Preparation method of polybutene oligomer
阅读说明：本技术 聚丁烯低聚物的制备方法 (Preparation method of polybutene oligomer ) 是由 曹东铉 李�真 金元熙 崔景信 于 2019-10-30 设计创作，主要内容包括：本发明提供一种聚丁烯低聚物的制备方法,该制备方法包括在有机金属催化剂的存在下,使包含卤代烃溶剂、非极性烃溶剂和异丁烯单体的聚合溶液低聚合的步骤。(The present invention provides a method for preparing polybutene oligomer, which comprises the step of oligomerizing a polymerization solution comprising a halogenated hydrocarbon solvent, a nonpolar hydrocarbon solvent and an isobutylene monomer in the presence of an organometallic catalyst.)
1. A method for preparing a polybutene oligomer, the method comprising:
a step of oligomerizing a polymerization solution comprising a halogenated hydrocarbon solvent, a nonpolar hydrocarbon solvent and an isobutylene monomer in the presence of an organometallic catalyst represented by the following formula 1:
[ formula 1]
In the formula 1, the first and second groups,
M1and M2Each independently selected from transition metals of groups 6 to 10 of the 5 th cycle and transition metals of groups 6 to 10 of the 6 th cycle, wherein M1And M2The bond between them is any one of a single bond to a four bond depending on the oxidation number of the metal,
S1and S2Each independently is a substituent comprising any one of oxygen, nitrogen, carbon and halogen atoms having one or more unshared electron pairs, wherein S is1And S2Respectively with M1And M2A coordinate bond is formed, and a metal oxide,
y and Z are each independently selected from O, S, N (R)m) And P, wherein RmIs hydrogen, or substituted or unsubstituted alkyl of 1 to 10 carbon atoms,
l is C (R)n) Wherein R isnIs hydrogen, substituted or unsubstituted alkyl of 1 to 20 carbon atoms, substituted or unsubstituted aryl of 6 to 20 carbon atoms, or substituted or unsubstituted amine group,
Rmand RnMay be combined with each other to form a heteroaryl group of 4 to 20 carbon atoms,
R1to R4Each independently hydrogen, a halogen group, or a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms,
a is an integer of 0 to 3,
b is an integer of 1 to 5 and,
a + b is 4 or 5 and,
o, p, q and r are each independently an integer of 1 to 5,
x and y are the same and are integers from 1 to 4.
2. The method for producing polybutene oligomers according to claim 1, wherein the weight ratio of the non-polar hydrocarbon solvent to the halogenated hydrocarbon solvent is from 85:15 to 15: 85.
3. The method for preparing polybutene oligomers according to claim 1, wherein the halogenated hydrocarbon solvent is one or more selected from the group consisting of monochloromethane, dichloromethane, trichloromethane, 1-chlorobutane and chlorobenzene.
4. The method for preparing polybutene oligomers according to claim 1, wherein the non-polar hydrocarbon solvent is one or more selected from the group consisting of butane, pentane, neopentane, hexane, cyclohexane, methylcyclohexane, heptane, octane, benzene, toluene, xylene, and ethylbenzene.
5. The method for preparing polybutene oligomer according to claim 1, wherein the oligomerization step is performed by a batch-type or continuous-type process.
6. The method for preparing polybutene oligomer according to claim 1, further comprising the step of removing the organometallic catalyst by filtering the oligomerization products.
7. The method for preparing polybutene oligomer according to claim 6, wherein the filtration is performed using a filter comprising one or more selected from the group consisting of diatomaceous earth, silica, zeolite, and alumina.
8. The method for preparing polybutene oligomer according to claim 6, wherein the step of drying the halogenated hydrocarbon solvent is not performed after the step of oligomerizing and before the filtering.
9. The method for preparing polybutene oligomer according to claim 1, wherein the step of washing the oligomerization products to remove the organometallic catalyst is not performed.
10. The method for producing polybutene oligomers according to claim 1, wherein,
M1and M2Each independently selected from Mo, W, Re, Ru, Os, Rh, Pd and Pt,
S1and S2Each independently is a halogen group; or a coordinating solvent molecule comprising a functional group selected from the group consisting of cyano, isocyano, ether, pyridyl, amide, sulfoxide, and nitro;
R1to R4Each independently is hydrogen, a halogen group, or a C1-C12 alkyl group substituted with a halogen group,
Rnis hydrogen, substituted or unsubstituted alkyl of 1 to 12 carbon atoms, aryl of 6 to 12 carbon atoms, or substituted or unsubstituted amine group,
Rmand RnMay be combined with each other to form a heteroaryl group of 4 to 12 carbon atoms.
