CN110003367B - Ziegler-Natta catalyst with dual-function external electron donor and application thereof - Google Patents

Abstract

The invention discloses a Z-N catalyst for α-olefin polymerization and an application thereof, in particular to a kind of compound composed of (A) a solid catalyst component, (B) a co-catalyst organoaluminum compound and (C) a bifunctional external electron donor compound The industrial production catalyst for α-olefin polymerization or copolymerization process, which is composed of magnesium chloride as a carrier, supports transition metals such as titanium, and a composite aromatic diacid diester/1,3-diether as an internal electron donor catalyst component; one or more organoaluminum as a cocatalyst; a bifunctional external electron donor composed of a composite external electron donor hydrocarbyl methyl (eth) silicon oxide and a polymerization temperature control agent organic acid ester; the Z- The N catalyst is used in the polymerization or copolymerization of α-olefins, and can control the polymerization reaction rate at a higher temperature, maintain the stable operation of the reactor, and stabilize the performance of the polymer.

Description

A Ziegler-Natta catalyst with bifunctional external electron donor and its application

technical field

The invention belongs to the technical field of preparation and application of alpha-olefin polymerization catalysts, and in particular relates to a bifunctional external electron donor of a Ziegler-Natta (Z-N) catalyst for alpha-olefin polymerization or copolymerization and its application.

Background technique

The Z-N catalyst system has been continuously developed since its inception, and has become the main body of the catalyst system for industrial olefin polymerization. Its development mainly goes through three stages: the progress of the carrier preparation process, the development of the internal electron donor and the improvement of the external electron donor. As an internal electron donor that promotes the development of Z-N catalysts, the monobasic acid esters of the third-generation Z-N catalysts, such as ethyl benzoate and ethyl p-ethoxybenzoate, have been developed to dibasic acid esters, such as the fourth-generation Z-N catalysts. The comprehensive performance of the catalyst is good, such as di(iso)butyl phthalate, etc. The 1,3-diether of the fifth generation Z-N catalyst is used as an internal electron donor (CN: ZL9980065.5) to prepare the catalyst component, which promotes the The development of the catalyst system also makes the research on the internal electron donor of the catalyst component become a hot spot. 1,3-Diether, such as 9,9-bis(methoxymethyl)fluorene, is used as a catalyst component for the synthesis of olefin polymerization by an internal electron donor. It has low polymerization temperature, high catalyst activity, and polyα-olefin. The isotacticity (percentage of xylene insoluble matter, the present invention is the percentage of n-hexane insoluble matter) is high, and even when no other external power supply is needed, the isotacticity of polyα-olefin is also high. 9,9-bis(methoxymethyl)fluorene can also be used as an external electron donor. However, the molecular weight distribution of polyolefins obtained by catalyzing olefin polymerization with 1,3-diether alone as an internal electron donor catalyst is narrow, which limits the application of polyolefins. The versatile di-n-(iso)-butyl phthalate and 1,3-diether are compounded as internal electron donor, and an olefin polymerization catalyst with both performances is obtained. As an external electron donor that controls the isotacticity of polyα-olefins and adjusts catalyst activity, it has also been developed from ester compounds to hydrocarbyl silicon alkoxides of the fourth generation Z-N catalysts. Hydrocarbyl alkoxy silicons with different structures control the isotacticity of polyalpha-olefins and other indicators, and then control the mechanical properties of polyalpha-olefin materials, and there are great differences. Dicyclopentyldimethoxysilicon can well control the isotacticity of polyα-olefins, methylcyclohexyldimethoxysilicon is a general external electron donor, and diphenyldimethoxysilicon is a common The external electron donor used. But they control the isotacticity of polyalpha-olefins, the mechanical properties of the material, the impact on the environment, and the price are very different. Composite external electron donors may be a very effective solution to these problems.

It is very important to control the polymerization reaction temperature. Exceeding the normal polymerization temperature range of 65-70 °C will cause explosion, softening of polymer particles, sticking to blocks, sticking to reactor walls, blocking pipelines, and even causing forced shutdown accidents. At abnormal polymerization temperature, the isotacticity and other indicators of polyalpha-olefin will also be changed, and even the produced polymer is "waste". This is a huge "risk" for the continuous polymerization process. For the α-olefin polymerization fluidized bed reaction, the control of the polymerization temperature and the control of the isotacticity of the polyα-olefin are more important. Because the polymerization or copolymerization of alpha-olefins is a violently exothermic reaction, the rate of polymerization or copolymerization of alpha-olefins is a key factor in controlling the polymerization temperature.

