CN104829762A

CN104829762A - Preparing method and application of catalyst for preparation of high-spherical low-particle-size polyolefin particles

Info

Publication number: CN104829762A
Application number: CN201510271254.1A
Authority: CN
Inventors: 李化毅; 罗志; 张辽云; 胡友良
Original assignee: Institute of Chemistry CAS
Current assignee: Institute of Chemistry CAS
Priority date: 2015-05-25
Filing date: 2015-05-25
Publication date: 2015-08-12
Anticipated expiration: 2035-05-25
Also published as: CN104829762B

Abstract

The invention provides a preparing method of catalyst for preparation of high-spherical low-particle-size polyolefin particles. The catalyst is used for olefinic polymerization, the prepared polyolefin particles are of high sphericalness, small particle size (averagely 50 micrometers to 30 micrometers), narrow particle size distribution and low bulk density (0.1g/mL to 0.4g/mL). By means such as adjusting the forming temperature of a catalyst carrier and forming time of the catalyst and using any added nanoparticle as a third component for accelerating the formation of the catalyst, the catalyst is of small particle size and high sphericalness; according to replication of heterogeneous catalysts, submicron polyolefin spherical particles are prepared.

Description

Preparation method and application of catalyst for preparing high-sphericity low-granularity polyolefin particles

Technical Field

The invention relates to the technical field of olefin polymerization, in particular to a preparation method and application of a catalyst for preparing polyolefin particles.

Background

Ziegler-Natta (Ziegler-Natta) catalysts are organometallic catalysts used for the synthesis of unbranched, highly stereoregular polyolefins, also known as Ziegler-Natta initiators, which belong to the group of coordination polymerization initiators. Ziegler first discovery of German organic chemist in 1956TiCl is₄/Et₃The Al system is effective at catalyzing ethylene polymerization at relatively low pressures, and the italian chemist nat subsequently developed this catalytic system for the isotactic polymerization of propylene, butadiene, isoamylene, etc., these catalysts later being referred to as ziegler-Natta catalysts.

From the invention of Ziegler-Natta catalysts in the 50 th of the 20 th century to decades now, Ziegler-Natta catalysts are continuously updated, starting from the first conventional crystalline form of TiCl₃And AlCl₃Eutectic crystal develops into MgCl with high activity and high performance₂And/or SiO₂The fourth generation and the fifth generation catalysts which are carriers not only improve the catalytic activity of the catalyst by hundreds to thousands of times, but also ensure that the isotacticity of the prepared polymer reaches more than 98 percent. The use of the high-activity Ziegler-Natta catalyst not only saves the traditional polyolefin deliming process, but also simplifies the production process of the olefin, saves the consumption of electric power and energy and greatly reduces the production cost.

Nowadays, there are many patents on the preparation of ziegler-natta catalysts, which mainly aim at improving the activity of the catalyst or various physical and chemical properties such as isotacticity, hydrogen tone, impact strength, etc. of polyolefin, and there is little attention paid to the particle size of the catalyst and polyolefin particles, mainly because the small particle size of either the catalyst or the polyolefin is not favorable in industrial production, and such research cannot bring economic benefits. There are also a few reports in the literature on the preparation of polyolefin nanoparticles by some specific methods, but such studies can only grasp the eyes of the reader in a novel way, but cannot be put into practical use.

However, the larger particle size of the polymer produced by the prior art can improve the production efficiency, but the low specific surface area caused by the large particle size limits the application of the polymer in aspects of blending modification, solid phase grafting and the like. On the other hand, 3D printing is a popular research area at present, and if polyolefin can be used as a raw material for 3D printing, undoubtedly, a huge market is opened for polyolefin. Three-dimensional powder bonding (3DP) and Selective Laser Sintering (SLS) are common two methods of 3D printing, which require material particles with a particle size of 1-100 μm and good flowability. While the particle size of polyolefins can be reduced by physical mechanical comminution, firstly processing costs are increased and secondly the chain integrity of the polymer is impaired, which damage can be detrimental to subsequent processing. It is of great interest to develop other methods for preparing spherical particles of polyolefins with smaller particle sizes (e.g., submicron size) in order to expand their application in blend modification, solid phase grafting and 3D printing.

