JPH06100735A - Polyolefin composition for rotary molding - Google Patents

Abstract

PURPOSE:To obtain the subject composition providing a rotary molded article having excellent packing especially at a corner part of a mold and internal smoothness, comprising a straight-chain polyethylene and a specific amount of a 3-methyl-1-butene-containing ethylene copolymer. CONSTITUTION:The objective composition comprises (A) a straight-chain polyethylene, a copolymer of ethylene and a 3-12C alpha-olefin and (B) a 3-methyl-1-butene- containing ethylene copolymer (content of 3-methyl-1-butene is 0.0001-1wt.%) obtained by catalytically polymerizing ethylene, 3-methyl-1-butene and optionally a 3-12C alpha-olefin in the presence of a catalyst composed of (i) a solid titanium catalytic component comprising a halogen-containing magnesium, a halogen- containing titanium and an electron donative compound as essential components, (ii) an organic aluminum and (iii) an organosilicon compound of the formula (R<1> is branched-chain hydrocarbon; R<2> and R<3> are hydrocarbon; (n) is in 2<=n<=3).

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 rotational molding polyethylene composition, and more particularly, to a rotational molding polyethylene composition which provides a rotational molding product having excellent smoothness at the corners of a mold and smooth inner surface.

[0002]

2. Description of the Related Art Linear polyethylene, which is a copolymer of ethylene and α-olefin, includes, for example, medium density polyethylene and linear low density polyethylene, but these resins are relatively inexpensive and resistant. Since it has excellent chemical properties and moldability, it is widely used as a material for rotational molding.

In the rotational molding method, a thermoplastic resin powder is put into a mold, heated from the outside while rotating the mold, the resin is melted and adhered to the inside of the mold to be molded, and the product is cooled. This is a molding method to obtain a hollow body by taking out, but with the flexibility of design, it is possible to manufacture a large-capacity molded product of 1 m ³ or more such as a large chemical tank, and the cost of the equipment and mold is relatively low. It has the advantage that it is suitable for small lot production of many kinds.

[0004]

On the other hand, on the other hand, the rotational molding method is a molding method which requires almost no molding pressure in the mold as compared with injection molding, hollow molding, etc., and therefore, the corners of the meat and irregularities on the inner surface are not formed. However, due to this improvement, there is a restriction on the mold design and a long heating and air cooling time is required, resulting in a long molding cycle and poor productivity. There is such a drawback.

Attempts to improve such defects include, for example, making the material easy to flow, homogenizing the particle size of the raw material powder, and controlling the particle size (preventing generation of whiskers during grinding). At present, there is no satisfactory improvement measure because the strength and physical properties of the molded product are deteriorated and the crushing cost is increased.

[0006] As a method of this improvement, the compounding of a crystallization nucleating agent generally used in injection molding or the like is considered.

Regarding the crystallization nucleating agent, it is known to blend benzylidene sorbitol or a specific nucleus substitution product thereof (JP-A-58-17135 and JP-A-58).
-219247, JP-A-61-133252).

However, in rotational molding, the above-mentioned benzylidene sorbitol or its specific nucleus-substituted product is effective in injection molding, but in rotational molding, it is relatively free from melt-kneading and the molding temperature is high.
Since the dispersion of the nucleating agent itself, deterioration of the effect due to decomposition, and the trouble of odor generation occur together, the molding conditions are restricted and the use is greatly limited.

On the other hand, there is a method of using a compound having a relatively high molecular weight as a nucleating agent. For example, JP-A-1-242646
In the publication, an ethylene polymer containing a highly crystalline 3-methyl-1-butene polymer has a high crystallization rate, and the above-mentioned improving effect as a nucleating agent is obtained. However, as far as the present inventors know, it is hard to say that the effect is still sufficient.

In the method described in the publication, various catalysts have been reported as a Ziegler-Natta catalyst which gives a 3-methyl-1-butene polymer having a particularly high degree of stereoregularity. None of the ones described are particularly highly crystalline 3-methyl-1-butene polymers obtained, and a master batch containing a 3-methyl-1-butene polymer is used as a propylene polymer. Since it is being produced, and the dispersibility in the ethylene polymer is reduced, the resulting ethylene polymer composition is 3-methyl-1-
Although the butene content was 0.6 wt%, which was large in quantity, the crystallization temperature was only 4.4 ° C as compared with the comparative example containing no 3-methyl-1-butene polymer. It is only rising.