SUMMARY OF THE INVENTION

The purpose of the present invention is to develop a new type of dual-functional composite external electron donor, which can automatically reduce the activity of the catalyst at abnormal polymerization temperature, change the polymerization reaction rate, and make the temperature quickly fall back to the normal polymerization temperature to achieve stable control of the reaction temperature. , to prevent the occurrence of explosion accidents. At the same time, even at a short abnormal polymerization temperature, the properties such as isotacticity and melt index of polyα-olefin are kept unchanged, and the main technical indicators such as mechanics and processability of poly-α-olefin materials are maintained. There are many kinds of hydrocarbyl hydrocarbyloxysilicon that constitute the external electron donor. Different structures of hydrocarbyl hydrocarbyloxysilicon have different effects on the performance of polyalpha-olefins. Using different structures of hydrocarbyl hydrocarbyloxysilicon compound as an external electron donor can Modulation of the properties of polyalphaolefins.

The main content of the present invention is to improve the performance of the Z-N catalyst for α-olefin polymerization, to develop an external electron donor with dual functions, and to develop a composite external electron donor that can not only self-control the polymerization activity, but also maintain various properties of the material. , and then constitute a catalyst system that can stably control the reaction temperature of industrial large-scale preparation of polyalpha-olefins, and can also ensure material properties at abnormal polymerization temperatures. The Z-N catalyst is composed of three components (A), (B) and (C), namely: catalyst component A, co-catalyst alkyl aluminum B and dual catalysts that automatically adjust catalyst activity and control the performance of polyalpha-olefins. A functional composite external electron donor C; where:

(1) The catalyst component A is composed of at least transition elements such as magnesium chloride supported titanium (ion) and a composite internal electron donor; the composite internal electron donor includes an aromatic diacid dialkyl ester and a 1,3-diether. There are many preparation methods for catalyst component A, and various transition metal compounds are used, added and generated. The present invention has no limited requirements on the preparation method, the raw materials used, and the type and quantity of the transition metal compound to be generated, and also has no limited requirements on the inert transition metal compound added in the preparation process. Roughly speaking, catalyst component A can be prepared by: ① the co-precipitation method of magnesium chloride alcoholate, composite internal electron donor and titanium tetrachloride; ② the method of supporting titanium tetrachloride and composite internal electron donor on spherical magnesium chloride alcoholate carrier Preparation; 3. Preparation by the method of magnesium chloride supported composite internal electron donor generated by the reaction of diethoxymagnesium and titanium tetrachloride. These belong to the usual methods for the preparation of the catalyst component A.

(2) The cocatalyst Alkyl aluminum B is at least one of the alkyl aluminums. Commonly used are triethylaluminum, triisobutylaluminum, dialkylaluminum hydride, alkyldihydrogenaluminum, dialkylaluminum halide, alkylaluminum dihalide, dialkylalkoxyaluminum, alkyldi Alkoxides. The cocatalyst is C _1-4 trialkylaluminum, and more importantly triethylaluminum is used.

(3) Dual-functional new composite external electron donor C includes a composite external electron donor and a polymerization temperature control agent. The combination of the composite external electron donor and the polymerization temperature control agent automatically adjusts the catalyst activity and maintains the basic properties of the polymer. The dual function the external electron donor. According to the type and content of the two internal electron donors in the catalyst component A, the type and amount of the composite external electron donor and the polymerization temperature control agent are selected to satisfy the polymerization activity of the catalyst at the abnormal polymerization temperature is lower than the normal polymerization temperature. Activity, and meet the requirements of maintaining normal polymerization temperature such as isotacticity and melt index of polyα-olefin. In the new dual-functional composite external electron donor C, the composite external electron donor includes two external electron donors, the first external electron donor is two dihydrocarbyldihydrocarbyloxysilicon with the same hydrocarbon group, and the second external electron donor is two. The external electron donor is two dihydrocarbyldihydrocarbyloxysilicon, hydrocarbyl trihydrocarbyloxysilicon or tetrahydrocarbyloxysilicon with different hydrocarbon groups, and the first external electron donor and the second external electron donor are The molar ratio is 1:9～9:1;

The molar ratio of the bifunctional composite external electron donor C to the molar ratio of the metal titanium ions in the catalyst component A is 1-500:1;

The molar ratio of the total number of moles of the bifunctional composite external electron donor C to the aluminum compound in the cocatalyst component B is 0.01-5:1.

The composite external electron donor and polymerization temperature control agent can well achieve that the polymerization activity of the catalyst at abnormal polymerization temperature is less than that of normal polymerization temperature, and can maintain the isotacticity, melt index and other indicators of polyα-olefin, especially It can meet and control the properties of polyalpha-olefins.

The composite external electron donor is composed of at least two kinds of hydrocarbyl silicon alkoxides. For the convenience of description, composite external electron donors are usually divided into the first type of external electron donors and the second type of external electron donors. The first external electron donor is RnSi( _OCH3 )(4- _{n )} or RnSi( _OCH2CH3 )( _{4 -n) ,} n= ² , and ^two hydrocarbon groups R1 and R2 are the same; the second external donor is a member of RnSi( _OCH3 )(4- _{n )} or RnSi( _OCH2CH3 )( _{4 -n) other} than the first external donor , this division is relative. The principle for the selection of the components of the composite external electron donor depends on the properties of the polyα-olefin to be prepared, that is, it depends on the composite internal electron donor of the catalyst A component.