Disclosure of Invention

In view of the above, the technical problem to be solved by the present invention is to provide a method for preparing a catalyst for preparing high sphericity low particle size polyolefin particles, the ziegler-natta catalyst prepared by the method has a relatively low particle size and a relatively high catalytic activity, and the ziegler-natta catalyst can be used for preparing polyolefin particles with high sphericity, submicron particle size, narrow particle size distribution and low bulk density.

In order to solve the above technical problems, the present invention provides a method for preparing a catalyst for preparing high sphericity low particle size polyolefin particles, comprising the steps of:

(a) mixing magnesium halide, an alcohol compound, an auxiliary agent, part of internal electron donor and a solvent to prepare a mixture I;

(b) adding the mixture I into a reactor, preheating to-30 ℃, and dropwise adding a titanium compound; or,

adding a titanium compound into a reactor, preheating to-30 ℃, and dropwise adding the mixture I;

(c) after the dropwise addition is finished, heating the reaction system to 90-130 ℃ after 30 minutes-3 hours, and adding the rest internal electron donor to continue the reaction;

(d) filtering liquid in the reaction system, adding the residual titanium compound, and continuing the reaction;

(e) after the reaction is finished, the catalyst is obtained by post-treatment.

According to the invention, said step (b) is replaced by the following step (b'):

(b') preparing a mixture II comprising nanoparticles, a dispersant and a solvent;

adding the mixture I and the mixture II into a reactor to obtain a mixture of the mixture I and the mixture II, preheating to-30 ℃, and dropwise adding a titanium compound; or,

the titanium compound is added to the reactor, preheated to-30 ℃ to 30 ℃, and the mixture of the mixture I and the mixture II is added dropwise.

According to the invention, in the mixture II of the step (b'), the nano particles are selected from at least one of nano silicon dioxide, nano titanium dioxide, nano zirconium dioxide, nano nickel oxide, nano magnesium chloride or nano carbon spheres.

Preferably, the nanoparticles have a particle size of 1 to 80nm, preferably 2 to 60 nm, more preferably 3 to 50 nm.

The addition mass of the nanoparticles is more than 0% and less than or equal to 200% relative to the addition mass of the magnesium halide, and preferably, the addition amount of the nanoparticles ranges from more than 0% to less than or equal to 20%.

According to the invention, in the mixture II of the step (b'), the solvent is at least one selected from linear alkanes with 5-20 carbons, branched alkanes with 5-20 carbons, aromatic hydrocarbons with 6-20 carbons or halogenated hydrocarbons thereof.

The dispersing agent is selected from titanium tetrachloride, silicon tetrachloride or a mixture of the titanium tetrachloride and the silicon tetrachloride.

In step (a), the mixing is carried out under heating and stirring to obtain a uniform and stable transparent mixture I.

In step (b'), ultrasonic dispersion treatment is performed at the time of deployment.

In the step (b) or (b'), the dropwise addition is carried out slowly.

In step (b) or (b'), the preferred reaction preheating temperature is from-20 ℃ to 30 ℃, more preferably from-20 ℃ to 20 ℃.

The reaction time of step (c) is 1 to 5 hours, preferably 2 to 3 hours.

The reaction of step (d) is continued for a period of 1 to 5 hours, preferably 2 to 3 hours.

The post-treatment in the step (e) can be washing the obtained product by using hexane and then drying; wherein the number of washing may be 1 to 10, preferably 3 to 6.

In the step (a), the magnesium halide is at least one selected from magnesium chloride, magnesium bromide and magnesium iodide.

In the step (a), the auxiliary agent may be a titanate compound.

In step (b) or (b'), the titanium compound has a general formula shown in formula I:

Ti(R)_nX_(4-n)

formula I

Wherein R is C1-C12 branched chain or straight chain alkyl, X is halogen, and n is 0, 1, 2 or 3.

