
Furthermore, in the preparation method of the isoolefin copolymer with wide molecular weight distribution provided by the invention, the isoolefin-conjugated diene copolymer with different molecular weight distribution can be obtained by adjusting the ratio of the carbocation compound and the styrene-containing macroinitiator in the initiating system.
Furthermore, in the preparation method of the isoolefin copolymer with wide molecular weight distribution, compared with the traditional butyl rubber polymerization method, the preparation method introduces the fluoroalkane as the diluent into the polymerization system, the polymer particles are in a glass state, the operation period of a polymerization kettle can be obviously prolonged, and the butyl rubber can be synthesized at a higher temperature.
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 present invention provides a process for preparing a broad molecular weight distribution isoolefin copolymer, characterized in that the process comprises the steps of:
under the reaction condition of low-temperature cationic polymer and in the presence of a diluent, carrying out contact reaction on an initiator solution and at least one isoolefin and at least one conjugated diene;
the initiator solution includes at least one carbocation providing compound, at least one lewis acid, and at least one styrene-containing macroinitiator.
In the preparation process of the isoolefin copolymer, the styrene-containing macroinitiator is added into a conventional butyl rubber initiation system, so that the weight average molecular weight of the isoolefin copolymer can be obviously improved, and the isoolefin copolymer with wide molecular weight distribution can be obtained.
According to the invention, the styrene-containing macroinitiator has the structure shown in formula I:
wherein, in formula I, n, m, a, b and h satisfy the following relations: n: (m + a + b): h =1:0.1-1:1; b/(m + a + b) is more than or equal to 0 and less than or equal to 80 percent.
In the invention, the initiator solution containing the styrene-containing macroinitiator shown in the formula I is used for preparing the isoolefin copolymer, and the content of each structural unit in the macroinitiator meets the specific relation, so that the macroinitiator can play a role of a grafting agent, and a3,4-structure formed after isoprene units in the macroinitiator are polymerized can play a role of an initiator, thereby preparing the isoolefin copolymer with high weight average molecular weight and wide molecular weight distribution.
In the present invention, the content of each structural unit in the styrene-containing polymer is described in "synthesis of butyl lithium-initiated styrene-isoprene-styrene triblock copolymer and structural and performance tables [ J ] materials report, 2014, 10: 371'.
Further, n, m, a, b, and h satisfy the following relationship: n: (m + a + b): h =1:0.4-0.8:1; b/(m + a + b) is more than or equal to 5 percent and less than or equal to 80 percent.
Further, n, m, a, b, and h satisfy the following relationship: n: (m + a + b): h =1:0.5-0.7:1; at 50% ≦ b/(m + a + b) ≦ 70%, the isoolefin copolymer thus obtained has a higher molecular weight and a broader molecular weight distribution.
According to the present invention, the weight average molecular weight of the styrene-containing macroinitiator is 1,000 to 100,000, and the molecular weight distribution is 1 to 3.
Further, the weight average molecular weight of the styrene-containing polymer is 10,000 to 50,000; the molecular weight distribution is 1-2.
In the present invention, the weight average molecular weight and the molecular weight distribution of the styrene-containing polymer were measured by LC-20A type liquid gel permeation chromatograph manufactured by Shimadzu corporation, japan.
In the present invention, the styrene-containing polymer is prepared by the following method:
the polymerization temperature is 40 ℃, the solvent is a mixed solvent, wherein 10ml of cyclohexane and 30 ml of tetrahydrofuran are adopted as the solvent, 3.8 ml of 0.1M butyl lithium heptane solution is added into the solvent, 4.2 ml of styrene is sequentially added, 1.5 ml of isoprene is added after 40 minutes of reaction, 4.2 ml of styrene is added after 50 minutes of reaction is continued, and methanol is used for termination after 40 minutes of reaction, so that the styrene-containing macroinitiator is prepared.
According to the invention, the compound providing a carbenium ion has the structure shown in formula II:
wherein, in the formula II, R 4 、R 5 And R 6 Each is C 1 -C 4 Alkyl or phenyl, and X is halogen.
Further, in the formula II, R 4 、R 5 And R 6 Each is C 1 -C 4 Alkyl, and X is Cl or Br.