For the ZN catalyst described in the above technical solution, wherein the external electron donor is selected from the hydrocarbyl hydrocarbyloxysilicon external electron donor that is usually selected for the fourth-generation ZN catalyst, to control the structure of the polyα-ene. Commonly used external electron donors are hydrocarbyl methoxy silicon R _n Si(OCH ₃ ) _(4-n) or hydrocarbyl ethoxy silicon R _n Si(OCH ₂ CH ₃ ) ₍₄ -n), generally n=0, 1 or 2. When n=0, the hydrocarbyl silicon alkoxides are tetramethoxy silicon and tetraethoxy silicon, which can be used as the second external electron donor. When n=1, the hydrocarbyl hydrocarbyl silicon oxides are hydrocarbyl trimethoxy silicon and hydrocarbyl triethoxy silicon, which can be used as the second external electron donor; R is C _1-18 straight or branched chain alkyl, C _5-10 cycloalkyl, alkylcycloalkyl or cycloalkylalkyl, _C6-10 phenyl, phenylalkyl or alkylphenyl. When n=2, R is two hydrocarbon groups R ¹ and R ² , R ¹ and R ² can be the same or different, R ¹ and R ² are the same as the first external electron donor, and R ¹ and R ² are not At the same time, it is the second external electron donor, R ¹ and/or R ² are C _1-18 straight or branched chain alkyl, C _5-10 cycloalkyl, alkylcycloalkyl or cycloalkylalkyl, C _6-10 phenyl, phenylalkyl or alkylphenyl. A composite external electron donor is composed of two or more of the external electron donors. Commonly used composite external electron donors are preferably composed of external electron donors for industrial polymerization catalysts of propylene.

Preferably, the first external electron donor is dimethyldimethoxysilicon, dimethyldiethoxysilicon, diethyldimethoxysilicon, diethyldiethoxysilicon, dipropylsilicon Dimethoxysilicon, Dipropyldiethoxysilicon, Diisopropyldimethoxysilicon, Diisopropyldiethoxysilicon, Dibutyldimethoxysilicon, Dibutyldiethoxysilicon Silicon, Diisobutyl Dimethoxy Silicon, Diisobutyl Diethoxy Silicon, Diamyl Dimethoxy Silicon, Dipentyl Diethoxy Silicon, Diisoamyl Dimethoxy Silicon , Diisoamyl diethoxy silicon, dihexyl dimethoxy silicon, dihexyl diethoxy silicon, dicyclopentyl dimethoxy silicon, dicyclopentyl diethoxy silicon, bicyclohexyl Dimethoxysilicon, dicyclohexyldiethoxysilicon, diphenyldimethoxysilicon, diphenyldiethoxysilicon.

Preferably, the second external electron donor is selected as: propyl trimethoxy silicon, propyl triethoxy silicon, butyl trimethoxy silicon, butyl triethoxy silicon, pentyl trimethoxy silicon, Amyl triethoxy silicon, isopentyl trimethoxy silicon, isopentyl triethoxy silicon, octyl trimethoxy silicon, octyl triethoxy silicon, isooctyl trimethoxy silicon, isooctyl Triethoxy silicon, decyl trimethoxy silicon, methyl cyclopentyl dimethoxy silicon, methyl cyclopentyl diethoxy silicon, methyl cyclohexyl dimethoxy silicon, methyl cyclohexyl Diethoxysilicon.

For the Z-N catalyst described in the above technical solution, wherein in the catalyst component A, the dialkyl aromatic diacid is di-n-(iso)butyl phthalate; the 1,3-diether is 2,3-diether 2-Dialkyl-1,3-dimethoxypropane, of which 9,9-bis(methoxymethyl)fluorene is commonly used, has been developed by the applicant into an industrialized product. A typical complex internal electron donor is composed of di-n-(iso)butyl phthalate and 9,9-bis(methoxymethyl)fluorene.

As an external electron donor, 1,3-diether, especially 9,9-bis(methoxymethyl)fluorene is also a good choice. Bis(perhydroisoquinoline)dimethoxysilicon is also an effective external electron donor.

For the ZN catalyst described in the above technical solution, the polymerization temperature control agent is at least one of fatty acid ester and fatty diacid diester. The fatty acid ester includes C _10-20 straight chain fatty acid C ₃ -C ₆ straight chain, branched chain alkyl ester, and the fatty diacid diester includes C _4-16 straight chain fatty acid C _2-8 straight chain , branched chain dialkyl esters. Branched alkyl esters of straight-chain fatty acids or dialkyl esters of straight-chain fatty diacids are important. Esters of natural fatty acids, natural fatty diacids, are preferred fatty acid esters.

Further, the polymerization temperature control agent is selected from at least one of C _10-20 straight chain fatty acid C _3-6 alkyl ester or C _4-16 straight chain fatty diacid C _2-8 dialkyl ester to form a polymerization temperature control external supply. Electron body C. Important fatty acid esters are isopropyl dodecanoate, isoamyl dodecanoate, isopropyl myristate, isopropyl hexadecanoate, isopropyl octadecanoate, diethyl adipate, hexanediol Di-n-butyl acid, diisobutyl adipate, diethyl suberate, di-n-butyl suberate, diisobutyl suberate, diethyl sebacate, di-n-butyl sebacate ester, diisobutyl sebacate.

