JPS6052163B2 - Method for producing ethylene polymer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [I] Background of the Invention 1 Technical Field The present invention relates to a method for producing ethylene polymers and copolymers by polymerizing ethylene.

In detail, there is a method for producing an ethylene polymer that is extremely easy to handle and polymerizes ethylene in the presence of a catalyst that is active even at low temperatures, and an ethylene/α-olefin copolymer that copolymerizes ethylene with a small amount of α-olefin. A manufacturing method is provided. 2. Prior Art A method of polymerizing ethylene using a catalyst in which chromium oxide is supported on a carrier such as silica, alumina, silica-alumina, zirconia, or tria is well known in the art as the Phillips method.

When using this Phillips catalyst, higher polymerization pressures and higher polymerization temperatures are generally required compared to Ziegler catalysts which can also be polymerized with ethylene, and the properties of the resulting polymers can also be slightly different. For example, when using this Phillips catalyst, the molecular weight of the polymer depends largely on the polymerization temperature, and in order to obtain a polymer with an average molecular weight of 50,000 to 100,000, it is generally necessary to set the polymerization temperature to 100 to 200°C.

If polymerization is carried out at such a temperature, the resulting polymer will be dissolved in the solvent, and the viscosity of the polymerization system will increase as the polymerization progresses. However, such an increase in viscosity worsens the diffusion of ethylene monomer within the polymerization system, causing an adverse effect on the polymerization reaction such as a decrease in the polymerization rate.

Therefore, in general, polymerization reactions using this type of Phillips catalyst must be carried out by adjusting the concentration of the produced polymer in the reaction solvent to a concentration of 20% or less, or by lowering the polymerization temperature to reduce the concentration of the produced polymer. must be polymerized in a state where it precipitates as a solid.

However, lowering the polymerization temperature to a temperature lower than this is not necessarily a preferable method because it results in a decrease in the polymerization rate. Furthermore, the Phillips catalyst contains impurities in ethylene and solvents, such as water, oxygen, oxides such as carbon monoxide or carbon dioxide, organic compounds such as sulfur or nitrogen or halogens, acetylenes or dienes, which act as catalyst poisons. It is said that it is necessary to remove down to Ppm order.

The differences between the Ziegler catalyst and the Phillips catalyst include differences in polymerization behavior, behavior toward organoaluminum compounds, and molecular structure of the resulting polymer, and the two catalysts have no similarities at all.

One of the reasons for these differences is that the polymerization mechanism of Ziegler's catalyst is coordination anionic polymerization, whereas the mechanism of Phillips catalyst is a type of cationic polymerization (Kagaku Dojinsha Publishing 1 Kagaku Jl95 @ Daika Volume No. 8, Page 614)
This is probably because it arises from this.

As a catalyst that improves the drawbacks of the above-mentioned Phillips catalyst, chromium oxide is supported on a carrier made of silica, alumina, or silica-alumina, and a catalyst with the general formula R3SiOAlR2 is used.
A catalyst comprising a pentaalkylsiloxyalane represented by (R is an alkyl group having 1 to 1.0 carbon atoms) was proposed (Japanese Patent Publication No. 1365/1983).

However, the pentaalkylsiloxyalane used as a component of this catalyst is generally produced from trimethylsilanol and trialkylaluminium, but this reaction is extremely rapid and requires well-controlled reaction techniques. In addition, trimethylsilanol, which is a raw material component, has an S1-0-H bond in its molecule, so it is extremely reactive and easily undergoes dehydration and condensation with the slightest stimulation or trace amount of acid or alkali, making it an extremely inconvenient compound to handle. It is.

Therefore, it is natural that, unlike these catalysts, it is desirable to establish an industrially advantageous method for producing ethylene polymers that uses a new catalyst that is extremely easy to handle, does not require purification, and is active even at relatively low temperatures. be.

[Old Summary of the Invention 1 Summary The present invention solves the above problems by using, as a catalyst component, a reaction product of a carboxylate of a metal from Group A or B of the Periodic Table or a specific alkyl aluminum compound. This is what I am trying to do.

