JPH0625481A - Polyethylene composition - Google Patents

Abstract

(57) [Summary] [Purpose] To provide a polyethylene composition which is excellent in molding processing characteristics such as drawdown resistance and wall thickness and impact strength, and is particularly suitable for large-scale blow molding. [Structure] A polymer component (X) comprising an ethylene homopolymer and / or a copolymer of ethylene and another α-olefin, and an ethylene-α- having a crystallinity of less than 30% and a carbon number of 3 or more. A polymer component (Y) comprising a copolymer with an olefin, wherein the proportion of the polymer component (X) is 80 to 99% by weight based on the total amount of the polymer components (X) and (Y); The proportion of the polymer component (Y) is 1 to 20% by weight, and the high load melt index is 0.5 to 1.
It is in the range of 0 g / 10 minutes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene composition, and more specifically, it has excellent molding processing characteristics such as drawdown resistance and uniform thickness and impact strength, and is particularly suitable for large blow molding. It is about things.

[0002]

2. Description of the Related Art Generally, in blow molding of polyethylene, characteristics such as drawdown resistance, fusion resistance of parison, and uniform thickness are important from the viewpoint of molding processing, and physical properties include rigidity and environment resistance. It is important to have excellent cracking properties and impact strength. In particular, in recent years, large blow-molded products have become remarkably widespread, and examples of large-scale molded products obtained by blow molding of polyethylene include gasoline tanks and drums of automobiles. The shape of these molded products may require a complicated shape having irregularities depending on the application. Further, in order to obtain a molded product excellent in impact strength, thick wall molding is also necessary.

Therefore, the above-mentioned characteristics in the molding process are important, and particularly in the molding of a heavy weight, a thick wall and a complicated shape, the drawdown resistance is excellent, the melt flow is uniform and the wall thickness is uniform. A resin capable of obtaining a molded product is required. On the other hand, in a gasoline tank of an automobile or the like, there is a demand for weight reduction, and therefore improvement of impact strength is also important.

In the case of so-called high-density polyethylene, the higher the average molecular weight, the better the physical properties such as impact resistance and environmental crack resistance, and generally, the melt tension at the time of melting also becomes large, and The drawdown is also smaller. However, when the average molecular weight is increased, the flow at the time of melting is deteriorated, causing melt fracture and rough skin, so that it is necessary to reduce the molding rate and the productivity is reduced.

There is a method of broadening the molecular weight distribution in order to improve the flow during melting. That is, when the molecular weight distribution is widened, the outflow ratio becomes high, the extrudability becomes good, and the molding speed can be increased. JP-A-57-158
No. 211 discloses a method for producing polyethylene having a wide molecular weight distribution by carrying out polymerization under specific conditions in the presence of a specific catalyst system.

[0006]

However, the polyethylene produced by the above method is certainly excellent in extrudability and environmental crack resistance, but especially in large-sized blow molding, the drawdown is large and the polyethylene is uniform. It is not sufficient in terms of the quality of the molded product, such as poor meatness and poor fusion of the parison.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a polyethylene composition that is excellent in molding processing characteristics such as drawdown resistance and wall thickness and impact strength, and is particularly suitable for large-scale blow molding. Especially.

[0007]

That is, the gist of the present invention is to provide a polymer component (X) comprising an ethylene homopolymer and / or a copolymer of ethylene and another α-olefin.
And the degree of crystallinity is less than 30%, ethylene and carbon number 3
The polymer component (Y) comprising a copolymer with the above α-olefin is contained, and the ratio of the polymer component (X) to the total amount of the polymer components (X) and (Y) is 80 to 80%. 99% by weight, the ratio of the polymer component (Y) is 1 to 20% by weight,
And the high load melt index is 0.5-10g
A polyethylene composition characterized by being in the range of / 10 minutes.

The present invention will be described in detail below. First, the polymer component (X) will be described. Polymer component (X)
Is an ethylene homopolymer and / or a copolymer of ethylene and another α-olefin. The polymer component (X) is generally produced using a catalyst system comprising a combination of a solid catalyst component called a Phillips-type catalyst or a Ziegler-type catalyst and a cocatalyst organometallic compound.