Therefore, the 3-methyl-1-butene polymer is not sufficiently effective as a nucleating agent which is usually required, and as a result, it is sufficiently effective for improving the above-mentioned problems in rotational molding. The current situation is that it is not recognized.

[0012]

[Means for Solving the Problems]

[Summary of the Invention] In view of such a current situation, the present inventors have
The above relatively high molecular weight compound, namely 3-methyl-
A polyethylene material having excellent inner circumference and smoothness at the mold corners even under molding conditions in which the molding cycle in rotational molding is shortened by using a nucleating agent of 1-butene polymer to improve productivity. As a result of earnest studies to provide a 3-methyl-1-butene-containing ethylene copolymer obtained by polymerization in the presence of a catalyst using a specific silicon compound, 3-methyl-1 The present invention has been completed by finding that the above-mentioned effects are effectively exhibited even when the amount of butene is small.

<Summary> That is, the polyethylene composition for rotomolding according to the present invention comprises the following components (X) and (Y) and has a 3-methyl-1-butene content of 0.0.
It is characterized in that it is 001 to 1% by weight. (X) A linear polyethylene that is a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms. (Y) Halogen-containing magnesium, halogen-containing titanium, and a solid titanium catalyst component containing an electron-donating compound as an essential component, an organoaluminum compound, and a general formula R ¹ R ² _3-n Si (OR ³ ) _n (where R ¹ is a branched hydrocarbon group, R ² and R ³
Are branched or straight chain hydrocarbon groups, and n is 2 ≦ n ≦
It is a number of three. 3) obtained by contacting ethylene, 3-methyl-1-butene and, if necessary, an α-olefin having 3 to 12 carbon atoms with a catalyst component formed from an organosilicon compound represented by the formula 3), and polymerizing the catalyst component. -Methyl-
1-Butene-containing ethylene copolymer.

<Effect> The polyethylene composition for rotomolding according to the present invention can be produced by using an ethylene copolymer containing 3-methyl-1-butene obtained by polymerization in the presence of a specific catalyst. Despite being low in the content of -methyl-1-butene, it enables the production of molded products with excellent corner smoothness and inner surface smoothness even under conditions where the molding cycle is shortened. is there.

[Detailed Description of the Invention] <Linear polyethylene ((X) component)> 3-methyl-1
As the linear polyethylene which is the component (X) to be blended with the butene-containing ethylene copolymer as a nucleating agent, use the one obtained by copolymerizing ethylene and α-olefin in the presence of a transition metal catalyst. You can

There are no particular restrictions on the catalyst or polymerization method in the production of this linear polyethylene, and examples of the catalyst include Ziegler type catalysts, Phillips type catalysts and Kaminsky type catalysts.
In the presence of these catalysts, a slurry method, a gas phase fluidized bed method (for example, the method described in JP-A-59-23011) or a solution method, or a pressure of 200 kg / cm ² or higher and a polymerization temperature of 150 ° C. or higher Bulk polymerization method etc. are mentioned.

The α-olefin used as a comonomer is an α-olefin having 3 to 12 carbon atoms (represented by R-CH = CH ₂ in the general formula, and R represents an alkyl group). Specifically, for example, propylene, 1-
Butene, 1-pentene, 1-hexene, 4-methyl-1
-Pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-pentene, 1-heptene, 1-octene, 1
-Nonene, 1-decene, etc., preferably 1-butene, 1-hexene, 4-methyl-1-pentene and 1
-Octene.

In this case, the α-olefin is not limited to one kind, and a multicomponent copolymer using two or more kinds such as a terpolymer is also included in the present invention as a preferable component (X).

As the component (X) of the present invention, linear polyethylene having a density of 0.945 g / cm ³ or less is particularly preferable.

