JPS58127710A - Production of polyethylene - Google Patents

Abstract

PURPOSE:To produce PE having excellent moldability at a high production rate, by employing a catalyst comprising a solid catalytic component of a special composition, a trialkylaluminum and a Cl-containing Al compound. CONSTITUTION:A catalyst is obtained by combining (A) a solid catalytic component containing at least Ti, Mg and Cl (e.g., a reaction product between MgCl2 and TiCl4) with (B) a trialkyl-aluminum of formulaI, wherein R<1> is a 1-8 C alkyl or cycloalkyl, and (C) a Cl-containing Al compound of formula II, wherein R<2>-R<1> and 0<n<=2, so that the molar ratio of A:(B+C) is 1:1-500, and the molar ratio of B:C is 1:0.5-20 (provided that B:C=1:0.5-100 when n=2 in formula II). Then, ethylene is polymerized for 10min-5hr in an inert solvent in the presence of the catalyst under conditions including an ethylene pressure of 0.5-15kg/cm<2>.G and a temperature of 50-95 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing polyethylene, and more specifically, it is possible to change the molecular weight distribution and grade of polyethylene by simply using a specific catalyst and appropriately selecting the proportions of each component of the catalyst. The present invention relates to a method for producing polyethylene with excellent molding properties at high productivity without requiring a deashing step.

Conventionally, highly active catalysts have been used to increase production efficiency when producing polyethylene.
Various technologies have been developed. For example, (1)% Kaisho 5
6-da 7.207 publication, (2) JP-A-Sho-37gg
Publication No. 1, (3) Japanese Unexamined Patent Publication No. 6233, (4
) Japanese Unexamined Patent Publication No. 31-3.2090 and (5) Japanese Patent Publication No. 7'7.27, etc. are known.

However, in (1), alcohol is required, the working process is complicated, and fish eyes occur in the resulting product, which has an unfavorable effect particularly on extrusion molded products such as sheets and films. It's a place.
In method (2), since the catalyst used is a non-supported type, a deashing step is required, resulting in a reduction in production efficiency. Furthermore, in (3) and (5), the molecular weight distribution of the polyethylene obtained is still not wide enough to a satisfactory extent.

However, in (4), the activity is improved by combining a catalyst and a co-catalyst, but the resulting polyethylene has a narrow molecular weight distribution, extremely poor fluidity, and has drawbacks such as the appearance of shark skin on the product surface.

An object of the present invention is to eliminate these drawbacks of the conventional techniques and provide a method for producing polyethylene with high production efficiency and excellent molding properties, especially the appearance of sheets and films. That is, the present invention provides (A) a solid catalyst component containing at least titanium, magnesium and chlorine, (B) a general formula R'3 Al (R' represents the number of carbon atoms/~ any alkyl group or cycloalkyl group); trialkylaluminum represented by and (C) general formula R2n
Using a catalyst prepared from a chlorine-containing aluminum compound represented by AlC13-n (R2 represents an alkyl group or cycloalkyl group having carbon number/~g, and n represents a real number satisfying O<n≦2). When producing polyethylene, the proportions of each component of the catalyst are set under the following conditions (1):
.

(11) (i) (A) component: ((B) component + (0) component) −
/:/~/2500 (more than molar) (g) (B) component: (C) component =/: 0.0! ;〜／：
20 (molar ratio), provided that the above general formula R2nA1c13
.

When n = 2, (B) component: (C) component -
/ : 0-3 to /2100 (molar ratio) is provided.

The catalyst used in the method of the present invention is the above (A), (B
) and (C) components, of which the (A) component, a solid catalyst component containing at least titanium, magnesium and chlorine, may be of various types without particular limitation. I can think.

For example, it can be obtained by reacting a magnesium compound, which is usually used as a carrier for a Ziegler catalyst, with a chlorine-containing titanium compound.

Here, various compounds can be used as the above-mentioned magnesium compound, but specifically, magnesium chloride, magnesium bromide, and magnesium iodide are used.

Located magnesium such as magnesium fluoride.

