Summary of the invention
Technical problem
The preparation method who the purpose of this invention is to provide a kind of polyolefin alloy, the rigidity and the toughness that overcome the PP/EPR reactor alloy of three stage polymerization prepared in the prior art are difficult to take into account, because the shortcoming that copolyreaction speed is low, catalytic efficiency is low that the polypropylene GRANULES densification is caused, solved multipolymer and easily be enriched in particle external surface, caused that particle glues wall, conglomeration etc. and influences the problem that continuous production carries out smoothly.
Technical scheme
The present invention is a principal monomer with ethene and propylene, carries out multi-stage polymeric with spherical high efficiency load type Ziegler-Natta catalyst, makes polypropylene/ethylene-propylene copolymer (PP/EPR) polyolefin alloy of particle form spherical in shape.
The prepared according to the methods of the invention polyolefin alloy is a main component with polypropylene and ethylene-propylene copolymer, removes catalyst component wherein, and wherein polyacrylic weight accounts for 70~90%, and the weight of ethylene-propylene copolymer accounts for 10~30%.
For overcoming the existing shortcoming of three stage polymerization technology of prior art, the method according to this invention shortens the propylene homopolymerization time, so that polypropylene GRANULES has suitable porosity; With the copolyreaction of the alternative time lengthening of the sequential polymerization of multistage, the polymer alloy of gained has excellent mechanical property, and polypropylene in the polymer alloy and ethylene-propylene copolymer content are regulated.
A kind of preparation method of polyolefin alloy comprises the steps:
1) slurry prepolymerization: with propylene, 1-butylene, vinylbenzene, or 4-methyl-1-pentene is monomer, at TiCl
4/ MgCl
2Carry out the slurry prepolymerization under the spherical supported type catalyzer of ID, trialkylaluminium and the external electron donor acting in conjunction, wherein ID is an internal electron donor;
2) the equal polymerization of propylene: the product of prepolymerization step is carried out propylene pressurization gas phase polymerization, 5~60 minutes reaction times in gas-phase polymerization reactor;
3) the sequential polymerization of multistage: monomer is switched to the propylene-ethylene gas mixture, the second of pressurizeing propylene gas phase copolymerization, 2~10 minutes reaction times; Again monomer is switched to propylene, repeating step 2), 5~30 minutes reaction times; The equal polymerization of the second that so hockets propylene gas phase copolymerization and propylene reaction, the total polymerization time in gas-phase polymerization reactor reach 140 minutes or more than, promptly make the polyolefin alloy that main component is polypropylene and ethylene-propylene copolymer.
According to the present invention, the used spherical supported type Ziegler-Natta catalyst of polyreaction is by (1) Primary Catalysts, i.e. TiCl
4/ MgCl
2ID, a kind of catalyst Precursors that contains titanium, magnesium, chlorine and organic electron donor (internal electron donor ID), internal electron donor ID can be diester or diether compound; (2) promotor plays the organo-aluminium compound of promoting catalysis; (3) external electron donor, a kind of organism of regulating the stereoselectivity effect that plays is formed.The Preparation of catalysts method is referring to CN87107586A and the disclosed method of CN1091748A.Catalyst Precursors is the fine particle shape solid with regular spheroid form, and the particulate median size is 30~150 microns, and specific surface area is greater than 250m
2/ g.Consisting of of Primary Catalysts: titanium 1.5~3.0%, chlorine 52~60%, magnesium 10~20%, ID 6.0~20.0%, inert solvent 1~6% (being weight percentage); Wherein ID is mainly diisobutyl phthalate, n-butyl phthalate, succinate or diether compound.Promotor is a trialkylaluminium, as triethyl aluminum, triisobutyl aluminium or the mixture of the two.External electron donor commonly used is R
2Si (OCH
3)
2, wherein R is phenyl, cyclohexyl, isobutyl-, tertiary butyl or isopentyl.