<3-Methyl-1-butene-Containing Ethylene Copolymer (Component (Y))> The 3-methyl-1-butene-containing ethylene copolymer used as the component (Y) in the present invention is an ethylene polymerization catalyst. By using 3-methyl-1-
It is preferably produced by a method in which butene is polymerized and ethylene is subsequently polymerized.

A copolymer obtained by copolymerizing ethylene and 3-methyl-1-butene as essential components and, if necessary, an α-olefin having 3 to 12 carbon atoms. This copolymer can be produced by contacting a so-called monomer at one time or stepwise with a polymerization catalyst, for example, a Ziegler type catalyst or a Kaminsky type catalyst, and polymerizing, but a preferred method is Substantially all 3 of the catalyst
-Methyl-1-butene is contacted to polymerize it, and then the remaining monomers are further contacted to complete the polymerization.

The 3-methyl-1-butene-containing ethylene copolymer as the component (Y) has a 3-methyl-1-butene content of 0. The content of 3-methyl-1-butene is not limited as long as it is 0001 to 1% by weight, and the component (Y) is 0.001 to 10% by weight, preferably 0. It is generally preferred to have a 3-methyl-1-butene content of 0.01-1% by weight.

The polymerization catalyst used for the copolymerization of 3-methyl-1-butene is a solid titanium catalyst component containing magnesium halide, titanium halide and an electron donating compound as essential components, an organoaluminum compound, and an organic compound. Those formed with silicon compounds are generally preferred.
In particular, a solid titanium component containing halogen-containing magnesium, halogen-containing titanium and an electron donating compound as essential components, an organoaluminum compound and a general formula R ¹ R ² _3-n Si (OR ³ ) _n (where R ¹ is A branched chain hydrocarbon group, R ² and R ³ are each a branched or straight chain hydrocarbon group, and n is 2 ≦
It is a number of n ≦ 3. The method using a catalyst formed from an organosilicon compound represented by

Here, the expression "formed from" means that, in addition to the case where the above-mentioned components are brought into contact with each other, a purposeful auxiliary component may be further brought into contact therewith, and the component is temporarily added. Alternatively, it means that they may be contacted in a stepwise manner. It means that other purposeful auxiliary steps may be carried out.

(1) Solid Titanium Catalyst Component As the halogen-containing magnesium contained in the solid titanium catalyst component used for producing the ethylene / 3-methyl-1-butene copolymer as the component (Y), Dihalides are preferred, for example magnesium chloride, magnesium bromide, and magnesium iodide can be used. Particularly preferred is magnesium chloride. It is desirable that the halogen-containing magnesium be substantially anhydrous.

The halogen-containing magnesium may be a halogen-containing magnesium obtained by treating a magnesium compound with an electron donating compound. Here, examples of the magnesium compound include magnesium oxide, magnesium hydroxide, hydrotalcite, magnesium carboxylate, alkoxymagnesium, aryloxymagnesium, alkoxymagnesium halide, aryloxymagnesium halide, and other organic magnesium compounds. be able to. Examples of the electron-donating compound include halosilane, alkoxysilane, silanol, aluminum compound, titanium halide compound, titanium tetraalkoxide, and the like.

Typical halogen-containing titanium is a halide of trivalent or tetravalent titanium. Preferable titanium halide is a compound represented by the general formula Ti (OR) _n X _4-n (wherein R is a C _{1 to} C ₁₀ hydrocarbon group and X is a halogen), and n = It is a tetravalent titanium halide compound of 0, 1 or 2.

Specifically, TiCl ₄ , Ti (OBu)
Although Cl ₃ and Ti (OBu) ₂ Cl ₂ can be exemplified, TiCl ₄ , Ti (O) are particularly preferable.
Bu) Titanium tetrahalide such as Cl ₃ or monoalkoxytrihalogenated titanium.

The electron-donating compound is usually used as a modifier of a Ziegler type catalyst, and any compound suitable for the present invention can be selected and used.

