JPH06211928A - Production of polyethylene - Google Patents

Abstract

PURPOSE:To obtain a polyethylene having an efficiently enhanced melt tension with a very low content of nonconjugated diene compound units. CONSTITUTION:A process for polymerization of ethylene or its mixture with a small amount of alpha-olefin by bringing the same into contact with a catalyst consisting of components (A) and (B) described below, which comprises the steps of producing a polymer having a melt index of 0.001-10g/10min at 190 deg.C under a load of 21.6kg in an amount of 0.1-99wt.% of the total polymer and producing a polymer having the melt index of 0.01-50,000g/10min. The component A is a transition metal compound obtained by bringing a solid catalyst component for a Ziegler catalyst containing titanium, magnesium and a halogen as the essential constituents into contact with a 30C or lower nonconjugated diene compound in the presence of an organoaluminum compound to effect prepolymerization. The component B is an organoaluminum compound.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing polyethylene having excellent moldability, that is, melt characteristics (melt tension). More specifically, it relates to a specific catalyst containing ethylene or ethylene and an α-olefin. The present invention relates to a method for producing polyethylene having a high melt tension by polymerizing at a stage.

[0002]

2. Description of the Related Art Conventionally, polyethylene produced by using a Ziegler catalyst containing titanium as a transition metal component has excellent solid physical properties such as rigidity and resistance to environmental cracking, but has low melt tension and poor moldability. There was a problem. However, in general, when polyethylene is formed into a film, a method such as an inflation method or a T-die method is adopted. Therefore, when the melt tension of polyethylene is low, especially in the inflation method, the extruded melt is solidified during the solidification process. It tends to be unstable, and it becomes difficult to obtain a stable tubular product. If a stable tubular product cannot be obtained during the inflation method and a uniform film cannot be produced, it is necessary to reduce the molding speed until a stable tubular product can be obtained. Polyethylene is extremely unproductive. In order to improve such problems of polyethylene produced by using a titanium-based Ziegler catalyst, JP-A-59-56412 has been disclosed.
The publication discloses a method of copolymerizing a non-conjugated diene when polymerizing ethylene or ethylene and an α-olefin.

[0003]

However, in order to obtain the effect of the non-conjugated diene in this production method, as far as the present inventors know, it is necessary to copolymerize a large amount of the non-conjugated diene in polyethylene. However, since the dienes are generally expensive, this production method is economically disadvantageous. Furthermore, according to this production method, it is necessary to introduce a non-conjugated diene compound into the polyethylene production plant, which requires separation and purification steps of the unreacted non-conjugated diene compound after polymerization, which complicates the process. Increasing costs is unavoidable, and when a large amount of non-conjugated diene compound is contained in polyethylene, cross-linking easily occurs when polyethylene is melted in the post-treatment step or molding process,
There were many problems such as promoting the generation of fish eyes. An object of the present invention is to solve the above problems and to provide a method for producing polyethylene in which the melt tension is extremely efficiently increased even when the content of the non-conjugated diene is extremely low.

[0004]

[Means for Solving the Problems]

[Summary of the Invention] <Summary> According to the present invention, a non-conjugated diene compound having 30 or less carbon atoms is polymerized using a solid catalyst component for Ziegler catalyst containing titanium, magnesium and halogen as essential components and an organoaluminum compound. When a polyethylene having a different melt index is produced in two steps by using a catalyst composed of a transition metal compound component and an organoaluminum compound component obtained by subjecting the prepolymerization treatment to In the discovery of the unexpected fact that the copolymerization is completely unnecessary, and the non-conjugated diene compound content is extremely low compared to the method of copolymerizing the non-conjugated diene compound during the production of polyethylene, it is possible to greatly improve the moldability. It is based.

Therefore, the method for producing polyethylene according to the present invention is a method for producing polyethylene by contacting ethylene or ethylene and a small amount of α-olefin with a catalyst comprising the following components (A) and (B) to polymerize the catalyst. The polymerization is carried out by carrying out the following two-step processes (1) and (2). Component (A): A solid catalyst component for Ziegler catalyst containing titanium, magnesium and halogen as essential components is contacted with a non-conjugated diene compound having 30 or less carbon atoms to polymerize the non-conjugated diene compound. A transition metal compound obtained by subjecting to a preliminary polymerization treatment. Component (B) Organoaluminum compound. Step (1): An amount of the polymer (a) having a melt index of 0.001 to 10 g / 10 min measured at 190 ° C. under a load of 21.6 kg, which corresponds to 0.1 to 99% by weight of the total polymer. The process of generating. Step (2): a step of producing a polymer (b) having a melt index of 0.01 to 50,000 g / 10 minutes measured at 190 ° C. under a load of 2.16 kg. However, when the melt indexes of the polymers (a) and (b) are measured under the same conditions, the melt index of the polymer (b) is larger than that value of the polymer (a).