As a polymerization temperature control agent, natural fatty acid glycerides are also a good choice.

Long-chain natural fatty acid esters are green chemicals and base materials for cosmetics. They remain in polyalphaolefins without affecting the application properties of polymers, and can also act as plasticizers. Linear fatty diacid diesters are also green chemicals, themselves plasticizers for polyalpha-enes. Natural fatty acid glycerides are also green chemicals, which remain in the polyα-ene without affecting the application properties of the polymer, and can also act as a plasticizer. The raw materials of long-chain natural fatty acid esters and straight-chain fatty diacid diesters come from natural resources, which are convenient and green, with simple processing technology, low price and sufficient market supply.

For the Z-N catalyst described in the above technical solution, specifically, in the catalyst component A, magnesium chloride is used as a carrier, the mass fraction of supported titanium is 2.0-3.8%, and the mass fraction of 1,3-diether is 1-13% %, the mass fraction of aromatic diacid dialkyl ester is 1-8%. The types and quantities of other transition metal compounds are not limited.

For the Z-N catalyst described in the above technical solution, specifically, the molar ratio of the bifunctional composite external electron donor C to the molar ratio of metal titanium ions (Ti) in the catalyst component A is 1 to 500:1, preferably 1 ~100:1.

For the Z-N catalyst described in the above technical solution, specifically, the molar ratio of the di-n-(iso)butyl phthalate to 9,9-bis(methoxymethyl)fluorene is 1～10:10～ 1.

For the Z-N catalyst described in the above technical solution, specifically, the molar ratio of the total amount of the composite external electron donor to the polymerization temperature control agent is 1-10:10.

For the Z-N catalyst described in the above technical solution, specifically, the molar ratio of the first external electron donor to the second external electron donor among the two external electron donors of the composite external electron donor is 1 :9 to 9:1.

The polymerization temperature control agent fatty acid ester and fatty diacid diester are combined with the composite external electron donor as an external electron donor. As the polymerization temperature increases, the polymerization activity decreases, and the polymerization activity at abnormal polymerization temperature is less than that at normal polymerization temperature. The activity of the temperature is 30-40%, even less than 50% of the activity at the normal polymerization temperature. Therefore, the present invention selects fatty acid esters and fatty diacid diesters as polymerization temperature control agents, and has obvious effect on automatically controlling the polymerization reaction rate. Under the abnormal polymerization temperature, it has the function of automatically controlling the polymerization reaction rate, that is, adjusting the polymerization temperature to quickly fall back to the normal polymerization temperature. At normal polymerization temperatures, the polymerization activity may also be lower than that of catalysts with only complex external electron donors. This is a major highlight of the present invention.

When the specific content of the two internal electron donors in the catalyst component A and the specific properties of the catalyst are required, the bifunctional novel composite external electron donor C can only contain the polymerization temperature control agent, fatty acid ester or fatty diacid diacid ester. For example, a general-purpose polypropylene film with an isotacticity of 95% is a qualified material. At this time, for some catalyst components A with a relatively high content of 9,9-bis(methoxymethyl)fluorene, only fatty acid esters are used as external electron donors to obtain polypropylene with isotacticity of 95%. At the same time, it can automatically adjust the polymerization temperature. This is the second highlight of the present invention.

The third highlight of the present invention is to flexibly select the type and amount of the external electron donor and the polymerization temperature control agent according to the relative contents of the two internal electron donors to form an external electron donor that automatically controls the catalyst activity.

The function of the external electron donor is to combine with the polymerization temperature control agent to form an external electron donor that automatically controls the catalyst activity, and the structure of the control polymer remains unchanged. The combination between the external electron donor and the polymerization temperature control agent can not only meet the requirement that the polymerization activity of the catalyst at abnormal polymerization temperature is less than its polymerization activity at normal polymerization temperature, and can achieve stable control of polymerization temperature, but also can achieve stable control of polymerization temperature at abnormal polymerization temperature. The properties of the polymer at the polymerization temperature remain unchanged, which is the fourth highlight of the present invention.

Different catalyst components A and different combinations of external electron donors have different effects on the properties of polyα-olefins. The external electron donors in the bifunctional external electron donors of the present application include two types, the first external electron donor and the second external electron donor, which constitute a composite external electron donor. The composite external electron donor and the polymerization temperature The interaction between the control agents, on the one hand, makes the catalyst performance change when the reaction temperature increases, changes the polymerization reaction rate, and makes the temperature quickly fall back to the normal polymerization temperature; The important properties such as the isotacticity of the poly-alpha-olefin remain unchanged, that is, the main properties of the poly-alpha-olefin generated at the normal polymerization temperature and the abnormal polymerization temperature remain unchanged, and the properties of the poly-alpha-olefin material are maintained. It is the fifth highlight of the present invention.