Further advance toOptionally, the carbenium ion providing compound is selected from t-butyl chloride (in formula II, R 4 、R 5 And R 6 Is methyl, X is Cl) and/or 2-chloro-2,4,4-trimethylpentane (in formula II, R is 4 And R 5 Is methyl, R 6 2,2-dimethylbutyl).
According to the invention, the Lewis acid is selected from at least one of aluminum trichloride, titanium tetrachloride, boron trifluoride and ethyl aluminum dichloride; preferably ethyl aluminium dichloride.
According to the invention, the concentration of the compound providing carbocation is 0.001-0.1mol/L based on the total weight of the initiator solution; the concentration of the macromolecular initiator containing styrene is 0.0001-0.01mol/L; the concentration of the Lewis acid is 0.0001-0.1mol/L.
In the present invention, the styrene-containing macroinitiator is preferably introduced into the polymerization system in the form of a solution, and the solvent used for preparing the solution of the styrene-containing macroinitiator is selected from dichloromethane and/or chloroform.
In the present invention, the Lewis acid is preferably introduced into the polymerization system in the form of a solution, and the solvent used for preparing the solution of the Lewis acid is at least one selected from the group consisting of heptane, n-hexane and pentane.
Further, the concentration of the compound providing carbocation is 0.005 to 0.05mol/L based on the total weight of the initiator solution; the concentration of the macromolecular initiator containing styrene is 0.001-0.005mol/L; the concentration of the Lewis acid is 0.01-0.1mol/L.
In the present invention, isoolefin copolymers having different molecular weight distributions can be obtained by adjusting the amount ratio of the carbonium ion-providing compound to the styrene-containing macroinitiator, and particularly, in a specific embodiment of the present invention, the amount ratio of the carbonium ion-providing compound to the styrene-containing macroinitiator is 10:1-1:100.
according to the invention, the diluent comprises at least one chloroalkane and at least one fluoroalkane.
In the invention, when the isoolefine copolymer is prepared, at least one fluorinated alkane is introduced into the diluent, the polymerization reaction temperature can be increased, the obtained polymer particles are in a glass state, the separation and recovery of the polymer are facilitated, and the polymerization reaction temperature can be increased by 10-20 ℃ compared with the method of simply adopting chlorinated alkane as the diluent.
According to the invention, the volume ratio of the chlorinated alkane to the fluorinated alkane is 8:2-2:8.
in the present invention, when the volume ratio of chloroalkane to fluoroalkane in the diluent satisfies the above range, a stable slurry system can be obtained, and thus an isoolefin copolymer having a broad molecular weight distribution, such as butyl rubber, can be obtained.
Further, the volume ratio of the chloroalkane to the fluoroalkane is 6:4-4:6.
according to the invention, the chlorinated alkane is selected from monochloromethane and/or dichloromethane; the fluoroalkane is selected from at least one of 1,1-difluoroethane, 1,1,1-trifluoroethane and 1,1,1,2-tetrafluoroethane.
According to the invention, the isoolefin has the structure shown in formula III:
wherein, in the formula III, R 1 Is C 1 -C 5 Alkyl or hydrogen of (a); r is 2 Is C 1 -C 5 Alkyl or C of 3 -C 5 Branched alkyl groups of (a).
Further, in the formula III, R 1 Is C 1 -C 4 The alkane of (1); r 2 Is C 1 -C 4 Of an alkane.
Further, in the formula III, R 1 Is methyl, R 2 Is a methyl group.
According to the invention, the conjugated diene is selected from isoprene and/or butadiene, preferably isoprene.
According to the present invention, the low temperature cationic polymerization conditions include: the polymerization temperature is-20 ℃ to 120 ℃, and the polymerization time is 1-30min.
Further, the low temperature cationic polymerization reaction conditions include: the polymerization temperature is-60 ℃ to 100 ℃, and the polymerization time is 5-20min.
According to the invention, the amount of isoolefin is 90-99wt% based on the total weight of isoolefin and conjugated diene; the amount of the conjugated diene is 1-9wt%.
Further, the amount of the isoolefin is 95-98wt% based on the total weight of the isoolefin and the conjugated diene; the amount of the conjugated diene is 2-5wt%.
