JPS648010B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a low density ethylene copolymer by a gas phase polymerization method using a highly active Ziegler type catalyst.

Polyethylene obtained by polymerization using a catalyst consisting of a transition metal compound and an organometallic compound is generally produced by a slurry polymerization method.
Only those with a value of 0.945 or higher are normally manufactured, which is considered to be the limit that will not cause fouling.

Medium-density or low-density polyethylene with a density of 0.945 g/cm ³ or less is normally produced exclusively by the so-called high-pressure method using radical catalysts, but very recently, high-temperature solution methods using Ziegler catalysts have also been attempted. It became. Furthermore, elastomers have also been produced by copolymerizing ethylene and other α-olefins using vanadium compounds.

However, the polymer synthesized by the above method is either a crystalline resin or an amorphous elastomer, and its characteristics are distinct. Each of these polyolefin-based plastics and elastomers exhibits excellent performance and is used for a variety of purposes. It is a common experience that an elastomer is required to have improved stress cracking resistance, or conversely, that an elastomer is required to have strength based on its crystallinity. However, it is well known that when the two components are mixed for such purposes, physical properties such as tensile strength and rigidity often deteriorate.

However, if it is possible to synthesize a soft or semi-rigid resin that has an intermediate structure between neither crystalline plastics nor elastomers and exhibits a high degree of elongation, that resin itself will meet the above objectives. By mixing it with other plastics, it is possible to impart elastomeric properties and improve the properties of plastics. However, little is known about such soft or semi-hard resins. Recently, several reports have been made on methods for producing resins that exhibit intermediate physical properties, but they have various drawbacks and many problems need to be solved before they can be implemented industrially. There is.

For example, in Special Publication No. 46-11028, ethylene
The method for producing α-olefin copolymers involves solution polymerization using aromatic hydrocarbon solvents, but this method has poor catalyst efficiency and is complicated to separate and recover the solvent because it is solution polymerization. It has some drawbacks.

Furthermore, Japanese Patent Publication No. 47-26185 proposes a method of copolymerizing ethylene and α-olefin using a halogenated aliphatic hydrocarbon as a solvent, but the halogenated hydrocarbon solvent acts as a molecular weight regulator. Because of this, a large amount of low molecular weight copolymer is produced, and the resulting molded product has the disadvantage of a sticky surface. The same patent publication also discloses a method using a lower hydrocarbon having 3 to 5 carbon atoms as a solvent, but when polymerization is carried out using these solvents, the reaction pressure cannot be increased due to the vapor pressure of the solvent. Moreover, in the solvent recovery process, it is necessary to compress and cool the recovered solvent in order to liquefy it.

Furthermore, JP-A-51-41784 discloses a method of slurry copolymerization of ethylene and butene-1, but even in this case, the polymerization temperature and raw material composition are specified in detail, and if the temperature exceeds this range, Disadvantages include that the slurry becomes milky or oyster-like, making it difficult to operate the reactor and transport the slurry.

The disadvantages of each of the above examples are that the catalyst activity is low, that separation and recovery of the solvent is complicated due to solution polymerization, and that a large amount of low molecular weight copolymer is produced due to chain transfer with the solvent. In the case of slurry polymerization, the polymerization temperature and raw material composition must be regulated in order to maintain the polymer slurry. A further disadvantage in these examples is that very large amounts of comonomer are required to be copolymerized.

In _recent years, much _research has been conducted on improving _catalytic activity.
It is known that a catalyst system in which a transition metal is supported on various Mg-containing solid supports such as (OH)Cl, and then combined with an organometallic compound can be a highly active catalyst for olefin polymerization. Also,
It is also known that reactants of various organomagnesium compounds such as RMgX, R ₂ Mg, and RMg (OR) with transition metal compounds can serve as excellent catalysts for the high polymerization of olefins (Japanese Patent Publication No. 39-12105, Belgian patent). No. 742112, Special Publication No. 13050, Special Publication No. 13050, Special Publication No. 13050
−9548 and others).

However, even when the density is reduced by slurry polymerization or solution polymerization using such a highly active catalyst with a carrier, the above-mentioned drawbacks have not been solved at all.

The present invention provides a novel method that solves these problems all at once.

