JPH1025319A - Polyethylene for medical containers and medical containers - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyethylene medical container which has good hygiene and flexibility, does not lose transparency even after sterilization, and does not cause wrinkles or deformation, and polyethylene for the medical container To provide. SOLUTION: Ethylene and α- having 3 to 12 carbon atoms are provided.
A copolymer with an olefin, having a density of 0.915 to
0.940 g / cm ³ , the MFR at 190 ° C. under a load of 2.16 kg is 0.1 to 10.0 g / 10 min, and the decane-soluble component content ratio (W) at room temperature and the density (d) But
W <80 × exp (-100 (d−0.88)) + 0.1, and the shear stress of the molten polymer at 190 ° C. is 2.4 × 10 ⁶ dyne /
The fluidity index (FI) defined by the shear rate when reaching cm ² , the MFR satisfies FI> 75 × MFR, the melt tension at 190 ° C. (MT) and the MFR are 5.5 × MFR ^-0.65 >MT> 2.2 × MFR ^-0.84
And a medical container comprising the polyethylene.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene for medical containers and a medical container, and more particularly, to a blood container, a medical device, and the like having excellent hygiene, flexibility, impact resistance, transparency and heat resistance. The present invention relates to a polyethylene suitable for a material of a medical container to be put therein and a medical container made of the polyethylene.

[0002]

BACKGROUND OF THE INVENTION As medical containers used at present, rigid containers made of glass, polyethylene, polypropylene and the like, and soft bags made of polyvinyl chloride containing a plasticizer are known. However, the above-described rigid container requires introduction of air using a ventilation needle or an infusion set with a ventilation hole when dripping a content liquid such as blood or a drug solution. Contamination may occur. On the other hand, a soft bag is different from the above-mentioned hard container when the content liquid is dropped, because the bag itself is squeezed by the atmospheric pressure together with the drop of the content liquid, so that introduction of air is unnecessary, and sanitation is improved. It has advantages such as excellent, convenient transportation, and small bulk of waste. However, this soft bag has problems such as the toxicity of the plasticizer and residual monomers contained in polyvinyl chloride.

On the other hand, for the purpose of improving flexibility, transparency, hygiene and the like, a medical bag using a polymer such as an ethylene / vinyl acetate copolymer or an elastomer for an intermediate layer has been proposed. JP-A-58-165866). However, in this medical bag, there is a problem in that the polymer used for the intermediate layer has poor heat resistance, so that the bag is wrinkled during sterilization. In addition, conventional medical bags made of polyethylene have a somewhat insufficient heat resistance and cannot be heated at a high sterilization temperature, so that the sterilization time is prolonged or sterilization is performed in a highly clean atmosphere. The inefficiency in the sterilization process, such as the need to perform it, poses a problem.

Therefore, it has good hygiene and flexibility, does not lose its transparency even after being sterilized at 115 ° C. for 30 minutes as shown in the Japanese Pharmacopoeia, and has excellent heat resistance, wrinkles and deformation. There is a demand for the emergence of a polyethylene medical container such as a medical bag made of a multilayer film, a medical bag made of a single-layer film, and a medical bottle made of a single layer. The emergence of polyethylene used for containers is desired.

[0005]

An object of the present invention is to solve the problems associated with the prior art as described above, and has good hygiene and flexibility, and has a temperature of 115 ° C.
Even if sterilization treatment is performed in 0 minutes, transparency is not lost, and furthermore, it is excellent in heat resistance and does not cause wrinkles or deformation, so that the polyethylene medical container and the moldability used for such medical container are improved. It aims to provide excellent polyethylene.

[0006]

The polyethylene for medical containers according to the present invention is a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms, and (i) having a density of 0.915 to 0.915.
0.940 g / cm ³ , (ii) 190 ° C.
2. Melt flow rate under a load of 16 kg is 0.1
(Iii) The decane-soluble component content ratio (W) and the density (d) at room temperature are W <80 × exp (−100 (d−0.88)). (Iv) 190 ° C. of the molten polymer
The fluidity index (F) defined by the shear rate when the shear stress reaches 2.4 × 10 ⁶ dyne / cm ² at
I (1 / sec)) and the melt flow rate (MFR (g
/ 10 min)) and the relationship FI> 75 × MFR is satisfied, and (v) the melt tension at 190 ° C. (MT (g)) and the melt flow rate (MFR)
(G / 10 minutes)) and 5.5 × MFR ^-0.65 >MT> 2.2 × MFR ^-0.84 .

[0007] Such polyethylene includes (A) a transition metal compound represented by the following formula (I) and ML _X ... (I) (wherein M represents a transition metal selected from Group IVB of the periodic table). , L represents a ligand coordinated to a transition metal atom, and at least two of the ligands L are substituted cyclopentadiene having only 2 to 5 substituents selected from a methyl group and an ethyl group. Is an enyl group, and the ligand L other than the substituted cyclopentadienyl group is a hydrocarbon group having 1 to 12 carbon atoms, an alkoxy group, an aryloxy group, a halogen atom, a trialkylsilyl group or a hydrogen atom, x represents the valence of the transition metal atom M.) (B) Copolymerization of ethylene and an α-olefin having 3 to 12 carbon atoms in the presence of an olefin polymerization catalyst containing an organoaluminum oxy compound Let It can be obtained by:

[0008] A medical container according to the present invention is characterized by being made of the polyethylene.

[0009]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the polyethylene for medical containers and the medical container according to the present invention will be specifically described.

[0010] The polyethylene for medical containers according to the present invention is a random copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms.

In such a polyethylene, the constituent units derived from ethylene are present in a proportion of 75 to 99% by weight, preferably 80 to 98% by weight, more preferably 85 to 96% by weight, and have 3 carbon atoms. It is desirable that the constitutional unit derived from the α-olefin of from 20 to 20 is present in the proportion of 1 to 25% by weight, preferably 2 to 20% by weight, more preferably 4 to 15% by weight.

The α-olefin having 3 to 20 carbon atoms includes propylene, 1-butene, 1-pentene, 1-pentene,
Hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-
Octadecene, 1-eicosene and the like.

