JPS6320844B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a soft or semi-rigid ethylene copolymer by a gas phase polymerization method using a highly active Ziegler type catalyst.

More specifically, the present invention provides a method for producing substantially solvent-free gas in the presence of a catalyst consisting of a solid substance containing a solid inorganic compound containing Mg, a halogen, a titanium compound, or a titanium compound and a vanadium compound, and an organoaluminum compound. By copolymerizing ethylene with 63.6 to 250 mol% of propylene to ethylene in phase state, melt index of 0.01 to 10 and density of 0.850 to 0.895 are obtained.
The present invention relates to a method for producing a copolymer, characterized in that a soft or semi-rigid ethylene-propylene copolymer is obtained.

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. These polyolefin-based plastics and elastomers each exhibit excellent performance and are used for a variety of purposes.
Depending on the purpose of use, for example, plastics may be required to have some elastomeric properties to improve their resistance to environmental stress cracking, or conversely, elastomers may be required to have strength based on their crystallinity. This is something we often experience on a daily basis. 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. be.

For example, in Special Publication No. 46-11028, ethylene
The method for producing α-olefin copolymers involves solution polymerization using an aromatic hydrocarbon solvent, 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 _{catalyst 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 the reaction products 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.

In other words, as a result of intensive research into the above-mentioned technical problems, the present inventors were able to solve various problems in solution polymerization or slurry polymerization, such as activity, bulk density, adhesion, and coarsening. It was possible to obtain a copolymer of ethylene and propylene with physical properties, and the method of the present invention allows for extremely stable gas phase polymerization reactions, and also eliminates the catalyst removal step.
Overall, we were able to complete a very simple gas phase polymerization method for ethylene and propylene.

That is, the present invention uses a catalyst consisting of a solid inorganic compound containing Mg, a solid material containing a halogen, a titanium compound or a titanium compound or a titanium compound and a vanadium compound, and an organoaluminum compound, and a catalyst consisting of ethylene and propylene in an amount of 63.6 to 250 mol% relative to ethylene. By copolymerizing ethylene and propylene by contacting the mixture in the gas phase, the melt index is 0.01 to 10 and the density is
The present invention relates to a method for producing an ethylene-propylene copolymer, which is characterized by obtaining an ethylene-propylene copolymer having a molecular weight of 0.850 to 0.895.
Using a catalyst consisting of a solid inorganic compound containing Mg, a solid substance containing a halogen and a titanium compound or a titanium compound and a vanadium compound, and an organoaluminium compound, and using ethylene and propylene in a quantitative ratio within the range specified in the present invention. By performing gas phase polymerization, the proportion of coarse particles and ultrafine particles produced is reduced, the particle properties are good, and the bulk density is reduced, even though the polymer produced is extremely highly active and has a low density with high stickiness. It has become clear that the gas phase polymerization reaction can be carried out very stably, with very little adhesion to the reactor and very little agglomeration of polymer particles. It must be said that it is a completely unexpected and surprising fact that the method of the present invention not only allows a gas phase polymerization reaction to be carried out very smoothly, but also that a low density ethylene copolymer can be easily obtained.

In addition, in the present invention, the copolymerization reaction can be carried out even at relatively low temperatures such as 50 to 80°C, and a low-density ethylene copolymer can be easily obtained. , which 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, which is 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.

In the method of the present invention, propylene copolymerized with ethylene controls the density and molecular weight of the copolymer, and the resulting copolymer has high transparency.
It has a good appearance and gloss, and has excellent flexibility and rubber elasticity not only at room temperature but also at low temperatures.

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 with these resins, properties such as impact resistance, cold resistance, and environmental stress cracking resistance can be improved. Can be done.

The catalyst system used in the present invention is a combination of a solid inorganic compound containing Mg, a solid substance containing a halogen and a titanium compound or a titanium compound and a vanadium compound, and an organoaluminium compound, and the solid substance includes, for example, a metal Magnesium, magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium chloride, etc., as well as magnesium, silicon, aluminum,
Double salts, double oxides, carbonates, chlorides containing a metal selected from calcium and magnesium atoms,
A titanium compound and, if necessary, a vanadium compound may be added to an inorganic solid support such as hydroxide, or one obtained by treating or reacting these inorganic solid supports with an oxygen-containing compound, a sulfur-containing compound, a hydrocarbon, or a halogen-containing substance. Examples include those supported by a method (containing Mg-halogen-Ti (or Ti-V)).