Therefore, the method for producing an ethylene polymer according to the present invention is (a
) chromium oxide supported on a carrier; (b) periodic table A
, b or a reaction product of a group metal carboxylate and a trialkylaluminum or an alkyl aluminum hydride.

As described above, in the present invention, stable carboxylic acid salts of metals from Group A, B or group of the periodic table are used in the production of catalyst components, so handling is extremely easy, and the reaction products with organoaluminum are It can be used as a catalyst component that does not require purification and isolation, and the use of this catalyst component provides an industrially extremely advantageous method for producing ethylene polymers that exhibits high activity even in relatively low-temperature polymerization.

Detailed Description of the Invention i Manufacture of Catalyst In this invention, the following component (a) in which chromium oxide is supported on a carrier such as silica, alumina, or silica-alumina, prepared by a known method described below. It is characterized by the use of a catalyst consisting of a combination of the following component (b), which is a reaction product of a carboxylate of a group A or group metal of the periodic table or an alkyl aluminum compound. .

l) Component (a) As the carrier on which the chromium oxide of the present invention is to be supported, carriers similar to those that can be used as a Phillips catalyst can be used, and representative carriers include silica,
Examples include alumina and silica-alumina.

Further, as a method for supporting chromium oxide on a carrier, it can be easily carried out by supporting a chromium compound by various methods such as impregnation, distillation, sublimation, etc., and then calcining it. .

Examples of the chromium compound include chromium oxides, nitrates, sulfates, oxalates, alcoholades, and organic compounds, and particularly preferred chromium compounds include chromium trioxide, chromium acetyl acetonate, and chromium nitrate.

After supporting these chromium compounds on the carrier, activation is performed by firing. This activation by firing is generally carried out in the presence of oxygen, but it can also be carried out in the presence of an inert gas or under reduced pressure.

The firing temperature is usually 300 to 1100℃, preferably 4
The treatment is carried out within a temperature range of 00 to 900°C for several minutes to several tens of hours, preferably 30 minutes to 1 hour. The amount of chromium compound supported is generally in the range of 0.05 to 10%, preferably 0.1 to 5% by weight of chromium metal relative to the carrier.

(2) Component (b) In the present invention, the reaction product of a carboxylate of a metal of group A or b of the periodic table and a trialkylaluminum or an alkyl aluminum hydride is a reaction product of the metal carboxylate and the alkyl aluminum compound in hexane. It can be easily obtained by reaction in the presence of an inert solvent such as , decane or methylcyclohexane.

The reaction of both compounds is initially carried out in a suspended state since the metal carboxylate is not soluble in an inert solvent.

Therefore, the usual method is to suspend the metal carbonic acid salt in an inert solvent, and then add the alkyl aluminum compound dropwise thereto, either diluted with the inert solvent or without being diluted. In addition, when the metal carphonate is in the form of lumps or coarse particles, it is preferable to use it after pulverizing it in terms of reactivity. The carboxylic acid salt of metal of group A, b or group of the periodic table used in the present invention has the general formula or (M is a metal ion of group A, b or group of the periodic table, R1 is a hydrogen atom or the same group as R2. .

R2 represents a hydrocarbon group such as an alkyl group, an alkenyl group, an aryl group, an alicyclic group, or a hydroxy hydrocarbon group. n represents the valence of the metal ion. ) There are carboxylic acid salts of metals of Groups A, B or Groups of the Periodic Table. In particular, carboxylic acid salts of metals A, B or group metals of the periodic table include, for example, Mg, Ca, Sr, B
a, Al, Fe, CO or N1 metal and formic acid, acetic acid,
Propionic acid, butyric acid, lauric acid, palmitic acid, stearic acid, benzoic acid, γ-cyclohexylbutyric acid, lactic acid,
tartaric acid, salicylic acid, oxalic acid, succinic acid, phthalic acid,
These include salts with mono- or dicarboxylic acids such as malic acid, and hydrated products thereof.