The composition of the polyethylene was determined by ¹³ C-NMR. That is, about 20 mm in a 10 mmφ sample tube.
A ¹³ C-NMR spectrum of a sample in which 0 mg of the copolymer powder was uniformly dissolved in 1 ml of hexachlorobutadiene was measured at a measurement temperature of 120 ° C. and a measurement frequency of 25.05 MHz.
3. Spectral width 1500 Hz, pulse repetition time
It is determined by measuring under measurement conditions of 2 sec and pulse width of 6 μsec.

The polyethylene for medical containers according to the present invention has the following properties (i) to (v). (I) The density ranges from 0.915 to 0.940 g / cm ³ , preferably from 0.920 to 0.940 g / cm ³ , more preferably from 0.920 to 0.935 g / cm ³ .

The density of polyethylene is JIS K71
It is measured at a temperature of 23 ± 0.1 ° C. according to Method D of 12. (Ii) The melt flow rate at 190 ° C. and a load of 2.16 kg is 0.1 to 10.0 g / 10 min, preferably 0.1 to 10.0 g / 10 min.
5 to 8.0 g / 10 min, more preferably 1.0 to 5.0 g
/ 10 minutes.

The melt flow rate is measured at 190 ° C. under a load of 2.16 kg according to ASTM D1238-65T using granulated pellets of polyethylene. The granulated pellets are powdered polyethylene 100
Parts by weight of tri (2,4-di-t) as a secondary antioxidant
-Butylphenyl) phosphate at 0.05 parts by weight,
N-octadecyl-3- (4'hydroxy-
0.1% by weight of 3 ′, 5′-di-t-butylphenyl) propionate and 0.05 part by weight of calcium stearate as a hydrochloric acid absorbent are blended. Thereafter, using a conical tapered twin-screw extruder manufactured by Haake Co., Ltd., the mixture is melt-extruded at a set temperature of 180 ° C. to prepare.

(Iii) n-decane soluble component amount fraction (W (% by weight)) and density (d (g / cm ³ )) at room temperature are as follows: W <80 × exp (−100 (d−0) .88)) + 0.1 preferably W <60 × exp (−100 (d−0.8
8)) + 0.1 More preferably, W <40 × exp (−100 (d−0.8
8)) The relationship represented by +0.1 is satisfied.

It can be said that such a polyethylene has a narrow composition distribution. n-decane soluble component fraction (W (% by weight))
Is defined as W = n-decane soluble component amount / (n-decane insoluble component amount and soluble component amount) × 100%.

The amount of n-decane-soluble components of polyethylene is determined by adding about 3 g of polyethylene to 450 ml of n-decane, and adding
After melting at 23 ° C., the solution is cooled to 23 ° C., the n-decane insoluble portion is removed by filtration, and the n-decane soluble portion is recovered from the filtrate.

A smaller amount of the soluble component means that the composition distribution is narrower. (Iv) The shear stress of the molten polymer at 190 ° C. is 2.4.
The fluidity index (FI (1 / sec)) defined by the shear rate when reaching 10 ⁶ dyne / cm ² and the melt flow rate (MFR (g / 10 min)) are FI> 75 × MFR It preferably satisfies the relationship of FI> 80 × MFR and more preferably FI> 85 × MFR.

In the case of producing a polyethylene having a narrow composition distribution by the prior art, the molecular weight distribution is generally narrowed at the same time, so that the flowability is deteriorated and the FI is reduced. In the polyethylene of the present invention, since FI and MFR satisfy the above-described relationship, low stress is maintained up to a high shear rate,
Good moldability.

The flow index at 190 ° C.
Stress is 2.4 × 10⁶dyne / cm ^TwoTime to reach
Speed. The flow index determines the shear rate
Push the resin out of the capillary while changing
It was determined by measuring the stress. That is, MT measurement
Capillary flow, manufactured by Toyo Seiki Seisakusho, using the same sample as
Using a property tester, resin temperature 190 ° C, shear stress range
Is 5 × 10^Four~ 3 × 10⁶dyne / cm^TwoMeasured in degrees
You.

The MFR of the polyethylene to be measured (g / g
10 minutes), the diameter of the nozzle (capillary) was changed as follows and measured. 1.0 mm when 10 ≧ MFR> 3 2.0 mm when 3 ≧ MFR> 0.8 3.0 mm when 0.8 ≧ MFR (v) Melt tension (MT (g)) at 190 ° C. and melt flow The rate (MFR (g / 10 min)) is 5.5 × MFR ^-0.65 >MT> 2.2 × MFR ^-0.84 5.0 × MFR ^-0.65 >MT> 2.5 × MFR ^-0.84 4.5 × MFR ^-0.65 >MT> 2.8 × MFR ^-0.84 .

The ethylene copolymer according to the present invention has a higher melt tension (M.sub.T) than a conventional ethylene copolymer.
T) is high and the moldability is good. If MT is too high,
Skin roughness may occur during molding, and the appearance of the molded article may deteriorate.

The melt tension is determined by measuring the stress when the molten polymer is stretched at a constant speed. That is, using a granulated polyethylene pellet as a measurement sample, using an MT measuring device manufactured by Toyo Seiki Seisaku-sho, resin temperature 190 ° C., extrusion speed 15 mm / min, winding speed 10
~ 20m / min, nozzle diameter 2.09mmφ, nozzle length 8
mm.

Catalyst The polyethylene according to the present invention as described above includes, for example,
(A) a transition metal compound represented by the following general formula (I);
(B) In the presence of an olefin polymerization catalyst containing an organoaluminum oxy compound, ethylene and carbon atoms having 3
To 12 α-olefins can be produced by copolymerizing the resulting copolymer such that the density of the obtained copolymer is 0.915 to 0.940 g / cm ³ .

The olefin polymerization catalyst and each catalyst component are described below. (A) Transition metal compound The transition metal compound (A) of Group IV of the periodic table containing a ligand having a cyclopentadienyl skeleton is specifically a transition metal compound represented by the following formula (I). .

ML _X (I) (wherein, M represents a transition metal selected from Group IVB of the Periodic Table, L represents a ligand coordinated to a transition metal atom, and at least two of these ligands) Is a substituted cyclopentadienyl group having only 2 to 5 substituents selected from a methyl group and an ethyl group, and the ligand L other than the substituted cyclopentadienyl group has a carbon atom number of Is a hydrocarbon group, an alkoxy group, an aryloxy group, a halogen atom, a trialkylsilyl group or a hydrogen atom of 1 to 12, and x represents the valence of the transition metal atom M.) In the above general formula (I), Represents a transition metal atom selected from Group IVB of the periodic table, specifically, zirconium, titanium or hafnium, and preferably zirconium.