11. The method for preparing polybutene oligomer according to claim 1, wherein the borate-type bulky anion of the organometallic catalyst represented by formula 1 is one or more selected from the group consisting of tetrakis (phenyl) borate, tetrakis (pentafluorophenyl) borate, tetrakis [3, 5-bis (trifluoromethyl) phenyl ] borate, and their derivatives.
12. The method for preparing polybutene oligomer according to claim 1, wherein the polybutene oligomer produced by the oligomerization has a number average molecular weight of 500 to 5,500.
Technical Field
[ Cross-reference to related applications ]
This application claims the benefit of priority based on korean patent application No.2018-0145928, filed on 23.11.2018, the entire contents of which are incorporated herein by reference.
Background
Generally, in processes for preparing oligomers or polymers by cationic polymerization of monomers, the extended polymer chain contains a reactive moiety having a positive charge. For example, the active moiety may be a carbonium ion (carbocation) or an oxonium ion.
As a catalyst or an initiator for such cationic polymerization, an aluminum-based or boron-based lewis acid is generally used. Examples of Lewis acid catalysts include AlX3、BX3(X ═ F, Br, Cl, I), and the like, and lewis acids are corrosive substances and generate halogen components such as HCl and HF during quenching, and the halogen components remain in the product, causing a problem of degradation of the product quality. In addition, lewis acid catalysts require a large amount of catalyst, and in order to remove the catalyst after the reaction, a large amount of base (NaOH, KOH, NH) is used4OH, etc.) and requires additional washing with water, thus, generating a large amount of wastewater.
Meanwhile, examples of the monomer capable of undergoing cationic polymerization include styrene, isobutylene, cyclopentadiene, dicyclopentadiene and derivatives thereof, and conventional examples include polyisobutylene obtained by polymerizing isobutylene.
Polyisobutenes are divided into low molecular weight, medium molecular weight and high molecular weight ranges according to the molecular weight range. The low molecular weight polyisobutylene has a number average molecular weight range of about 10,000 or less and includes the product group of normal polybutene and highly reactive polybutene (HR-PB). Highly reactive polybutenes contain carbon-carbon double bonds predominantly at the end of the polybutene and use terminal vinylidene functionality ((C))>80%) high reactivity polybutene after introduction of functional groupThe polymers are useful as fuel additives or engine oil additives. For the polymerization of such highly reactive polybutenes, use is made in the conventional art of, for example, BF3But the catalyst is toxic and of the gaseous type and is difficult to handle. In addition, in order to improve reactivity and selectivity, a boron-alcohol or boron-ether complex is prepared and used, but there is a problem in that the activity of the catalyst is reduced with time.
Meanwhile, according to the solvent-linked organometallic catalyst (macro. rapid commu., volume 20, phase 10, page 555-559) studied by professor kuhn of munich industries university, problems related to product quality deterioration and corrosivity due to toxic components such as conventional boron-based lewis acid catalysts can be solved, but since the reaction time is substantially as long as 16 hours to obtain a high conversion rate, structural isomerization occurs by the reaction of a part of the product with the catalyst with the increase of time, exo-content (exo-content) is reduced, and competitiveness is lower than that of the lewis acid catalyst. Therefore, there is a demand for the development of an organometallic catalyst that solves the above-mentioned drawbacks as a novel catalyst for the production of oligomers, in particular, polyolefins such as polyisobutylene.
In this context, the inventors of the present invention found that polybutene oligomers having a low molecular weight can be efficiently produced using a carbon-carbon organometallic catalyst by using a novel organometallic catalyst prepared by introducing a coordinating solvent molecule and a bulky anion into a transition metal precursor having an impeller structure, and completed the present invention.
[ Prior art documents ]
[ patent document ]
Korean registered patent publication No.10-0486044(2005.4.29)
[ non-patent document ]
Rapid Commun, Vol.20, No.10, p.555-559 (1999.9.16)
Disclosure of Invention
Technical problem
The present invention uses an organometallic catalyst having a cationic structure containing a transition metal and a bulky borate-type anionic structure and uses a mixed solvent to solve the limitations of the conventional lewis acid catalyst, and thus, it is possible to efficiently prepare polybutene oligomer capable of controlling the molecular weight of the product in a low range.