In step (d), preferably, the temperature of the reaction system is raised to 90 ℃ to 130 ℃ over a period of 40 minutes to 3 hours, more preferably, the temperature of the reaction system is raised to 100 ℃ to 120 ℃ over a period of 40 minutes to 2 hours.

Correspondingly, the invention also provides application of the catalyst prepared by the method in catalyzing olefin homopolymerization or copolymerization. The olefin is selected from ethylene, propylene or butylene.

The invention also provides polyolefin particles which are directly prepared by adopting a polymerization method, the polymerization catalyst is the catalyst prepared by the method, the polyolefin particles are spherical, the average particle size is between 50 and 300 mu m, and the bulk density is between 0.1 and 0.4 g/mL.

According to the invention, the olefin is selected from ethylene, propylene or butene.

The invention also provides the use of the above polyolefin particles in 3D printing.

The invention also provides a 3D printing method which is characterized by using the polyolefin particles.

The invention has the beneficial effects that:

compared with the prior art, firstly, the catalyst prepared by the process is used for olefin polymerization, the directly produced polyolefin particles have small particle size, higher sphericity of the particles, narrower particle size distribution and low bulk density because the forming temperature of a catalyst carrier and the forming time of the catalyst are adjusted and nano particles are optionally added to be used as a third component to accelerate the forming of the catalyst. Secondly, the catalyst prepared by the process has higher activity when being used for olefin polymerization. Finally, the preparation method of the catalyst capable of directly obtaining the submicron polyolefin particles provided by the invention has simple process and is easy for industrial production. Experimental results show that the Ziegler-Natta catalyst prepared by the invention can prepare polyolefin particles with the average particle size of 50-300 mu m, higher sphericity, narrower particle size distribution and low bulk density (between 0.1-0.4g/mL) during olefin polymerization.

Compared with the conventional Ziegler-Natta catalyst preparation process, the preparation method provided by the invention has the advantages that the particle size of the prepared polyolefin particles is obviously reduced, and the bulk density of the polyolefin is obviously reduced. The polyolefin has extremely high specific surface area, high heat resistance, abrasion resistance and excellent fluidity (>2g/10min), and can meet certain special process requirements, such as being used as a raw material for blends, polyolefin grafting or modification and 3D printing. The method is simple and easy for industrial production.

Detailed Description

As previously mentioned, the present invention discloses a method for preparing a catalyst for preparing high sphericity low particle size polyolefin particles, comprising the steps of:

(e) after the reaction is finished, the catalyst is obtained by post-treatment.

According to the invention, the said mixture I is preferably as followsThe preparation method comprises the following steps: mixing magnesium halide and an alcohol compound in an organic solvent, heating and preserving heat, adding an auxiliary agent and part of internal electron donor, and reacting at a certain temperature to obtain a stable and uniform mixture I. The alcohol compound is selected from C_1-C₁₅Fatty alcohol compound of (2), C₃-C₁₅And C₆-C₁₅The aromatic alcohol compound (b) is preferably one or more selected from methanol, ethanol, ethylene glycol, n-propanol, isopropanol, 1, 3-propanediol, butanol, isobutanol, hexanol, heptanol, n-octanol, isooctanol, nonanol, decanol, sorbitol, cyclohexanol, and benzyl alcohol, and more preferably ethanol, butanol, hexanol, and isooctanol. The internal electron donor is at least one of monoester, diester, monoether and diether compounds, and is more preferably selected from diester or diether. The solvent is at least one of linear alkane with 5-20 carbons, branched alkane with 5-20 carbons, aromatic hydrocarbon with 6-20 carbons or halogenated hydrocarbon thereof, preferably at least one of toluene, chlorobenzene, dichlorobenzene or decane. In the invention, the magnesium halide has the function of a carrier in the preparation of the catalyst capable of directly obtaining submicron polyolefin particles, is one of the components of the traditional Ziegler-Natta catalyst, can ensure that the prepared catalyst has proper shape, size and mechanical strength, and simultaneously, the carrier can ensure that the active component is dispersed on the surface of the carrier, thereby obtaining higher specific surface area and improving the catalytic efficiency of the active component per unit mass. In addition, the alcohol compound serves to dissolve the magnesium halide, which is a carrier. In the preparation of the mixture I, the temperature of the obtained mixed solution is preferably 110 ℃ to 130 ℃, more preferably 130 ℃, the incubation time is preferably 1 to 3 hours, more preferably 2 to 3 hours, and the reaction time after addition of the auxiliary agent and the like is 0.5 to 2 hours, more preferably 1 hour. Thus, the magnesium halide is dissolved by the alcohol compound at high temperature to give a mixture I.