According to the invention, the halogenated alkane is used in an amount of 100 to 1000 parts by weight, based on 100 parts by weight of isoolefin and conjugated diene; the amount of the initiator solution is 0.1-5 parts by weight.
Further, the halogenated alkane is used in an amount of 400 to 800 parts by weight based on 100 parts by weight of isoolefin and conjugated diene; the initiator solution is used in an amount of 0.1 to 1 part by weight.
In the present invention, the method further comprises adding a terminating agent to the polymerization system to terminate the polymerization reaction.
Preferably, the terminator is selected from at least one of methanol, ethanol, butanol, and tert-butanol. The amount of the terminator can be adjusted according to the actual needs, for example, the amount of the terminator is 1 to 5wt% of the total amount of the isoolefin and the conjugated diene.
In the present invention, the method further comprises a step of removing unreacted monomers and solvent, specifically: the polymer solution obtained by the reaction was mixed with an equal volume of water, and unreacted monomers and solvent were removed at 100 ℃.
In a second aspect, the present invention provides a broad molecular weight distribution isoolefin copolymer prepared by the above process.
According to the present invention, the broad molecular weight distribution isoolefin copolymer has a weight average molecular weight of 200,000 to 1,000,000; the broad molecular weight distribution isoolefin copolymer has a molecular weight distribution greater than 3.
In the present invention, the weight average molecular weight and the molecular weight distribution of the broad molecular weight distribution isoolefin copolymer are measured by LC-20A liquid gel permeation chromatograph manufactured by Shimadzu corporation of Japan.
Further, the broad molecular weight distribution isoolefin copolymer has a weight average molecular weight of 400,000 to 800,000; the molecular weight distribution of the wide molecular weight distribution isoolefin copolymer is 3.3-5.
The present invention will be described in detail below by way of examples.
In the following examples and comparative examples, the conversion of monomer was measured by a weighing method.
Conversion (%) = (weight of obtained polymer/total weight of monomer added) × 100%; wherein the conversion of isobutylene is obtained after homopolymerization of isobutylene and the conversion of styrene is obtained after homopolymerization of styrene.
The molecular weight and molecular weight distribution of the polymer are determined by LC-20A liquid gel permeation chromatograph manufactured by Shimadzu corporation, and single-pore chromatographic column
And
the four columns are used together. The mobile phase is tetrahydrofuran, and the flow rate is 0.7mL/min; the concentration of the sample solution is 2mg/mL, and the sample injection amount is 200 mu L; the test temperature is 35 ℃; monodispersed polystyrene was used as a standard.
The content of the structural units in the macromolecular grafting agent is measured by the following method: synthesis of butyl lithium-initiated styrene-isoprene-styrene triblock copolymers and structural and performance tables [ J ] material reports 2014, 10:371 the solvents and monomers used were purified prior to use by methods commonly used in the art, and the polymerization and initiator solutions were prepared in a dry box commercially available from MBRAUN, germany, equipped with a low temperature cold bath.
Preparation example 1
The polymerization temperature is 40 ℃, the solvent is a mixed solvent, wherein 10ml of cyclohexane and 1 ml of tetrahydrofuran are added, then 3.8 ml of 0.1M butyl lithium solution in heptane is added into the solvent, then 4.2 ml of styrene are sequentially added, 1.5 ml of isoprene is added after 40 minutes of reaction, 4.2 ml of styrene is added after 50 minutes of reaction is continued, methanol is used for termination after 40 minutes of reaction, the styrene-containing macroinitiator is prepared and is marked as macroinitiator A1, and the Mw =28,000, MWD =1.62, b/(M + a + b) =26%, and n: (m + a + b): h =1:0.6:1.
preparation example 2
A macroinitiator A2 containing styrene was prepared by the method of preparation example 1, except that: the amount of tetrahydrofuran added was 2 ml, and the macroinitiator A2 was determined to have Mw =30,200, mwd =1.35, b/(m + a + b) =40%, n: (m + a + b): h =1:0.6:1.
preparation example 3
A macroinitiator A3 containing styrene was prepared by the method of preparation example 1, except that: the amount of tetrahydrofuran added was 3 ml, and it was determined that the Mw =31,200, mwd =1.24, b/(m + a + b) =60%, n: (m + a + b): h =1:0.6:1.