<Effect> When the polymerization of ethylene or ethylene and an α-olefin is carried out in two steps under specific conditions using the transition metal compound component preliminarily polymerized according to the present invention, an extremely low non-conjugated diene compound is obtained. It is possible to efficiently produce polyethylene having a unit content of which melt tension is increased.

[Detailed Description of the Invention] (1) Polymerization Catalyst The catalyst used in the present invention comprises a specific component (A) and a specific component (B). Here, “consisting of” does not mean that it is only the listed components, ie, components (A) and (B),
It does not preclude the coexistence of other purposeful ingredients.

<Component (A)> The component (A) is a non-conjugated diene compound having 30 or less carbon atoms in the presence of an organoaluminum compound, which is a solid catalyst component for Ziegler catalyst containing titanium, magnesium and halogen as essential components. It is a transition metal compound component obtained by subjecting it to a preliminary polymerization treatment in which it is polymerized. Any known solid component capable of polymerizing ethylene can be used as the solid component for the Ziegler catalyst, which contains titanium, magnesium and halogen as essential components to be subjected to the prepolymerization treatment. For example, those described below can be used.

Solid component to be subjected to prepolymerization treatment As a magnesium compound used as a magnesium source for producing the solid component , magnesium halide, dialkoxymagnesium, alkoxymagnesium halide, magnesium oxyhalide, dialkylmagnesium, oxidized Examples thereof include magnesium, magnesium hydroxide, magnesium compounds such as magnesium carboxylates, and the like. The titanium compound serving as the titanium source is represented by the general formula Ti (OR ¹ ) _4-m X _m or Ti.
(OR ² ) _3-n X _n (wherein R ¹ and R ² are hydrocarbon residues, preferably those having about 1 to 10 carbon atoms, X is halogen, and m and n are each 0 ≦ m. ≦ 4, 0 ≦ n
<Number of 3 is shown. ) Titanium compounds and T
iCl ₃ may be mentioned.

Specific examples of the titanium compound represented by Ti (OR ¹ ) _4-m X _m include TiCl ₄ , TiBr ₄ ,
_{Ti (OC 2 H 5) Cl} 3, Ti (OC 2 H 5) 2 Cl
₂ , Ti (OC ₂ H ₅ ) ₃ Cl, Ti (O-iC)
₃ H ₇ ) Cl ₃ , Ti (O-nC ₄ H ₉ ) Cl ₃ , Ti
_{(O-nC 4 H 9)} 2 Cl 2, Ti (OC 2 H 5) Br
₃ , Ti (OC ₂ H ₅ ) (OC ₄ H ₉ ) ₂ Cl, Ti
_{(O-nC 4 H 9)} 3 Cl, Ti (O-C 6 H 5) Cl
_{3, Ti (O-iC 4} H 9) 2 Cl 2, Ti (OC 5 H
₁₁ ) Cl ₃ , Ti (OC ₆ H ₁₃ ) Cl ₃ , Ti (OC _{2
H 5) 4, Ti (O} -nC 3 H 7) 4, Ti (O-nC
_{4 H 9) 4, Ti (} O-iC 4 H 9) 4, Ti (O-n
_{C 6 H 13) 4, Ti} (O-nC 8 H 17) 4 and Ti
[OCH ₂ CH (C ₂ H ₅ ) C ₄ H ₉ ] _{4 and the} like.

A specific example of the titanium compound represented by Ti (OR ² ) _3-n X _n is Ti (OC ₂ H ₅ ) C.
_{l 2, Ti (OC 2 H} 5) 2 Cl, Ti (O-iC 3 H
_{7) Cl 2, Ti (O} -iC 3 H 7) 2 Cl, Ti (O
_{-NC 4 H 9) Cl 2,} Ti (O-nC 4 H 9) 2 C
1, Ti (OC ₂ H ₅ ) Br ₂ , Ti (OC ₂ H ₅ ).
_{(OC 4 H 9) Cl,} Ti (OC 6 H 5) Cl 2, T
_{i (OC 6 H 11) Cl} 2, Ti (OC 2 H 5) 3, Ti
_{(O-nC 3 H 7)} 3, Ti (O-nC 4 H 9) 3 and _{Ti (O-nC 6 H 11} ) is ₃ and the like.

The TiCl ₃ is obtained by reducing TiCl ₄ with hydrogen [TiCl ₃ (H)], with titanium metal [TiCl ₃ (T)], or with aluminum metal [TiCl ₃ (A)]. ], And those reduced with an organoaluminum compound (eg, TiCl ₃ by reduction with diethylaluminum chloride), and many others. In the present invention, TiCl _{3 to be} used
The catalytic performance may not be the same because the catalytic activity may differ depending on the type of the, but all that can be used as the TiCl ₃ component of the so-called Ziegler catalyst (including Ziegler-Natta catalyst) are used. be able to. Therefore, this TiCl ₃ is pure TiC
l need not be _3, for example, be those TiCl 3 1/3 moles of AlCl ₃ as _(A) are added, or may be obtained by introducing a post, such a co-ingredient, also unavoidably In addition or intentionally, a small amount of unreduced TiCl ₄ or over-reduced TiCl _2, or an oxidation product of a reducing agent may be contained.