The method of using the composite external electron donor and the polymerization temperature control agent of the present application is flexible and convenient, and the composite external electron donor and the polymerization temperature control agent can be added to the polymerization system at the same time, or can be added to the polymerization system separately.

Usually, the industrial polymerization temperature of propylene is 65-70 °C, and the abnormal polymerization temperature is defined in this application as 80-120 °C. Experiments have shown that at 90 °C, the polymerization activity of propylene is more than 30% lower than that of 70 °C. At 110 °C, propylene The polymerization activity is very small, and even some systems have polymerization activity close to zero. Therefore, the present invention determines that the abnormal polymerization reaction temperature of the external electron donor C with bifunctional action is 90°C.

The Z-N catalyst described in any one of the above technical solutions is applied to the polymerization and copolymerization of α-olefin, and the applications include: propylene polymerization, 1-butene polymerization, propylene and ethylene copolymerization, 1-butene It is used in the copolymerization reaction of ethylene and ethylene, and the copolymerization reaction of propylene and 1-butene. It is important to use it in the polymerization reaction of propylene and the copolymerization reaction of propylene and ethylene.

The improved Z-N catalyst of the present invention is used for propylene polymerization, and the isotacticity of the obtained polypropylene is 95-99%, depending on the composite internal electron donor of solid catalyst component A, di-n-(iso)-butyl phthalate and Molar ratio of 9,9-bis(methoxymethyl)fluorene and combination of bifunctional external electron donor C. When the internal electron donor ratio and the combination of C are determined, the isotacticity of polypropylene is determined accordingly. Even when the polymerization temperature is raised to 90-120 °C, the isotacticity of polypropylene remains unchanged, even at the normal polymerization temperature. The isotacticity, melt index, etc. of the produced polypropylene, even if the explosion occurs, the isotacticity and melt index of the produced polypropylene remain basically unchanged, which ensures the quality of the polypropylene.

According to the molar ratio of 1,3-diether and dialkyl aromatic diacid in the catalyst component A, adjust the compound external electron donor hydrocarbyl alkoxy silicon, polymerization temperature control agent fatty acid ester type, mutual The molar ratio between them maintains the high activity of the catalyst and the stable operation of polypropylene suitable for isotacticity.

The polymerization and copolymerization of the α-olefin is a continuous polymerization reaction, especially a continuous gas phase polymerization reaction. The continuous polymerization is carried out in one or more reactors connected in series; the continuous polymerization is carried out in a fluidized bed reactor.

The bifunctional external electron donor of the present invention is suitable for various polymerization and copolymerization processes of α-olefin, especially suitable for continuous polymerization, especially continuous gas phase polymerization, suitable for continuous polymerization and copolymerization of α-olefin. It is carried out in more than one reactor operated in series, especially in a fluidized bed reactor.

The composite external electron donor and the polymerization temperature control agent of the present invention are added to the reactor by various methods: the composite external electron donor and the polymerization temperature control agent are added together or separately with the catalyst component A and/or the cocatalyst component B at the same time Add to the reactor; in the process of connecting more than one reactor in series, the external electron donor and the polymerization temperature control agent are added to the first reactor at the same time as the catalyst component A and the cocatalyst component B, respectively, or the external electron donor can be added first. In the first reactor, the polymerization temperature control agent was subsequently added to different reactors.

beneficial effect

(1) According to the molar ratio of 1,3-diether and dialkyl aromatic diacid in catalyst component A, adjust the ratio of two kinds of hydrocarbyl alkoxy silicon of compound external electron donor, fatty acid ester of polymerization temperature control agent, etc. The species and the molar ratio between them can maintain the high activity of the catalyst and adjust the isotacticity of the polyalpha-olefin to 95-99.9%, thereby expanding the application range of the polyalpha-olefin.

(2) The catalytic activity of adding the polymerization temperature control agent can be higher than that of the catalyst using the external electron donor alone, which expands the selection range of the two external electron donors of the catalyst.

(3) At different temperatures, the isotacticity, melt index, etc. of the polyα-ene obtained by the polymerization of propylene using the catalyst system remain unchanged. It ensures the quality of polyα-ene during the whole polymerization process, including abnormal polymerization temperature.

(4) The catalyst system of the dual-function external electron donor of the present invention has achieved good results in the industrial mobile stirred tank polymerization process and in the gas phase fluidized bed polymerization process, preventing the occurrence of explosion.

(5) The bifunctional external electron donor of the present application adopts the synergistic effect of the composite external electron donor and the polymerization temperature control agent, which can automatically control the relationship between the reactivity and the reaction temperature; the external electron donors of different structures— - Hydrocarbyl alkoxy silicon has different properties for polyalpha-olefins, and the external electron donors of the two structures are used in combination, giving polyalpha-olefins complementary properties of two external electron donors, and more importantly, polyalpha-olefins Materials will have new properties.