In the present invention, as a so-called "internal donor",
That is, when the transition metal component of the Ziegler type catalyst is prepared, the electron donating compound preferably used is Si-
Selected from the group consisting of an organosilicon compound having an OC bond, a polyvalent carboxylic acid having at least two carboxyl groups, a polyhydric alcohol or polyhydric phenol having at least two hydroxyl groups (the former is preferred), and a hydroxy-substituted carboxylic acid. Is a corresponding ester of a polyfunctional compound. Suitable as the ester of the polyfunctional compound is, for example, an ester of an aliphatic or aromatic polycarboxylic acid, particularly preferably a dicarboxylic acid diester, in which at least one of the ester groups has 2 or more carbon atoms. Is an ester of an alkyl group of. Specific examples of preferable dicarboxylic acid esters include diesters of phthalic acid, maleic acid or substituted malonic acid, and alcohols having 2 or more carbon atoms, and particularly preferable are phthalic acid and alcohols having 4 or more carbon atoms. Is a diester of. Moreover, as the organosilicon compound having a Si—O—C bond, an organosilicon compound used for producing an ethylene polymer described later is preferable.

[0031] (2) an organoaluminum compound used for the production of the ethylene polymer is a (Y) component used in the organic aluminum compound present invention have the general formula AlR' _n X _3-n (where R'is C _{1 to} C ₁₂ , preferably C _{1 to} C ₈ hydrocarbon group residue, X is a halogen or alkoxy group, n
Is preferably 0 <n ≦ 3).

Specific examples of such an organoaluminum compound include triethylaluminum and tri-aluminum.
n-propyl aluminum, tri-n-butyl aluminum, triisobutyl aluminum, tri-n-hexyl aluminum, trioctyl aluminum, diethyl aluminum hydride, diisobutyl aluminum hydride, diethyl aluminum monochloride,
Examples include ethylaluminum sesquichloride and diethylaluminum monoethoxyside. Of course, two or more of these organoaluminum compounds can be used in combination.

When such a catalyst is not used, a highly crystalline 3-methyl-1-butene-containing ethylene copolymer cannot be obtained and the effect of the present invention cannot be obtained.

(3) Organosilicon Compound As the organosilicon compound used for producing the ethylene polymer used in the present invention, an organosilicon compound represented by the following formula is used. R ¹ R ² _3-n Si (OR ³ ) _n (wherein R ¹ is a branched hydrocarbon group, R ² and R ³ are branched or linear hydrocarbon groups, respectively, and n is 2 ≦ n ≦ 3.
Is the number of. ) R ¹ is preferably branched from a carbon atom adjacent to a silicon atom. In that case, the branching group is preferably an alkyl group, a cycloalkyl group or an aryl group (for example, a phenyl group or a methyl-substituted phenyl group).

More preferable R ¹ is a carbon atom adjacent to a silicon atom, that is, a carbon atom at the α-position is secondary or tertiary. Particularly, those having a structure in which three alkyl groups are released from the carbon atom bonded to the silicon atom are preferable.

The carbon number of R ¹ is preferably 3 to 20, and 4 to
10 is particularly preferred. R ² is preferably a branched or linear aliphatic hydrocarbon group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms. R ³ is an aliphatic hydrocarbon group, preferably an aliphatic hydrocarbon group having 1 to 4 carbon atoms. Specific examples of such an organic silicon compound are as follows.

[0037]

[Chemical 1] (CH ₃ ) ₃ CSi (CH ₃ ) (OCH ₃ ) ₂ , (CH
₃ ) ₃ CSi (HC (CH ₃ ) ₂ ) (OCH ₃ ) ₂ ,
_{(CH 3) 3 CSi (CH} 3) (OC 2 H 5) 2, (C
₂ H ₅ ) ₃ CSi (CH ₃ ) (OCH ₃ ) ₂ , (C
H ₃ ) (C ₂ H ₅ ) CHSi (CH ₃ ) (OC
_{H 3) 2, ((CH} 3) 2 CHCH 2) 2 Si (OCH
₃ ) ₂ , C ₂ H ₅ C (CH ₃ ) ₂ Si (CH ₃ ) (OC
_{H 3) 2, C 2 H} 5 C (CH 3) 2 Si (CH 3) (O
C ₂ H ₅ ) ₂ , (CH ₃ ) ₃ CSi (OCH ₃ ) ₃ ,
(CH ₃ ) ₃ CSi (OC ₂ H ₅ ) ₃ , ((CH ₃ ) _{3
C) 2 Si (OCH 3)} 2, ((CH 3) 3 C) 2 Si
(OC ₂ H ₅ ) ₂ , (C ₂ H ₅ ) ₃ CSi (OC
₂ H ₅ ) ₃ , (CH ₃ ) (C ₂ H ₅ ) CHSi (OCH
₃ ) ₃ , (iC ₃ H ₇ ) ₂ Si (OCH ₃ ) ₂ , (iC
₃ H ₇ ) ₂ Si (OC ₂ H ₅ ) ₂ , (iC ₄ H ₉ ) ₂ S
i (OCH ₃ ) ₂ , (C ₆ H ₁₁ ) Si (CH ₃ ) (OC
_{H 3) 2, (C 6} H 11) 2 Si (OCH 3) 2