Magnesium hydroxide, magnesium oxide, magnesium sulfate, magnesium carbonate or hydroxymagnesium chloride, hydroxymagnesium bromide, hydroxymagnesium iodide, hydroxymagnesium hydroxylodenide, methoxymagnesium, ethoxymagnesium, flopoxymagnesium, butoxymagnesium, etc. Alkoxymagnesium, methoxymagnesium chloride.

Alkoxymagnesium halides such as methoxymagnesium bromide, ethoxymagnesium chloride, ethoxymagnesium bromide, propoxymagnesium chloride, propoxymagnesium bromide, butoxymagnesium chloride, and poxymagnesium zolomide.

Allyloxymagnesium and allyloxymagnesium halides such as allyloxymagnesium chloride and allyloxymagnesium bromide.

Furthermore, methylmagnesium chloride, methylmagnesium bromide, ethylmagnesium chloride, ethylmadanesium bromide, propylmagnesium chloride, progylmagnesium bromide, butylmagnesium chloride.

Examples include alkylmagnesium halides such as butylmagnesium bromide, and mixtures thereof. On the other hand, examples of the chlorine-containing titanium compounds include titanium tetrachloride (Tj, C10), titanium trichloride (TiCl3), and adducts of titanium trichloride and aluminum chloride (TiCl3., AlCl3).

Dichloromethoxytitanium (CH30TiC12),
Trichloroethoxytitanium (C2H50TiC13)
+) Lichloropropoxy titanium (C3R70TiC1
3) r dichlorodipropoxy titanium ((c3H70)
2 TiCl2 ) +dichlorodiethoxytita7 (
(C2HsO)2TiC12), mo/ri00triethoxytitanium ((C2H50)3TiC1), and the like. Furthermore, when a chlorine-containing compound is used as the above-mentioned magnesium compound, titanium tetrabromide (Ti
Br4), titanium tetraiodide (Ti4), etc. can be used.

The solid catalyst component (A) may be produced as described above, but more preferably, the above magnesium compound is first modified using silicon tetrachloride or the like, and then reacted with a chlorine-containing titanium compound. What you get by doing so is good.

Next, the trialkyl aluminum represented by the general formula R'3A1, which is the component (B) of the catalyst, has R' of carbon number/~
Any alkyl group or cycloalkyl group may be used, and preferred examples include trimethylaluminum, triethylaluminum, triisopropylaluminium, and triinphthylaluminium.

Trioctyl aluminum etc.

Next, the general formula R2nA1c13- which is the (0) component of the catalyst
In the chlorine-containing aluminum compound represented by n, R2 may be any alkyl group or cycloalkyl group with carbon number/~, and n may be a real number satisfying 0<n≦2. Suitable examples of this compound include diethylaluminum monochloride, diisoprogylaluminium monochloride, diisobutylaluminum monochloride, dioctylaluminum monochloride, ethylaluminum dichloride, isozolobylaluminium dichloride.

Examples include ethylaluminum sesquichloride.

In the method of the present invention, the above (A) and (B)
, (c) A catalyst prepared from each component is used, and the usage ratio of each component is determined according to the conditions (+) and (ii) described above.
) must be satisfied.

This condition (1), that is, component (A): component (B) and (
c) The condition that the sum of components = /: / ~ /: 30θ (molar ratio) is important for increasing the polymerization activity and maintaining a high level of the effect of expanding the molecular weight distribution of the obtained polyethylene. . If the ratio of component (A) is larger than the range of conditions 7- above, the ratio of components (B) and (C) will be relatively small, so the amount of alkyl aluminum effective as an activator will be small. As a result, polymerization activity is significantly reduced. On the other hand, if the proportion of component (A) is smaller than the range of the above conditions, the resulting polyethylene will have a narrow molecular weight distribution and the intended purpose cannot be achieved. In addition, what is most preferable in the above condition (1) is (A) component: ((B) component + (C) component) -/:
ta~/:1I-00c molar ratio).