Specifically, it is an object to provide a process for preparing highly reactive polybutene oligomers having a high exo content.
Technical scheme
In order to control the number average molecular weight of polybutene to less than 10,000, specifically to a desired low molecular weight range, a method of controlling the reaction temperature of the oligomerization step, controlling the amount of catalyst, or using a molecular weight controlling agent may be used as a conventional technique.
However, the reaction is mainly performed at room temperature due to the characteristics of the catalyst used in the present invention, and thus the control of the molecular weight range by controlling the temperature is limited. In addition, since most of the organometallic catalysts of the present invention are expensive, an economic burden is generated in terms of controlling the amount of the catalyst. In addition, if a molecular weight controlling agent is added, the additive remains in the final product, thereby reducing the quality thereof and incurring additional costs.
Accordingly, one embodiment of the present invention provides a method for preparing polybutene oligomer, comprising: a step of oligomerizing a polymerization solution comprising a halogenated hydrocarbon solvent, a nonpolar hydrocarbon solvent and an isobutylene monomer in the presence of an organometallic catalyst represented by the following formula 1:
[ formula 1]
In the formula 1, the first and second groups,
M1and M2Each independently selected from transition metals of groups 6 to 10 of the 5 th cycle and transition metals of groups 6 to 10 of the 6 th cycle, and M1And M2The bond between them is any one of a single bond to a four bond depending on the oxidation number of the metal,
S1and S2Each of which isIndependently is a substituent comprising any of oxygen, nitrogen, carbon and halogen atoms having one or more unshared electron pairs, wherein S is1And S2Respectively with M1And M2A coordinate bond is formed, and a metal oxide,
y and Z are each independently selected from O, S, N (R)m) And P, wherein RmIs hydrogen, or substituted or unsubstituted alkyl of 1 to 10 carbon atoms,
l is C (R)n) Wherein R isnIs hydrogen, substituted or unsubstituted alkyl of 1 to 20 carbon atoms, substituted or unsubstituted aryl of 6 to 20 carbon atoms, or substituted or unsubstituted amine group,
Rmand RnMay be combined with each other to form a heteroaryl group of 4 to 20 carbon atoms,
R1to R4Each independently hydrogen, a halogen group, or a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms,
a is an integer of 0 to 3,
b is an integer of 1 to 5 and,
a + b is 4 or 5 and,
o, p, q and r are each independently an integer of 1 to 5, and
x and y are the same and are integers from 1 to 4.
Advantageous effects
The method for producing polybutene oligomer of the present invention using a mixture solvent comprising a halogenated hydrocarbon solvent and a nonpolar hydrocarbon solvent can control the molecular weight of the product to a low range and efficiently produce polybutene oligomer, and in addition, can reduce toxicity due to the halogenated hydrocarbon solvent.
In addition, according to the preparation method of the present invention, the catalyst is always dissolved in the reaction product, and the problem of the structure isomerization reaction caused by the reaction with polybutene can be solved, and highly reactive polybutene having a high exo-content can be stably obtained.
Further, according to the preparation method of the present invention, the catalyst can be easily removed by simple filtration without performing a washing step of the oligomer, and the problems of generation of a large amount of wastewater and degradation of product quality due to the residue of the catalyst in the conventional washing method can be solved.
Detailed Description
Hereinafter, the present invention will be described in more detail to help understanding the present invention. It should be understood that the words or terms used in the specification and claims of this invention should not be construed as meanings defined in commonly used dictionaries. It should also be understood that the words or terms should be construed as having meanings consistent with their meanings in the technical idea of the invention, based on the principle that the inventor can appropriately define the meanings of the words or terms to best describe the invention.
The terminology used in the description is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular is also intended to include the plural unless the context clearly dictates otherwise.
The term "composition" as used in this disclosure includes mixtures of materials comprising the respective compositions and reaction products and decomposition products formed from the materials of the respective compositions.
The term "oligomerization" as used in this disclosure refers to the oligomerization of olefins. Depending on the amount of olefin polymerized, oligomerization is referred to as terpolymerization or tetrapolymerization, and it is collectively referred to as multipolymerization.
The term "oligomer" as used in this disclosure refers to a lower polymer having a number average molecular weight in the range of less than 10,000 formed by oligomerizing monomers.