example 1
(1) Preparation of initiator solution
Firstly, 0.36 g of macroinitiator A1 is dissolved in 26 g of dichloromethane;
60 g of methylene chloride are weighed out and 4 ml of a 0.9mol/L solution of ethyl aluminum dichloride in heptane, 0.20 g of tert-butyl chloride and 10ml of a solution of the macroinitiator A1 prepared above are added in succession. Wherein, based on the total weight of the initiator solution, the concentration of the macroinitiator A1 is 0.005mol/L, the concentration of the tert-butyl chloride is 0.046mol/L, and the concentration of the ethyl aluminum dichloride is 0.06mol/L. The dosage ratio of the tert-butyl chloride to the macroinitiator A1 is 1:0.8.
(2) Polymerisation reaction
Under the protection of nitrogen, 50mL of methane chloride precooled to-80 ℃ and 50mL of 1,1,1,2-tetrafluoroethane (methane chloride/1,1,1,2-tetrafluoroethane = 1:1) are sequentially added into a three-neck flask with stirring slurry in a cooling bath at-95 ℃, 16.8g of isobutene is added, polymerization is carried out under stirring, 10mL of prepared initiator solution is slowly dripped to initiate polymerization, the temperature of a polymerization system is kept at-80 +/-2 ℃, 5 mL of methanol is added for termination after 30 minutes of polymerization, the polymer solution obtained after termination is poured into a beaker and filled with clean water with the same volume, the beaker is placed in a constant-temperature water bath at 100 ℃ to remove unreacted monomers and solvents, and after three times of water washing, the beaker is naturally air-dried and is placed in a vacuum oven to be dried to constant weight, so as to prepare the copolymer P1. The weight average molecular weight and the molecular weight distribution of the copolymer P1 are shown in Table 1.
Example 2
(1) Preparation of initiator solution
Firstly, 0.28 g of macroinitiator A1 is dissolved in 26 g of dichloromethane;
60 g of methylene chloride are weighed out and 4 ml of a 0.9mol/L solution of ethyl aluminum dichloride in heptane, 0.20 g of tert-butyl chloride and 10ml of a solution of the macroinitiator A1 prepared above are added in succession. Wherein, by the total weight of the initiator solution, the concentration of the macroinitiator A1 is 0.0038mol/L, the concentration of the tert-butyl chloride is 0.046mol/L, and the concentration of the dichloroethylaluminum is 0.06mol/L. The dosage ratio of the tert-butyl chloride to the macroinitiator A1 is 1:0.7.
(2) Polymerisation reaction
Under the protection of nitrogen, 40mL of methane chloride precooled to-80 ℃ and 60mL of 1,1,1,2-tetrafluoroethane (methane chloride/1,1,1,2-tetrafluoroethane = 4:6) are sequentially added into a three-neck flask with stirring slurry in a cooling bath at-95 ℃, 16.8g of isobutene is added, polymerization is carried out under stirring, 10mL of prepared initiator solution is slowly dripped to initiate polymerization, the temperature of a polymerization system is kept at-80 +/-2 ℃, 5 mL of methanol is added for termination after 30 minutes of polymerization, the polymer solution obtained after termination is poured into a beaker and filled with clean water with the same volume, the beaker is placed in a constant-temperature water bath at 100 ℃ to remove unreacted monomers and solvents, and after three times of water washing, the beaker is naturally air-dried and is placed in a vacuum oven to be dried to constant weight, so as to obtain the copolymer P2. The weight average molecular weight and the molecular weight distribution of the copolymer P2 are shown in Table 1.
Example 3
(1) Preparation of initiator solution
0.28 g of macroinitiator A1 was first dissolved in 26 g of dichloromethane.
60 g of methylene chloride are weighed out and 4 ml of a 0.9mol/L solution of ethyl aluminum dichloride in heptane, 0.20 g of tert-butyl chloride and 10ml of the solution of the macroinitiator A1 prepared above are added in this order. Wherein, by the total weight of the initiator solution, the concentration of the macroinitiator A1 is 0.0038mol/L, the concentration of the tert-butyl chloride is 0.046mol/L, and the concentration of the dichloroethylaluminum is 0.06mol/L. The dosage ratio of the tert-butyl chloride to the macroinitiator A1 is 1:0.7.