Examples of the titanium compound and vanadium compound here include halides, alkoxy halides, oxides, and halogenated oxides of titanium and vanadium. 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 solid material obtained by supporting the above-mentioned solid carrier with a titanium compound and, if necessary, a vanadium compound, is used in combination with an organoaluminum compound.

Specific examples of these catalysts include, for example, MgO-RX-TiCl ₄ system (Japanese Patent Publication No. 51-3514),
Mg―SiCl ₄ ―ROH―TiCl ₄ system (Special Publication No. 50-23864
), MgCl ₂ -Al(OR) ₃ -TiCl ₄ system (Special Publication No. 1971-
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 1977-
11710), Mg-POCl ₃ -TiCl ₄ system (Special Publication No. 1171-
153), MgCl ₂ - TlCl ₄ system (JP-A-51-133386)
An example of a preferred catalyst system is a combination of a solid substance such as (in the above formula, R represents an organic residue) and an organoaluminum compound.

In these catalyst systems, titanium compounds and vanadium compounds can also be used as adducts with organic carboxylic acid esters, or the above-mentioned magnesium-containing inorganic compound solid carrier can be used after contact treatment with organic carboxylic acid esters. You can also do that. Moreover, there is no problem in using an organoaluminum compound as an adduct with an 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 alkyl esters of benzoic acid, anisic acid, 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 propylene 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. However, as is well known, the density of the produced polymer can vary depending on the selection of temperature and pressure. In other words, even within the above-mentioned range of conditions, a medium-low density ethylene copolymer having a density higher than 0.910 may be produced, so conditions are appropriately selected according to a conventional method to prevent this from occurring. 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 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 contacted can be selected within a wide range, but usually, the solid substance is treated with 1 g to 50,000 g, preferably about 5 g to 30,000 g of α-olefin, and 1 g to 500 g of α-olefin is added per 1 g of the solid substance.
- It is desirable to react with olefin. At this time, the pressure at the time of contact can be arbitrarily selected, but usually -1 to 100 kg/cm ² . It is desirable that the contact be made under a pressure of 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 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 propylene used in the method of the present invention is 63.6 to 250 mol% based on ethylene.
It is necessary to use it within the range of . If the melt index falls outside this range,
It is not possible to obtain an ethylene-propylene copolymer having a density of 0.01 to 10 and a density of 0.850 to 0.910. Further, the amount of propylene 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
- It is also possible to copolymerize by adding various dienes such as hexadiene, vinylnorbornene, ethylidenenorbornene, and dicyclopencdiene.

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 80°C, the above solid substance was fed to the autoclave at a rate of 250 mg/hr, and triethylaluminum was fed at a rate of 50 m-mol/hr, and the composition of ethylene, propylene, and hydrogen in the gas fed to the autoclave by a blower ( molar ratio) is 55% and 35% (i.e. mol% relative to ethylene), respectively.
Polymerization was carried out while adjusting the amount to be 63.6 mol%) and 10%.

The produced polymer is melt index (MI)
The bulk density was 1.1, the bulk density was 0.375, and the density was 0.895, 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 269,000g polyethylene/g-Ti.

After 10 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. In other words, in the slurry polymerization shown in Comparative Example 1, it was impossible to perform stable continuous operation for a long period of time, whereas by following the method of the present invention, it was possible to perform extremely stable continuous operation for a long time. it is obvious.

Press-molded products of this copolymer are transparent.
No surface stickiness, strength at break 220Kg/cm ² ,
The elongation was 600%.

Furthermore, this copolymer could be easily granulated using an extruder and formed into a film of uniform thickness using a high-pressure polyethylene blown film manufacturing machine.

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.