The term "polymer" has a concept opposite to that of an oligomer and refers to a polymer compound having a number average molecular weight of 10,000 or more formed by polymerizing monomers.
The term "alkyl" in the present invention may refer to a monovalent aliphatic saturated hydrocarbon, and may include straight-chain alkyl groups such as methyl, ethyl, propyl, and butyl, and branched-chain alkyl groups such as isopropyl, sec-butyl, tert-butyl, and neopentyl.
The term "aryl group" in the present invention may refer to a cyclic aromatic hydrocarbon, and may include a monocyclic aromatic hydrocarbon forming one ring and a polycyclic aromatic hydrocarbon forming two or more rings.
The term "allyl" in the present invention refers to a compound of formula H2C＝CH-CH2R, wherein R refers to the remainder of the substituent.
The terms "comprising," "including," and "having," as well as derivatives thereof, whether or not specifically disclosed, are not intended to exclude the presence of optional additional components, steps, or processes. In order to avoid any uncertainty, all compositions claimed through use of the term "comprising" may contain optional additional additives, adjuvants or compounds, including polymers or any other substances, unless stated to the contrary. On the contrary, the term "consisting essentially of does not include those not necessary for operation, and excludes optional other components, steps or processes from the scope of the optional following description. The term "consisting of" excludes optional components, steps or processes not specifically described or illustrated.
1. Preparation method of polybutene oligomer
One embodiment of the present invention provides a method for preparing polybutene oligomer comprising the step of oligomerizing a polymerization solution comprising a halogenated hydrocarbon solvent, a nonpolar hydrocarbon solvent and an isobutylene monomer in the presence of an organometallic catalyst represented by formula 1.
The method for producing polybutene oligomer of the present invention is characterized by the step of conducting oligomerization by using a mixture solvent comprising a halogenated hydrocarbon solvent and a nonpolar hydrocarbon solvent. In this case, the effect of reducing the toxicity of the halogenated hydrocarbon solvent can be achieved as compared with the case of using the halogenated hydrocarbon solvent alone.
In addition, the polarity of the solvent affects reactivity during polymerization of polybutene, and polybutene oligomers in a low molecular weight range can be obtained by controlling the dielectric constant of the mixture solvent by mixing a halogenated hydrocarbon solvent with a non-polar hydrocarbon solvent.
In addition, in the case where only a nonpolar hydrocarbon solvent is used in the conventional art, there is a problem in that the catalyst is always dissolved in the reaction product and reacts with polybutene to cause a structural isomerization reaction. According to the present invention, the catalyst is hardly dissolved in the nonpolar hydrocarbon solvent in the mixture solvent, the above problems can be solved and highly reactive polybutene with a high exo content can be stably obtained.
In addition, in the case of using the halogenated hydrocarbon solvent alone, the catalyst is partially dissolved in the halogenated hydrocarbon solvent, and it becomes difficult to remove the catalyst from the polybutene oligomer product. For example, in the process of removing the catalyst by filtering the polybutene oligomer thus obtained, in the case of using a halogenated hydrocarbon solvent alone, the catalyst is dissolved in the solvent and discharged to cause a problem of contaminating the filter. However, in the case of using the mixture solvent of the present invention, the catalyst is hardly dissolved in the nonpolar hydrocarbon solvent, and the effect of reducing the filter contamination due to the discharge phenomenon can be achieved, and thus, there is an economic advantage of extending the life of the filter column.
The weight ratio of the non-polar hydrocarbon solvent to the halogenated hydrocarbon solvent in the mixture solvent may be 95:5 to 5:95, preferably 85:15 to 15:85, 80:20 to 20:80, more preferably 80:20 to 30:70 or 75:25 to 30: 70.
If the above weight ratio is satisfied, the molecular weight of the polybutene oligomer thus produced can be easily controlled, polybutene oligomer having a high exo content can be obtained, and removal of the catalyst after oligomerization can be easily performed.
If the halogenated hydrocarbon solvent or the nonpolar hydrocarbon solvent is not mixed, the effect of controlling the molecular weight of the polybutene oligomer may not be achieved, and the exo-content of the polybutene oligomer obtained thereby may be reduced. Therefore, in order to prepare polybutene having a suitable degree of molecular weight and high exo content, it is preferable to satisfy the above weight ratio, and if the weight ratio is optimized within the preferable range, polybutene having high exo content can be prepared.