Next, the above-mentioned condition (g) is the ratio of components (B) and (c), which, like the above-mentioned condition (1), maintains high polymerization activity and a high effect of expanding the molecular weight distribution of polyethylene. This is extremely important. Condition (11) of B is in the normal case, that is, when n in the general formula R2nA1c13-n is O<n<2, (B) component: (C) component -
/20, θ is ~/::lO (molar ratio), preferably component (B): component (C) -/ : 0.7 ~ /:/7
(molar ratio). Here, if the proportion of component (B) is too small, the polymerization activity will be markedly reduced, causing a problem in the quality of the product without deashing. On the other hand, if the proportion of component (B) is too high, the resulting polyethylene will not have a sufficiently wide molecular weight distribution.

Furthermore, the above condition (11) is based on the general formula R2nA1c13
- When n in n = 2, component (B):
(C) component -/20,s~/:10OC molar ratio), preferably component (B):component (C) -/:/~/near 0 (molar ratio). Here, if the proportion of component (B) is too small or too large, problems such as a decrease in polymerization activity and a decrease in the effect of broadening the molecular weight distribution will occur as in the case described above.

In producing polyethylene by the method of the present invention, the above (A), (B), and (c) are added to the reaction system.
It is carried out by using a catalyst prepared from the components in a predetermined ratio and introducing ethylene into the reaction system. There are no particular restrictions on the polymerization method and conditions, and solution polymerization is used.

Both suspension polymerization and gas phase polymerization are possible, and both continuous and discontinuous polymerizations are possible, and not only single-stage polymerization but also multi-stage polymerization can be performed. Butane as the reaction medium.

Pentane, n-hexane, cyclohexane, heptane,
Inert solvents such as benzene and toluene are preferred. Furthermore, the ethylene pressure in the reaction system is O,,! 5'～/Left Ky/
crl G, preferably /~/OK9/cr
; i G, the reaction temperature is SO ~ 95 °C, preferably O θ ~ 90 °C, /θ minutes ~ s hours, preferably 3
The desired polyethylene can be obtained by reacting for 0 minutes to 3 hours. The molecular weight during polymerization may be controlled by known means such as hydrogen.

The types of polyethylene that can be polymerized by the method of the present invention are not only ethylene homopolymers, but also ethylene and a small amount of α-olefin, α-olefins having 3 to 10 carbon atoms such as fluorene, butene/, pentene/, etc. - Examples include copolymers with olefins.

Since the method of the present invention uses the above-mentioned catalyst, the catalyst activity is extremely high, and a sufficient effect can be obtained even with a small amount of use. As a result, the deashing step (catalyst removal step) can be omitted. Moreover, according to the method of the present invention, (A), (
By simply selecting the proportions of the three types of catalyst components B) and (0), it is possible to easily adjust the molecular weight distribution and change the grade of the resulting polyethylene. Therefore, there is no need to prepare many types of catalysts as in the past, there are fewer defective products due to grade changes, and there is no need to clean the tank every time the grade is changed. Furthermore, even for grades in which the molecular weight distribution could not be expanded conventionally without multi-stage polymerization, the method of the present invention makes it possible to produce the required grade of polyethylene in a single stage.

Therefore, according to the method of the present invention, workability and production efficiency are dramatically increased.

In addition, the polyethylene obtained by the method of the present invention can be molded with low resin pressure and has a wide molecular weight distribution, so it can be used to produce thin films and sheets with excellent mechanical strength and less fish idel. Extrusion molded products such as hollow molded products, and even injection molded products with beautiful outer surfaces can be easily formed.

Next, examples of the present invention will be shown. All operations on the male side of Example 11 below were performed under an argon stream. In addition, the evaluation of molecular weight distribution was 2/2/2 for the melt index (MX2.16) at 790°C and
, the melt flow ratio (FR) is the ratio of the melt index (Ml21.6) of the AKy load. Furthermore, the resin pressure was evaluated by using an inflation molding machine with a diameter of 1Q mm, using a die at 793° C., and showing a pressure measurement value of the breaker plate out at a discharge rate of 2011/min. Furthermore, for fish eyes (including Dell), a film with a thickness of O μ is obtained by inflation molding at a Siburo ratio of /, 5, and the diameter of the film surface of the 1000 crl is Q,
Evaluation was made by counting the number of fish eyes larger than mm.