L represents a ligand coordinated to a transition metal atom M, and at least two of the ligands L are substituted with only 2 to 5 substituents selected from a methyl group and an ethyl group. It is a cyclopentadienyl group, and each ligand may be the same or different. The substituted cyclopentadienyl group is a substituted cyclopentadienyl group having two or more substituents, preferably a cyclopentadienyl group having two or three substituents, and a disubstituted cyclopentadienyl group. More preferably a 1,3-substituted cyclopentadienyl group. In addition, each substituent may be the same or different.

In the above formula (I), the ligand L other than the substituted cyclopentadienyl group coordinated to the transition metal atom M is a hydrocarbon group having 1 to 12 carbon atoms, an alkoxy group, an aryloxy group. , A halogen atom, a trialkylsilyl group or a hydrogen atom.

Examples of the hydrocarbon group having 1 to 12 carbon atoms include an alkyl group, a cycloalkyl group, an aryl group and an aralkyl group.
Methyl group, ethyl group, n-propyl group, isopropyl group,
alkyl groups such as n-butyl group, isobutyl group, sec-butyl group, t-butyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group and decyl group; cycloalkyl groups such as cyclopentyl group and cyclohexyl group; An aryl group such as a phenyl group and a tolyl group; and an aralkyl group such as a benzyl group and a neophyl group can be exemplified.

Examples of the alkoxy group include methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, t-butoxy, pentoxy, hexoxy, octoxy and the like. Can be exemplified.

Examples of the aryloxy group include a phenoxy group. A halogen atom is fluorine,
Chlorine, bromine and iodine. Examples of the trialkylsilyl group include a trimethylsilyl group, a triethylsilyl group, and a triphenylsilyl group.

Examples of the transition metal compound represented by the general formula (I) include bis (dimethylcyclopentadienyl) zirconium dichloride, bis (diethylcyclopentadienyl) zirconium dichloride, and bis (methylethylcyclopentadienyl). ) Zirconium dichloridebis (dimethylethylcyclopentadienyl) zirconium dichloride, bis (dimethylcyclopentadienyl) zirconium dibromide, bis (dimethylcyclopentadienyl) zirconium methoxychloride, bis (dimethylcyclopentadienyl) zirconium ethoxycyclolide , Bis (dimethylcyclopentadienyl) zirconium butoxycyclolide, bis (dimethylcyclopentadienyl) zirconium diethoxide, bis (dimethylcyclopentadiene) Nil) zirconium methyl chloride, bis (dimethylcyclopentadienyl) zirconium dimethyl, bis (dimethylcyclopentadienyl) zirconium benzyl chloride, bis (dimethylcyclopentadienyl) zirconium dibenzyl, bis (dimethylcyclopentadienyl) zirconium Phenyl chloride, bis (dimethylcyclopentadienyl) zirconium hydride chloride and the like can be mentioned.

In the above examples, disubstituted cyclopentadienyl ring includes 1,2- and 1,3-substituted, and trisubstituted 1,2-, 3- and 1,2,4- Including substitutions. In the present invention, a transition metal compound in which zirconium metal is replaced with titanium metal or hafnium metal in the zirconium compound as described above can be used.

Among these transition metal compounds represented by the general formula (I), bis (1,3-dimethylcyclopentadienyl) zirconium dichloride, bis (1,3-diethylcyclopentadienyl) zirconium dichloride ,
Bis (1-methyl-3-ethylcyclopentadienyl) zirconium dichloride is particularly preferred.

In the present invention, a transition metal compound component containing at least one transition metal compound represented by the general formula (I) is used as the transition metal compound component. (B) Organoaluminum Oxy Compound The organoaluminum oxy compound (B) may be a conventionally known benzene-soluble aluminoxane, or a benzene-insoluble organoaluminum oxy as disclosed in JP-A-2-276807. It may be a compound.

The aluminoxane as described above can be prepared, for example, by the following method. (1) Compounds containing adsorbed water or salts containing water of crystallization, for example, magnesium chloride hydrate, copper sulfate hydrate,
An organic aluminum compound such as trialkylaluminum is added to a hydrocarbon medium suspension such as aluminum sulfate hydrate, nickel sulfate hydrate or cerous chloride hydrate, and adsorbed water or water of crystallization is added to the organic aluminum. A method of reacting with a compound.

(2) A method in which water, ice or steam is allowed to directly act on an organoaluminum compound such as trialkylaluminum in a medium such as benzene, toluene, ethyl ether or tetrahydrofuran.

(3) A method of reacting an organoaluminum compound such as trialkylaluminum with an organotin oxide such as dimethyltin oxide or dibutyltin oxide in a medium such as decane, benzene or toluene.

The aluminoxane may contain a small amount of an organic metal component. Alternatively, the solvent or unreacted organoaluminum compound may be removed from the recovered aluminoxane solution by distillation, and then redissolved in the solvent.

Specific examples of the organoaluminum compound used in preparing the aluminoxane include trimethylaluminum, triethylaluminum, tripropylaluminum, triisopropylaluminum, and tri-n-aluminum.
Trialkylaluminum such as butylaluminum, triisobutylaluminum, trisec-butylaluminum, tritert-butylaluminum, tripentylaluminum, trihexylaluminum, trioctylaluminum, tridecylaluminum; tricyclohexylaluminum, tricyclooctylaluminum, etc. Tricycloalkylaluminum; dialkylaluminum halides such as dimethylaluminum chloride, diethylaluminum chloride, diethylaluminum bromide and diisobutylaluminum chloride; dialkylaluminum hydrides such as diethylaluminum hydride and diisobutylaluminum hydride; dimethylaluminum methoxide, diethylaluminum ethoxy And dialkylaluminum aryloxides such as diethylaluminum phenoxide.

Of these, trialkylaluminum and trialkylaluminum are particularly preferred. Further, as the organoaluminum compound represented by the general formula _{(i-C 4 H 9)} x Al y (C 5 H 10) z (x, y, z are each a positive number, the z ≧ 2x) represented by Isoprenyl aluminum can also be used.