The titanium compound serving as the titanium source is TiX '.
_It may be a molecular compound obtained by reacting ₄ (where X ′ represents halogen) with an electron donor. Specific examples of such a molecular compound include TiCl ₄ .CH ₃ COC.
₂ H ₅ , TiCl ₄ · CH ₃ CO ₂ C ₂ H ₅ , TiCl
₄・ C ₆ H ₅ NO ₂ , TiCl ₄・ CH ₃ COCl, T
iCl ₄ · C ₆ H ₅ COCl, TiCl ₄ · C ₆ H ₅ C
O ₂ C ₂ H ₅ , TiCl ₄ .ClCOC ₂ H ₅ and T
iCl ₄ · _{C 4 H 4} O, and the like. As the halogen source, the halogen contained in the compounds such as the above-mentioned halogen source and titanium source is usually used, but other known halogenating agents can also be used.

Known electron donors can be used when producing the solid component. Examples of the electron donor include oxygen-containing electron donors such as alcohols, phenols, ketones, aldehydes, carboxylic acids, esters of organic or inorganic acids, ethers, acid amides, and acid anhydrides. , Nitrogen-containing electron donors such as ammonia, amines, nitriles, and isocyanates. Specific examples of such electron donors are described in, for example, JP-A-63-48307.

This solid component is produced by using the above-mentioned titanium source, magnesium source and halogen source and, if necessary, other components such as an electron donor by the following production method. (A) A method of bringing a magnesium halide, an electron donor and a titanium-containing compound into contact with each other. (B) A method of bringing magnesium halide, an electron donor, and a titanium halogen-containing compound into contact with silica, alumina or silica-alumina. (C) A method of bringing a titanium halogen compound and / or a halogen compound of silicon into contact with a solid component obtained by contacting a magnesium halide with a titanium tetraalkoxide and a specific polymer silicon compound. (D) A method in which a magnesium compound is dissolved with titanium tetraalkoxide and an electron donor, and a titanium compound is brought into contact with a solid component precipitated by a halogenating agent or a titanium halogen compound. (E) A method in which an organomagnesium compound such as a Grignard reagent is allowed to act with a halogenating agent, a reducing agent, etc., and then an electron donor and a titanium compound are brought into contact with it. (F) A method of bringing a halogenating agent and / or a titanium compound into contact with an alkoxymagnesium compound in the presence or absence of an electron donor.

The solid component used in the present invention includes, in addition to the above essential components, silicon compounds such as SiCl ₄ , CH ₃ SiCl ₃ and alkyl hydrogen polysiloxane, and Al (O).
iC ₃ H ₇ ) ₃ , Al (OC ₂ H ₅ ) ₃ , Al (OCH
₃ ) ₂ Cl, AlCl ₃ , aluminum compounds such as AlBr ₃ , and B (OCH ₃ ) ₃ and B (OC
Other components such as boron compounds such as ₂ H ₅ ) ₃ and B (OC ₆ H ₅ ) ₃ can also be used, and these may remain in the solid component as components such as silicon, aluminum and boron.

The amount of each compound used may be arbitrary as long as the effects of the present invention can be recognized, but generally, the following range is preferable. The amount of titanium compound used is
With respect to the amount of the magnesium compound used, the molar ratio may be in the range of 1 × 10 ^{−4 to} 1000, preferably in the range of 0.01 to 10. The amount of the halogen source compound used may be in the range of 1 to 1000 in terms of molar ratio with respect to magnesium of the magnesium compound used,
It is preferably within the range of 4 to 100. When the electron donating compound is used, the amount thereof may be in the range of 1 × 10 ⁻³ to 10 and preferably in the range of 0.01 to 5 with respect to the amount of the magnesium compound used. is there.

The contact conditions of the respective components constituting these solid components may be arbitrary as long as the effects of the present invention are recognized, but the following conditions are generally preferred. The contact temperature is about -50 to 200 ° C, preferably 0 to 100 ° C,
Is. Examples of the contacting method include a mechanical method using a rotary ball mill, a vibration mill, a jet mill, a medium stirring pulverizer, and the like, and a method of contacting by stirring in the presence of an inert diluent. Examples of the inert diluent used at this time include aliphatic or aromatic hydrocarbons and halohydrocarbons, and polysiloxanes. The titanium content in the solid component produced as described above is usually 0.01 to
It is 30% by weight, preferably 0.1 to 20% by weight.

