JPH0446907A - Polymerization of ethylene - Google Patents

Abstract

PURPOSE:To polymerize ethylene without clogging of piping or a change in reaction temperature by bringing ethylene into contact with a catalyst comprising two specified components at a specified temperature under a specified pressure. CONSTITUTION:Ethylene or both ethylene and at least one alpha-olefin are polymerized by contact with a catalyst comprising a solid composition (A) obtained by mixing and grinding a magnesium halide, titanium trichloride, a silicon halide and a compound selected from the following compounds (a) to (e) having at least one 10C or higher long-chain hydrocarbon group: (a) an alcohol, (b) a carboxylic acid, (c) a metal salt of a carboxylic acid, (d) an amide and (e) an ester and an organoaluminum compound (B) having a halogen group at 125 deg.C or above under a pressure of 200kg/cm<2> or above.

Description

Detailed Description of the Invention [Background of the Invention] Technical Field The present invention is directed to
The present invention relates to a method of polymerizing ethylene at the above temperature. The present invention can also be considered as a method for producing ethylene polymers.

<Prior art> In recent years, as seen in British Patent No. 828.828, a method has been developed in which ethylene is polymerized at high temperature and pressure by coordination ion polymerization using a Ziegler type catalyst using a high-pressure polyethylene polymerization apparatus. is proposed.

Recently, this method has been used to copolymerize ethylene and α-olefin and control the density of the ethylene copolymer to produce linear low-density polyethylene (LLDPE).
Methods of manufacturing are also known.

The above method is extremely advantageous in that existing high-pressure polyethylene production equipment can be used as is, and no new investment capital is required for the industrial production of LLDPH.

However, when Ziegler type catalysts are used at high temperatures and high pressures, the following problems are observed compared to low temperature and low pressure polymerizations where these catalysts are generally used.

When a catalyst is supplied to a high-pressure reactor using a high-pressure pump, the catalyst is required to have a sufficiently small particle size and to be free of coarse particles. This is because if the average particle size is large or excessively coarse particles are present, pipe clogging may occur or reaction temperature may fluctuate.

To meet such requirements, there are techniques disclosed in Japanese Patent Publication No. 486183 and Japanese Patent Application Laid-Open No. 59-204604, but these techniques do not sufficiently eliminate coarse particles and cause the above-mentioned problems. Alternatively, since coarse particles are virtually completely eliminated, it becomes necessary to pre-treat the catalyst with a large amount of α-olefin, which may cause problems such as a significant increase in the viscosity of the catalyst dispersion. It is.

[Summary of the invention]

Summary of the Invention The present invention aims to provide a solution to the above points, and attempts to achieve this aim by using a specific embodiment of a combination catalyst.

That is, the method of polymerizing ethylene according to the present invention requires a pressure of at least 200 kg/cI# and a pressure of at least 125
The method is characterized in that ethylene or ethylene and at least one α-olefin are brought into contact with a catalyst consisting of component A and component B described below at a temperature of 0.degree. C. for polymerization.

Component A A solid composition obtained by mixing and pulverizing the following compounds (1) to (4).

(1) Magnesium halide, (2) Titanium trichloride, (3) Silicon halide, (4) The following compound group (a) having at least one long-chain hydrocarbon group with 10 or more carbon atoms (e) A compound selected from (i) alcohol, (b) carboxylic acid, (c) carboxylic acid metal salt, (d) amide, (e) ester, and component B: an organoaluminum compound having a halogen group.

[Detailed description of the invention]

(I) Component A This is a solid composition obtained by mixing and pulverizing the following compounds (1) to (4). Such a solid composition contains components other than compounds (1) to (4) that are inevitably present, components that have an advantageous effect on the present invention, or components that do not substantially inhibit the effects of the present invention. A predetermined amount can be included.

(1) Magnesium halides, specifically M g F 2, M g Cl 2, Mg
There are Br2 and Mg12. Among these, MgCl2 is particularly preferred.