The above-mentioned organoaluminum compound is
Used alone or in combination. As the solvent used in the preparation of the aluminoxane, benzene, toluene, xylene, cumene, aromatic hydrocarbons such as cymene,
Aliphatic hydrocarbons such as pentane, hexane, heptane, octane, decane, dodecane, hexadecane and octadecane; alicyclic hydrocarbons such as cyclopentane, cyclohexane, cyclooctane and methylcyclopentane; petroleum distillates such as gasoline, kerosene and light oil And hydrocarbon solvents such as halides of the above-mentioned aromatic hydrocarbons, aliphatic hydrocarbons and alicyclic hydrocarbons, especially chlorinated products and brominated products. In addition, ethers such as ethyl ether and tetrahydrofuran can also be used. Among these solvents, aromatic hydrocarbons are particularly preferred.

In the benzene-insoluble organic aluminum oxy compound, the Al component soluble in benzene at 60 ° C. is 10% or less, preferably 5% or less in terms of Al atom.
It is particularly preferably at most 2%, and is insoluble or hardly soluble in benzene.

The solubility of the organoaluminum oxy compound in benzene was determined by suspending the organoaluminum oxy compound corresponding to 100 milligram atoms of Al in 100 ml of benzene, mixing the mixture at 60 ° C. for 6 hours with stirring, and adding a jacket. Using a G-5 glass filter, 6
After filtration at 0 ° C. while hot, the solid part separated on the filter is washed four times with 50 ml of benzene at 60 ° C., and the amount (x mmol) of Al atoms present in the whole filtrate is measured. (X%).

(C) Particulate Carrier The olefin polymerization catalyst used in the present invention is a solid catalyst in which at least one of (A) the transition metal compound and (B) the organoaluminum oxy compound is supported on a particulate carrier. There may be.

The carrier (C) is an inorganic or organic compound having a particle size of 10 to 300 μm, preferably 20 to 300 μm.
A 200 μm granular or particulate solid is used. Among them, a porous oxide is preferable as the inorganic carrier, and specifically, SiO ₂ , Al ₂ O ₃ , MgO, ZrO ₂ ,
TiO ₂ , B ₂ O ₃ , CaO, ZnO, BaO, ThO _{2 and the} like or a mixture thereof, for example, SiO ₂ -MgO, SiO
_2- Al ₂ O ₃ , SiO ₂ -TiO ₂ , SiO ₂ -V ₂ O ₅ , Si
O ₂ —Cr ₂ O ₃ and SiO ₂ —TiO ₂ —MgO can be exemplified. Among them, those containing at least one component selected from the group consisting of SiO ₂ and Al ₂ O ₃ as a main component are preferable.

The above inorganic oxide contains a small amount of Na ₂ C
O ₃ , K ₂ CO ₃ , CaCO ₃ , MgCO ₃ , Na ₂ SO ₄ ,
Al ₂ (SO ₄ ) ₃ , BaSO ₄ , KNO ₃ , Mg (NO ₃ )
₂ , carbonates such as Al (NO ₃ ) ₃ , Na ₂ O, K ₂ O and Li ₂ O, sulfates, nitrates and oxide components may be contained.

The type of the fine particle carrier (C) is
And the properties differ depending on the production method, but are preferably used in the present invention.
The particulate carrier to be used has a specific surface area of 50 to 1000 m.
^Two/ G, preferably 100 to 700 m^Two/ G, pores
0.3-2.5cm in volume^Three / G
No. The fine particle carrier may be 100 to 1000 as needed.
℃, preferably 150-700 ℃
You.

Further, examples of the particulate carrier that can be used in the present invention include a granular or particulate solid of an organic compound having a particle size of 10 to 300 μm. Examples of these organic compounds include (co) polymers mainly composed of α-olefins having 2 to 14 carbon atoms such as ethylene, propylene, 1-butene and 4-methyl-1-pentene, or vinylcyclohexane and styrene. A polymer or copolymer as a main component can be exemplified.

(D) Organoaluminum Compound The olefin polymerization catalyst used in the production of the polyethylene according to the present invention comprises (A) the transition metal compound and (B) the organoaluminum oxy compound, and if necessary, (C) Although formed from a carrier, (D) an organoaluminum compound may be used if necessary.

As the (A) organoaluminum compound used as required, for example, an organoaluminum compound represented by the following general formula (II) can be exemplified. R ¹ _n AlX _3-n (II) (wherein, R ¹ represents a hydrocarbon group having 1 to 12 carbon atoms, X represents a halogen atom or a hydrogen atom, and n represents 1 to
3. In the general formula (II), R ¹ has ^{1 to 1} carbon atoms.
A hydrocarbon group such as an alkyl group, a cycloalkyl group or an aryl group, specifically, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, an isobutyl group, a pentyl group, a hexyl group, Octyl, cyclopentyl, cyclohexyl, phenyl, tolyl and the like.

Specific examples of such an organoaluminum compound include the following compounds. Trialkylaluminum such as trimethylaluminum, triethylaluminum, triisopropylaluminum, triisobutylaluminum, trioctylaluminum, tri-2-ethylhexylaluminum; alkenylaluminum such as isoprenylaluminum; dimethylaluminum chloride, diethylaluminum chloride, diisopropylaluminum chloride, diisobutyl Dialkylaluminum halides such as aluminum chloride and dimethylaluminum bromide; alkylaluminum sesquichlorides such as methylaluminum sesquichloride, ethylaluminum sesquichloride, isopropylaluminum sesquichloride, butylaluminum sesquichloride and ethylaluminum sesquibromide; Aluminum dichloride, ethyl aluminum dichloride, isopropyl aluminum dichloride, alkyl aluminum dihalides such as ethyl aluminum dibromide; diethylaluminum hydride, and alkyl aluminum hydride such as diisobutyl aluminum hydride.