Preliminary Polymerization Preliminary polymerization treatment using a non-conjugated diene compound is carried out by using the above-mentioned solid catalyst component for Ziegler catalyst containing titanium, magnesium and halogen as essential components in the presence of an organic aluminum compound such as hexane and heptane. Inert hydrocarbons such as aliphatic hydrocarbons, aromatic hydrocarbons such as benzene, toluene and xylene, and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane, in a slurry state or in the substantial absence of solvent It is carried out in the presence or absence of hydrogen in the phase state. The non-conjugated diene compound used in this prepolymerization treatment has a carbon number of 30 or less, and it is common to use a compound represented by the following general formula (I).

[0020]

[Chemical 1]

(In the formula, R ^{3 to} R ⁶ are the same or different,
Hydrogen or a hydrocarbon residue having 1 to 10 carbon atoms, preferably hydrogen or a hydrocarbon residue having 1 to 7 carbon atoms, p
And q are 0 or a positive integer and 1 ≦ p +
It is a number that satisfies q ≦ 26. ) Specific examples of such a non-conjugated diene compound include 1,4-pentadiene, 1,5-hexadiene, 1,6-heptadiene,
1,7-octadiene, 1,8-nonadiene, 1,9-
Decadiene, 1,10-undecadiene, 1,11-dodecadiene, 1,12-tridecadiene, 1,13-tetradecadiene, 1,14-pentadecadiene, 1,1
5-hexadecadiene, 1,19-eicosadiene, 2
-Methyl-1,4-pentadiene, 3-methyl-1,4
-Pentadiene, 2-methyl-1,5-hexadiene,
3-methyl-1,5-hexadiene, 3,4-dimethyl-1,5-hexadiene, 3,5-diethyl-1,6-
Heptadiene, 3-methyl-1,7-octadiene, 3-methyl-1,9-decadiene and the like can be mentioned.

Of these, preferred compounds are those in which p and q are numbers satisfying 4 ≦ p + q ≦ 16 in the general formula (I), and particularly preferred compounds are R ³ and R ⁴ in the general formula (I). Are both hydrogen, and p
And q are numbers satisfying 4 ≦ p + q ≦ 12. Specific examples of particularly preferred compounds include 1,7-octadiene, 1,8-nonadiene, 1,9-decadiene, 1,10-undecadiene, 1,11-dodecadiene, 1,12-tridecadiene, 1,13-tetradiene. Decadiene, 1,14-pentadecadiene, 1,15-hexadecadiene, 3-methyl-1,7-octadiene, 3
-Methyl-1,9-decadiene and the like can be mentioned. However,
Among the above-mentioned non-conjugated diene compounds, 1,5-hexadiene and 1,6-heptadiene are likely to undergo cyclopolymerization during the polymerization, so that it is necessary to use them in a larger amount than other non-conjugated diene compounds. , 5-hexadiene,
The cost of using 1,6-heptadiene is higher than the cost of using other non-conjugated diene compounds.

The prepolymerization treatment is carried out by "contacting" the non-conjugated diene compound with the solid catalyst component for the Ziegler catalyst. Here, "contacting" means performing the prepolymerization treatment with the non-conjugated diene alone. However, it means that the prepolymerization treatment may be carried out with a mixture of the non-conjugated diene compound and the α-olefin having 2 to 20 carbon atoms. Rather, it is preferable to carry out the prepolymerization treatment with a mixture of the non-conjugated diene compound and an α-olefin having 2 to 20 carbon atoms. Preferred α-olefins in this case include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 3-methyl-1-
Butene and 4-methyl-1-pentene and the like,
Ethylene is particularly preferable. Two or more kinds of these α-olefins can be mixed and used.

When the prepolymerization treatment is carried out in the presence of both the non-conjugated diene compound and the α-olefin, the number of moles of the non-conjugated diene compound charged to 1 mol of the α-olefin is usually 0. 001-100 mol,
It is preferably 0.01 to 50 mol. The content of non-conjugated diene compound units in this prepolymerized polymer is
Usually 0.01 to 20 mol%, preferably 0.1 to 10
Mol%. If the content of the non-conjugated diene compound is less than 0.01 mol, no remarkable effect is exerted on the melting characteristics of the produced polyethylene, whereas if it exceeds 20 mol%, the transition metal catalyst component cannot maintain the particle shape and the viscosity of the transition metal catalyst component cannot be maintained. The catalyst becomes extremely difficult to handle because it becomes a dense state.