(6) The bifunctional external electron donor C of the present application includes a composite external electron donor, which obviously improves the mechanical properties of the polyalpha-olefin material, improves the processing performance of the polyalpha-olefin material, and broadens the use of the polyalpha-olefin.

Detailed ways

The following non-limiting examples are used to illustrate the combination and properties of the composite external electron donor and the polymerization temperature control agent suitable for the catalyst system, so as to facilitate a more comprehensive understanding of the present invention by those of ordinary skill in the art. However, these implementations The examples in no way constitute any limitation of the invention.

Various external electron donors and polymerization temperature control agents supplied in the market have been designed and formed into several composite external electron donor/polymerization temperature control agent combinations. Each combination group is formulated into a 10% hexane solution to ensure that each test of repeatability. The experiment is to carry out the bulk polymerization of propylene in a 5L autoclave. Each experiment is performed according to the following procedures, respectively, only the composite external electron donor and the composite external electron donor/polymerization temperature control agent combination are performed. In each experiment, the amount of polypropylene produced before reaching the polymerization temperature was measured. The method was to heat up the polymerization kettle at a constant speed. When the polymerization temperature was reached, the propylene in the reaction kettle was immediately emptied, and the dried polypropylene was weighed. Then the polymerization experiment was carried out. The polymerization kettle was heated at a constant rate. When the polymerization temperature was reached, the time was recorded. After 1 h of reaction, the propylene in the reaction kettle was immediately vented, and the dried polypropylene was weighed. When calculating the catalyst activity, the polypropylene generated before reaching the polymerization temperature was deducted. amount. The pressure of the reactor before each stop of the polymerization is the saturated vapor pressure of propylene at the polymerization temperature. Each experiment was done three times and the average value was obtained. The polymer samples were retained for testing other performance data.

The catalyst activity in the present application is the average value of multiple calibrations, which is called the standard catalytic activity.

Example

Take 0.02g of catalyst A component, 1.5ml of cocatalyst triethylaluminum, the first external electron donor C, the second external electron donor D and the polymerization temperature control agent B, and design different combinations. The experimental results are as follows Table 1.

Comparative ratio

Using the same method, take 0.02 g of catalyst A component, 1.5 ml of cocatalyst triethylaluminum, external electron donor C, and polymerization temperature control agent B, and design different combinations. The comparative experimental results are shown in Table 2.

The Z-N catalyst catalyzes the normal polymerization temperature of α-olefin at 65-70°C, and the polymerization reaction is a strong exothermic reaction. The bifunctional external electron donor C of the present application can effectively control the polymerization reaction rate, that is, stably control the polymerization reaction temperature. When the reaction temperature reached 90°C, the polymerization activity was reduced by more than 30% compared with the polymerization activity at 70°C. Even if an explosion accident occurs in the production process, the polymerization temperature is difficult to exceed 90 °C.

The Ziegler-Natta catalyst of the bifunctional external electron donor of the invention can effectively control the polymerization temperature at 70-120 DEG C, and can keep the isotacticity and melt index of the polyalpha-olefin stable. Generally, the performance of the catalyst is an important evaluation index at a temperature of 20 °C (70-90 °C) above the normal temperature. The polymerization temperature is too much higher than the normal temperature, which is of little significance for the evaluation of the performance of the catalyst. Therefore, the present invention focuses on analyzing the performance of the catalyst at 70-90°C.

As can be seen from Table 1, in the polymerization method of the present application, when the polymerization reaction temperature exceeds the normal polymerization temperature, the activity of the catalyst can be effectively and automatically controlled, so that the polymerization reaction rate decreases and the temperature quickly falls back to the normal polymerization temperature. At the same time, as the polymerization temperature increases, the isotacticity of the product remains unchanged and the melt index is stable.

It can also be seen from Table 1 that in the polymerization method of the present application, the isotacticity of the generated polyα-olefin is arbitrarily adjusted between 95 and 99%, while maintaining good melt index performance; the isotacticity and melt index of the product are in A larger range has been adjusted, broadening the use of polyalpha-olefins.

It can be seen from Table 2 that with the increase of the reaction temperature, the activity of the catalyst can be automatically controlled, so that the activity of the polymerization reaction decreases, which is beneficial for the temperature to quickly fall back to the normal polymerization temperature. However, with the increase of temperature, there is no stable law to follow in the changes of product isotacticity and melt index. Once detonation occurs in the production process, the properties of the obtained polyalphaolefin are difficult to guarantee, and even a batch of waste products are produced. This is a huge threat to the continuous polymerization production process.

This shows that the excellent effect of the composite external electron donor on controlling the isotacticity and melt index of the product is obvious.