Further, the organic aluminum compound (D) is
Using a compound represented by the following general formula (III)
Can also. R¹ _nAlY_3-n ... (III) (wherein, R¹Is R in the above general formula (II)¹Similar to carbonization
Y represents -OR ^TwoGroup, -OSiR^Three _ThreeGroup, -OA
lR^Four _TwoGroup, -NR^Five _TwoGroup, -SiR⁶ _ThreeGroup or -N
(R⁷) AlR⁸ _TwoAnd n is 1-2, and R^Two, R
^Three, R^FourAnd R⁸Is methyl group, ethyl group, isopropyl
Group, isobutyl group, cyclohexyl group, phenyl group, etc.
And R^FiveRepresents a hydrogen atom, a methyl group, an ethyl group,
Propyl, phenyl, trimethylsilyl, etc.
R⁶And R⁷Represents a methyl group, an ethyl group, etc.
You. ) Specific examples of such an organoaluminum compound include:
The following compounds are used.

(1) A compound represented by R ¹ _n Al (OR ² ) _3-n , for example, dimethyl aluminum methoxide, diethyl aluminum ethoxide, diisobutyl aluminum methoxide, etc. (2) R ¹ _n Al (OSiR ³⁾ ₃ ) a compound represented by _3-n ,
For example, Et ₂ Al (OSi Me ₃ ), (iso-Bu) ₂ Al
(OSiMe ₃ ), (iso-Bu) ₂ Al (OSiEt ₃ )
_{^{Like; (3) R 1 n Al}} (OAlR 4 2) a compound represented by _3-n,
For example, Et ₂ AlOAlEt ₂ , (iso-Bu) ₂ AlOA
l (iso-Bu) _{2, ^{etc.; (4) R 1 n Al}} (NR 5 2) a compound represented by _3-n, e.g., _{Me 2 AlNEt 2, Et 2 AlNHMe} , Me 2 Al
NHEt, Et ₂ AlN (SiMe ₃ ) ₂ , (iso-Bu) ₂
AlN etc. _{(SiMe 3) 2; (5} ) R 1 n Al (SiR 6 3) a compound represented by _3-n, e.g., (iso-Bu) such as _{2 AlSi Me 3; (6)} R 1 n Al (N (R ⁷⁾ AlR ⁸ ₂₎ a compound represented by _3-n, e.g., _{Et 2 AlN (Me) AlEt 2} , (iso
Etc. _{-Bu) 2 AlN (Et) Al} (iso-Bu) 2.

[0057] Among the organic aluminum compounds represented by the general formula (II) and (III), general formula R ¹ ₃ Al,
_{^{R 1 n Al (OR 2)}} 3-n, R 1 n Al (OAlR 4 2) 3-n
The compound represented by is preferable, and a compound in which R is an isoalkyl group and n = 2 is particularly preferable.

Catalyst Preparation The olefin polymerization catalyst comprises (A) a transition metal compound (component (A)) and (B) an organoaluminum oxy compound (component (B)) and, if necessary, (C) fine particles. Carrier, (D) organoaluminum compound (component (D))
Can be prepared by contacting The order of contact of the components at this time is arbitrarily selected, but the particulate carrier (C) and the component (B) are mixed and contacted, then the component (A) is mixed and contacted, and if necessary, the components ( D)
Are preferably mixed and contacted.

The contact of the above components can be carried out in an inert hydrocarbon solvent. Specific examples of the inert hydrocarbon medium include propane, butane, pentane, hexane, heptane, octane, decane, dodecane and kerosene. Aliphatic hydrocarbons such as cyclopentane, cyclohexane and methylcyclopentane; aromatic hydrocarbons such as benzene, toluene and xylene; halogenated hydrocarbons such as ethylene chloride, chlorobenzene, dichloromethane and the like. And the like.

In mixing and contacting the component (A), the component (B), the particulate carrier (C) and, if necessary, the component (D), the component (A) is usually added in an amount of 5 parts per gram of the particulate carrier (C). × 10 ^{-6 to} 5 × 10 ^-4 mol, preferably 10 ^-5 to 2
Used in an amount of ^10-4 mol, and the concentration of the component (A) is about ^10-4 to ^2x10-2 mol / liter, preferably 2x1
It is in the range of 0 ^-4 to 10 ^-2 mol / l. Component (B)
The atomic ratio (Al / transition metal) of aluminum and the transition metal in the component (A) is usually 10 to 500, preferably 20 to 200. Atomic ratio (Al-d / Al-b) of aluminum atom (Al-d) of component (D) and aluminum atom (Al-b) of component (B) used as required.
Is usually in the range of 0.02 to 3, preferably 0.05 to 1.5. The mixing temperature at the time of mixing and contacting the component (A), the component (B), the particulate carrier (C) and, if necessary, the component (D) is usually -50 to 150 ° C, preferably -2.
0 to 120 ° C., and the contact time is 1 minute to 50 hours, preferably 10 minutes to 25 hours.

The catalyst for olefin polymerization obtained as described above contains 5 × 10 ^{-6 to} 5 × 10 ^-4 gram atoms of transition metal atoms derived from the component (A) per gram of the fine particle carrier (C). Preferably, it is supported in an amount of 10 ^{-5 to} 2 × 10 ^-4 gram atom, and aluminum atom derived from the component (B) and the component (D) is 10 ^-3 to 1 g per 1 g of the particulate carrier (C).
5 × 10 ⁻² gram atoms, preferably 2 × 10 ⁻³ to 2 × 1
^Preferably, it is carried in an amount of 0 ^-2 gram atoms.

The catalyst used for the production of polyethylene is
A prepolymerized catalyst obtained by prepolymerizing an olefin in the presence of the components (A), (B), the particulate carrier (C) and, if necessary, the component (D) as described above may be used. The prepolymerization is carried out by introducing an olefin into an inert hydrocarbon solvent in the presence of the component (A), the component (B), the particulate carrier (C) and, if necessary, the component (D). It can be carried out.

The olefin used in the prepolymerization includes ethylene and an α-olefin having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, 1
-Dodecene, 1-tetradecene and the like. Among them, ethylene used in the polymerization or a combination of ethylene and an α-olefin is particularly preferred.