The content of the non-conjugated diene compound in the examples described below is determined by quantifying the ethylenically unsaturated bond contained in the non-conjugated diene compound by ¹ H-NMR spectrum, and corresponding infrared absorption spectrum of 908 cm ^-1. A calibration curve is prepared using the absorbance at the absorption peak of ¹ , the absorption at 908 cm ^-1 in the infrared absorption spectrum of each sample is measured, and the calibration curve is used. As the organoaluminum compound used in the prepolymerization treatment, an organoaluminum compound known as a promoter for a Ziegler catalyst is used. Specific examples thereof include triethyl aluminum, triisobutyl aluminum, trihexyl aluminum, trioctyl aluminum, tridecyl aluminum, diethyl aluminum chloride, diisobutyl aluminum chloride, diethyl aluminum hydride, diisobutyl aluminum hydride and diethyl aluminum ethoxide. Two or more kinds of these organoaluminum compounds may be mixed and used.

The amount of the organoaluminum compound used in the prepolymerization treatment is such that the gram atomic ratio of aluminum to titanium metal (A
The 1 / Ti ratio) is usually 0.001 to 1000, preferably 0.01 to 500. The proportion of the solid component used during the prepolymerization treatment is usually 10 ⁻⁵ to 10 gram atom / liter, preferably 10 ⁻⁴ to 1 gram, as the concentration of titanium metal atom in the solid component in the polymerization reaction system. The range is atoms / liter. The prepolymerization temperature is usually 0.
The temperature is in the range of to 120 ° C, preferably 10 to 110 ° C. The α-olefin pressure during the prepolymerization treatment is usually atmospheric pressure to 50 kg / cm ² G, preferably 0.1 to ²⁰ kg / cm ²
The range is G. Also, hydrogen can be used as a molecular weight modifier during the prepolymerization. The amount of prepolymerization per 1 g of the solid component is usually 0.05 to 400 g, preferably 0.1 to 200 g, particularly preferably 0.5 to 100 g.
g.

The transition metal compound component preliminarily polymerized is used as a catalyst for producing polyethylene after prepolymerization treatment to remove unreacted non-conjugated diene compound, etc., and then filtration and / or washing with an inert solvent. Preferably. Examples of the inert solvent include aliphatic hydrocarbons such as hexane and heptane, aromatic hydrocarbons such as benzene, toluene and xylene, and alicyclic hydrocarbons such as cyclohexane and methylcyclohexane.

<Component (B)> The component (B) is an organoaluminum compound. As such an organoaluminum compound, an organoaluminum compound known as a promoter for a Ziegler catalyst is used. Specifically, (a)
Trialkylaluminums such as trimethylaluminum, triethylaluminum, triisobutylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum, etc., (b) Alkylaluminum halides such as diethylaluminum monochloride, diisobutylaluminum monochloride, ethylaluminum sesquichloride. , Ethyl aluminum dichloride, etc., (C) dialkyl aluminum hydride, such as diethyl aluminum hydride, diisobutyl aluminum hydride, etc.
(D) Alkyl aluminum alkoxides such as diethyl aluminum ethoxide, diethyl aluminum butoxide, and diethyl aluminum phenoxide. Two or more kinds of these organoaluminum compounds may be mixed and used.

<Production of Polyethylene> In the method for producing polyethylene according to the present invention, ethylene or a small amount of ethylene and a small amount of ethylene are added to a catalyst comprising the above-mentioned transition metal compound component (component (A)) and organoaluminum compound component (component (B)). The method for producing polyethylene by contacting and polymerizing the α-olefin as described above, which comprises performing the following two steps (1) and (2). Step (1): An amount of the polymer (a) having a melt index of 0.001 to 10 g / 10 min measured at 190 ° C. under a load of 21.6 kg, which corresponds to 0.1 to 99% by weight of the total polymer. The process of generating. Step (2): a step of producing a polymer (b) having a melt index of 0.01 to 50,000 g / 10 minutes measured at 190 ° C. under a load of 2.16 kg. However, when the melt indexes of the polymers (a) and (b) are measured under the same conditions, the melt index of the polymer (b) is larger than that value of the polymer (a). In both processes, slurry is slurried in an inert hydrocarbon solvent such as an aliphatic hydrocarbon such as hexane and heptane, an aromatic hydrocarbon such as benzene, toluene and xylene, and an alicyclic hydrocarbon such as cyclohexane and methylcyclohexane. In the state (slurry polymerization), the polymer is dissolved in the inert hydrocarbon solvent (solution polymerization), or in the gas phase (gas phase polymerization) in the substantial absence of solvent. The proportion of the transition metal compound component used in the polymerization of ethylene is usually 10 ⁻⁷ as the concentration of titanium metal atoms contained in the transition metal compound component in the polymerization reaction system.
-10 ^-1 gram atom / liter, preferably 10 ^{-6 -1}
The range is 0 ^-2 grams atom / liter.