Specifically, calcium formate, cobalt formate, barium formate, calcium acetate, cobalt acetate, iron acetate, barium acetate, magnesium acetate, aluminum acetate, nickel acetate, calcium propionate, cobalt propionate, magnesium propionate, calcium butyrate, butyric acid. Magnesium, barium butyrate, calcium laurate, aluminum laurate, magnesium laurate, aluminum palmitate, calcium palmitate, barium palmitate, magnesium palmitate, aluminum stearate, calcium stearate, nickel stearate, barium stearate, magnesium stearate , iron benzoate, aluminum benzoate, cobalt benzoate, aluminum benzoate, calcium benzoate, aluminum lactate, calcium lactate, iron lactate, nickel lactate, magnesium lactate, aluminum oxalate, calcium oxalate, barium succinate, magnesium succinate, These include iron malate.

Among them, high-grade fatty acid salts (having 8 or more carbon atoms) are relatively preferably used. On the other hand, alkylaluminum compounds have the general formula RnAlY3-n (where R has 1 to 20 carbon atoms).
(Y is a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, and n is 1, 2, or 3, respectively) can be used.

Specific compounds include trialkyl aluminum such as trimethylaluminum, triethylaluminum, tri-n-propylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, tri-n-decylaluminum, shell aluminum hydride, diisobutyl There are alkyl aluminum hydrides such as aluminum hydride and isobutyl aluminum dihydride.

The reaction between the alkylaluminum compound and the metal carboxylate is generally carried out in the temperature range of -20 to 200°C.
The alkyl aluminum compound is added dropwise to the suspension of the metal carboxylate in an inert solvent over a period of several minutes at a temperature range of -10 to 400 C, and then the process is carried out for about 50 hours.
React for 1 to 10 hours at a temperature range of 150°C.

The amounts of the alkyl aluminum compound and metal carboxylate used are generally in the range of 1 to 501, preferably 2 to 20, in terms of the alkylaluminum compound/metal carboxylate molar ratio.

Two or more metal carboxylates and alkyl aluminum compounds may be used as a mixture, or two or more of the obtained reaction products may be used as a mixture. Furthermore, the resulting reaction product has the general formula AlRnX3-.

(R is a hydrocarbon group, X is a halogen atom, an alkoxy group,
Organoaluminum compounds, where n is 1≦n (3 numbers), such as diethylaluminium, um chloride,
Diisobutylaluminum chloride, ethylaluminum dichloride, diethylaluminum methoxide,
Diethylaluminum ethoxide, diethylaluminum phenoxide, etc. are added to the alkyl aluminum compound. It may be used in an amount of 1 or less in molar ratio.
(3) Catalyst preparation The quantitative ratio of component (a) and component (b) is carried out at an A1/Cr atomic ratio of 1 to 3, preferably 2 to 100. The preparation method for this catalyst is the usual one! It can be carried out by a method essentially the same as the mixed preparation method.

For example, a method in which component (a) and component (b) are directly fed separately into a polymerization container and the catalyst is formed simultaneously with the progress of polymerization, or component (a) and component (b) are mixed in advance in a polymerization solvent. Alternatively, the catalyst components may be formed and then fed into a polymerization vessel. 2. Polymerization of ethylene The catalyst thus prepared is used to polymerize ethylene, and the ethylene polymerization reaction according to the method of the present invention usually involves the following steps:
This is carried out by dispersing a catalyst in an inert solvent, supplying ethylene or ethylene and other olefins, and maintaining the mixture at a predetermined temperature and pressure.

Saturated hydrocarbons and aromatic hydrocarbons such as hexane, heptane, cyclohexane, benzene, and toluene are used as the inert solvent.

The polymerization reaction of ethylene is carried out at relatively low temperatures and pressures.

That is, the polymerization temperature ranges from room temperature to 200° C., and the polymerization pressure ranges from normal pressure to 100k9/C7rl to fully achieve the purpose. Furthermore, when polymerizing ethylene according to the present invention, a small amount of a monomer that can be copolymerized with ethylene, such as α-olefin such as propylene, butene-1, hexene-1, etc., is allowed to coexist in the polymerization reaction zone. Ethylene copolymers containing up to % by weight can be produced.