Table 1

Note: A catalyst component, A ₁ magnesium chloride alcoholate, composite internal electron donor and titanium tetrachloride co-precipitation method, which contains 2.78% titanium, 1.71% diisobutyl phthalate, 9,9- Di(methoxymethyl)fluorene 5.31%; A ₂ Spherical magnesium chloride alcoholate carrier supporting titanium tetrachloride and composite internal electron donor, wherein titanium 3.01%, diisobutyl phthalate 3.07%, 9,9-bis(methoxymethyl)fluorene 5.14%; A ₃ prepared by the method of magnesium chloride supporting composite internal electron donor generated by the reaction of diethoxymagnesium and titanium tetrachloride, wherein titanium 2.73%, phthalic acid 9.20% of di-n-butyl ester, 1.54% of 9,9-bis(methoxymethyl)fluorene. B polymerization temperature control agent, wherein B ₁ isopropyl dodecanoate, B ₂ isopropyl myristate, B ₃ isopropyl hexadecate, B ₄ isopropyl octadecanoate, B ₅ diethyl suberate ester. C The first external electron donor, wherein C ₁ dimethyldimethoxy silicon, C ₂ diisopropyl dimethoxy silicon, C ₃ diisobutyl dimethoxy silicon, C ₄ dicyclopentane Dimethoxysilicon. D The second external electron donor, wherein D ₁ propyl trimethoxy silicon, D ₂ propyl triethoxy silicon, D ₃ tetraethoxy silicon, D ₄ methylcyclohexyl dimethoxy silicon, D ₅ 9,9-bis(methoxymethyl)fluorene.

Table 2

Note: A catalyst component: A ₁ magnesium chloride alcoholate, composite internal electron donor and titanium tetrachloride co-precipitation method, which contains magnesium 17.17%, titanium 2.24%, diisobutyl phthalate, 2.68% , 9,9-bis(methoxymethyl)fluorene 12.14%; A ₂ Spherical magnesium chloride alcoholate carrier supporting titanium tetrachloride and composite internal electron donor, which contains 18.23% magnesium, 3.11% titanium, o Diisobutyl phthalate 6.07%, 9,9-bis(methoxymethyl) fluorene 5.14%; A ₃ Method for preparing the composite internal electron donor supported by magnesium chloride supported by the reaction of diethoxymagnesium and titanium tetrachloride , which contains 18.16% magnesium, 3.14% titanium, 5.32% diisobutyl phthalate, and 11.89% 9,9-bis(methoxymethyl)fluorene. B polymerization temperature control agent: B ₁ isopropyl myristate, B ₂ isopropyl hexadecanoate, B ₃ isopropyl octadecanoate. C external electron donor: C ₁ diisobutyldimethoxy silicon, C ₂ methylcyclohexyl dimethoxy silicon, C ₃ propyl trimethoxy silicon. Experimental parameters: the molar ratio of external electron donor to titanium is 20; the mass ratio of C external electron donor to B polymerization temperature control agent is 20:80.

Claims (8)