The amount of the organoaluminum compound used in the ethylene polymerization is the gram atom ratio of aluminum to titanium metal (Al / T) in the transition metal compound component.
i ratio) is from 0.1 to 2000, preferably from 1 to 1000,
Is the range. 1 g of solid component excluding prepolymerized polymer
The ethylene polymerization yield per unit is usually 100 to 100,0.
It is in the range of 00 g, preferably 500 to 50,000 g, and is usually in the range of 10 to 50,000 g, preferably 50 to 20,000 g, per 1 g of the transition metal compound component containing the prepolymerized polymer.

The content of the non-conjugated diene compound unit in 1 g of the polyethylene is 1 × 10 ^-8 mol or more, usually 1 × 10 ^-8.
To 1 × 10 ⁻⁴ mol, preferably 1 × 10 ⁻⁷ to 1 × 10 ⁻⁵
The range is mol. If the amount is less than 1 × 10 ^-8 mol, no significant effect is exerted on the melting characteristics of the polyethylene, and 1 × 10 ^-4
If it exceeds the molar amount, it is economically disadvantageous. However, the content of the non-conjugated diene compound unit is estimated by calculation from the amount of the non-conjugated diene compound unit contained in the transition metal compound component. When the α-olefin is copolymerized, the α-olefin has 3 to 20 carbon atoms, preferably 3 to 12 carbon atoms, for example, propylene, 1-butene, 1-
Examples include pentene, 1-hexene, 1-heptene, 1-octene, 1-decene and 4-methyl-1-pentene. The content of α-olefin contained in polyethylene is preferably 0 to 10 mol%. The polymerization of ethylene is
Usually room temperature to 250 ° C, preferably 50 ° C to 120
At a temperature of ℃. The polymerization pressure is ethylene pressure and usually normal pressure to
100kg / cm ² G, preferably 1~50kg / cm ² G, the range of.

In the process of the present invention, the polymerization is carried out in two steps, and the second step polymerization (step (2)) is carried out in the presence of at least a part of the product of the first step polymerization (step (1)). Done. The two-step polymerization reaction can be performed by either a continuous polymerization method or a batch polymerization method. In the case of continuous polymerization, two reactors may be connected in series and the reaction product obtained by polymerization in the first reactor may be introduced into the second reactor to continue the polymerization. In the case of batch polymerization, one reactor can be used for successive reactions. Further, hydrogen can be used as a molecular weight modifier in either or both of step (1) and step (2).

In the production method of the present invention, the melt index at 190 ° C. under a load of 21.6 kg is 0.001 to 10 g / 1 in the first stage polymerization (step (1)).
The polymer (a) is produced for 0 minutes, and the melt index at 190 ° C. under a load of 2.16 kg is 0.01 to 50000 g / 10 in the second stage polymerization (step (2)).
Minute amount of the polymer (b) is produced, and the content of the polymer (a) in all the polymers is 0.1 to 99% by weight, and the melt indexes of the polymers (a) and (b) are the same. It is necessary to make the melt index of the component (b) larger than that of the component (a) when measured by.

The melt index of the polymer (a) at 190 ° C. under a load of 21.6 kg is usually 0.001 to 0.001.
10 g / 10 minutes, preferably 0.005-5 g /
It is 10 minutes, particularly preferably 0.01 to 1 g / 10 minutes. On the other hand, 190 ° C. of the polymer (b), 2.16 kg
The melt index under load is usually 0.01 to
50,000 g / 10 minutes, preferably 0.01-3
0000 g / 10 minutes, particularly preferably 0.01 to
It is 10,000 g / 10 minutes.

The melt index at 190 ° C. under a load of 2.16 kg is measured based on ASTM D-1238, and the melt index under a load of 190 ° C. and 21.6 kg is 2.16 k in the above method.
It is measured by changing g load to 21.6 kg load. The ratio of the melt indexes of both polymers (polymer (b) / polymer (a)) under the same measurement conditions is usually in the range of 10 ³ to 10 ⁹ , preferably 1
The range is from 0 ⁴ to 10 ⁸ . In addition, 190% of the total polymer
The melt index at 2.degree.
Usually 0.001 to 300 g / 10 minutes, preferably 0.0
05-200 g / 10 minutes, particularly preferably 0.01-1
00 g / 10 minutes. The content of the polymer (a) in the total polymer is usually 0.1 to 99% by weight, preferably 0.5 to 85% by weight, particularly preferably 1 to 70% by weight.

[0036]

EXAMPLES The following examples are for explaining the present invention in more detail, and the present invention is not limited to the following examples as long as the gist thereof is not exceeded. Melt tension as a measure of formability is 190 ° C, orifice is 2.1
mmφ × 8 mm, take-up speed 4 m / min, extrusion speed 10 mm / min. Melt index (abbreviated as MI) is AS
Based on TM D-1238, it measured at 190 degreeC and a 2.16 kg load. The density was measured by the density gradient tube method of JIS K-6760.