(2) Titanium trichloride Titanium trichloride is produced by reducing titanium tetrachloride with hydrogen (
There are many other types, such as T I Cl 3 (H) ), those reduced with aluminum metal (T s C13 (A) ), and those reduced with organic aluminum.

Therefore, this titanium trichloride in the present invention is purely TiC
13, for example, it may be added or such an auxiliary component may be introduced afterwards.

(3) Silicon halide Silicon halide has the general formula S L X n R
4-.

(Here, X is a halogen, R is a hydrocarbon group having 1 to 6 carbon atoms, and n is 2≦n≦4).

Specific examples include silicon tetrachloride, bromine tetrachloride, methyltrichlorosilane, ethyltrichlorosilane, and dichlorodiethylsilane. Among these, silicon tetrachloride is particularly preferred.

(4) A compound selected from the following compound groups (a) to (e), which has at least one long-chain hydrocarbon group with a carbon number of 10 or more. (B), (C), (D), and (E).

(a) One of the ROM components (4) is alcohol. Here, R
is a long-chain hydrocarbon group (preferably a saturated or unsaturated alkyl group) having 10 or more carbon atoms, preferably 12 or more (the upper limit is about 40).

Specifically, n-decanol, n-dodecanol, n-
Examples include hexadecanol and stearyl alcohol.

(b) RCOOH Other specific examples of component (4) are carboxylic acids. Here, R has 10 or more carbon atoms, preferably 12 or more (the upper limit is 4
0) long-chain hydrocarbon group (preferably a saturated or unsaturated alkyl group).

Specifically, n-decanoic acid, dodecanoic acid, oleic acid,
Examples include stearic acid.

(c) (RCOO) M is a carboxylic acid metal salt. Here, at least one R
is a long-chain hydrocarbon group (preferably a saturated or unsaturated alkyl group) having 10 or more carbon atoms, preferably 12 or more (the upper limit is about 40). M is a metal atom having a valence of 1 to 4 (preferably Na, Mg, Zn), and n is an integer of 1 to 4 corresponding to the valence of M. When n is 2 or more, it is preferable that the plurality of carboxylic acid moieties have the same R.

Specifically, there are sodium oleate, magnesium stearate, zinc stearate, and the like.

(d) RCONRIR2 is an amide. Here, R, R1 and R2 are hydrogen atoms or hydrocarbon groups, and at least one of them has 10 or more carbon atoms, preferably 12 or more carbon atoms (the upper limit is 4
0) long-chain hydrocarbon groups, which may be the same or different.

Specific examples include oleic acid amide and stearic acid amide.

(e) RCOOH3 is an ester. At least one of R and R3 has a carbon number of 10 or more, preferably 12 or more (the upper limit is about 40)
are long-chain hydrocarbon groups, which may be the same or different.

Specific examples include stearyl acetate, stearyl methacrylate, and ethyl oleate.

Among these, (a), (b), (d), and (e) are preferred, and (e) is particularly preferred.

(5) Quantitative Ratio The quantitative ratios of compounds (1) to (4) can be arbitrary as long as the effects of this invention are recognized.

In this catalyst, the molar ratio of magnesium halide to titanium trichloride is 1 to 50, preferably 2 to 40, and more preferably 2.5 to 30. When the molar ratio is less than 1, the activity per titanium atom is low and the polymer may be colored. On the other hand, if it exceeds 50, the activity per catalyst decreases.

The amount of the compound of component (3) is 0 based on the total weight of the four components.
．． It is 1 to 20% by weight, preferably 1 to 10% by weight. If it is less than 0.1% by weight, the effect of reducing the particle size of the catalyst will not be exhibited, and if it exceeds 20% by weight, the effect will not change, and further use is wasteful.

The amount of the compound of component (4) is 1 based on the total weight of the four components.
-20% by weight, preferably 2-15% by weight. 1
If it is less than 20% by weight, the effect of suppressing the formation of coarse particles of the catalyst is poor, and if it exceeds 20% by weight, sticking occurs during the pulverization process, making mixing and pulverization difficult.