That is, as a result of intensive research into the above-mentioned technical problems, the present inventors were able to solve various problems such as activity, bulk density, adhesion, and coarsening that were problems in solution or slurry polymerization, and the present invention The invention has been completed, and the method of the present invention makes it possible to carry out a gas phase polymerization reaction in an extremely stable manner, and also to omit the catalyst removal step. We were able to complete the polymerization method.
Furthermore, it has become clear that the copolymer of ethylene and butene-1 obtained by carrying out the method of the present invention has excellent physical properties.

That is, the present invention provides (a) a double salt, double oxide, carbonate, chloride or hydroxide containing a metal selected from silicon, aluminum and calcium and a magnesium atom, (b) magnesium hydroxide, (c) At least one solid inorganic compound selected from the group consisting of magnesium carbonate, (d) magnesium oxide, and (e) magnesium chloride with at least one substance selected from oxygen-containing compounds, sulfur-containing compounds, hydrocarbons, and halogen-containing substances. 10 to 45 mol of ethylene and ethylene in a substantially solvent-free gas phase in the presence of a solid substance containing a treated or reacted substance and a titanium compound or a titanium compound and a vanadium compound and a catalyst consisting of an organoaluminum compound. melt index 0.01 to 10 by copolymerizing % butene-1,
The present invention relates to a method for producing a copolymer, characterized by obtaining a soft or semi-rigid ethylene-butene-1 copolymer having a density of 0.850 g/cm ³ or more and less than 0.910 g/cm ³ . By carrying out gas phase polymerization using a catalyst consisting of a specified solid substance and an organoaluminium compound and using ethylene and butene-1 in the quantitative ratio within the range specified in the present invention, the resulting polymer has extremely high activity and is sticky. Despite its high low density, the proportion of coarse particles and ultrafine particles produced is reduced, the particle properties are good, the bulk density is high, and it is extremely resistant to adhesion to the reactor and agglomeration of polymer particles. It has become clear that the gas phase polymerization reaction can be carried out very stably with a small amount of gas. The fact that the method of the present invention not only makes it possible to carry out the gas phase polymerization reaction extremely smoothly, but also that low-density ethylene copolymers can be easily obtained is a totally unexpected and surprising fact. No.

In addition, in the present invention, the copolymerization reaction can be carried out even at a relatively low temperature such as 50 to 80°C, and a low-density ethylene copolymer can be easily obtained. This is very advantageous and is another advantage of the present invention. Furthermore, the method of the present invention is characterized in that a low density ethylene copolymer with a high melt index can be easily obtained.
This point is also another advantage of the present invention. That is, due to these advantages, as described above, the soft to semi-hard copolymers described in the present invention can be efficiently obtained by gas phase polymerization.

Butene-1, which is copolymerized with ethylene in the method of the present invention, controls the density and molecular weight of the copolymer, and the resulting copolymer has high transparency;
It has good appearance and gloss, and has excellent flexibility and rubber elasticity not only at room temperature but also at low temperature. On the other hand, despite having such flexibility, the strength of the copolymer obtained by the present invention is equal to or higher than that of ordinary polyolefin resins. Furthermore, since it contains almost no impurities such as unsaturated bonds and catalyst residues, it has excellent weather resistance, chemical resistance, and electrical properties such as dielectric loss, breakdown voltage, and specific resistance. It also shows extremely excellent performance in terms of impact resistance and environmental stress cracking resistance. Therefore, the copolymer obtained by the method of the present invention can be molded into film sheets, hollow containers, electric wires, and various other products by existing molding methods such as extrusion, hollow molding, injection, press, and vacuum molding, and can be used for various purposes. be able to.

In addition, since the copolymer obtained by the method of the present invention contains olefin as a component, it has a composition very similar to that of polyolefin resin, and has low crystallinity, so it cannot be used with other polyolefin resins, such as high density and It is particularly compatible with low-density polyethylene, polypropylene, and ethylene-vinyl acetate copolymers, and by blending it with these resins, properties such as impact resistance, cold resistance, and environmental stress cracking resistance can be improved. I can do it.

The solid substances in the catalyst system used in the present invention include magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium chloride, and double salts, double oxides, and carbonates containing magnesium atoms and metals selected from silicon, aluminum, and calcium. Titanium compounds or titanium and vanadium compounds supported by a known method on salts, chlorides, or hydroxides, and optionally treated or reacted with oxygen-containing compounds, sulfur-containing compounds, hydrocarbons, or halogen-containing substances. can be mentioned.