<Preparation of Catalyst A> 50 fully substituted with N ₂
Flask 0 cc, ml of dehydrated and deoxygenated n- heptane 200 cc, then MgCl ₂ 19 g (0.2 mol) and _{Ti (O-nC 4 H 9} ) 4 136cc (0.
4 mol) was added, and these were reacted at 95 ° C. for 1 hour.
Then, the temperature was lowered to 40 ° C., 30 cc of methylhydropolysiloxane was added, and the mixture was reacted for 3 hours and then thoroughly washed with n-heptane. The Ti content of this product was 14.2% by weight. Next, add 5.2 cc of SiCl ₄ and add 1 at 25 ° C.
React for a time, then add 19 cc of TiCl ₄ at 50 ° C.
After reacting for 2 hours at room temperature, it was thoroughly washed with n-heptane. The Ti content was 11.0% by weight.

<Preparation of Catalyst B> A 1 liter flask, which had been sufficiently N ₂ -substituted, was subjected to sufficient dehydration and deoxygenation of n-
Add 75 cc of heptane and put into MgCl ₂ (ball mill crush 2
4 hours) 10 g (0.1 mol) and Ti
(O-nC ₄ H ₉ ) ₄ 10 cc (0.03 mol) was added,
These were reacted at 70 ° C. for 3 hours. Then, a mixture of 5.4 cc of n-butanol / 5.4 cc of n-heptane was added to 210
It was introduced from a spray nozzle for 10 seconds so as to form droplets of μm, and reacted at 70 ° C. for 1 hour. Then TiCl ₄
After adding 0.02 mol and reacting at 70 ° C. for 2 hours, n
-Wash thoroughly with heptane. The Ti content was 10.5% by weight.

<Preparation of Catalyst C> A stainless steel pot having an internal volume of 1 liter was filled with 900 cc of a 12.7 mmφ stainless steel ball in an apparent volume, and TiCl ₃ (A
Type) 17.5 g, MgCl ₂ 165 g and methyl methacrylate 9.2 g were sealed in under an N ₂ atmosphere and pulverized with a vibration mill for 48 hours. The vibration mill had an amplitude of 5 mm and the motor speed was 1700 rpm. After crushing, take out the mixed crushed solid composition from the mill in a dry box,
About 180 g was recovered. The Ti content of this product was 3.5% by weight.

<Examples 1 to 7> Prepolymerization treatment In a 1.5 liter autoclave, n-heptane 800 was added.
cc, and 1.9 g of triisobutylaluminum at 80 ° C., 9.6 g of the above catalysts A to C, non-conjugated diene compounds shown in Table 1 or Table 3, hydrogen 40 vol% and total pressure 2 kg / cm ² G. The prepolymerization treatment was carried out while supplying the consumed ethylene and maintaining the total pressure. After completion of the prepolymerization treatment, the catalyst was transferred to a 2-liter flask and thoroughly washed with n-heptane. Tables 1 to 4 show the results of the prepolymerization treatment.

3 liters of n-heptane was placed in an autoclave having a total weight of 5 liters, and 1.0 g of triethylaluminum was added at 85 ° C.
60 mg of the transition metal compound component subjected to the above prepolymerization in terms of solid component only excluding the prepolymerized polymer, and 11.7 g of butene-1 were added, and a mixed gas of hydrogen / ethylene (molar ratio 0.06) was added. It was charged until the total pressure became 3 kg / cm ² G, and then the polymerization operation was carried out while continuously supplying ethylene so as to maintain the total pressure of 3 kg / cm ² G (first-stage polymerization). Next, after adding 1.0 g of triethylaluminum and raising the temperature to 100 ° C., hydrogen and ethylene are supplied so that the hydrogen / ethylene ratio becomes 5.0 in molar ratio, and the total pressure is 18 kg / cm ² G And then, total pressure 18kg /
Polymerization was carried out while continuously supplying ethylene so as to maintain cm ² G (second-stage polymerization). The polymerization time was set so that the polymerization yields of the first and second stages were the same. The polymerization yield was determined by the cumulative amount of ethylene fed. The polymerization yields obtained by summing the first-stage polymerization, the second-stage polymerization, the first-stage polymerization and the second-stage polymerization, and the results of measuring the physical properties of the obtained polymer are as shown in Tables 1 to 4.

Comparative Example 1 Polyethylene was produced in the same manner as in Example 1 except that the prepolymerization treatment was not carried out.

Comparative Example 2 Example 1 was repeated except that the non-conjugated diene compound was not used during the prepolymerization treatment and the prepolymerization time was 2.5 hours.
Polyethylene was produced in the same manner as in.

Comparative Example 3 Example 3 was repeated except that the non-conjugated diene compound was not used during the prepolymerization treatment and the prepolymerization time was 3.5 hours.
Polyethylene was produced in the same manner as in.