(6) Mixing and Grinding The mixing and grinding of the four components (1) to (4) can be carried out using any grinding device that allows close contact between the four components. Since mixing and pulverization should be carried out without contact with moisture or air, rotary ball mills, rod mills, impact mills, vibrating mills, and other various types of mills can be used as long as this point is taken into account. The degree of mixed pulverization only needs to be sufficient to obtain the desired significant improvement effect of mixed pulverization of the four components (1) to (4),
Therefore, the grinding method, grinding conditions, grinding time, etc. may be selected from this point of view. In vibration mills, rotary ball mills, etc., the grinding time required to obtain the desired catalyst composition is determined by a combination of various conditions such as ball filling rate, light content of the ground sample, ball diameter, rotational frequency or vibration frequency, and grinding temperature. Although the time varies, in general, a product with sufficiently improved catalytic performance can be obtained by grinding within 100 hours. Grinding can be carried out either wet or dry. In a typical mixed grinding method, the four components (1) to (4) are all ground in a mixed state from the beginning, depending on the rice type and amount, but each ingredient is sequentially added to the mixed grinding area. Alternatively, it is also possible to add it in portions over time.

(n) Component B Component B is represented by an organic alumina having a halogen group (here, R4 is a hydrocarbon residue having 1 to 10 carbon atoms, X is a halogen, and m is a number of 0<m≦2). Preferably, the compound is

Specific examples of this compound include alkyl aluminum halides such as diethylaluminum monochloride, diisobutyl aluminum monochloride, ethyl aluminum sesquichloride, and ethyl aluminum dichloride. Further, it is also possible to use trialkylaluminum or alkyl aluminum alkoxide in combination with the above alkyl aluminum halide. In that case, the combined ratio is preferably in the range of 0.01 to 0.5 (molar ratio) to the alkyl aluminum halide.

[I[[] Formation of catalyst (1) Usage ratio of component A and component B The usage ratio of component A and component B is not particularly limited. , more preferably in the range of 1 to 50.

(2) Contact between component (A) and component (B) The catalyst of the present invention is formed by bringing the aforementioned component A and component B into contact within or outside the polymerization zone and combining them.

In order to make the particle size of the solid composition of component A sufficiently small,
When component A and component B are brought into contact, it is preferred that a small amount of alpha-olefin or diene be present. The α-olefin or diene used in this case is suitably one having 4 to 20 carbon atoms, preferably 4 to 12 carbon atoms. Specific examples of such a-olefins or dienes include 1-butene, 1-hexene, 1-octene, 1,4-hexadiene, and 1,4-methylhexadiene. (mV) Polymerization of ethylene (1) Polymerization device Although the polymerization method of the present invention can be carried out as a batch operation,
More preferably, the polymerization is carried out in a continuous manner.

As the polymerization apparatus, those commonly used in high-pressure radical polymerization of ethylene can be used. Specifically, there is a continuous stirring type disposable reactor or a continuous large tube reactor.

The polymerization can be carried out as a single-zone process using these single reactors, but multiple reactors can be used in series, possibly with connected condensers, or the interior can be modified to create a multi-zone process. It is also possible to use a single reactor that is effectively divided into several zones.In a multizone process, the reaction conditions in each zone are varied so that the polymer obtained in each of those reactors or zones is It is common practice to adjust the monomer composition, catalyst temperature, molecular weight modifier concentration, etc. for each reactor or reaction zone to control the characteristics of the reactor.When multiple reactors are connected in series In addition to the combination of two or more seed reactors or two or more tubular reactors, a combination of one or more seed reactors and one or more tubular reactors may also be used. can.

The polymer produced in one or more reactors can be separated from unreacted monomers and treated as in conventional high-pressure processes without removing the catalyst residues. can. Removal of catalyst residues is a very expensive and time consuming step in conventional methods using Ziegler catalysts at low pressure. The unreacted monomer mixture is mixed with an additional amount of the same monomer, repressurized and recycled to the reactor. The additional amount of monomer added as described above is of a composition that returns the composition of the mixture to that of the original feed; this additional amount of monomer is generally separated from the polymerization vessel. It has a composition roughly equivalent to that of the polymer.