The titanium compound or titanium and vanadium compound mentioned here includes halides, alkoxy halides, oxides, and halogenated oxides of these metals. Specific examples of these include titanium tetrachloride, titanium tetrabromide, titanium tetraiodide, monoethoxytrichlorotitanium, diethoxydichlorotitanium, triethoxymonochlorotitanium, tetraethoxytitanium, monoisopropoxytrichlorotitanium, diisopropoxydichlorotitanium, Examples include tetravalent titanium compounds such as tetraisopropoxytitanium, various titanium trihalides obtained by reducing titanium tetrahalides with hydrogen, aluminum, titanium, or organometallic compounds; Trivalent titanium compounds such as compounds obtained by reducing alkoxytitanium with organometallic compounds, tetravalent vanadium compounds such as vanadium tetrachloride, pentavalent vanadium compounds such as vanadium oxytrichloride and orthoalkylvanadate. , trivalent vanadium compounds such as vanadium trichloride and vanadium triethoxide.

Among these titanium compounds and vanadium compounds, tetravalent titanium compounds are particularly preferred.

As the catalyst of the present invention, a combination of a solid material obtained by supporting a titanium compound or a titanium and vanadium compound on the solid carrier described above and an organoaluminum compound is used.

Specific examples of these catalysts include, for example, MgO-RX-TiCl ₄ system (Japanese Patent Publication No. 51-3514),
MgCl ₂ −Al(OR) ₃ −TiCl ₄ system (Special Publication No. 1987-152,
Special Publication No. 52-15111), MgCl ₂ −SiCl ₄ −ROH−
TiCl ₄ series (JP-A-49-106581), Mg (OOCR) ₂ −
Al (OR) ₃ −TiCl ₄ system (Special Publication No. 11710, Showa 52-11710), Mg
−POCl ₃ −TiCl ₄ system (Special Publication No. 51-153), MgCl ₂
An example of a preferable catalyst system is one in which an organoaluminum compound is combined with a solid substance (in the above formula, R represents an organic residue) such as -AlOCl-TiCl ₄ system (Japanese Patent Application Laid-Open No. 133386/1986). .

In these catalyst systems, a titanium compound or a titanium and vanadium compound can also be used as an adduct with an organic carboxylic acid ester, or after contacting the above-mentioned magnesium-containing inorganic compound solid support with an organic carboxylic acid ester. You can also use Further, there is no problem in using the organoaluminum compound as an adduct with the organic carboxylic acid ester. Furthermore, in all cases of the present invention, catalyst systems prepared in the presence of organic carboxylic acid esters can be used without any problem.

As the organic carboxylic acid ester, various aliphatic, alicyclic, and aromatic carboxylic acid esters are used, and aromatic carboxylic acids having 7 to 12 carbon atoms are preferably used. Specific examples include benzoic acid,
Examples include alkyl esters of anisic acid and toluic acid, such as methyl and ethyl.

Specific examples of organoaluminum compounds used in the present invention include general formulas R ₃ Al, R ₂ AlX, RAlX ₂ ,
Organoaluminum compounds of R ₂ AlOR, RAl _{( OR} )X and R 3 Al ₂ triethylaluminum, triisobutylaluminum, trihexylaluminum,
Examples include trioctylaluminum, diethylaluminum chloride, ethylaluminum sesquichloride, and mixtures thereof.

In the present invention, the amount of the organoaluminum compound to be used is not particularly limited, but it can usually be used in an amount of 0.1 to 1000 times the amount of the transition metal compound.

In the polymerization reaction, a mixture of ethylene and butene-1 is polymerized in the gas phase. As the reactor used, known reactors such as a fluidized bed and a stirring tank can be used.

The polymerization reaction temperature is usually 20 to 110°C, preferably
The temperature is 50 to 100℃, the pressure is normal pressure to 70Kg/ ^cm2・G,
Preferably it is 2 to 60 kg/cm ² ·G. Although the molecular weight can be controlled by adjusting the polymerization temperature, the molar ratio of the catalyst, the amount of comonomer, etc., it is effectively carried out by adding hydrogen to the polymerization system. of course,
Using the method of the present invention, two-stage or more multi-stage polymerization reactions with different polymerization conditions such as hydrogen concentration, comonomer concentration, and polymerization temperature can be carried out without any problem.