(2) Polymerisation reaction
Under the protection of nitrogen, 50mL of methane chloride precooled to-80 ℃ and 50mL of 1,1-difluoroethane (methane chloride/1,1-difluoroethane = 1:1) are sequentially added into a three-neck flask with stirring slurry placed in a cooling bath at-95 ℃, 16.8g of isobutene is added, polymerization is carried out under stirring, 10mL of the prepared initiator solution is slowly dripped to initiate polymerization, the temperature of a polymerization system is kept at-80 +/-2 ℃, 5 mL of methanol is added after 30 minutes of polymerization reaction for termination, the polymer solution obtained after termination is poured into a beaker and injected with clean water, the beaker is placed in a constant-temperature water bath at the same volume and is subjected to 100 ℃ to removal of unreacted monomers and solvents, after three times of water washing, natural air drying is carried out, and the beaker is placed in a vacuum oven to be dried to constant weight, so as to prepare the copolymer P3. The weight average molecular weight and the molecular weight distribution of the copolymer P3 are shown in Table 1.
Example 4
(1) Preparation of initiator solution
Firstly, 0.28 g of macroinitiator A1 is dissolved in 26 g of dichloromethane;
60 g of methylene chloride are weighed out and 4 ml of a 0.9mol/L solution of ethyl aluminum dichloride in heptane, 0.20 g of tert-butyl chloride and 10ml of the solution of the macroinitiator A1 prepared above are added in this order. Wherein, by the total weight of the initiator solution, the concentration of the macroinitiator A1 is 0.0038mol/L, the concentration of the tert-butyl chloride is 0.046mol/L, and the concentration of the dichloroethylaluminum is 0.06mol/L. The dosage ratio of the tert-butyl chloride to the macroinitiator A1 is 1:0.7.
(2) Polymerisation reaction
Under the protection of nitrogen, 50mL of methane chloride precooled to-80 ℃ and 50mL of 1,1,1-trifluoroethane (methane chloride/1,1,1-trifluoroethane = 1:1) are sequentially added into a three-neck flask with stirring slurry placed in a cooling bath at-95 ℃, 16.8g of isobutene is added, polymerization reaction is carried out under stirring, 10mL of prepared initiator solution is slowly dripped to initiate polymerization, the temperature of a polymerization system is kept at-80 +/-2 ℃, 5 mL of methanol is added for termination after 30 minutes of polymerization reaction, the polymer solution obtained after termination is poured into a beaker and filled with clean water with the same volume, the beaker is placed in a constant-temperature water bath at 100 ℃ to remove unreacted monomers and solvents, after three times of water washing, natural air drying is carried out, and the beaker is placed into a vacuum oven to be dried to constant weight, so as to prepare the copolymer P4. The weight average molecular weight and the molecular weight distribution of the copolymer P4 are shown in Table 1.
Example 5
(1) Preparation of initiator solution
60 g of methylene chloride are weighed out and 4 ml of a 0.9mol/L solution of ethyl aluminum dichloride in heptane, 0.20 g of tert-butyl chloride and 10ml of the solution of the macroinitiator A1 prepared above are added in this order. Wherein, by the total weight of the initiator solution, the concentration of the macroinitiator A1 is 0.0038mol/L, the concentration of the tert-butyl chloride is 0.046mol/L, and the concentration of the dichloroethylaluminum is 0.06mol/L. The dosage ratio of the tert-butyl chloride to the macroinitiator A1 is 1:0.7.
(2) Polymerisation reaction
Under the protection of nitrogen, 50mL of precooled dichloromethane to-80 ℃ and 50mL of 1,1,1-trifluoroethane (dichloromethane/1,1,1-trifluoroethane = 1:1) are sequentially added into a three-neck flask with stirring slurry in a cooling bath at-95 ℃, 16.8g of isobutene is added, polymerization reaction is carried out under stirring, 10mL of the prepared initiator solution is slowly dripped to initiate polymerization, the temperature of a polymerization system is kept at-80 +/-2 ℃, 5 mL of methanol is added after 30 minutes of polymerization reaction for termination, the polymer solution obtained after termination is poured into a beaker and is injected with equal volume of clear water, the beaker is placed in a constant-temperature water bath at 100 ℃ to remove unreacted monomers and solvents, after three times of water washing, the mixture is naturally air-dried and is placed into a vacuum oven to be dried to constant weight, and the copolymer P5 is prepared. The weight average molecular weight and the molecular weight distribution of the copolymer P5 are shown in Table 1.