The catalyst is, for example, injected as a finely divided dispersion in a suitable inert liquid directly into the reactor using a high-pressure pump. Suitable inert liquids include, for example, white spirit, hydrocarbon oils, pentane, hexane, cyclohexane, heptane, toluene, higher branched chain saturated aliphatic hydrocarbons, and mixtures of these liquids. The dispersion is preferably kept under a nitrogen blanket to avoid contact with water and air before introducing it into the reactor.

Ethylene and other monomers must also be substantially free of water and oxygen.

As mentioned above, the resulting polymer can be processed without removing the catalyst. This is because the catalyst used in the present invention has a very high activity, and therefore a high conversion rate of monomer to polymer can be achieved using an extremely small proportion of catalyst.

(2) Monomers and comonomers The polymerization carried out using the catalyst system of the present invention is a homopolymerization of ethylene or ethylene with the general formula R-C)I-CH2
copolymerization with at least one other α-olefin represented by In the case of homopolymerization of ethylene, the resulting polymer is usually high-density polyethylene with a specific gravity in the range of 0.95 to 0.97.

Specific examples of the comonomer represented by the general formula R-CH-CH2 (where R is a hydrocarbon residue having 1 to 12 carbon atoms) include propylene, butene-1, pentene-1, and hexene. -1, heptene-1, octene-1, nonene-1
, 4-methylpentene-1, decene-1, etc. These α-olefins can be contained up to 30% by weight in the resulting copolymer.
Preferably up to 3 to 20% by weight can be copolymerized. Copolymerization of ethylene with these alpha-olefins provides polymers with a wide range of specific gravities. The specific gravity of the resulting polymer is controlled by the number of comonomers, the feed composition of the comonomers, and the like. Specifically, the density is 0.890 to 0. about 955, preferably 0.89
Polymers with desired densities within the range of ~0.94 can be obtained.

The method of the present invention is particularly suitable for producing the above-mentioned copolymers, and can provide medium to low density ethylene copolymers in high yield.

These copolymers not only have a density different from that of conventional low-pressure processed high-density polyethylene, but also have different properties from conventional high-pressure processed low-density polyethylene, namely, they have substantially no long chain branching, and Molecular weight distribution (Q value) is also 3-5
It is a polymer with excellent mechanical strength, especially tensile strength, and environmental destructive stress.

(3) Polymerization conditions (1) Polymerization pressure The polymerization pressure employed in the present invention is at least 20
0 kg/c-, preferably 300 to 4,000
kg/cj, more preferably 500-.3, 500
) cg/cj.

(11) Polymerization temperature The polymerization temperature is at least 125°C, but preferably 125°C.
50 to 350°C, more preferably 200 to 320°C,
is within the range of

Although it is not a woody matter in the present invention, under the combined conditions of polymerization pressure and polymerization temperature employed, the polymerization reaction mixture may form a single fluid phase or separate into two phases. good.

(III) Reactor feed gas composition The reactor feed gas composition employed in the present invention includes 5 to 100% by weight of ethylene, 0 to 95% by weight of at least one α-olefinic comonomer, and a molecular weight regulator. Usually, the hydrogen content is in the range of 0 to 20 mol%.

(Iv) Residence Time The average residence time in the reactor is related to the duration of activity of the catalyst under the reaction conditions employed. The half-life of the catalyst used is influenced by temperature among other reaction conditions, and as the lifetime of the catalyst increases, it is preferable to increase the residence time of the monomer in the reactor. The average residence time employed in the present invention is within the range of 2 to 600 seconds, preferably 10 seconds to 150 seconds, and more preferably 10 seconds to 120 seconds.

[Example of practical experience]

Example-1 Production of catalyst component 12.7 m in a stainless steel pot with an internal volume of 1 liter
■Appearance of φ stainless steel ball is 900m1 in volume
Filled with 340 g of metallic aluminum-reduced titanium trichloride (T iC13 (AA), which had been previously pulverized for 40 hours, 130 g of anhydrous magnesium chloride, 15 g of stearyl methacrylate, and 15 g of silicon tetrachloride were sealed in a nitrogen atmosphere and subjected to vibration. The mixture was ground in a mill for 80 hours. After the grinding was completed, the mixed and ground solid composition was taken out from the mill in a dry box. The Ti content in this solid composition was 4.9% by weight. (a).