In addition, in the present invention, by bringing the catalyst system into contact with an α-olefin and then using it in a gas phase polymerization reaction, the polymerization activity is greatly improved,
It is also possible to operate more stably than in the untreated case. Various α-olefins can be used at this time, but α-olefins having 3 to 12 carbon atoms are preferred, and α-olefins having 3 to 8 carbon atoms are more preferred.
Examples of these α-olefins include propylene, butene-1, pentene-1, 4-methylpentene-1, heptene-1, hexene-1,
Examples include octene-1 and mixtures thereof. The temperature and time during contact between the catalyst of the present invention and α-olefin can be selected within a wide range, for example, 0 to 200°C, preferably 0 to 110°C.
The contact treatment can be carried out in 1 minute to 24 hours.

The amount of α-olefin to be brought into contact can be selected within a wide range, but it is usually 1 g to 1 g per 1 g of the solid substance.
50000g, preferably about 5g to 30000g of α-olefin, and 1g to 1g per 1g of the solid material.
It is desirable to react 500 g of alpha-olefin. At this time, the pressure at the time of contact can be arbitrarily selected, but it is usually desirable to contact under a pressure of -1 to 100 kg/cm ² ·G.

During the α-olefin treatment, the entire amount of the organoaluminum compound used may be combined with the solid substance and then brought into contact with the α-olefin, or a part of the organoaluminum compound used may be combined with the solid substance. Afterwards gaseous α-
The polymerization reaction may be carried out by contacting with olefin and adding the remaining organoaluminum compound separately during the gas phase polymerization of ethylene. Further, when the catalyst and the α-olefin are brought into contact, there is no problem even if hydrogen gas coexists, and there is no problem even if other inert gases such as nitrogen, argon, helium, etc. coexist.

The amount of butene-1 used in the method of the present invention needs to be in the range of 10 to 45 mol% based on ethylene. Outside this range, the melt index targeted by the present invention is 0.01.
10 to 10 and a density of less than 0.850 to 0.910 g/cm ³ cannot be obtained. Further, the amount of butene-1 used can be easily adjusted by changing the composition ratio of the gas phase in the polymerization vessel.

Furthermore, in the method of the present invention, butadiene, 1,4-hexadiene, 1,5
- Various dienes such as hexadiene, vinylnorbornene, ethylidenenorbornene and dicyclopentadiene can also be added for copolymerization.

Examples will be described below, but these are for illustrative purposes in carrying out the present invention, and the present invention is not limited thereto.

Example 1 1000 g of anhydrous magnesium chloride, 50 g of 1,2-dichloroethane and 170 g of titanium tetrachloride were ball milled at room temperature in a nitrogen atmosphere for 16 hours to support the titanium compound on the carrier. 1g of this solid substance
Contains 35mg of titanium per serving.

A stainless steel autoclave was used as the apparatus for gas phase polymerization, and a loop was formed with a blower, a flow control valve, and a dry cyclone for separating the produced polymer, and the temperature of the autoclave was controlled by flowing hot water through the jacket.

The polymerization temperature was set at 80°C, and the above solid substances were fed into the autoclave at a rate of 250 mg/hr and triethylaluminum at a rate of 50 m-mol/hr, and ethylene, butene-1 and hydrogen in the gas fed to the autoclave were controlled by a blower. Polymerization was carried out while adjusting the composition (molar ratio) to be 74%, 16%, and 10%, respectively.

The produced polymer is melt index (MI)
1.3, bulk density 0.391, and density 0.897, and although the density was extremely low, there was no stickiness and most of the powder was 300 to 600μ in size. Also, the polymerization activity is
It had a very high activity of 201,500g polymer/g-Ti.

After 10 hours of continuous operation, the polymerization was stopped and the inside of the autoclave was inspected, and no polymer was found to be attached to the inner wall, stirrer, or polymer extraction tube. In other words, it is clear that in the slurry polymerization shown in Comparative Example 1, it was impossible to carry out stable continuous operation for a long time, whereas by following the method of the present invention, it is possible to carry out very stable continuous operation for a long time. It is.