The preparation method of polyolefin alloy of the present invention comprises several steps such as slurry prepolymerization, the equal polymerization of propylene and the sequential polymerization of multistage.Each step concrete operation method and processing condition are as follows:
Step 1) is the slurry prepolymerization, adopts slurry polymerization processes.Prepolymerized monomer is a propylene, also can be 1-butylene, vinylbenzene, or 4-methyl-1-pentene, and solvent is normal heptane, normal hexane, sherwood oil, normal butane or propane.Prepolymerized processing condition are: 0~60 ℃ of temperature, and preferred temperature is 20~50 ℃; Monomer concentration is 0.1~1.0mol/L, or propylene pressure is 0.1~0.2MPa.Promotor is a trialkylaluminium, as triethyl aluminum or triisobutyl aluminium or their mixture.The mol ratio of aluminium is Ti: Al=1 in titanium in the Primary Catalysts and the promotor: 50~200.The mol ratio of external electron donor compound and titanium is external electron donor: Ti=5~20: 1.Select the alr mode and the stirring velocity of prepolymerization reaction, not destroy the globosity of polymerization resulting polymers/catalyst particle.The prepolymerization reaction times is 3~60 minutes.Preferred 3~20 g polypropylene of prepolymerized degree/g catalyzer.
Carry out step 2 after the prepolymerization reaction) the equal polymerization of propylene, adopt the vapour phase polymerization mode.Polymkeric substance/catalyst particle the suspension of prepolymerization gained is transferred in the reactor of a belt stirrer, removal of solvents under agitation can be pressed into propylene/hydrogen gas mixture to predetermined pressure in still according to circumstances, be warming up to preset temperature and carry out polymerization.Polymerization process condition is: 70~90 ℃ of polymeric reaction temperatures, partial pressure of propylene are 0.5~2.0MPa, and hydrogen partial pressure is 0.0~0.2MPa, and polymerization time is 5~60 minutes; Obtain the form of spherical particles polypropylene of rule.
By prior art, will carry out one to two section ethylene-propylene gas phase copolymerization after the equal polymerization of propylene, at the reactor residence time in ethylene-propylene gas-phase copolymerization stage all more than 30 minutes.The present invention improves ethylene-propylene gas phase copolymerization step, closes with propylene-ethylene gas phase copolymerization and the propylene gas-phase homopolymerization that repeatedly hockets, i.e. the sequential polymerization of multistage substitutes.
According to the present invention, step 2) after the equal polymerization of propylene, then carries out the sequential polymerization of step 3) multistage.Concrete operating process is, step 2) after the equal polymerization reaction of propylene is finished, carry out the propylene-ethylene gas phase copolymerization, propylene pressure in the polymerization reactor is reduced to normal pressure, vacuumize pressure is reduced to 2~30mmHg, rapidly the propylene/ethylene mixed gas is charged into reactor and boosts to 0.3~2.0MPa then, carry out copolyreaction.Temperature of reaction is 70~90 ℃, and the molar content of ethene is 20~70% in the propylene/ethylene gas mixture, and preferred ethene molar content is 30~60%.Needs according to regulating molecular weight of copolymer can add the hydrogen that dividing potential drop is 0.0~0.2MPa according to circumstances.The copolyreaction time is 2~10 minutes.After the propylene-ethylene gas phase copolymerization is finished, switch to the equal polymerization reaction of propylene, propylene-ethylene mixture pressure in the polymerization reactor is reduced to normal pressure, vacuumize pressure is reduced to 2~30mmHg, rapidly propylene is charged into reactor then and boost to 0.5~2.0MPa, polymerization process condition is with step 2), polymerization time is 5~30 minutes.After the equal polymerization of propylene reaction is finished, set by step 3) carry out the propylene-ethylene gas phase copolymerization.So finish the once switching that second third is copolymerized to the propylene homopolymerization.Then alternately repeat multistage propylene-ethylene gas phase copolymerization and propylene gas-phase homopolymerization,, finish the sequential polymerization procedure of multistage up to carrying out last propylene-ethylene gas phase copolymerization or propylene gas-phase homopolymerization.
The total reaction time of the sequential polymerization procedure of multistage should be at least 80~150 minutes, or the time of whole pressurization vapour phase polymerization reaches 140 minutes or when above, but termination reaction obtains final product.All polymerisate is 3000~60000: 1 with the ratio of the weight of catalyzer.
Adopt the sequential polymeric advantage of multistage of second third copolymerization and propylene homopolymerization to be: polypropylene that generates in step 3) and second random copolymer of propylene all are limited in step 2) in the tiny hole of the spheric polypropylene granule interior that generates, polypropylene primary granule and ethylene-propylene copolymer primary granule alternating growth are on catalyzer primary granule surface, make the size of polypropylene phase region and ethylene-propylene copolymers phase region become very tiny, and weave in more closely mutually, increase alternate bonding force, can obviously improve the mechanical property of polymkeric substance.