(4) Polymerization As described above, the polymerization of the ethylene copolymer as the component (Y) is carried out in advance in the presence of the above catalyst in the presence of 3-methyl-1.
A preferred method is to polymerize butene and then ethylene to this polymer. Further, if necessary, an α-olefin having 3 to 12 carbon atoms may be copolymerized at any stage.

The 3-methyl-1-butene-containing ethylene copolymer as the component (Y) is prepared from the 3-methyl-1-butene-containing ethylene copolymer as described above.
The methyl-1-butene content is preferably 0.001 to 10% by weight. If the 3-methyl-1-butene content is too low, the effect of the present invention is not clearly exhibited, and if it is too high, the dispersibility in the component (X) deteriorates, which is not preferable. Further, the ethylene content in the ethylene copolymer as the component (Y) is not clearly defined, but the ethylene content is 5
It is preferably 0% by weight or more. Furthermore, (Y)
The melt flow rate of the component is preferably higher than the melt flow rate of the component (X). When the melt flow rate of the ethylene copolymer is less than the melt flow rate of the linear polyethylene component, 3-methyl-1
-It is not preferable because the dispersibility of the butene-containing ethylene copolymer deteriorates.

<Composition> The proportion of component (Y) to component (X) is such that the 3-methyl-1-butene content in the composition of the present invention is 0.0001 to 1% by weight, preferably 0.00.
It may be determined so as to be 1 to 0.01% by weight. 3-
When the methyl-1-butene content is below this range, the improvement effect which is the object of the present invention is insufficient. On the other hand, even when it exceeds this range, no further improvement effect is sufficiently exerted, and economically. It is a disadvantage.

The polyethylene composition for rotomolding of the present invention comprises, in addition to the above-mentioned components, various components conventionally used in this field, such as an antioxidant, a heat stabilizer and an ultraviolet absorber, depending on the purpose of use and application. , Lubricant, cross-linking agent, colorant,
A dispersant, a filler, an antistatic agent, a pigment and the like can be added. Also, a small amount of a thermoplastic resin that can be kneaded with the component (X) and the component (Y) can be blended. This is why the polyethylene composition for rotational molding is defined as "comprising" the components listed above in the present invention.

When the linear polyethylene is blended in the rotational molding polyethylene composition of the present invention, the mixing method is as follows:
There is no particular limitation, and any known method can be used.

That is, the above-mentioned respective components may be blended in a predetermined amount and mixed by a commonly used Henschel mixer, super mixer or the like, and further pulverized directly into powder suitable for rotational molding, or a single-screw kneader and By a continuous kneading and melting method using a twin-screw kneader such as FCM or CIM, or a batch type melt kneading method such as roll or Banbury,
It is also preferable to once knead, granulate, and then pulverize.

In the crushing, an impact crusher such as a turbo type or a Balman mill type is generally used as a crusher suitable for polyethylene.

In carrying out the rotational molding, any conventional molding method can be employed at a molding temperature at which the substantial resin temperature is below the melting point of the contained 3-methyl-1-butene polymer.

[0046]

EXAMPLES The following examples and comparative examples serve to more specifically describe the polyethylene composition for rotomolding according to the present invention. However, the present invention is not limited to these examples without departing from the gist thereof.