The above-mentioned organometallic compound is usually an organoaluminum compound, for example, the general formula AlR _m X _3-m
(In the formula, R is a hydrocarbon group having up to 20 carbon atoms, X is an alkoxy group or a halogen atom, and m is a number of 1 to 3).

In the above general formula, R has 1 to 1 carbon atoms.
4 represents a hydrocarbon group, specifically, for example, methyl,
Examples thereof include alkyl groups such as ethyl, propyl, isobutyl, hexyl, 2-methylpentyl, octyl, decyl and dodecyl, cycloalkyl groups such as cyclohexyl and cyclohexylmethyl, aryl groups such as phenyl and naphthyl, and aralkyl groups such as benzyl. . Specific examples of the organic aluminum compound include, for example, triethyl aluminum, tripropyl aluminum, triisobutyl aluminum, trihexyl aluminum, trioctyl aluminum, diethyl aluminum monochloride,
Examples thereof include methoxydiethylaluminum, ethoxydiethylaluminum, diethylaluminum phenolate and the like.

A preferred example of a Phillips type catalyst system is a catalyst system comprising a combination of chromium oxide supported on silica or silica-alumina and an organoaluminum compound. The carrier-supported chromium can be prepared as follows. First, a suitable chromium compound is supported on silica or a silica-alumina carrier. Examples of the chromium compound include chromium oxides, halides, oxyhalides, phosphates, sulfates, oxalates, alcoholates, organic compounds, and the like. Preferred chromium compounds are chromium trioxide and chromium acetonate. Acetyl, chromium sulfate, t-butyl chromate. As a supporting method, various methods such as impregnation, distillation and sublimation can be adopted. The amount of the chromium compound supported is 0.1 to 10% by weight, preferably 0.
It is selected from the range of 1 to 5% by weight.

Next, the carrier supporting the chromium compound is fired. The chromium compound is easily converted into chromium oxide and activated by firing. Such activation is generally carried out in the presence of oxygen, but it can also be carried out in the presence of an inert gas or under reduced pressure. The firing temperature is usually 300 to 1100 ° C, preferably 400 to 1000 ° C.
Selected from the temperature range of, the firing time is several minutes to several tens hours,
It is preferably selected from the range of 30 minutes to 10 hours.

In the present invention, a catalyst component containing an olefin polymer can also be used. Such a catalyst component is oxidized with the carrier by bringing the chromium oxide supported on the carrier into contact with the olefin used in the main polymerization reaction for a short time under the polymerization conditions in the presence of an organoaluminum compound and an inert hydrocarbon solvent. A polymer of 1 to 200 g is produced per gram of the component unit made of chromium, and then the catalyst-polymer composition is separated from the unreacted material and the solvent by a separation means such as decantation, and a hydrocarbon solvent is further added. It can be obtained by using and washing.

The Phillips type catalyst system (combination of a catalyst component containing chromium oxide or olefin polymer supported on a carrier and an organoaluminum compound) is prepared by separately supplying both components into a polymerization reactor. Any of the methods of mixing both components outside the polymerization reactor may be used.
The ratio of both components is usually 0.01 to 100, preferably 0.1 to 50 as the Al / Cr atomic ratio.

The polymer component (X) is produced by the Phillips type catalyst system as follows. The polymerization reaction is usually performed at a temperature of 0 to 200 ° C., preferably 50 to 110 ° C., a pressure condition of atmospheric pressure to 200 atmospheric pressure, preferably atmospheric pressure to 100 atmospheric pressure, in the substantial absence of oxygen or water, ethylene or ethylene. And 0.1 to other α-olefins.
It is carried out by supplying hydrogen of 1000 mol%, preferably 1 to 800 mol%. Examples of the other α-olefin include propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, 1-octene and the like. Other α-olefins are used in a proportion of 10 mol% or less with respect to ethylene.