In the prepolymerization, the component (A) is
Usually 10 ^{-6 to} 2 × 10 ^-2 mol / l, preferably 5
× 10 ^-5 to 10 ^-2 used in an amount of mol / liter, the component (A) is particulate carrier (C) 1 g per usually 5 × 10 ^-6
It is used in an amount of up to 5 × 10 ^-4 mol, preferably 10 ^-5 to 2 × 10 ^-4 mol. The atomic ratio (Al / transition metal) between aluminum of the component (B) and the transition metal in the component (A) is as follows:
Usually it is 10-500, preferably 20-200. The atomic ratio (Al-d / Al-b) of the aluminum atom (Al-d) of the component (D) and the aluminum atom (Al-b) of the component (B) used as needed is usually 0.02 to 3, preferably in the range of 0.05 to 1.5. Prepolymerization temperature is-
The temperature is 20 to 80 ° C, preferably 0 to 60 ° C, and the prepolymerization time is 0.5 to 100 hours, preferably about 1 to 50 hours.

The olefin polymer produced by the prepolymerization is
0.1 to 500 g, preferably 0.2 to 300 g, more preferably 0.5 to 200 g per 1 g of the fine carrier (C).
Desirably, the amount is g. Further, the prepolymerization the catalyst, particulate carrier (C) 1 g per component (A) is about 5 × 10 ^-6 ~5 × 10 ^-4 gram atom as a transition metal atom, preferably 10 ^-5 ~2 × 10 ^- Carried in an amount of ⁴ grams atom,
The aluminum atom (Al) derived from the component (B) and the component (D) has a molar ratio (Al / M) to the transition metal atom (M) derived from the component (A) of 5 to 200, preferably 10 to 200. It is desirable that the catalyst be carried in an amount in the range of 150.

The prepolymerization can be carried out either in a batch system or a continuous system, and can be carried out under reduced pressure, normal pressure or under pressure. In the prepolymerization,
Intrinsic viscosity [η] measured in decalin at least 135 ° C. in the coexistence of hydrogen in the range of 0.2 to 7 dl / g;
It is desirable to produce a prepolymer of preferably 0.5 to 5 dl / g.

The polyethylene of the present invention is prepared by adding ethylene to an α-olefin having 3 to 20 carbon atoms, for example, propylene,
Copolymerizes butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene Obtained by:

In the present invention, the copolymerization of ethylene and α-olefin is carried out in a gas phase or a liquid phase in the form of a slurry. In slurry polymerization, an inert hydrocarbon may be used as a solvent, or an olefin itself may be used as a solvent.

Specific examples of the inert hydrocarbon solvent used in the slurry polymerization include aliphatic hydrocarbons such as butane, isobutane, pentane, hexane, octane, decane, dodecane, hexadecane and octadecane; cyclopentane, methylcyclopentane , Cyclohexane,
Alicyclic hydrocarbons such as cyclooctane; aromatic hydrocarbons such as benzene, toluene and xylene; gasoline;
Examples include petroleum fractions such as kerosene and light oil. Among these inert hydrocarbon media, aliphatic hydrocarbons, alicyclic hydrocarbons, petroleum fractions and the like are preferred.

In the case of carrying out the slurry polymerization method or the gas phase polymerization method, the olefin polymerization catalyst as described above is usually used in a concentration of 10 ^-8 to 1 as transition metal atom concentration in the polymerization reaction system.
0 ^-3 gram atoms / liter, preferably 10 ^-7 to 10 ^-4
Preferably, it is used in an amount of gram atoms / liter.

In the main polymerization, the same organic aluminum oxy compound and / or organic aluminum compound (D) as the component (B) may be added. At this time, the atomic ratio (Al / M) of the aluminum atom (Al) derived from the organic aluminum oxy compound and the organic aluminum compound to the transition metal atom (M) derived from the transition metal compound (A) is 5 to 300. , Preferably 10 to 20
0, more preferably 15 to 150.

When performing the slurry polymerization method, the polymerization temperature is usually in the range of −50 to 100 ° C., preferably 0 to 90 ° C. When performing the gas phase polymerization method, the polymerization temperature is: Usually, it is in the range of 0 to 120 ° C, preferably 20 to 100 ° C.

The polymerization pressure is usually from normal pressure to 100 kg /
cm ² , preferably ² to 50 kg / cm ² under pressure, and the polymerization can be carried out in any of a batch system, a semi-continuous system, and a continuous system.

Further, the polymerization can be carried out in two or more stages having different reaction conditions. Medical container The medical container according to the present invention is a bag made of a multilayer film,
It is a bag made of a single-layer film or a bottle made of a single layer, and at least one layer of a multilayer film, a single-layer film, and a single-layer bottle are formed of the above-described polyethylene.

The medical container according to the present invention can be manufactured by a water-cooled or air-cooled inflation method, a T-die method, a dry lamination method, an extrusion lamination method, a blow molding method, or the like.

As a method for forming a medical bag, an inflation method and a co-extrusion T-die method are preferable from the viewpoint of hygiene and economy, and a hollow molding method is preferable for forming a medical bottle.

The medical container of the present invention has a thickness of 0.05 to
It is 1.00 mm, preferably 0.1 to 0.7 mm, and more preferably 0.15 to 0.3 mm. If the thickness of the container is 0.05 mm or more, the impact resistance is good and there is no practical problem.

[0078]

Industrial Applicability The polyethylene for medical containers according to the present invention has a narrow molecular weight distribution and a narrow composition distribution and a low polymer content. Furthermore, it has excellent moldability.

Since the medical container according to the present invention is molded from the above-mentioned polyethylene, it has good hygiene and flexibility, and has a temperature of 115 ° C., 3 ° C.
Even if the sterilization treatment is performed in 0 minutes, the transparency is not lost, the heat resistance is excellent, and no wrinkling or deformation occurs.

It is to be noted that a retort food container can be produced from the linear polyethylene used in the present invention. This retort food container has very good transparency even after retort treatment (sterilization treatment), has impact resistance and flexibility, and is excellent in heat resistance.

[0081]

EXAMPLES Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples.

The evaluation of the physical properties of polyethylene and the evaluation of the physical properties of hollow molded articles and films were performed as follows. Molecular weight distribution (Mw / Mn) Waters GPC model ALC-GPC-150C
Was measured by The measurement conditions were as follows: PSK-GMH-HT manufactured by Toyo Soda Co., Ltd. was used as the column, and orthodichlorobenzene (ODCB) solvent was used at 140 ° C.