According to the invention, said mixture II is preferably prepared as follows: and adding the nano particles, the dispersing agent and the solvent into a reaction vessel, and carrying out ultrasonic treatment to obtain a uniform mixture II. The nano particles are preferably at least one of nano silicon dioxide, nano titanium dioxide, nano zirconium dioxide, nano nickel oxide, nano magnesium chloride or nano carbon spheres, and more preferably are nano silicon dioxide and nano titanium dioxide. The particle size of the nanoparticles is preferably 1 to 80nm, more preferably 10 to 50 nm. The addition mass of the nanoparticles is preferably 0% to 200%, more preferably 0% to 20%, relative to the addition mass of the magnesium halide. The time of the ultrasonic treatment is preferably 2 hours. In the present invention, the nanoparticles are introduced as seeds in order to accelerate the shaping of the support and to reduce the particle size of the catalyst particles; both the dispersing agent and the solvent, including sonication, are intended to aid in the dispersion of the nanoparticles, thus facilitating the function of the seed for each nanoparticle.

According to the invention, in step (b) or (b'), the preferred titanium compound is TiCl₄。

According to the scheme, the preparation method of the Ziegler-Natta catalyst is simple in process and easy for industrial production. In addition, the Ziegler-Natta catalyst prepared by the invention can prepare polypropylene particles with the average particle size of 50-300 μm, higher sphericity, narrower particle size distribution and low bulk density (0.1-0.4 g/mL) during propylene polymerization. Through research, the catalyst prepared by the invention is used for propylene polymerization to obtain polypropylene particles, the particle size is reduced by 20-30 times compared with other particles, the particle size distribution is obviously narrowed, and the bulk density can be as low as 0.1 g/mL.

Meanwhile, the Ziegler-Natta catalyst is applied to homopolymerization or copolymerization of ethylene, propylene and butylene, and the particle size can be obviously reduced. The Ziegler-Natta catalyst can be applied to polymerization of ethylene, propylene and butylene monomers, and is suitable for processes such as slurry, gas phase and bulk polymerization.

To further illustrate the technical solutions of the present invention, the following preferred embodiments of the present invention are clearly and completely described in connection with the examples, but it should be understood that the descriptions are only for further illustrating the features and advantages of the present invention and are not to be construed as limiting the claims of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

4.94g of anhydrous magnesium chloride, 18.9g of isooctyl alcohol and 30ml of decane are sequentially added into a reactor fully replaced by high-purity nitrogen, the temperature is raised to 130 ℃ under stirring and maintained for 2 hours, then 2.65g of tetrabutyl titanate and 2.05g of diisobutyl phthalate are added, the reaction is carried out for 1 hour at the temperature of 130 ℃, and finally the mixture is cooled to room temperature to form a uniform transparent solution, namely a mixture I.

200ml of titanium tetrachloride was added to the reaction vessel, stirred and preheated to 0 ℃ and the mixture I was added dropwise to the titanium tetrachloride over about 2 hours. After the dropwise addition, the temperature was raised to 110 ℃ within 2 hours. 1.23g of diisobutylphthalate as an internal electron donor was added. After reacting at this temperature for 2 hours, the reaction liquid was removed, and 200ml of titanium tetrachloride was added again to react for 2 hours. And finally, removing reaction liquid, washing the remaining solid substance with hexane at 60 ℃ for 10 times, and drying to obtain the catalyst.