The polymerization reaction needs to be carried out in the presence of a solvent. Examples of the solvent include n-butane and
Examples thereof include aliphatic hydrocarbons such as isobutane, hexane, heptane, and octane, alicyclic hydrocarbons such as cyclopentane and cyclohexane, and aromatic hydrocarbons such as benzene and toluene. The catalyst concentration is not particularly limited, but it is usually selected so that the amount of chromium is 0.01 to 500 mg, preferably 0.1 to 50 mg, per liter of the solvent. For the polymerization reaction, various types of reactors such as a tank type, a tube type, and a column type are used, and either a continuous type or a batch type may be adopted. Further, either one-step polymerization or multi-step polymerization of two or more steps may be used.

Examples of the solid catalyst component in the Ziegler type catalyst include titanium trichloride, vanadium trichloride, titanium tetrachloride, or a catalyst component in which a halo alcoholate of titanium is supported on a magnesium compound-based carrier, and coprecipitation of the magnesium compound and the titanium compound. Examples of the catalyst component include a substance or a eutectic. Suitable examples of Ziegler-type catalyst systems include
A catalyst system comprising a combination of (a) a reaction product of an oxygen-containing organic compound of magnesium, an oxygen-containing organic compound of titanium, and an aluminum halogen compound, and (b) an organic aluminum compound. Such a catalyst system can be prepared according to known methods.

The production of the polymer component (X) using the Ziegler type catalyst system is preferably carried out as follows. That is, a catalyst system comprising (a) a reaction product of an oxygen-containing organic compound of magnesium, an oxygen-containing organic compound of titanium, and an aluminum halogen compound, and (b) an organoaluminum compound is used, and a catalyst system of 50-100 in a hydrocarbon solvent is used. Polymerization of ethylene alone or ethylene with other α-olefins is carried out at a temperature of ° C. And, the polymerization reaction is more preferably carried out by a multistage polymerization method.

The above-mentioned multistage polymerization is a method in which polymerization is further carried out in the second reaction zone in the presence of the reaction product obtained by carrying out the polymerization in the first reaction zone. Then, the above multistage polymerization is preferably carried out under the conditions defined in the following (1) and (2). (1) By carrying out polymerization of ethylene alone or ethylene with another α-olefin in either one of the first and second reaction zones, the total polymer production amount is 50 to 50%.
A polymer (A) having a viscosity average molecular weight of 60 to 150,000 is produced at a ratio of 95% by weight. (2) By polymerizing ethylene alone or ethylene with another α-olefin in the other reaction zone, the α-olefin content is 10% by weight or less at a rate of 5 to 50% by weight based on the total amount of the polymer produced. , Viscosity average molecular weight is 20
~ 4 million polymer (B) is produced.

The two-step polymerization may be carried out either continuously or batchwise. In the case of the continuous system, the reactors are connected to a series of two units, and the reaction mixture obtained by the polymerization in the first reactor is introduced into the second reactor to continue the polymerization.
If necessary, a flash tank capable of purging most of the hydrogen in the reaction system is installed between the two reactors. In the case of the batch system, the reaction is performed sequentially in one reactor. The preferred reaction format is a continuous system.

First, the polymerization reaction (1) will be described. The viscosity average molecular weight of the polymer (A) is determined by measuring the intrinsic viscosity in a 130 ° C. tetralin solution, and using the following formula (1).
It is a value calculated from the formula of the viscosity average molecular weight represented by [Η] = 4.60 × 10 ⁻⁴ × M ^0.725 (1) In the above formula, [η] represents the intrinsic viscosity and M represents the viscosity average molecular weight.

In the second reaction zone, when the polymer (A) is produced in the presence of the polymer (B) produced in the first reaction zone, the viscosity average of the polymer (A) is obtained. For the molecular weight, [η] _A is calculated from the following formula (2) to calculate the viscosity average molecular weight. [Η] _A = (100 [η] -W _B [η] _{B) / W A ··· (2} ) In the above formulas, [η] _A is the intrinsic viscosity of the polymer (A),
[Η] _B is the intrinsic viscosity of the polymer (B), [η] is the intrinsic viscosity of all the polymers finally obtained in the second reaction zone, and W _A is the polymer produced in the second reaction zone ( A)% by weight, W _B
Indicates the weight% of the polymer (B) produced in the first reaction zone.