Maximum Peak Temperature by DSC (Tm) The peak temperature (Tm) was measured using a DSC-7 apparatus manufactured by PerkinElmer. Temperature at maximum peak position in endothermic curve (Tm)
Is to pack about 5 mg of the sample into an aluminum pan at 10 ° C / min.
After the temperature was raised to 0 ° C and kept at 200 ° C for 5 minutes,
It is determined from an endothermic curve when the temperature is lowered to room temperature at a rate of 10 ° C./minute and then at a rate of 10 ° C./minute.

Haze (Transparency) The haze as an index of the transparency of a hollow molded article and a film which has been retorted at 115 ° C. for 30 minutes is ASTM D-1.
It was measured according to 003-61.

Light Transmittance in Water (Transparency) The light transmittance in water of a hollow molded article and a film retorted at 115 ° C. for 30 minutes was measured in accordance with the Japanese Pharmacopoeia Plastic Container Test Method.

Appearance The appearance of the hollow molded article and the film which had been retorted at 115 ° C. for 30 minutes was visually observed, and the appearance was evaluated by X when deformation was observed, and the appearance was evaluated when no deformation was observed. Is indicated by ○.

Young's Modulus (Flexibility) The Young's modulus was measured according to JIS K6781.

[0088]

[Production Example 1] Production of polyethylene (A-1) [Preparation of catalyst] Silica 10 dried at 250 ° C for 10 hours
After suspending the suspension in 154 liters of toluene,
Cooled to ° C. Thereafter, a toluene solution of methylaminooxane (Al = 1.33 mol / liter) 57.5.
One liter was added dropwise over one hour. At this time, the temperature in the system is set to 0
C. Subsequently, the reaction was carried out at 0 ° C. for 30 minutes, then the temperature was raised to 95 ° C. over 1.5 hours, and the reaction was carried out at that temperature for 20 hours. Thereafter, the temperature was lowered to 60 ° C., and the supernatant was removed by a decantation method. After the solid component thus obtained was washed twice with toluene, toluene 100
Resuspended in liters. Into this system, a toluene solution of bis (1,3-dimethylcyclopentadienyl) zirconium dichloride (Zr = 27.0 mmol / l) 1
6.8 liters were dropped at 80 ° C. for 30 minutes, and further reacted at 80 ° C. for 2 hours. After that, remove the supernatant,
By washing twice with hexane, 3.5 m / g was obtained.
A solid catalyst containing g of zirconium was obtained.

[Preparation of Preliminary Polymerization Catalyst] 870 g of the solid catalyst obtained above and 260 g of 1-hexene were added to 87 liters of hexane containing 2.5 mol of triisobutylaluminum, and the ethylene was preliminarily prepared at 35 ° C. for 5 hours. By performing the polymerization, a prepolymerized catalyst in which 10 g of polyethylene was prepolymerized per 1 g of the solid catalyst was obtained.

[Polymerization] Using a continuous fluidized-bed gas-phase polymerization apparatus, ethylene and 1-hexene were copolymerized at a total pressure of 20 kg / cm ² -G and a polymerization temperature of 80 ° C. 0.33 mmol of the prepolymerized catalyst prepared above in terms of zirconium atoms
/ H, 10 mmol / h of triisobutylaluminum
And ethylene, 1-hexene, hydrogen and nitrogen were continuously supplied to maintain a constant gas composition during the polymerization (gas composition; 1-hexene / ethylene = 0.
02, hydrogen / ethylene = 1.2 × 10 ⁻³ , ethylene concentration = 70%).

The yield of the obtained polyethylene (A-1) was
The weight was 60 kg / hr, the density was 0.923 g / cm ³ , the MFR was 1.5 g / 10 min, and the decane-soluble portion at room temperature was 0.41 part by weight. Table 1 shows the properties of the obtained polyethylene (A-1).

[0092]

Production Example 2 In the preparation of the catalyst component of Production Example 1, bis (1,3-dimethylcyclopentadienyl) zirconium dichloride was used instead of the toluene solution of bis (1,3-dimethylcyclopentadienyl) zirconium dichloride. Solution of Zinc (Zr; 28.1 mmol / L) 2.
Polymerization was carried out in the same manner as in Production Example 1 except that 9 l and 10.9 l of a toluene solution of bis (1,3-n-butylmethylcyclopentadienyl) zirconium dichloride (Zr; 34.0 mmol / l) were used. A catalyst was obtained.

[Polymerization] The density and MFR were adjusted as shown in Table 1, and a polyethylene (A-2) was obtained in the same manner as in Production Example 1 except that the above-mentioned olefin polymerization catalyst was used. Table 1 shows the properties of the obtained polyethylene (A-2).

[0094]

[Production Example 3] [Preparation of catalyst for olefin polymerization] In a nitrogen stream, 10 mol of commercially available anhydrous magnesium chloride was suspended in 50 liters of dehydrated and purified hexane, and ethanol 60 was stirred.
After the mol was added dropwise over 1 hour, the mixture was reacted at room temperature for 1 hour.

Then, 27 mol of diethylaluminum chloride was added dropwise to the reaction solution at room temperature, and the mixture was stirred for 1 hour.
Subsequently, after adding 100 mol of titanium tetrachloride, the system was cooled to 70%.
The temperature was raised to ℃ and the reaction was carried out with stirring for 3 hours. The generated solid part was separated by decantation, washed repeatedly with purified hexane, and then used as a hexane suspension.

[Production of Polyethylene (A-3)] In a continuous polymerization reactor of 200 liters, dehydrated and purified solvent hexane was continuously supplied at 80 liters / hr and the catalyst with a carrier was converted to titanium at 1.2 mmol / hr continuously. 13 kg / hr ethylene, 1-butene 1
3.0 kg / hr, 100 liters / hr of hydrogen were continuously supplied, polymerization temperature was 145 ° C., and total pressure was 30 kg / cm ² −
G, the residence time was 1 hour, and the copolymer was prepared under the conditions that the concentration of the copolymer with respect to the solvent hexane was 12 g / l.

The polyethylene (A-3) obtained as described above has a density of 0.920 g / cm ³ , a melt flow rate of 2.0 g / 10 min, and a decane-soluble portion at 23 ° C. Is 10% by weight, and Mw / Mn is 2.
8, and the Tm was 116.2 ° C. Table 1 shows the properties of the obtained polyethylene (A-3).