And, be the regular spherical particle of diameter 1~5mm through above-mentioned steps polymerization gained PP/EPR alloy, the good fluidity of particle.Inter-adhesive between the particle, caking phenomenon do not take place in the polymerization process, and the problem that particle adheres to the still wall does not take place yet.These characteristics make stirring, temperature control, the product in the polymerization process shift operation such as conveying and all are easy to carry out reposefully, help to realize continuous and stable production on the large scale industry device.
Beneficial effect
The method according to this invention prepares the PP/EPR reactor alloy, on the one hand owing to adopted the propylene homopolymerization of lasting short period and the polymerization technique that the second copolymerization of propylene repeatedly hockets, make the fine pore in the alloy particle be difficult for being filled up by EPR, ethylene propylene copolymer can be evenly dispersed in the polypropylene matrix more, PP and EPR biphase consistency further improve, and prepared polyolefin alloy has higher modulus in flexure and very high resistance to impact shock simultaneously.On the other hand, because the alloy particle that obtains under this technology contains more pore, monomer more easily is diffused into particle inside and carries out polyreaction, thereby its total polymerization activity is apparently higher than three stage polymerization technology of the prior art, help improving reactor and catalyst utilization, reduce production costs.
Adopt the PP/EPR reactor alloy of polymerization technique preparation of the present invention to show excellent mechanical property, existing very high rigidity has very high resistance to impact shock again.Method according to GB/T1843 and GB/T9341 is measured, and its modulus in flexure is 800~1100MPa, and the simply supported beam notched Izod impact strength can reach 13KJ/m
2More than.
Describe the present invention below in conjunction with embodiment.Scope of the present invention is not exceeded with embodiment, but is limited by the scope of claim.
Embodiment
The preparation of embodiment 1 spherical PP particle
(1) prepolymerization
Under protection of inert gas, in a three-necked bottle that has a mechanical stirring device, add sherwood oil, promotor Al (C successively
2H
5)
3, external electron donor Ph
2Si (OCH
3)
2And 0.02g Primary Catalysts.In the promotor in aluminium and the Primary Catalysts mol ratio of titanium be 60: 1, the mol ratio of promotor and external electron donor is 25: 1.The main component of Primary Catalysts has: TiCl
4, MgCl
2, and diisobutyl phthalate, be the spherical particle of particle diameter 20~150 μ.Its titanium content is 2.5~3.5% (wt).Under 20 ℃ of constant temperature, be promptly to begin polymerization after the propylene gas of 0.1MPa with the inert gas replacement in the reaction flask.After prepolymerization was carried out 30 minutes, the polypropylene of generation and the weight ratio of Primary Catalysts were 22.7: 1.
(2) propylene gas-phase homopolymerization
In the withstand voltage reactor of 0.5L, the resulting suspension that contains polymkeric substance/catalyst particle of prepolymerization is transferred in the still, solvent is extracted in decompression out, charges into propylene to 0.6MPa pressure, is warming up to 60 ℃, under agitation reacts after 1 hour to stop, and gets product 58g.The gained polypropylene is the spheroidal particle of rule, and median size is 1mm.Recording its porosity with mercury penetration method is 37%.
The preparation of embodiment 2PP/EPR reactor alloy
By carrying out prepolymerization and propylene polymerization with embodiment 1 identical operations process and reaction conditions.
After propylene polymerization stopped in 1 hour, still inner propene pressure is reduced to-0.09MPa (gauge pressure) and keeping for 30 seconds, be pressed into propylene-ethylene gas mixture (molar content of ethene is 40%) then to 0.4MPa, continue reaction 10 minutes down at 60 ℃, afterwards still inner propene-ethene mixture pressure is reduced to-0.09MPa (gauge pressure) and keeping for 10 seconds, be pressed into propylene then to 0.6MPa, continue reaction 30 minutes down at 60 ℃.Again still inner propene pressure is reduced to-0.09MPa (gauge pressure) and keeping for 10 seconds, be pressed into propylene-ethylene gas mixture (molar content of ethene is 40%) then, continue reaction 10 minutes down at 60 ℃ to 0.4MPa.At last still inner propene-ethene mixture pressure is reduced to-0.09MPa (gauge pressure) and keeping for 10 seconds, be pressed into propylene then, continue reaction 30 minutes down, finish reaction at 60 ℃ to 0.6MPa.Sequential polyreaction total reaction time is 80 minutes, and second third copolymerization and propylene homopolymerization have been switched 2 times.The final product 115g that gets, product is the regular spherical particle, the content of ethylene-propylene random copolymer is 17.8% (wt) in the product.