The significance of the conditions in the polymerization reaction (1) is as follows. When the viscosity average molecular weight of the polymer (A) is less than 60,000, the impact strength of the obtained polymer (final polymer) is low, and when it exceeds 150,000, the moldability is low. If the amount produced exceeds 95% by weight,
The resulting polymer (final polymer) has low impact strength and environmental crack resistance, and when it is less than 50% by weight, moldability becomes low. The polymerization reaction of (1) above is performed at 50 ° C to 100 ° C.
At 10 ° C for 10 minutes to 10 hours, 0.5 to 100 kg /
It may be carried out under a pressure of cm ² (gauge).

Next, the polymerization reaction (2) will be described. The viscosity average molecular weight of the polymer (B) is determined in the same manner as described above. Then, in the second reaction zone, the first
When the polymer (B) is produced in the presence of the polymer (A) produced in the reaction zone of, the viscosity average molecular weight of the polymer (A) is calculated from the following formula (3): [η] _B Obtain and calculate the viscosity average molecular weight. [Η] _B = (100 [η] -W ' _A [η] _A ) W' _B (3) In the above formula, [η] _B is the intrinsic viscosity of the polymer (B),
[Η] _A is the intrinsic viscosity of the polymer (A), [η] is the intrinsic viscosity of the entire final polymer obtained in the second reaction zone, W ′
_A is the weight% of the polymer (A) obtained in the first reaction zone,
W _'B indicates the weight percent of the polymer obtained in the second reaction zone (B).

The significance of the conditions in the polymerization reaction (2) is as follows. When the viscosity average molecular weight of the polymer (B) is less than 200,000, impact strength, tear strength and environmental crack resistance of the obtained polymer (finally produced polymer) are lowered and 4
When it exceeds, 000,000, the moldability is deteriorated. Production amount is 5
If it is less than 5% by weight, impact strength and environmental crack resistance of the obtained polymer (final polymer) will be low. 50% by weight
When it exceeds, the moldability becomes low. The polymerization reaction of (2) above is carried out under the same conditions as the reaction of (1) above. The order of the polymerization reaction may be the order of forming the polymer (A) and then the polymer (B), or the reverse order.

The polymer component (X) has a high load melt index of 0.5 to 5 g / 10 minutes and a density of 0.
It is preferably in the range of 950 to 0.965 g / 10 minutes. Due to such characteristics, the polymer component (Y) described later
When mixed with the polyethylene composition of the present invention, the high load melt index of the polyethylene composition can be easily adjusted to the range of 0.5 to 10 g / 10 minutes.

Next, the polymer component (Y) will be described. The polymer component (Y) has a crystallinity of less than 30% and is composed of a copolymer of ethylene and an α-olefin having 3 or more carbon atoms. The α-olefin as a copolymerization component includes propylene, butene-1, hexene-1, decene-1, 4,
-Methyl pentene-1, 4-methyl butene-1 etc. can be mentioned. Of these, propylene and butene-1 are particularly preferable.

Polymer component (Y) having a crystallinity of less than 30%
Can be obtained, for example, by copolymerizing ethylene and α-olefin using a catalyst system consisting of a vanadium compound such as vanadium oxytrichloride and vanadium tetrachloride and an organoaluminum compound among Ziegler type catalyst systems. In this case, the proportion of ethylene is 50 mol% or more, preferably 80 to 95 mol%.

An ethylene copolymer which is particularly suitable as the polymer component (Y) is an ethylene copolymer commercially available from Mitsui Petrochemical Industry Co., Ltd. under the Tufmer trademark, for example,
"Tuffmer A-4085", "Tuffmer A-409"
0 "and" Tufmer A-20090 "(both are ethylene-butene-1 copolymers).

The polyethylene composition of the present invention contains the above-mentioned polymer component (X) and polymer component (Y). The ratio of both is 80 to 99% by weight of the polymer component (X) and 1 to 20% by weight of the polymer component (Y) with respect to the total amount of the polymer components (X) and (Y). Is. When the proportion of the polymer component (Y) is less than 1% by weight, the impact strength is not improved so much, and when it exceeds 20% by weight, the density of the composition is decreased and the melt tension is decreased, and the drawdown is caused at the time of molding. Easier to do. The polyethylene composition of the present invention has a high load melt index of 0.5 to 10.
It has a characteristic in the range of g / 10 minutes and is particularly suitable as a large blow molding composition.