The methods for measuring the physical properties shown in the examples are as follows. The measurement was performed using a molded product, and the test piece was prepared by cutting from the flat portion of the molded product and provided for the measurement. (1) Inner surface concavity and convexity: The inner surface concavo-convex state of the molded product was judged according to the following evaluation ranks. ◯: Even if the inner surface is touched by hand, there is no unevenness and it is smooth. B: When the inner surface is touched by hand, there are relatively large irregularities. X: When the inner surface is touched by hand, the unevenness is severe and the surface is wavy. (2) Meat around the corner part: judged according to the following evaluation ranks. ○: The resin is evenly applied to the corners. Δ: The resin is accumulated in the corners and the wall thickness is large. X: A large amount of resin was accumulated in the corners, and bridging (bridge) occurred partially.

<Production Example of Ethylene Copolymer Containing 3-Methyl-1-butene> [Production Example-1] (a) Preparation of solid catalyst component Glass three-necked flask with a volume of 500 ml equipped with a thermometer and a stirring rod After purging with nitrogen, 75 ml of purified heptane, 75 ml of titanium tetrabutoxide and 10 ml of
g anhydrous magnesium chloride are added. 90 ° C flask
The temperature is raised to 2, and magnesium chloride is completely dissolved in 2 hours.

Next, the flask is cooled to 40 ° C., and 15 ml of methylhydrogenpolysiloxane is added to precipitate a magnesium chloride / titanium tetrabutoxide complex. After washing this with purified heptane, 8.7 ml of silicon tetrachloride and 2.0 g of phthaloyl chloride are added, and the mixture is kept at 50 ° C. for 2 hours. The solid catalyst component obtained here was washed with heptane. The titanium content in this solid catalyst component is 2.
It was 7% by weight.

(B) 3-Methyl-1-butene polymerization 500 ml in a stirring autoclave having an internal volume of 1 liter
Of purified heptane, 0.8 g of the solid catalyst component prepared above, 32 g of 3-methyl-1-butene, 2 g of triisobutylaluminum and 0.6 g of tert-butylmethyldimethoxysilane were introduced at 50 ° C. for 3 hours. Reacted for hours. Then, it was washed with purified heptane to remove unreacted components.

The polymerization amount of 3-methyl-1-butene in this polymer was 25 g per 1 g of the solid catalyst, and the melting point of this polymer was 306 ° C.

(C) Ethylene Polymerization After thoroughly replacing the stirring autoclave having an internal volume of 3 liters with ethylene, 1.5 liters of sufficiently dehydrated n-heptane was introduced and maintained at 75 ° C., and further 7 kg of ethylene was added.
The pressure was increased to / cm ² G.

Then triethylaluminum 0.38
g, tert-butylmethyldimethoxysilane 0.16 g and the above 3-methyl-1-butene polymerized catalyst component 78.
0 g (including 30 mg of solid catalyst) was introduced, and polymerization was carried out at 75 ° C. for 3 hours while adjusting the gas phase hydrogen concentration to 45% by volume.

Thereafter, ethylene was purged, the polymerization was stopped by adding 10 ml of butanol, filtration,
After drying, 150 g of ethylene copolymer powder was obtained.
This ethylene copolymer powder contained 5000 ppm of 3-methyl-1-butene and had a melt flow rate of 50 g / 10 minutes. This was used as the component (Y) to secure the required sample amount and used in the following experiments.

<Production and Experiment of Polyethylene Composition for Rotational Molding> As a linear polyethylene which is the component (X), 5.0 g / melt flow rate obtained by a gas phase polymerization process in the presence of a Ziegler type catalyst. For 10 minutes, a density of 0.935 g / cm ³ , and a linear low-density polyethylene (Mitsubishi Polyethylene LL UR950G manufactured by Mitsubishi Petrochemical Co., Ltd.) having a 1-butene content of 4.0% by weight as a copolymerization component described above (Y. ) Ingredients are added in the proportions shown in Table 1, mixed for 3 minutes with a Henschel mixer, pelletized with a uniaxial granulator,
Turbo pellets manufactured by Turbo Kogyo Co., Ltd. T-
Grinded with 250 type, average particle size 250μm, 500μ
A powder containing 8% by weight of a coarse particle size component of m or more and 8% by weight of a fine particle component of 100 μm or less was obtained.