Bulk polymerization of propylene: under the protection of high-purity nitrogen, a 5L high-pressure reaction kettle is dried and deaerated, 20mg of the catalyst, 12ml of triethyl aluminum and 3ml of external electron Donor Donor-P are added, 1200g of propylene is added, polymerization reaction starts, the system temperature is maintained at 70 ℃, the reaction time is 60 minutes, and the activity of the obtained catalyst and the property of the polypropylene are shown in Table 1.

Example 2

The mixture I was added to the reactor, stirred and preheated to 0 ℃ and 100mL of titanium tetrachloride was added dropwise to the reactor over 1 hour. After the dropwise addition, the temperature was raised to 110 ℃ within 2 hours. 1.23g of diisobutylphthalate as an internal electron donor was added. After reacting at this temperature for 2 hours, the reaction liquid was removed, and 200ml of titanium tetrachloride was added again to react for 2 hours. And finally, removing reaction liquid, washing the remaining solid substance with hexane at 60 ℃ for 10 times, and drying to obtain the catalyst.

Example 3

The catalyst preparation method and polymerization method were the same as in example 1, except that the preheating temperature of the reaction vessel was changed to 10 ℃. The activity of the catalyst and the properties of the polypropylene obtained are shown in Table 1.

Example 4

The catalyst preparation method and polymerization method were the same as in example 2, except that the preheating temperature of the reaction vessel was changed to 10 ℃. The activity of the catalyst and the properties of the polypropylene obtained are shown in Table 1.

Example 5

0.494g of 20nm nano silicon dioxide, 50mL of toluene and 10mL of silicon tetrachloride are added into a reactor fully replaced by high-purity nitrogen, fully stirred and uniformly mixed, and then ultrasonic treatment is carried out for 2 hours to obtain a transparent and uniform solution, namely a mixture II.

200ml of titanium tetrachloride were added to the reaction vessel, stirred and preheated to-20 ℃ and the mixture of mixture I and mixture II was added dropwise to the titanium tetrachloride over about 1 hour. After the dropwise addition, the temperature was raised to 110 ℃ within 2 hours. 1.23g of diisobutylphthalate as an internal electron donor was added. After reacting at this temperature for 2 hours, the reaction liquid was removed, and 200ml of titanium tetrachloride was added again to react for 2 hours. And finally, removing reaction liquid, washing the remaining solid substance with hexane at 60 ℃ for 10 times, and drying to obtain the catalyst.

Example 6

0.494g of 20nm nano silicon dioxide, 150mL of toluene and 10mL of silicon tetrachloride are added into a reactor fully replaced by high-purity nitrogen, fully stirred and uniformly mixed, and then ultrasonic treatment is carried out for 2 hours to obtain a transparent and uniform solution, namely a mixture II.

The mixture I and the mixture II were added to a reaction vessel, stirred and preheated to-20 ℃ and 100mL of titanium tetrachloride was added dropwise to the reaction vessel over 1 hour. After the dropwise addition, the temperature was raised to 110 ℃ within 2 hours. 1.23g of diisobutylphthalate as an internal electron donor was added. After reacting at this temperature for 2 hours, the reaction liquid was removed, and 200ml of titanium tetrachloride was added again to react for 2 hours. And finally, removing reaction liquid, washing the remaining solid substance with hexane at 60 ℃ for 10 times, and drying to obtain the catalyst.

Example 7

The same catalyst preparation method and polymerization method as in example 5 were carried out, except that the amount of 20nm nano-silica added was changed to 0.998 g. The activity of the catalyst and the properties of the polypropylene obtained are shown in Table 1.

Example 8

The same catalyst preparation method and polymerization method as in example 6 were carried out, except that the amount of 20nm nano-silica added was changed to 0.998 g. The activity of the catalyst and the properties of the polypropylene obtained are shown in Table 1.

Example 9

The same catalyst preparation method and polymerization method as in example 1 were carried out, except that the time for heating the reaction vessel to 110 ℃ was 1 hour after completion of mixing the mixture I with titanium tetrachloride. The activity of the catalyst and the properties of the polypropylene obtained are shown in Table 1.