In the preparation of the polyethylene composition of the present invention, a predetermined amount of the polymer component (X) and the polymer component (Y) may be directly mixed and kneaded, or
The polymer component (Y) prepared in high concentration in advance may be used as a masterbatch. And as a kneader,
A screw type extruder, a Banbury mixer, a roll or the like can be used. Further, in the polyethylene composition of the present invention, various additives which are usually used by adding to polyethylene, for example, an antioxidant, a weather resistance stabilizer, a heat stabilizer, etc. are used within a range not impairing the object of the present invention. You may mix.

[0032]

EXAMPLES Next, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist. Physical properties in the following examples were measured by the following methods. (1) Melt Index (MI) According to ASTM-D1238, temperature 190 ° C., load 2.
It was measured at 16 kg. (2) High load melt index (HLMI) It is a value measured with a load of 21.6 kg in the above MI measurement.

(3) Density The density was measured by the density gradient tube method specified in JIS K-6760. (4) Melt tension (melt tension) Molten resin having a temperature of 190 ° C. is 0.44 g / min. (Orifice: 1 mm diameter, L / D = 5, inflow angle of nozzle is 6
0 °), and this was 0.94 m / min. It is indicated by the melt tension (g) after 4 minutes in the case of being wound up with.

(5) Ballast effect Shimadzu flow tester (caliber: 1 mm, L / D:
5 、 Nozzle inflow angle: 90 °)
Die swell ratio (relative extrudate cross-sectional area / nozzle cross-sectional area = α ₁₀₀ ) measured under conditions of ℃ and 100 sec ^-1
Expressed as (6) Izod impact strength Measured with a notched piece of a press plate in accordance with JIS K-7110.

Comparative Examples 1 and 2 and Examples 1 to 4 <Production of Polymer Component (X) (Ethylene-Butene-1 Copolymer) with Phillips Catalyst> (1) Preparation of Solid Catalyst Commercially available silica (W. R Grace and Campani grade 952, specific surface area 342 m ² / g) was impregnated with an aqueous solution of chromium trichloride, dried at 120 ° C., and then activated under dry air at 800 ° C. to obtain a catalyst component containing 1% by weight of chromium. Obtained.

1000 g of the carrier-supported catalyst component thus obtained, 21.9 g of triethylaluminum, and 200 liters of n-hexane were placed in a 400 liter reactor, and 5 kg of ethylene was supplied at 80 ° C. for 1 hour to obtain hydrogen in the reactor. / Catalyst reacting while maintaining the pressure ratio of ethylene to 1.0-
A polyethylene mixture was obtained. After supplying ethylene, it was washed by decantation using n-hexane.

(2) Polymerization reaction In a reactor having a capacity of 1 m ³ , the catalyst-polyethylene mixture obtained above was used as a catalyst component in the state of n-hexane slurry at a rate of about 3.5 g / HR and n-hexane was 200. While supplying ethoxydiethylaluminum at a rate of liter / HR and a rate of 1.8 g / HR, adjusting the partial pressure ratio of hydrogen / ethylene in the gas phase to 0.6, butene in the gas phase-1 /
The partial pressure ratio of ethylene was kept at 0.004 and continuous polymerization reaction was carried out for 4 days to obtain an ethylene-butene-1 copolymer.

The above ethylene-butene-1 copolymer 10
Antioxidant (“Irganox 101
0 ") and 0.1 part by weight of calcium stearate.
25 parts by weight were added and mixed, and the mixture was pelletized using an extruder having a diameter of 90 mm, and the physical properties were measured. The results are shown in Table 1 (Comparative Example 1).

<Preparation of Polyethylene Composition> For the above copolymer, as a polymer component (Y), “Tuffmer A-
4085 "(crystallinity 20%, MI 3.6 ethylene-
Butene-1 copolymer and butene-1 content 14 mol%) were mixed in the proportions shown in Table 1, melt-kneaded into pellets by using an extruder having a diameter of 20 mm, and physical properties were measured. The results are shown in Table 1. As is clear from Table 1, Examples 1 to 1
The composition of 4 has a ballast effect as compared with the composition of Comparative Example 1.
Impact strength is improved without significantly impairing melt tension. Further, the composition of Comparative Example 2 has a high HLMI and high impact strength, but the density and the melt tension are greatly reduced.