In addition, the halogenated hydrocarbon solvent may be one or more selected from the group consisting of monochloromethane, dichloromethane, trichloromethane, 1-chlorobutane and chlorobenzene.
In addition, the nonpolar hydrocarbon solvent may be an aliphatic hydrocarbon solvent or an aromatic hydrocarbon solvent. For example, the aliphatic hydrocarbon solvent may be one or more selected from butane, pentane, neopentane, hexane, cyclohexane, methylcyclohexane, heptane and octane, and the aromatic hydrocarbon solvent may be one or more selected from benzene, toluene, xylene and ethylbenzene.
The oligomerization step of the present invention may be carried out by a batch type or continuous type process. In the case of a continuous type process, the mixture solvent may preferably contain a halogenated hydrocarbon solvent and an aromatic hydrocarbon solvent. In the case of a continuous type process, the reactive monomer and the polymer may be present together, and the coupling phenomenon of polybutene may be carried out. If an aromatic hydrocarbon solvent is contained as the nonpolar solvent, such a coupling phenomenon can be controlled and polybutene having a high exo content can be obtained.
In the step of oligomerizing the isobutylene monomer, the amount of the isobutylene monomer may be 1 to 50% by weight, preferably 5 to 25% by weight, based on the total weight of the polymerization solution. In addition, the amount of the catalyst may be 0.005 to 1% by weight, preferably 0.01 to 0.025% by weight, based on the total weight of the polymerization solution. If the above numerical range is satisfied, the oligomerization reaction can be efficiently performed, but if an excessive amount outside the numerical range is added, the polymerization efficiency does not increase much compared to the increase in the raw material cost.
The organometallic catalyst used in the step of oligomerization of isobutylene monomer has an advantage of solving various problems of the conventional Lewis acid catalyst. For example, conventional lewis acid catalysts are corrosive but the organometallic catalysts used in the present invention are not corrosive. In addition, the organometallic catalyst of the present invention requires a small amount to be used to obtain the same degree of effect, and saves the catalyst cost.
Specifically, the organometallic catalyst used in the present invention is represented by the following formula 1:
[ formula 1]
M1And M2Each independently selected from transition metals of groups 6 to 10 of the 5 th cycle and transition metals of groups 6 to 10 of the 6 th cycle, e.g. M1And M2Can be selected from Mo, W, Re, Ru, Os, Rh, Pd and Pt, and M1And M2The bond between (a) and (b) is any of a single bond to a four bond depending on the oxidation number of the metal.
S1And S2Each independently is a substituent comprising any one of oxygen, nitrogen, carbon and halogen atoms having one or more unshared electron pairs, and S1And S2Respectively with M1And M2A coordinate bond is formed, and a metal oxide,
y and Z are each independently selected from O, S, N (R)m) And P, wherein RmIs hydrogen, or substituted or unsubstituted alkyl of 1 to 10 carbon atoms,
l is C (R)n) Wherein R isnIs hydrogen, substituted or unsubstituted alkyl of 1 to 20 carbon atoms, substituted or unsubstituted aryl of 6 to 20 carbon atoms, or substituted or unsubstituted amine group,
Rmand RnMay be combined with each other to form a heteroaryl group of 4 to 20 carbon atoms,
R1to R4Each independently hydrogen, a halogen group, or a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms,
a is an integer of 0 to 3, b is an integer of 1 to 5, a + b is 4 or 5,
o, p, q and r are each independently an integer of 1 to 5, and
x and y are the same and are integers from 1 to 4.
In one embodiment, S1And S2Each independently is a halogen group; or a coordinating solvent molecule comprising a functional group selected from the group consisting of a cyano group, an isocyano group, an ether group, a pyridyl group, an amide group, a sulfoxide group and a nitro group,
R1to R4Each independently hydrogen, a halogen group, or a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms substituted with a halogen group, more preferably 1 to 4 carbon atoms substituted with a halogen group,
Rnis hydrogen, a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms, a substituted or unsubstituted aryl group of 6 to 20 carbon atoms, or a substituted or unsubstituted amine group, preferably is hydrogen, a substituted or unsubstituted alkyl group of 1 to 12 carbon atoms, an aryl group of 6 to 12 carbon atoms, or a substituted or unsubstituted amine group, and
Rmand RnMay be combined with each other to form a heteroaryl group of 4 to 12 carbon atoms.