<Comparative Example 4> In Example 1, the non-conjugated diene compound was not used in the prepolymerization treatment, the prepolymerization time was 2.5 hours, and the 1st stage polymerization of ethylene Polyethylene was produced in the same manner as in Example 1 except that 9-decadiene was copolymerized so that the content of 1,9-decadiene in the polymer after the second stage polymerization was the same as in Example 1. It was

Comparative Example 5 Polyethylene was produced in the same manner as in Example 1 except that the ethylene polymerization was carried out under the following conditions. Polymerization 3 liters of n-heptane was put into an autoclave of 5 liters, and triethylaluminum was added to 1.0 at 100 ° C.
g, 60 mg of the transition metal compound component preliminarily polymerized in Example 1 in terms of solid component excluding the prepolymerized polymer was added, and hydrogen and ethylene were added so that the hydrogen / ethylene ratio became 5.0. To supply a total pressure of 18 kg
/ Cm ² G, and then the polymerization operation was carried out while continuously supplying ethylene so as to maintain the total pressure of 18 kg / cm ² G. Then, the polymerization temperature to 85 ° C., the supply of ethylene was purged residual pressure in the polymerization system after stopping, within three polymerization system was N ₂ purged with further N ₂ gas (5kg / cm ² G) .
Thereafter, 1.0 g of triethylaluminum and 11.7 g of butene-1 were added, and hydrogen and ethylene were supplied so that the hydrogen / ethylene ratio became 0.06 in a molar ratio, and the total pressure was adjusted to 3 kg / cm ² G. Polymerization was carried out while continuously supplying ethylene so as to maintain 3 kg / cm ² G. According to this comparative example, when a high melt index polyethylene is produced in the first stage polymerization and a low melt index polyethylene is produced in the second stage polymerization, that is, when the conditions of the present invention are not satisfied, the effect of improving the melt tension is improved. I know there isn't.

<Example 8> Polymerization 3 liters of n-heptane was placed in an autoclave of 5 liters, and 1.0 g of triethylaluminum was added at 85 ° C.
The transition metal compound component preliminarily polymerized in Example 1 is calculated as 60 in terms of solid component excluding prepolymerized polymer.
mg and 130 g of hexene-1 and 5 kg of ethylene
/ Cm ² G until the total pressure became 5 kg / cm ² G, and then the polymerization operation was carried out while continuously feeding ethylene (first stage polymerization). Then add hydrogen to a total pressure of 5.2.
Insert until 5 kg / cm ² G, then total pressure 5.25k
Polymerization was carried out while continuously feeding ethylene so as to maintain g / cm ² G (second-stage polymerization). The results are shown in Table 5.
And as shown in Table 6.

<Comparative Example 6> In Example 8, after adding 130 g of hexene-1, 0.25 kg / cm 2 of hydrogen was added.
Add ² G and ethylene to 5.25 kg / cm ² G,
Then, a polymerization operation was carried out while continuously supplying ethylene so that the total pressure was maintained at 5 kg / cm ² G. Result is,
As shown in Table 5 and Table 6.

Comparative Example 7 Polyethylene was produced in the same manner as in Example 8 except that the prepolymerization treatment was not performed.

[0050]

[Table 1]

[0051]

[Table 2]

[0052]

[Table 3]

[0053]

[Table 4]

[0054]

[Table 5]

[0055]

[Table 6]

[0056]

The transition metal compound component preliminarily polymerized according to the present invention is used for ethylene or ethylene and α
-By carrying out the polymerization of olefins in two steps, it is possible to efficiently produce polyethylene having an extremely low melt content of non-conjugated diene compound units, as described above in the [Summary of the Invention] section.

[Brief description of drawings]

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

Claims (1)

[Claims] 1. A method for producing polyethylene by contacting ethylene or a small amount of α-olefin with a catalyst composed of the following components (A) and (B) to polymerize the mixture, wherein Steps (1) and (2)
A method for producing polyethylene, characterized in that it is carried out by carrying out. Component (A): A solid catalyst component for Ziegler catalyst containing titanium, magnesium and halogen as essential components is contacted with a non-conjugated diene compound having 30 or less carbon atoms to polymerize the non-conjugated diene compound. A transition metal compound obtained by subjecting to a preliminary polymerization treatment. Component (B): Organoaluminum compound. Step (1): An amount of the polymer (a) having a melt index of 0.001 to 10 g / 10 min measured at 190 ° C. under a load of 21.6 kg, which corresponds to 0.1 to 99% by weight of the total polymer. The process of generating. Step (2): a step of producing a polymer (b) having a melt index of 0.01 to 50,000 g / 10 minutes measured at 190 ° C. under a load of 2.16 kg. However, when the melt indexes of the polymers (a) and (b) are measured under the same conditions, the melt index of the polymer (b) is larger than that value of the polymer (a).