Furthermore, the molecular weight of the produced polymer can also be adjusted by allowing hydrogen to be present in the polymerization reaction zone.

The amount of hydrogen that should be present varies depending on the polymerization conditions and the required molecular weight of the ethylene polymer, so it is necessary to adjust the amount introduced accordingly. Since the catalyst of the present invention is quickly deactivated by moisture, oxygen, etc., it is desirable to use sufficiently purified ethylene, hydrogen, solvent, etc. to be supplied to the polymerization system.

Furthermore, due to its extremely high catalytic activity, the polyethylene produced by the method of the present invention has excellent hue, thermal stability, and oxidative stability even without a deashing step.

Example 3 Example 1) Synthesis of component (a) A slurry prepared by immersing 12 g of commercially available silica (#952, manufactured by Davison, USA) in 40 ml of an aqueous solution containing 0.2 g of chromium trioxide was heated to 120°C. dry.

The obtained solid was placed in a quartz tube and fired at 800° C. for 1 hour in dry air, then cooled to room temperature and degassed under reduced pressure. The catalyst component prepared in this way contains 0.00% chromium. It contained 3% of slag. ) Synthesis of component (b) Into a 200 ml flask purged with argon gas, 40 ml of n-decane and 1.97 g of calcium stearate were sequentially charged, and at 20°C, 2.97 g of triethylaluminum was added under stirring.
Drip g with a pipette.

Immediately raise the temperature to 100°C and react for 5 hours. (3)
Polymerization of Ethylene Under an argon atmosphere, 500 ml of sufficiently dehydrated and deoxygenated n-hexane was placed in a receiver with an internal volume of 500 ml, and 0.263 mmol of the above component (b) as aluminum and 70 mg of component (a) were added to prepare the catalyst. A slurry was prepared.

Next, a stainless steel autoclave having an internal volume of 1e and equipped with a stirring and temperature control device was sufficiently purged with argon, then replaced with ethylene, and the above-mentioned catalyst slurry was introduced in an ethylene atmosphere.

Temperature 90℃, hydrogen partial pressure 1.3kg/d1 ethylene partial pressure 4
．． Constant pressure polymerization was carried out at 2k9/Cm for 9 cycles while continuously supplying ethylene. After the polymerization, the polymer slurry was filtered and dried under reduced pressure at 85°C for 5 hours until the bulk density was 0.2.
165 g of polymer of 89 g/ML was obtained.

The catalyst yield at this time was 2400 g/g/g/component (a)
(290,000 g-PE/g-Cr). In addition, the melt index (ASTM-Dl238-65T) of this polyethylene at 190°C and under a load of 2.16 kg is
) is 0.06g/1077!77
! It was hot. Comparative Example 1 Only 0.105 mmol of triethylaluminum was used instead of component (b), and component (a)
) Polymerization of ethylene was carried out in the same manner as in Example 1 except that 97.8m9 was used in combination.

As a result, 106 g of a polymer having a bulk density of 0.24 g/ml and a melt index of 0.07 was obtained.

The catalyst yield at this time was 1100 g-PE/g one component (a)
(140,000 g-PE/g-Cr). Examples 2 to 11 The same operations as those for the synthesis of component (b) in Example 1 were carried out by changing the alkylaluminum compound, metal carboxylate, their molar ratio, synthesis temperature, and synthesis time as shown in Table 1. Component (b) was synthesized, and ethylene was polymerized in the same manner as in Example 1.

The results are shown in Table-1.

Claims (1)

[Scope of Claims] 1. A reaction product of (a) chromium oxide supported on a carrier, (b) a carboxylate of a group IIa, IIIb or VIII metal of the periodic table, and a trialkylaluminum or alkyl aluminum hydride. . A method for producing an ethylene polymer, comprising polymerizing ethylene in the presence of a catalyst consisting of.