Comparative Example 3, Examples 5 and 6 <Production of Polymer (X) (Ethylene Polymer) by Phillips Catalyst> The same catalyst as in Example 1 was used, and the partial pressure ratio of hydrogen to ethylene in the gas phase was 0. The homopolymerization of ethylene was carried out by adjusting the ratio to 0.4 to obtain an ethylene polymer. The above ethylene polymer was pelletized in the same manner as in Example 1 and the physical properties were measured. The results are shown in Table 2 (Comparative Example 3). <Preparation of Polyethylene Composition> The same polymer component (Y) as that used in Example 1 was mixed with the above polymer in a ratio shown in Table 2, and melt-kneaded using an extruder having a diameter of 20 mm. Then, it was pelletized and the physical properties were measured. The results are shown in Table 2. As is clear from Table 2, the compositions of Examples 5 and 6 have significantly improved impact strength as compared with the composition of Comparative Example 3.

Comparative Example 4, Examples 7 and 8 <Production of Polymer Component (X) (Ethylene-Butene-1 Copolymer) by Two-Step Polymerization Using Ziegler Catalyst> (1) Preparation of Solid Catalyst 23 g of ethoxymagnesium, 60.9 g of tributoxymonochlorotitanium and 7.4 g of n-butanol were placed in a 1 liter flask, mixed at 150 ° C. for 6 hours for homogenization and then cooled, and 750 ml of n-hexane was added to obtain a uniform solution. And Then, 92.2 g of ethylaluminum sesquichloride was added dropwise over 3 hours at 40 ° C. with stirring,
Then, the mixture was stirred for 7 hours. The washing was repeated using n-hexane to obtain 44 g of a solid catalyst.

(2) Polymerization reaction 1 liter of n-hexane and 0.4 mmol of diethylaluminum monochloride were placed in a 2 liter stainless steel autoclave, and when the temperature was raised to 77 ° C., the partial pressure was 4.4 kg / cm ² . Supplying hydrogen, partial pressure 4kg / cm
25 mg of the above solid catalyst component was supplied while ethylene was supplied so as to be ₂ . When the total pressure was kept constant and the fed ethylene reached 320 g, the first-stage polymerization was terminated, and then cooled to 50 ° C., and 25 g of polymer was extracted. The amount of polymerization in the first stage polymerization reaction was equivalent to 85% by weight of the total amount of polymer produced. Then, ethylene was fed at a partial pressure of 4 kg / cm, a hydrogen partial pressure of 0.16 kg / cm ² , and a butene-1 partial pressure of 0.24 kg / cm ² , respectively, and the polymerization amount was 15% by weight of the total polymer production amount. The second-stage polymerization was carried out until After the weight was completed, the solvent was separated and dried to obtain 347 g of an ethylene-butene-1 copolymer.

The viscosity average molecular weight of the first stage polymer measured in 135 ° C. tetralin was 85,000, and the viscosity average molecular weight of the ethylene-butene-1 copolymer was 180,000. Further, the viscosity average molecular weight of the second-stage polymer obtained from the above formulas (1) and (3) was 950,000. The above ethylene-butene-1 copolymer was pelletized in the same manner as in Example 1 and the physical properties were measured. The results are shown in Table 3 (Comparative Example 4).

<Preparation of Polyethylene Composition> The same polymer component (Y) as that used in Example 1 was mixed with the above polymer in the ratio shown in Table 3, and an extruder having a diameter of 20 mm was used. Then, the mixture was melt-kneaded, pelletized, and the physical properties were measured. The results are shown in Table 3. As is clear from Table 3,
In the compositions of Examples 7 and 8, the addition of the polymer component (Y) significantly improved the impact strength without significantly impairing the melt tension and the dispersion effect.