[0098]

[Table 1]

[0099]

Example 1 Polyethylene (A-1) obtained in Production Example 1
Was pelletized by an extruder, and a hollow molded article was molded under the following molding conditions.

[Production of hollow molded article]
Cylinder temperature 1 using a Placo blow molding machine
60-180 ° C, die temperature 180 ° C, mold temperature 20
° C, blow pressure 3kg / cm ^Two400μ thickness under -G condition
m of a hollow molded article was molded.

The obtained hollow molded article was heated at 115 ° C.
After the retort treatment for 30 minutes, haze, light transmittance in water, appearance, and Young's modulus were measured and evaluated by the methods described above. Table 2 shows the results.

[0102]

Example 2 Polyethylene (A-2) obtained in Production Example 2
Was pelletized with an extruder, and a hollow molded article was formed and evaluated in the same manner as in Example 1. Table 2 shows the results.

[0103]

Comparative Example 1 [Production of Hollow Molded Article] The polyethylene (A-3) obtained in Production Example 2 was molded under the same conditions as in Example 1 to obtain a hollow molded article.

The obtained hollow molded article was heated at 115 ° C.
After the retort treatment for 30 minutes, haze, light transmittance in water, appearance and Young's modulus were measured or evaluated by the methods described above. Table 2 shows the results.

[0105]

[Table 2]

[0106]

Example 3 [Production of Film] The polyethylene (A-1) produced in Production Example 1 was subjected to a cylinder temperature of 180 to 220 ° C. and a die temperature of 22 by a cast film molding machine manufactured by Modern.
The film was formed under the conditions of 0 ° C. and a roll temperature of 30 ° C. to obtain a film having a thickness of 200 μm.

The obtained film was heated at 115 ° C. for 3 hours.
After the retort treatment for 0 minute, haze, light transmittance in water, appearance and Young's modulus were measured or evaluated by the methods described above. Table 3 shows the results.

[0108]

Example 4 [Production of film] In the same manner as in Example 3, except that the polyethylene (A-2) produced in Production Example 2 was used instead of the polyethylene (A-1). Thickness 2
A film of 00 μm was obtained.

The obtained film was heated at 115 ° C. for 3 hours.
After the retort treatment for 0 minute, haze, light transmittance in water, appearance and Young's modulus were measured or evaluated by the methods described above. Table 3 shows the results.

[0110]

Comparative Example 2 Production of Film In the same manner as in Example 3, except that the polyethylene (A-3) produced in Comparative Example 1 was used instead of the polyethylene (A-1). Thickness 2
A film of 00 μm was obtained.

The obtained film was heated at 115 ° C. for 3 hours.
After the retort treatment for 0 minute, haze, light transmittance in water, appearance and Young's modulus were measured or evaluated by the methods described above. Table 3 shows the results.

[0112]

[Table 3]

[0113]

Example 5 [Production of Film] The polyethylene (A-1) produced in Production Example 1 was molded by an air-cooled inflation method under the following molding conditions to produce a film having a thickness of 50 μm and a width of 450 mm.

[Molding conditions] Molding machine: Placo LM 65 mmφ inflation molding machine (manufactured by Placo, high-pressure low-density polyethylene resin specification) Screw: L / D = 28, CR = 2.8, with intermediate mixing Is: 200 mmφ (diameter), 1.2 mm (lip width) Air ring: 2 gap type Molding temperature: 200 ° C. Take-off speed: 18 m / min The obtained film is subjected to a retort treatment at 115 ° C. for 30 minutes and then haze. The light transmittance, appearance and Young's modulus in water were measured or evaluated by the methods described above. Table 4 shows the results.

[0115]

Example 6 Production of Film A film having a thickness of 50 μm was obtained from the polyethylene (A-2) produced in Production Example 2 in the same manner as in Example 5.

The obtained film was heated at 115 ° C. for 3 hours.
After the retort treatment for 0 minute, haze, light transmittance in water, appearance and Young's modulus were measured or evaluated by the methods described above. Table 4 shows the results.

[0117]

Comparative Example 3 [Production of Film] From the polyethylene (A-3) produced in Comparative Example 1, a film having a thickness of 50 μm was obtained in the same manner as in Example 5.

The obtained film was heated at 115 ° C. for 3 hours.
After the retort treatment for 0 minute, haze, light transmittance in water, appearance and Young's modulus were measured or evaluated by the methods described above.

Table 4 shows the results.

[0120]

[Table 4]

Claims (3)

[Claims] 1. An ethylene having an α of 3 to 12 carbon atoms.
-A copolymer with an olefin, wherein (i) the density is 0.
(Ii) 1 in the range of 915 to 0.940 g / cm ³ ;
The melt flow rate at 90 ° C. under a load of 2.16 kg is in the range of 0.1 to 10.0 g / 10 minutes, and (iii) the decane-soluble component amount ratio (W) and the density (d) at room temperature are W <80 × exp (−100 (d−0.88)) + 0.1, (iv) 190 ° C. of the molten polymer
The fluidity index (F) defined by the shear rate when the shear stress reaches 2.4 × 10 ⁶ dyne / cm ² at
I (1 / sec)) and the melt flow rate (MFR (g
/ 10 min)) and the relationship FI> 75 × MFR is satisfied, and (v) the melt tension at 190 ° C. (MT (g)) and the melt flow rate (MFR)
(G / 10 minutes)) and 5.5 × MFR ^-0.65 >MT> 2.2 × MFR ^-0.84 . (A) a transition metal compound represented by the following general formula (I): ML _X (I) (wherein M represents a transition metal selected from Group IVB of the periodic table; Represents a ligand coordinated to a transition metal atom, and at least two of the ligands L are a substituted cyclopentadienyl group having only 2 to 5 substituents selected from a methyl group and an ethyl group. And the ligand L other than the substituted cyclopentadienyl group is a hydrocarbon group having 1 to 12 carbon atoms, an alkoxy group, an aryloxy group, a halogen atom, a trialkylsilyl group or a hydrogen atom, and x is (The valence of the transition metal atom M is shown.) (B) Copolymerization of ethylene with an α-olefin having 3 to 12 carbon atoms in the presence of an olefin polymerization catalyst containing an organoaluminum oxy compound Procurement obtained by Polyethylene according to claim 1. 3. A medical container comprising the polyethylene according to claim 1 or 2.