The preparation of embodiment 3PP/EPR reactor alloy
By carrying out prepolymerization and propylene polymerization with embodiment 1 identical operations process and reaction conditions.
After propylene polymerization stopped in 1 hour, still inner propene pressure is reduced to-0.09MPa (gauge pressure) and keeping for 30 seconds, be pressed into propylene-ethylene gas mixture (molar content of ethene is 40%) then to 0.4MPa, continue reaction 5 minutes down at 60 ℃, afterwards still inner propene-ethene mixture pressure is reduced to-0.09MPa (gauge pressure) and keeping for 10 seconds, be pressed into propylene then to 0.6MPa, continue reaction 15 minutes down at 60 ℃.Switch to second third copolymerization again and repeat said process, the second that hockets third copolymerization and propylene homopolymerization, sequential polymerization total reaction time is 80 minutes, second third copolymerization therebetween and propylene homopolymerization are switched 4 times.The final product 116g that gets, product is the regular spherical particle, the content of ethylene-propylene random copolymer is 15.3% (wt) in the product.
The preparation of embodiment 4PP/EPR reactor alloy
By carrying out prepolymerization and propylene polymerization with embodiment 1 identical operations process and reaction conditions.
After propylene polymerization stopped in 1 hour, still inner propene pressure is reduced to-0.09MPa (gauge pressure) and keeping for 30 seconds, be pressed into propylene-ethylene gas mixture (molar content of ethene is 40%) then to 0.4MPa, continue reaction 2.5 minutes down at 60 ℃, afterwards still inner propene-ethene mixture pressure is reduced to-0.09MPa (gauge pressure) and keeping for 10 seconds, be pressed into propylene then to 0.6MPa, continue reaction 7.5 minutes down at 60 ℃.Switch to second third copolymerization again and repeat said process, the second that hockets third copolymerization and propylene homopolymerization, sequential polymerization total reaction time is 80 minutes, second third copolymerization therebetween and propylene homopolymerization are switched 8 times.The final product 149g that gets.Product is the regular spherical particle, porosity 23%, and the content of ethylene-propylene random copolymer is 17.5% (wt) in the product.
The preparation of comparative examples 5PP/EPR reactor alloy
In embodiment 5, propylene prepolymerization and propylene polymerization schedule of operation are identical with embodiment 1 with reaction conditions.After propylene polymerization carries out 1 hour, still inner propene pressure is reduced to-0.09MPa (gauge pressure) and keeping for 30 seconds, be pressed into propylene-ethylene gas mixture (molar content of ethene is 40%) then to 0.4MPa, continue reaction 20 minutes down, the final product 99g that gets at 60 ℃.Product is the regular spherical particle, and the content of ethylene-propylene random copolymer is 20.1% (wt) in the product.
To embodiment 2~5 resulting polymers alloy samples, measure its modulus in flexure and simply supported beam breach shock strength respectively according to the method for GB/T1843 and GB/T9341, the results are shown in table 1.Switching times in the table is meant the number of times that switches to the propylene homopolymerization from second third copolymerization.
Table 1
Embodiment |
Switching times (inferior) |
Catalytic efficiency (g polymkeric substance/g catalyzer) |
Modulus in flexure (MPa) |
Shock strength (kJ/m
2)
|
2 |
2 |
2370 |
853 |
11.1 |
3 |
4 |
2390 |
826 |
9.6 |
4 |
8 |
3070 |
916 |
13.6 |
5 |
0 |
1810 |
705 |
10.3 |
As seen from the above table, prepared polyolefin alloy has higher modulus in flexure and very high resistance to impact shock simultaneously according to the present invention, has high tenacity and high inflexible premium properties concurrently; And catalytic efficiency is significantly increased.