Preparation of Catalyst Dispersion Add 480 ml of thoroughly degassed and purified n-hexane to a 1-liter flask that has been thoroughly purged with nitrogen, and then add 5 g of the solid component (a) described above and 7.4 g of diethylaluminium chloride. Therefore, the atomic ratio of A I / T i was set to 12. Next, sufficiently degassed and purified hexene-1 was added to adjust the hexene/Ti molar ratio to 30, and the mixture was stirred at 400 rpg+ for 2 hours to obtain a catalyst suspension. This was designated as catalyst (a)-1.

The average particle diameter of solid component (a) in catalyst (a)-1 was measured using a light transmission type viscosity distribution meter manufactured by Seishin Enterprise Co., Ltd., and was found to be 0.5 μm or less.

In addition, catalyst (a)-1 was filtered using a glass filter with an average pore diameter of 100 μm to determine the amount of coarse particles with a diameter of 100 μm or more, but no coarse particles were detected.

Further, the viscosity of catalyst (a)-1 was measured using a B-type viscometer manufactured by Tokyo Keiki Co., Ltd., and was found to be 10 cp.

High-pressure polymerization of ethylene In a stirred autoclave type continuous reactor having an internal volume of 1.5 liters, ethylene and hexene-1 were copolymerized under the reaction conditions shown in Table 1. As a result of polymerization, there is no coloration;
Good hue value -0.6, MFR -1.16, density -
0.9197 polymers were obtained. The activity of the catalyst is as follows: catalyst yield (g・PE7g・solid catalyst component)−35,00
It was 0. In addition, because the catalyst was sufficiently fine, a constant amount of catalyst was stably supplied to the reactor from the catalyst supply line, and there was no blockage of the catalyst supply line due to catalyst sedimentation, and the reaction temperature was No changes occurred.

Examples 2 to 5 Example 1 except that stearyl methacrylate was changed to the compound shown in Table 1 in the production of the catalyst component of Example 1.
A catalyst dispersion was prepared and ethylene was polymerized in exactly the same manner. The results were as shown in Tables 1 and 2.

Comparative Examples 1 and 2 Metallic aluminum-reduced titanium trichloride (T iCl B (A A )) used as a catalyst component in Example 1
A catalyst dispersion liquid was prepared using only this as a catalyst component.

In Comparative Example 1, the hexene-1/Ti molar ratio was set to 16, but coarse particles remained. Further, in the comparative example, the catalyst dispersion liquid was set at 30, but the viscosity of the catalyst dispersion liquid increased so much that it was impossible to inject the dispersion liquid into the reactor. The results are shown in Tables 1 and 2.

Comparative Examples 3 and 4 Catalyst dispersions were prepared in the same manner as in Example 1 except that stearyl methacrylate was changed to a compound shown in Table 1 that does not contain a long-chain alkyl group, and ethylene polymerization was carried out in the same manner as in Example 1. I did it. The results were as shown in Tables 1 and 2.

[Brief explanation of the drawing]

FIG. 1 is intended to assist in understanding the technical content of the present invention regarding Ziegler catalysts.

Claims (1)

[Claims] A pressure of at least 200 kg/cm^2 and at least 1
At a temperature of 25°C, ethylene or ethylene and at least one α-
A method for polymerizing ethylene, which is characterized by polymerizing it by bringing it into contact with an olefin. Component A A solid composition obtained by mixing and pulverizing the following compounds (1) to (4). (1) Magnesium halide, (2) Titanium trichloride, (3) Silicon halide, (4) The following compound group (a) having at least one long-chain hydrocarbon group with 10 or more carbon atoms (e) A compound selected from (i) alcohol, (b) carboxylic acid, (c) carboxylic acid metal salt, (d) amide, (e) ester, and component B: an organoaluminum compound having a halogen group.