A press molded product of this copolymer was transparent, had no stickiness on the surface, had a strength at break of 210 kg/cm ² and an elongation of 750%.

Further, this copolymer could be easily granulated using an extruder, and furthermore, it could be easily formed into a blown film.

Comparative Example 1 Using the same catalyst as in Example 1, continuous slurry polymerization was carried out at 85°C using hexane as a solvent.

The ratio of solid substance is 5 mg/hr, triethylaluminum is 1 m-mol/hr, hexane is 40/hr, ethylene is 8 Kg/hr, butene-1 is 8 Kg/hr (50 mol% relative to ethylene), and hydrogen is 3 Nm ³ /hr. Continuous polymerization was carried out by supplying

The produced polymer was continuously extracted as a slurry, but the polymer particles in the slurry extracted were significantly swollen from the initial stage of polymerization, and the hexane layer was milky. After 2 hours, the slurry extraction pipe became clogged, and the polymerization had to be stopped. When the inside of the reactor was inspected, a large amount of polymer was found adhering to the inner wall and the stirrer.

The resulting polymer has an MI of 1.8, a bulk density of 0.246, and a density of
It had a value of 0.913. Despite this very large addition of the comonomer butene-1, the density of the resulting polymer was not sufficiently reduced, clearly indicating an example of very inefficient polymerization.

The press-molded product of this copolymer had a sticky surface, a strength at break of 145 kg/cm ² and an elongation of 680%.

Example 2 830 g of anhydrous magnesium chloride, 50 g of aluminum oxychloride and 170 g of titanium tetrachloride were ball milled in the same manner as in Example 1. The solid material obtained contained 41 mg titanium per gram.

Polymerization was carried out in the same manner as in Example 1 at 80° C. by feeding this solid substance at a rate of 200 mg/hr and triethylaluminum at a rate of 50 mmol/hr. However, the composition in the gas phase is ethylene, butene-1, and hydrogen at 65:
The ratio was 25:10 (molar ratio).

After 10 hours of continuous operation, polymerization was stopped and the inside of the reactor was inspected, but no polymer was observed at all.

The obtained polymer had an MI of 2.9, a bulk density of 0.403, a density of 0.863, and a polymerization activity of 302,000 g polymer/g-Ti. The press-molded product of this copolymer was transparent and had no stickiness on the surface, and had a strength at break of 185 Kg/cm ² and an elongation of 750%.

When the pellets granulated using an extruder were blended with 10% high-density polyethylene and formed into a blown film, the transparency was significantly improved compared to when high-density polyethylene was used alone.

Comparative Example 2 Continuous solution polymerization was carried out using the same catalyst as in Example 2 and n-paraffin as a solvent.

That is, 25 mg/hr of the solid material synthesized in Example 2 and n-paraffin containing 5 mmol of triethylaluminum were supplied at a rate of 40/hr, and 8 kg/hr of ethylene and 19 kg/hr of butene-1 (relative to ethylene) were supplied at a rate of 40/hr. (120 mol%) and hydrogen at a rate of 0.1 Nm ³ /hr, and continuous polymerization was carried out at 160°C.

The obtained copolymer had an MI of 1.8 and a density of 0.931.
The polymerization activity was 82000 g polymer/g-Ti.
In addition, press-molded products of this copolymer have a strength at breakage of
The weight was 150Kg/cm ² and the elongation was 570%.

In this way, in the case of solution polymerization, although a large excess of butene-1 is used relative to ethylene, the density does not decrease much and the polymerization activity is also low, which is an example of inefficient polymerization. That is clear.

Example 3 Anhydrous magnesium chloride 830g, anthracene 120g
g and 180 g of titanium tetrachloride were ball milled in the same manner as in Example 1 to obtain a solid material. The solid material contained 40 mg titanium per gram.

Using the same equipment as in Example 1, a solid substance was prepared at 80°C.
500mg/hr, triisobutylaluminum 150m-
The ratio (mole ratio) of ethylene, butene-1 and hydrogen in the gas phase was 68:21:
Continuous polymerization was carried out while adjusting the molecular weight to 11.

When the reactor was opened after 10 hours of stable continuous operation, there was no adhesion at all.