[0045]

TABLE 1 Comparative Example implementation Example 1 2 1 2 3 4 <polymer component X> copolymer (1) 100 75 99 95 90 85 <polymer component Y> TAFMER A-4085 0 25 1 5 10 15 <Physical properties> HLMI 3.5 6.1 3.5 4.0 4.5 4.8 Density 0.956 0.939 0.955 0.953 0.950 0.946 Melt tension 10.5 6.2 10.5 9.2 8.6 8.2 Balance effect 4.4 4.3 4.4 4.5 4.3 4.3 Impact strength 27.0 53.5 30.5 35.8 44.5 53.0 ────────── ─────────────────────────── Copolymer (1): Ethylene-butene-1 copolymer with Phillips catalyst

[0046]

TABLE 2 Comparative Example implementation Example 3 5 6 <polymer component X> copolymer (2) 100 95 90 <polymer component Y> TAFMER A-4085 0 5 10 <Physical Properties> HLMI 1.5 1.7 2.0 Density 0.957 0.954 0.950 Melt tension 13.3 12.5 12.0 Balance effect 4.6 4.5 4.4 Impact strength 38.4 47.5 56.3 ────────────────────────────────── — Copolymer (2): Ethylene polymer with Phillips catalyst

[0047]

TABLE 3 Comparative Example implementation Example 4 7 8 <polymer component X> copolymer (3) 100 95 90 <polymer component Y> TAFMER A-4085 0 5 10 <Physical Properties> HLMI 5.1 5.6 6.3 Density 0.955 0.953 0.950 Melt tension 8.3 7.9 7.6 Balance effect 4.8 4.7 4.8 Impact strength 44.5 54.9 67.3 ───────────────────────────────── — Polymer (3): Ethylene-butene-1 copolymer obtained by two-step polymerization using Ziegler catalyst

[0048]

EFFECTS OF THE INVENTION According to the present invention described above, a polyethylene composition is provided which is excellent in molding processing characteristics such as drawdown resistance and thickness uniformity and impact strength, and is particularly suitable for large-scale blow molding.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area C08L 23:08)

Claims (4)

[Claims] 1. A polymer component (X) consisting of an ethylene homopolymer and / or a copolymer of ethylene and another α-olefin, having a crystallinity of less than 30% and having an ethylene content of 3 or more. The polymer component (Y) comprising a copolymer with an α-olefin is contained, and the ratio of the polymer component (X) to the total amount of the polymer components (X) and (Y) is 80.
To 99% by weight, the ratio of the polymer component (Y) is 1 to 20% by weight, and the high load melt index is 0.
A polyethylene composition, characterized in that it is in the range of 5 to 10 g / 10 minutes. 2. As the polymer component (X), ethylene or ethylene and other α-olefins are polymerized in the presence of a polymerization catalyst comprising a combination of chromium oxide supported on silica or silica-alumina and an organoaluminum compound. The polyethylene composition according to claim 1, wherein the polymer thus obtained is used. 3. A catalyst system comprising, as the polymer component (X), a reaction product of (a) an oxygen-containing organic compound of magnesium, an oxygen-containing organic compound of titanium and an aluminum halogen compound, and (b) an organic aluminum compound. The polyethylene composition according to claim 1, wherein ethylene is used alone or a polymer obtained by polymerizing ethylene with another α-olefin is used in a hydrocarbon solvent at a temperature of 50 to 100 ° C. 4. The following (1) as the polymer component (X):
And a polymer obtained by a multistage polymerization method in which, in the presence of a reaction product obtained by polymerizing in the first reaction zone under the conditions defined in (2), further polymerization is performed in the second reaction zone. The polyethylene composition according to claim 1, which is used. (1) By carrying out polymerization of ethylene alone or ethylene with another α-olefin in either one of the first and second reaction zones, the total polymer production amount is 50 to 50%.
A polymer (A) having a viscosity average molecular weight of 60 to 150,000 is produced at a ratio of 95% by weight. (2) By polymerizing ethylene alone or ethylene with another α-olefin in the other reaction zone, the α-olefin content is 10% by weight or less at a rate of 5 to 50% by weight based on the total amount of the polymer produced. , Viscosity average molecular weight is 20
~ 4 million polymer (B) is produced.