In one embodiment, S1And S2May be a halogen group; or one or more selected from acetonitrile, propionitrile, 2-methylpropionitrile, trimethylacetonitrile, benzonitrile, dialkyl ethers such as diethyl ether and diallyl ether, pyridine, dimethylformamide, dimethylsulfoxide, nitromethane, nitrobenzene and derivatives thereof, and may be an unshared pair of electrons of oxygen, nitrogen or carbon with M1And M2Coordination solvent molecules forming coordination bonds.
In the organometallic catalyst, the borate-type bulky anion may be one or more selected from the group consisting of tetrakis (phenyl) borate, tetrakis (pentafluorophenyl) borate, tetrakis [3, 5-bis (trifluoromethyl) phenyl ] borate, and derivatives thereof.
In one embodiment, if the metal is molybdenum and the bulky anion is tetrakis (pentafluorophenyl) borate, the organometallic catalyst of the invention may be one or more selected from the group consisting of compounds represented by the following formulae.
In the preparation method of polybutene oligomer according to the present invention, the step of removing the organometallic catalyst by washing the oligomerization product is not separately performed after the step of performing oligomerization. Instead, the catalyst can be easily removed by filtering the oligomeric product.
The filtration may be performed using a filter comprising one or more selected from porous materials, for example, diatomaceous earth, silica, zeolite, and alumina. In this case, the catalyst is considered to be filtered by the adsorption principle of the porous material or the like. Therefore, in the case of using glass fibers or a filter having a small pore size, the filtration efficiency of the catalyst may be reduced.
The preparation method of polybutene oligomer of the present invention may further comprise a step of drying the remaining solvent after the filtration step.
For example, the drying temperature may be 30 ℃ to 200 ℃ or 40 ℃ to 150 ℃, and the vacuum may be 300 torr or less, 200 torr or less, or 100 torr or less. Thus, the desired polybutene oligomer can be efficiently obtained. In addition, the drying method is not particularly limited, and may be performed by a usual method.
In addition, in the method for preparing polybutene oligomer of the present invention, the step of drying the halogenated hydrocarbon solvent may be separately performed or not performed after the step of performing oligomerization and before filtration. In the case where the drying step is performed, the drying conditions may be the same as those described above without specific limitations.
In the case where the drying step of the halogenated hydrocarbon solvent is separately performed, there is an advantage in that polybutene oligomer of even higher purity is obtained. However, according to the present invention, the catalyst can be easily removed by simple filtration as described above, and a step of separately drying the halogenated hydrocarbon solvent after the step of oligomerization and before filtration can be omitted, and there is an advantage of simplifying the process.
2. Polybutene oligomers
Another embodiment of the present invention provides a polybutene oligomer prepared according to the method for preparing the polybutene oligomer.
In the present invention, the oligomerization step may be performed by a batch type or a continuous type, and the number average molecular weight range and Polydispersity (PDI) of the resulting polybutene oligomer may be varied depending on the process.
For example, the number average molecular weight of the polybutene oligomer may be 5,500 or less, or 4,500 or less, or 4,200 or less, or 3,900 or less, or 3,500 or less, and 500 or more, or 750 or more, or 1000 or more, or 1200 or more.
Additionally, the oligomers may have a Polydispersity (PDI) of 1.5 to 3.0 or 1.8 to 2.5.
In addition, the exo content of the polybutene oligomer prepared by the preparation method may be 50% to 99%, preferably 74% to 99%, preferably 80% to 99%, preferably 89% to 98%, preferably 94% to 98%. The exo content means a case where a carbon-carbon double bond is located at the terminal of polyolefin, and if the exo content is increased, it means that highly reactive polyolefin, for example, highly reactive polybutene (HR-PB) is well produced.
If the reaction time of the oligomerization using the catalyst is increased, the exo content tends to be decreased due to the structural isomerization reaction of polybutene. Since the catalyst is always dissolved in the reaction product, there is a limitation due to the reaction with polybutene oligomer. However, according to the preparation method of the present invention, a mixture solvent of a halogenated hydrocarbon solvent and a nonpolar hydrocarbon solvent is used, and the dissolution phenomenon of the catalyst in the solvent may be reduced. Therefore, the limitation of reducing the profile content as described above can be solved.
Hereinafter, embodiments of the present invention will be described in detail to help understanding of the present invention. However, the following embodiments are merely examples, and the present invention may be changed and modified in many different forms and should not be construed as being limited to the embodiments set forth in the specification, and such changes and modifications should be included in the appended claims.