Next, 900 g of these was charged into a cylindrical mold having a capacity of 20 liters, and after taking a heating time of 20 minutes at an oven heating temperature of 350 ° C. in a thermobox type rotary molding machine, It moved to the process of air cooling and water cooling.

At this time, the air cooling time was variously changed as shown in Table 1, and the meat around and the inner surface irregularity at the corners of the obtained molded product were examined. The results are shown in Table 1.

[0058]

[Table 1] Example 2 In Example 1, linear low density polyethylene UR950
Production was performed in the same manner as in Example 1 except that G was 99% by weight and the 3-methyl-1-butene-containing ethylene copolymer was 1% by weight, and rotation molding and evaluation were performed. The results are shown in Table 2.

Example 3 3-methyl-1-butene polymerization was carried out using the solid catalyst component in the production example of Example 1 to obtain 2 per 1 g of the solid catalyst component.
5 g of poly-3-methyl-1-butene was obtained.

(D) Ethylene / 1-butene copolymerization 300 g of powdered high density polyethylene as a catalyst dispersion medium was introduced into an autoclave having an internal volume of 20 liter equipped with a temperature controller and a stirring blade, and the inside was sufficiently filled with ethylene. Replace. At 55 ° C., 0.1 g of triethylaluminum and 0.1 g of the above solid catalyst component were introduced.

Next, hydrogen / 1-butene / ethylene was introduced into each autoclave so as to have a constant partial pressure ratio, and polymerization was started while maintaining the total pressure at 20 kg / cm ² G. 90
Polymerization was performed at 5 ° C. for 5 hours, and polyethylene used as a catalyst dispersion medium was separated from the obtained polymer to obtain a melt flow rate of 4.8 g / 10 minutes and a density of 0.935 g / cm ³ ,
Polyethylene powder having a 1-butene content of 4.0% by weight 2.
5 kg was obtained.

<Rotation molding experiment> The same procedure as in Example 1 was carried out.
The results are shown in Table 2.

[0063]

[Table 2] Example 4 3-Methyl-1-butene polymerization was carried out as follows using the solid catalyst component in the production example of Example 1.

In a stirred autoclave having an internal volume of 1 liter, 500 ml of purified heptane, 0.8 g of a solid catalyst component, 3.2 g of triisobutylaluminum and 0.
Introduce 6 g of tert-butylmethyldimethoxysilane,
The reaction was carried out at 0 ° C for 3 hours. Then, it was washed with purified heptane to remove unreacted components.

The polymerization amount of 3-methyl-1-butene in this polymer was 2.5 g per 1 g of the solid catalyst component.

<Rotary Molding Experiment> The same procedure as in Example 1 was conducted.
The results are shown in Table 3.

[0067]

[Table 3]

[0068]

The specific polyethylene composition for rotomolding according to the present invention provides a rotomolded article excellent in the meat around the corners of the mold and the smoothness of the inner surface. I have just done it.

Claims (1)

[Claims] 1. A polyethylene composition for rotomolding, comprising the following components (X) and (Y) and having a 3-methyl-1-butene content of 0.0001 to 1% by weight. . (X) A linear polyethylene that is a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms. (Y) Halogen-containing magnesium, halogen-containing titanium, and a solid titanium catalyst component containing an electron-donating compound as an essential component, an organoaluminum compound, and a general formula R ¹ R ² _3-n Si (OR ³ ) _n (where R ¹ is a branched hydrocarbon group, R ² and R ³
Are branched or straight chain hydrocarbon groups, and n is 2 ≦ n ≦
It is a number of three. 3) obtained by contacting ethylene, 3-methyl-1-butene, and optionally an α-olefin having 3 to 12 carbon atoms with a catalyst formed from an organosilicon compound represented by the formula (3), and polymerizing the catalyst. -Methyl-1
-Butene-containing ethylene copolymers.