Example 6
(1) Preparation of initiator solution
0.28 g of macroinitiator A1 was first dissolved in 26 g of dichloromethane.
60 g of methylene chloride are weighed out and 4 ml of a 0.9mol/L heptane solution of ethyl aluminum dichloride, 0.18 g of 2-chloro-2,4,4, -trimethylpentane and 10ml of the macroinitiator solution prepared above are added in succession. Wherein, based on the total weight of the initiator solution, the concentration of the macroinitiator A1 is 0.0038mol/L, the concentration of the 2-chloro-2,4,4, -trimethylpentane is 0.028mol/L, and the concentration of the dichloroethylaluminum is 0.06mol/L. 2-chloro-2,4,4, the ratio of the amounts of trimethylpentane to macroinitiator A1 is 1.28:1.
(2) Polymerisation reaction
Under the protection of nitrogen, 50mL of dichloromethane precooled to-80 ℃ and 50mL of 1,1,1-trifluoroethane (dichloromethane/1,1,1-trifluoroethane = 1:1) are sequentially added into a three-neck flask with stirring slurry placed in a cooling bath at-95 ℃, 16.8g of isobutene is added, polymerization is carried out under stirring, 10mL of the prepared initiator solution is slowly dripped to initiate polymerization, the temperature of a polymerization system is kept at-80 +/-2 ℃, 5 mL of methanol is added after 30 minutes of polymerization for termination, the polymer solution obtained after termination is poured into a beaker and is injected with equal volume of clear water, the beaker is placed in a constant-temperature water bath at 100 ℃ to remove unreacted monomers and solvents, after washing with water for three times, natural air drying is carried out, and the beaker is placed in a vacuum oven to be dried to constant weight, so as to obtain the copolymer P6. The weight average molecular weight and the molecular weight distribution of the copolymer P6 are shown in Table 1.
Example 7
An isoolefin copolymer was prepared by following the procedure of example 2, except that macroinitiator A2 was used in place of macroinitiator A1. A copolymer P7 was obtained. The weight average molecular weight and the molecular weight distribution of the copolymer P7 are shown in table 1.
Example 8
An isoolefin copolymer was prepared by following the procedure of example 2, except that the macroinitiator A3 was used in place of the macroinitiator A1. A copolymer P8 was obtained. The weight average molecular weight and the molecular weight distribution of the copolymer P8 are shown in Table 1.
Example 9
An isoolefin copolymer was prepared according to the method of example 2, except that in step (2) the volume ratio of methyl chloride to 1,1,1,2-tetrafluoroethane was 3:7, a copolymer P9 was obtained. The weight average molecular weight and the molecular weight distribution of the copolymer P9 are shown in Table 1.
Example 10
An isoolefin copolymer was prepared according to the method of example 2, except that in step (2) the volume ratio of methyl chloride to 1,1,1,2-tetrafluoroethane was 1:9. a copolymer P10 was obtained. The weight average molecular weight and the molecular weight distribution of the copolymer P10 are shown in Table 1.
Comparative example 1
An isoolefin copolymer was prepared as in example 1, except that a low molecular weight polybutadiene was used in place of the macroinitiator A1. A copolymer D1 was obtained. The weight average molecular weight and the molecular weight distribution of the copolymer D1 are shown in Table 1.
TABLE 1
| Example numbering | Weight average molecular weight | Molecular weight distribution |
| Example 1 | 692500 | 3.92 |
| Example 2 | 632100 | 3.92 |
| Example 3 | 562400 | 4.05 |
| Example 4 | 724100 | 4.05 |
| Example 5 | 768400 | 4.01 |
| Example 6 | 572600 | 4.05 |
| Example 7 | 465200 | 3.65 |
| Example 8 | 859200 | 4.02 |
| Example 9 | 795200 | 3.95 |
| Example 10 | 567800 | 3.68 |
| Comparative example 1 | 325600 | 3.12 |
As can be seen from the results in Table 1, the isoolefin copolymers obtained in examples 1 to 10 using the process of the present invention have higher weight average molecular weights and a broader molecular weight distribution.