1. a Z-N catalyst for the preparation of polyalpha-olefin, characterized in that: comprising the catalyst component A of the inner electron donor supported by magnesium chloride, the cocatalyst alkylaluminum B and the outer electron donor C with dual functions; in: (1) The catalyst component A is at least composed of magnesium chloride supported titanium ions and a composite internal electron donor; the composite internal electron donor includes one of di-n-butyl phthalate or diisobutyl phthalate. species and 9,9-bis(methoxymethyl)fluorene; (2) cocatalyst alkylaluminum B is at least one of triethylaluminum and triisobutylaluminum; (3) The external electron donor C with dual functions includes a composite external electron donor and a polymerization temperature control agent, and the polymerization temperature control agent is at least one of fatty acid ester and fatty diacid diester; In the external electron donor C with dual functions, the composite external electron donor includes two external electron donors. The external electron donor is two dihydrocarbyl dihydrocarbyloxysilicon, hydrocarbyl trihydrocarbyloxysilicon or tetrahydrocarbyloxysilicon with different hydrocarbon groups, and the moles of the first external electron donor and the second external electron donor The ratio is 1:9～9:1; The molar ratio of the external electron donor C with dual functions to the metal titanium ion in the catalyst component A is 1-500:1; The molar ratio of the bifunctional external electron donor C to the aluminum compound in the cocatalyst component B is 0.01-5:1; In the catalyst component A, magnesium chloride is used as a carrier, the mass fraction of supported titanium is 2.0-3.8%, the mass fraction of 9,9-bis(methoxymethyl)fluorene is 1-13%, and the mass fraction of di-n-phthalate is 2.0-3.8%. The mass fraction of butyl phthalate or diisobutyl phthalate is 1-8%; the di-n-butyl phthalate or diisobutyl phthalate and 9,9-bis(methoxymethyl) ) The molar ratio of fluorene is 1～10:10～1; The molar ratio of the composite external electron donor to the polymerization temperature control agent is 1-10:10. 2. The ZN catalyst according to claim 1, characterized in that: the composite external electron donor is Si(OCH ₃ ) ₄ , Si(OCH ₂ CH ₃ ) ₄ , R _n Si(OCH ₃ ) _{(4 -n)} or R _n Si(OCH ₂ CH ₃ ) _(4-n) , and n=1 or 2; the Si(OCH ₃ ) ₄ and Si(OCH ₂ CH ₃ ) ₄ are the second type of external electron donor body; when n=1, the R _n Si(OCH ₃ ) _(4-n) or R _n Si(OCH ₂ CH ₃ ) _(4-n) is the second external electron donor; R is C _{1 -12} straight or branched chain alkyl; C _5-10 cycloalkyl, alkyl cycloalkyl or cycloalkyl alkyl; C _6-10 phenyl, phenylalkyl or alkylphenyl; when n= 2, R is two hydrocarbon groups R ¹ and R ² , R ¹ and R ² may be the same or different, when R ¹ and R ² are the same, the R _n Si(OCH ₃ ) _(4-n) or R _n Si(OCH ₂ CH ₃ ) _(4-n) is the first external electron donor; when R ¹ and R ² are different, the R _n Si(OCH ₃ ) _(4-n) or R _n Si(OCH ₂ CH ₃ ) _(4-n) is the second external electron donor; R ¹ and/or R ² are C _1-12 straight or branched chain alkyl; C _5-10 cycloalkyl, alkylcycloalkyl or cycloalkylalkyl; C _6-10 phenyl, phenylalkyl or alkylphenyl. 3. The Z-N catalyst according to claim 1 or 2, wherein the first external electron donor is dimethyldimethoxysilicon, dimethyldiethoxysilicon, diethyldimethoxysilicon Methoxysilicon, Diethyldiethoxysilicon, Dipropyldimethoxysilicon, Dipropyldiethoxysilicon, Diisopropyldimethoxysilicon, Diisopropyldiethoxysilicon Silicon, dibutyldimethoxysilicon, dibutyldiethoxysilicon, diisobutyldimethoxysilicon, diisobutyldiethoxysilicon, diisoamyldimethoxysilicon, Diisoamyldiethoxysilicon, Dicyclopentyldimethoxysilicon, Dicyclopentyldiethoxysilicon, Dicyclohexyldimethoxysilicon, Dicyclohexyldiethoxysilicon, Dicyclohexyldiethoxysilicon Phenyldimethoxysilicon, diphenyldiethoxysilicon; The second external electron donor is propyl trimethoxy silicon, propyl triethoxy silicon, butyl trimethoxy silicon, butyl triethoxy silicon, pentyl trimethoxy silicon, pentyl triethoxy silicon Silicon, isopentyl trimethoxy silicon, isopentyl triethoxy silicon, octyl trimethoxy silicon, octyl triethoxy silicon, isooctyl trimethoxy silicon, isooctyl triethoxy Silicon, decyltrimethoxysilicon, decyltriethoxysilicon, methylcyclopentyldimethoxysilicon, methylcyclopentyldiethoxysilicon, methylcyclohexyldimethoxysilicon or methylcyclohexyldimethoxysilicon cyclohexyldiethoxysilicon. 4. ZN catalyst according to claim 1, is characterized in that: described polymerization temperature control agent is at least one in fatty acid ester, fatty diacid diester, comprises C _10-20 straight chain fatty acid C _3-6 Straight-chain, branched-chain alkyl ester, C _4-16 straight-chain aliphatic diacid C _2-6 straight-chain, branched-chain dialkyl ester. 5. Z-N catalyst according to claim 4 is characterized in that: described polymerization temperature control agent is the ester of natural fatty acid, comprises n-propyl laurate, isopropyl laurate, n-amyl laurate , Isoamyl dodecanoate, n-propyl myristate, isopropyl myristate, isoamyl myristate, n-propyl myristate, isopropyl myristate, n-propyl myristate, Isopropyl octadecanoate; Fatty diacid diester selected from diethyl adipate, di-n-butyl adipate, diisobutyl adipate, diethyl suberate, di-n-butyl suberate , Diisobutyl suberate, diethyl sebacate, di-n-butyl sebacate, diisobutyl sebacate. 6. A Z-N catalyst for preparing poly-alpha-olefin according to claim 1, characterized in that: said preparing poly-alpha-olefin comprises: propylene polymerization, 1-butene polymerization, ethylene and propylene Copolymerization reaction, ethylene and 1-butene copolymerization reaction, propylene and 1-butene copolymerization reaction. 7. The application of the Z-N catalyst according to any one of claims 1 or 6 in the preparation of polyalpha-olefin, characterized in that: the polymerization and copolymerization of the alpha-olefin are continuous polymerization, and the continuous polymerization The reactor is more than one reactor in series, and the reactor for continuous polymerization is a fluidized bed reactor. 8. The application according to claim 7 is characterized in that: in the polymerization and copolymerization reaction of the α-olefin, the composite external electron donor and the polymerization temperature control agent are added into the reactor by various methods: the composite external electron donor The polymer and the polymerization temperature control agent are added to the reactor together or separately with the catalyst component A and/or the cocatalyst component B; in the process of more than one reactor in series, the composite external electron donor and the polymerization temperature control agent are separately added to the catalyst. Component A and co-catalyst component B are added to the first reactor at the same time, or the composite external electron donor can be added to the first reactor first, and the polymerization temperature control agent is then added to different reactors.