Example 10

The same catalyst preparation method and polymerization method as in example 2 were carried out, except that the time for heating the reaction vessel to 110 ℃ was 1 hour after completion of mixing the mixture I with titanium tetrachloride. The activity of the catalyst and the properties of the polypropylene obtained are shown in Table 1.

TABLE 1 catalytic Activity of Ziegler-Natta catalysts prepared according to the examples of the present invention and Properties of the Polypropylene produced

As can be seen from the data in Table 1, the average particle size of the polypropylene particles prepared by the catalyst preparation method provided by the invention is 50 μm-300 μm, the polypropylene has a lower bulk density, and the bulk density can be as low as 0.1 g/mL. Moreover, the experimental results show that: within a certain range, with the increase of the preheating temperature, the heating time is shortened and the addition amount of the nano particles is increased, so that the average particle size of the finally obtained polypropylene particles is reduced, and the bulk density is reduced.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a catalyst for preparing high sphericity low particle size polyolefin particles comprising the steps of:

(e) after the reaction is finished, the catalyst is obtained by post-treatment.

2. The method of claim 1, wherein step (b) is replaced by the following step (b'):

3. The method according to claim 2, wherein in the mixture II in the step (b'), the nanoparticles are selected from at least one of nano silicon dioxide, nano titanium dioxide, nano zirconium dioxide, nano nickel oxide, nano magnesium chloride or nano carbon spheres. Preferably, the nanoparticles have a particle size of 1 to 80nm, preferably 2 to 60 nm, more preferably 3 to 50 nm.

Preferably, in the mixture II of the step (b'), the solvent is at least one selected from linear alkanes with 5-20 carbons, branched alkanes with 5-20 carbons, aromatic hydrocarbons with 6-20 carbons or halogenated hydrocarbons thereof. The dispersing agent is selected from titanium tetrachloride, silicon tetrachloride or a mixture of the titanium tetrachloride and the silicon tetrachloride.

4. The process according to any one of claims 1 to 3, wherein in step (a), the mixing is carried out under heating with stirring to obtain a uniform and stable transparent mixture I.

Preferably, in step (a), the magnesium halide is selected from at least one of magnesium chloride, magnesium bromide or magnesium iodide.

Preferably, in the step (a), the auxiliary may be a titanate-based compound.

5. The production method according to any one of claims 1 to 4, wherein in the step (b'), the ultrasonic dispersion treatment is performed at the time of the preparation.

Preferably, in step (b) or (b'), the dropwise addition is a slow dropwise addition.

Preferably, in step (b) or (b'), the reaction preheating temperature is preferably from-20 ℃ to 30 ℃, more preferably from-20 ℃ to 20 ℃.

Preferably, in step (b) or (b'), the titanium compound has the general formula shown in formula I:

Ti(R)_nX_(4-n)

formula I

6. The process according to any one of claims 1 to 5, wherein the reaction time in step (c) is from 1 to 5 hours, preferably from 2 to 3 hours.

Preferably, the reaction of step (d) is continued for a period of 1 to 5 hours, preferably 2 to 3 hours.

Preferably, the post-treatment in step (e) may be washing the resultant product with hexane, followed by drying; wherein the number of washing may be 1 to 10, preferably 3 to 6.

7. Use of a catalyst prepared by the process of any one of claims 1 to 6 for the catalysis of homo-or co-polymerisation of olefins.

Preferably, the olefin is selected from ethylene, propylene or butene.

8. Polyolefin particles directly prepared by a polymerization process, wherein the polymerization catalyst is the catalyst prepared by the method of any one of claims 1 to 6, the polyolefin particles are spherical, have an average particle size of 50 to 300 μm, and have a bulk density of 0.1 to 0.4 g/mL.

Preferably, the olefin is selected from ethylene, propylene or butene.

9. Use of the polyolefin particles of claim 8 in 3D printing.

10. A 3D printing method, characterized in that the polyolefin particles according to claim 8 are used.