The resulting polymer has an MI of 2.6, a bulk density of 0.374, and a density of
0.878, and the polymerization activity is 137000g polymer/g
-It was Ti. Press-molded products of this copolymer were transparent, had no stickiness on the surface, had a strength at break of 200 kg/cm ² and an elongation of 800%.

Example 4 Magnesium oxide 400g and aluminum chloride 1.3
950 g of the reaction product obtained by reacting Kg at 300° C. for 4 hours and 180 g of titanium tetrachloride were treated in the same manner as in Example 1 to obtain a solid material. The solid substance is 1
Contains 40mg of titanium per gram.

Using the same apparatus as in Example 1, 500
mg/hr and triisobutyl aluminum 250m
Continuous polymerization was carried out at 80°C by supplying the catalyst at a rate of -mol/hr and by adjusting the ratio (molar ratio) of ethylene, butene-1 and hydrogen in the gas phase to 75:15:10. .

After 16 hours of continuous operation, polymerization was stopped and the inside of the reactor was inspected, but no polymer was observed.

The resulting polymer has an average particle size of 600μ, a narrow particle size distribution, almost perfectly spherical particles, a bulk density of 0.391, an MI of 0.71,
The density was 0.902, and the polymerization activity was 231,000 g polymer/g-Ti. Further, a press-molded product of this copolymer was transparent, had no stickiness on the surface, had a strength at break of 260 kg/cm ² and an elongation of 600%.

Example 5 Magnesium oxide 400g and aluminum chloride 1.3
Reactant obtained by reacting with Kg at 300℃ for 4 hours
950g, titanium tetrachloride 180g and VO
(OC ₂ H ₅ ) ₃ was ball milled for 14 hours at room temperature under a nitrogen atmosphere to support the titanium compound and vanadium compound on the carrier. This solid material contained 40 mg titanium and 9.8 mg vanadium per gram.

A stainless steel autoclave was used as the gas phase polymerization apparatus, a loop was created with a blower, a flow rate controller, and a dry cyclone, and the temperature of the autoclave was adjusted by flowing hot water through the jacket.

The polymerization temperature was 80°C, the above solid material was fed into the autoclave at a rate of 600 mg/hr and triisobutylaluminum 250 m-mol/hr, and
Composition (mole ratio) of ethylene, butene-1 and hydrogen in the gas supplied to the autoclave by the blower
Five polymerizations were carried out while adjusting the amounts to 75%, 15%, and 10%, respectively.

The produced polymer is melt index (MI)
0.65, bulk density 0.401, and density 0.905, and although the density was extremely low, there was no stickiness, and the particles were almost perfectly spherical with an average particle size of 600 μm and a narrow particle size distribution. In addition, the polymerization activity is 216,000g polymer/g-
It was highly active with Ti.

After 16 hours of continuous operation, polymerization was stopped and the inside of the autoclave was inspected, and no polymer was observed on the inner wall, stirrer, or polymer outlet tube.

A press molded product of this copolymer was transparent, had no stickiness on the surface, had a strength at break of 280 kg/cm ² and an elongation of 630%.

Further, this copolymer could be easily granulated using an extruder, and furthermore, it could be easily formed into a blown film.

[Brief explanation of drawings]

FIG. 1 is a flowchart showing the steps for preparing a catalyst used in the method of the present invention.

Claims (1)

[Claims] 1 (a) a double salt, double oxide, carbonate, chloride or hydroxide containing a metal selected from silicon, aluminum and calcium and a magnesium atom, (b) magnesium hydroxide, (c) magnesium carbonate, (d) Treat or react at least one solid inorganic compound selected from the group consisting of magnesium oxide and (e) magnesium chloride with at least one substance selected from oxygen-containing compounds, sulfur-containing compounds, hydrocarbons, and halogen-containing substances. In the presence of a catalyst consisting of a solid material containing a titanium compound or a titanium compound and a vanadium compound and an organoaluminum compound, 10 to 10% of
By copolymerizing 45 mol% butene-1, the melt index is 0.01 to 10 and the density is
A method for producing a copolymer, characterized in that a soft or semi-rigid ethylene-butene-1 copolymer having a weight of 0.850 g/cm ³ or more and less than 0.910 g/cm ³ is obtained.