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 (13)
1. A process for preparing a broad molecular weight distribution isoolefin copolymer, comprising the steps of:
under the reaction condition of low-temperature cationic polymer and in the presence of a diluent, carrying out contact reaction on an initiator solution and at least one isoolefin and at least one conjugated diene;
the initiator solution includes at least one carbocation providing compound, at least one lewis acid, and at least one styrene-containing macroinitiator.
2. The method of claim 1, wherein the styrene-containing macroinitiator has the structure of formula I:
wherein in formula I, n, m, a, b and h satisfy the following relations: n: (m + a + b): h =1:0.1-1:1; b/(m + a + b) is more than or equal to 0 and less than or equal to 80 percent;
preferably, in formula I, n, m, a, b and h satisfy the following relationship: n: (m + a + b): h =1:0.4-0.8:1; b/(m + a + b) is more than or equal to 5 percent and less than or equal to 80 percent.
3. The production method according to claim 1 or 2, wherein the weight average molecular weight of the styrene-containing macroinitiator is 1,000 to 100,000, and the molecular weight distribution is 1 to 3.
4. The production method according to any one of claims 1 to 3, wherein the compound that supplies a carbenium ion has a structure represented by formula II:
wherein, in the formula II, R 4 、R 5 And R 6 Each is C 1 -C 4 Alkyl or phenyl, X is halogen;
preferably, the compound providing carbenium ion is selected from t-butyl chloride and/or 2-chloro-2,4,4-trimethylpentane.
5. The production method according to any one of claims 1 to 4, wherein the Lewis acid is at least one selected from the group consisting of aluminum trichloride, titanium tetrachloride, boron trifluoride and ethyl aluminum dichloride; preferably ethyl aluminium dichloride.
6. The production method according to any one of claims 1 to 5, wherein the concentration of the carbocation-providing compound is 0.001 to 0.1mol/L based on the total weight of the initiator solution; the concentration of the macromolecular initiator containing styrene is 0.0001-0.01mol/L; the concentration of the Lewis acid is 0.0001-0.1mol/L.
7. The production method according to any one of claims 1 to 6, wherein the diluent comprises at least one chloroalkane and at least one fluoroalkane;
preferably, the volume ratio of the chloroalkane to the fluoroalkane is 8:2-2:8, preferably 6:4-4:6.
8. the process according to claim 7, wherein the chlorinated alkane is selected from monochloromethane and/or dichloromethane; the fluoroalkane is selected from at least one of 1,1-difluoroethane, 1,1,1-trifluoroethane, and 1,1,1,2-tetrafluoroethane.
9. The production method according to any one of claims 1 to 8, wherein the isoolefin has a structure represented by formula III:
wherein R is 1 Is C 1 -C 5 Alkyl or hydrogen of (a); r is 2 Is C 1 -C 5 Alkyl or C 3 -C 5 A branched alkyl group of (a);
preferably, the conjugated diene is selected from isoprene and/or butadiene.
10. The production method according to any one of claims 1 to 9, wherein the low-temperature cationic polymerization reaction conditions include: the polymerization temperature is-20 ℃ to 100 ℃, and the polymerization time is 1-30min.
11. The production process according to any one of claims 1 to 10, wherein the isoolefin is used in an amount of 90 to 99% by weight based on the total weight of the isoolefin and the conjugated diene; the dosage of the conjugated diene is 1 to 10 weight percent;
preferably, the diluent is used in an amount of 100 to 1000 parts by weight, based on 100 parts by weight of the isoolefin and the conjugated diene; the initiator solution is used in an amount of 0.01 to 5 parts by weight.
12. A broad molecular weight distribution isoolefin copolymer produced by the process of any one of claims 1 to 11.
13. The broad molecular weight distribution isoolefin copolymer of claim 12, wherein the isoolefin copolymer has a weight average molecular weight of from 200,000 to 1,000,000; the isoolefin copolymer has a molecular weight distribution of greater than 3;
preferably, the weight average molecular weight of the isoolefin copolymer is 400,000 to 800,000; the isoolefin copolymer has a molecular weight distribution of 3.3 to 5.
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