Examples/~5 and Comparative Examples/~5 (1) Preparation of solid catalyst component Magnesium jetoxide/in n-heptane 50-
0,! i' (g, g mmol) and commercially available anhydrous magnesium sulfate/, 04 g (g, g mmol) and further silicon tetrachloride/, 5.9 (g, g mmol) toethanol/, AI <33 ．． ．． 2 mi IJ mo 12
- was added and the reaction was carried out in gooC for 7 hours.

Next, add titanium tetrachloride sme<qs mmol) and add 9
The reaction was carried out at g0C for 3 hours. After the reaction, the mixture was left to cool and stand, and the supernatant liquid was removed by decanting. Next, add n-heptane 1
Add 00-, stir, let stand, and remove the supernatant for 3 cleaning steps.
After repeating, 200 g of n-hebutane was added to obtain a dispersion of solid catalyst components. The amount of titanium supported on this product was determined by a colorimetric method, and the result was that it was a l12Q-T17g-carrier.

(2) Polymerization of ethylene 2 was carried out in a stainless steel autoclave containing dry hexane/t, the solid catalyst component prepared above as the (A) component, triethylaluminum as the (B) component, and (C
) Add a predetermined amount of diethylaluminium or ethylaluminum dichloride and other ingredients as ingredients,
Further, hydrogen was metered so that the polyethylene had the melt index (M engineering) shown in Table 1, and ethylene was continuously supplied so that the total pressure of the reactor was g -3K9 / crl G, and the mixture was stirred for 730 minutes at gooC. The reaction was carried out while After the reaction was completed, the obtained polyethylene was washed and dried, and its FR1 resin pressure and fish eyes were measured. The results are shown in Table 1.

Examples B~// and Comparative Example Otsu 2 were placed in a stainless steel autoclave containing dry hexane O, St and (A) as in Examples/~3 above.
(B), (c) The catalyst component is added, hydrogen is weighed so that the obtained polyethylene has the intrinsic viscosity [η] shown in Table 2, and the total pressure of the reactor is 7? /
Continuously supply ethylene so that crl a is 90
After reacting at 7.20 minutes with stirring at 10°C, the temperature was lowered to 1IO°C. The reactor was then degassed, and after adding O, St dry hexane, polyethylene was added to the second
Hydrogen was metered to give M as shown in the table, and ethylene was continuously supplied so that the total pressure of the reactor was 3 K9/crl G, and the reaction was carried out at gθ°C with stirring for 3θ minutes. After the reaction was completed, the obtained polyethylene was washed and dried, and its FR1 resin pressure and fish eyes were measured. The results are shown in Table 2.

Example/2.73 and Comparative Example 7 Polymerization was carried out under the same conditions as in Example B, except that the catalyst composition shown in Table 3 was used. After the reaction was completed, the FR and resin pressure of the obtained polyethylene were measured.

The results are shown in Table 3. Note that the resin pressure is 23 mm)
Measurements were made using a blow molding extruder.

Claims (1)

[Claims] 1. (A) a solid catalyst component containing at least titanium, magnesium and chlorine, (B) general formula R'3Al
(R' represents the number of carbon atoms/~ represents an alkyl group or cycloalkyl group) and (C) a trialkylaluminum represented by the general formula R2nAlCl3. (R2 represents an alkyl group or a cycloalkyl group having carbon number/~g,
n represents a real number satisfying Own≦2. ) When producing polyethylene using a catalyst prepared from a chlorine-containing aluminum compound represented by
A) Component: ((B) component + (0) component) -/:/~/:
Left 00 Upper left 0 ratio) (ii) (B) component: (C component -/: 0.0
3~/: 20 (molar ratio), provided that n=2 in the above general formula R2nAlCl3
In the case of (B) component: (C) component -i: o, s~/:/
1. A method for producing polyethylene, characterized in that θ0 (molar ratio) is selected to satisfy θ0 (molar ratio).