5 mg of solid substance/triethylaluminum
Continuous polymerization was carried out by supplying hexane at a rate of 1 m-mol/hr, ethylene at 8 kg/hr, propylene at 9.6 kg/hr (80 mol% relative to ethylene), and hydrogen at a rate of 3 Nm ³ /hr.

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 1.4, a bulk density of 0.253, and a density of
It was 0.930. It is clear that even though a large amount of the comonomer propylene was added, the density of the resulting polymer was not sufficiently reduced, and this was an example of a very disadvantageous polymerization. When this copolymer was press-molded, the surface was sticky, the strength at break was 160 kg/cm ² , and the elongation was 800%.

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 m-mol/hr. However, the composition in the gas phase is ethylene, propylene, and hydrogen 45:
The ratio was 40:15 (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 0.411, and a density of 0.865. The polymerization activity was 318,000 g polymer/g-Ti. When this copolymer was press-molded, it was transparent and had no stickiness on the surface.The strength at break was 190Kg/cm ² and the elongation was 700%.
It was hot.

The granules were granulated using an extruder and formed into a film using high-density polyethylene and pellet blend.
Addition of 10% reduces haze of 30μ thick film by 63%
It suddenly decreased to 10%.

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

In other words, 25 mg of the solid substance synthesized in Example 2 and n-paraffin containing 5 mmol of triethylaluminum were supplied at a rate of 40/hr, and ethylene was 8 kg/hr and propylene was 14 kg/hr (relative to ethylene). (117 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 1.5 and a density of 0.931.
The polymerization activity was 97000 g polymer/g-Ti.
Although the propylene was used in large excess relative to ethylene, the density did not decrease much and the polymerization activity was also low, which clearly shows that this is an example of inefficient polymerization. In addition, the strength at break of a press molded product of this copolymer is 17Kg/cm 2 , and the elongation is 17Kg/cm ² .
It was 480%.

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―
It was supplied at a rate of mol/hr, and the ratio (mole ratio) of ethylene, propylene and hydrogen in the gas phase was 43:42:
Continuous polymerization was carried out while adjusting the molecular weight to 15. When the reactor was opened after polymerization was completed, there was no adhesion inside the reactor.

The resulting polymer has an MI of 2.3, a bulk density of 0.398, and a density of
0.880, and the polymerization activity is 141000g polymer/g
-It was Ti. Press-molded products of this copolymer were transparent and had no stickiness on the surface, and had a strength at break of 190 Kg/cm ² and an elongation of 850%.

Example 4 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 substance is 1
It contained 39 mg titanium and 9.7 mg vanadium per gram.

A stainless steel autoclave was used as the equipment for gas phase polymerization, and a loop was created 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 80°C, and the above solid materials were fed into the autoclave at a rate of 600 mg/hr and triisobutylaluminum at a rate of 250 mmol/hr. ratio)
Polymerization was carried out while adjusting the amounts to 55%, 40%, and 10%, respectively.

The resulting polymer was almost perfectly spherical particles with an average particle size of 630μ and a narrow particle size distribution, a bulk density of 0.380, a melt index (MI) of 0.85, and a density of 0.892, and the particles had no stickiness. The polymerization activity was 224,000 g polyethylene/g-Ti.

Furthermore, when the 16-hour continuous polymerization was stopped and the inside of the autoclave was inspected, no polymer was found to be attached to the inner wall, stirrer, or polymer extraction tube.

The press-molded product of this copolymer was transparent, had no stickiness on the surface, had a strength at break of 220 kg/cm ² and an elongation of 680%.

Claims (1)

[Claims] 1. A method for producing a soft or semi-rigid polymer by copolymerizing ethylene and α-olefin, a catalyst comprising a solid inorganic compound containing Mg, a halogen, and a titanium compound or a titanium compound and a vanadium compound. 63.6 to ethylene for ethylene and ethylene in the gas phase substantially free of solvent in the presence of
By copolymerizing 250 mol% propylene, melt index 0.01 to 10 and density
A method for producing a copolymer, characterized in that a soft or semi-rigid ethylene-propylene copolymer having a molecular weight of 0.850 to 0.895 is obtained.