JPH1180259A - Polyethylene resin for large blow-molded product, its production and large blow-molded container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a resin desirable for blow-molding large cans for industrial chemicals and containers for use in container trucks or trains by selecting a polyethylene resin specified in a density, a melt flow rate, a molecular weight distribution, a melt tension, a content of boiling n-hexane extractibles and an environmental stress cracking time. SOLUTION: A polyethylene is selected which has a density of 0.94-0.97 g/cm<3> (JIS K6760-1981), a melt flow rate of 1-15 g/10 min (HLMFR) (JIS K7210-1976, condition 7, at 190 deg.C under a load of 21.6 kg), a weight-average molecular weight/number-average molecular weight (GPC) of 8-15 and a melt tension(MT) of 15-65 g (at 190 deg.C), satisfying the relationship: logMT >=-0.455×logHLMFR+1.64 and having a content of boiling n-hexane extractibles of 0.2 wt.% or below and an environmental stress cracking resistance time of 350 hr or above. A large molding made from this resin has excellent low-temperature drop strength and good skin and is capable of long repeated use.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large-size blow molding which can be used repeatedly as a large industrial chemical can or container container, has excellent low-temperature drop strength, has good skin of molded products, and can be used repeatedly for a long period of time. The present invention relates to a polyethylene resin and a container.

[0002]

2. Description of the Related Art When a high-density polyethylene resin becomes a high molecular weight grade having a weight average molecular weight of about 200,000, it has a large melt tension, and also has an excellent impact strength and environmental stress cracking time (ESCR). For this reason, high molecular weight grades are used in the manufacture of industrial parts such as gasoline tanks and large hollow molded products such as industrial chemical cans and container containers. However, since fluidity is reduced by increasing the molecular weight,
Molding processability is reduced, and the surface of the molded product is rough. Also,
For large-size blow molding, the melt elasticity (melt tension, die swell) is low.
SCR was also in short supply. Therefore, two-stage polymerization methods and three-stage polymerization methods have been proposed for the purpose of expanding the molecular weight distribution and improving fluidity. In addition, for the purpose of improving mechanical strength and ESCR, short-chain branching is performed on high-molecular-weight components. A method of introducing a large number of methods (Japanese Patent Application Laid-Open No. 54-10044, etc.) has been proposed.

[0003] Although the flow characteristics and the ESCR are slightly improved by these methods, the large-sized molded product still has insufficient low-temperature drop strength, a good ESCR, and the molded product does not have rough skin. The development of polyethylene resin for blow molding has not been completed.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to a polyethylene resin for large-size blow molding, which is suitable for large-size blow molding because the polyethylene resin has a large melt tension and is hard to be uneven in thickness. When used as a container or container, it is intended to have excellent low-temperature drop strength, good molded product skin, and long-term reusability.

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the above problems can be solved by using a polyethylene resin having a specific property, and have reached the present invention.

That is, it is a large-sized blow molding polyethylene resin having the following characteristics (1) to (6).

(1) Density (JIS K6760-198)
1) is 0.94 to 0.97 g / cm ³ , (2) 190
° C, melt flow rate at 21.6 Kg load (JIS
K7210-1976, condition 7, HLMFR) 1-1
5 g / 10 min, (3) a ratio (Mw / Mn) of weight average molecular weight (Mw) to number average molecular weight (Mn) determined by gel permeation chromatography (GPC) of 8 to 15, (4) 190 ° C. Melt tension (MT, unit g) at 15 to 65 g, and 190 ° C., 21.6 kg
Melt flow rate of load (JIS K7210-19)
76, Condition 7, HLMFR) are as follows: LogMT ≧ −0.455 × LogHLMFR + 1.6
(5) Boiling normal hexane extraction amount is 0.2% by weight or less, (6) Environmental stress cracking time (ES
CR) is 350 hours or more.
(I) A low molecular weight ethylene homopolymer or ethylene and α- having 3 to 20 carbon atoms satisfying the following (a) and (b):
35 to 60% by weight of an olefin copolymer, (a) o-dichlorobenzene (hereinafter abbreviated as ODCB)
The intrinsic viscosity (η1) at 140 ° C. using a solvent is 0.6 to
1.5 dl / g (b) Density (JIS K6760-1981) is 0.9
5 to 0.98 g / cm ³ and (II) high molecular weight ethylene satisfying the following (c) and (d) and 3 to 20 carbon atoms
(C) ODCB, intrinsic viscosity (η2) at 140 ° C. of 4 to 1
5 dl / g (d) Density (JIS K6760-1981) is 0.8
A production method in which a mixture comprising ⁹ to 0.95 g / cm ³ is subjected to a crosslinking treatment is preferred. Hereinafter, the polyethylene resin for large blow molding of the present invention will be described in more detail.

The polyethylene resin for large blow molding of the present invention is obtained by polymerizing ethylene alone or ethylene and an α-olefin having 3 to 20 carbon atoms in the presence of a highly active catalyst, using a hydrocarbon having 6 or more carbon atoms as a solvent. Can be manufactured. Examples of the α-olefin having 3 to 20 carbon atoms include propylene, 1-butene, 4-methyl-1-pentene, 1-pentene, 1-hexene, 1-octene, 1-nonene,
-Decene, 1-hexadecene, 1-octadecene and the like.

As the highly active catalyst, Ziegler catalysts,
A so-called metallocene catalyst is suitable. Among them, 10 kg of ethylene (co) polymer per 1 g of catalyst
As described above, preferably, a resin that can produce 30 kg or more can be used to obtain a polyethylene resin having a low ash content. A catalyst system using an inorganic oxide such as silica, silica-alumina, or silica-titania as a carrier for the catalyst is not suitable for the present invention.

Specific examples of such a highly active catalyst include:
For example, Ziegler catalysts include catalysts comprising a solid catalyst component (A) essentially comprising titanium, magnesium and halogen and an organoaluminum compound (B). More specifically, JP-A-48-66178, JP-A-50-66178
No. 51587, JP-A-55-78005, JP-A-56
-61406, JP-A-56-155205, JP-A-57-212210, JP-A-59-58005, JP-A-60-262802, JP-A-4-351616
JP-A-5-287020, JP-A-7-41513
And the catalysts proposed in Japanese Patent Publication No.

In order to manufacture the large-sized blow-molded polyethylene resin of the present invention, when used as a chemical container, the concentration of metal impurities eluted is kept low, and a resin of low molecular weight polymer which causes dust is generated. In order to limit the incorporation into the solvent, a slurry polymerization method using a saturated hydrocarbon having 6 or more carbon atoms as a solvent for the polymerization is preferable. Hydrocarbons having 5 or less carbon atoms cannot dissolve and remove very low molecular weight polymers called by-products during polymerization,
It is not preferable because it is difficult to achieve a boiling normal hexane extraction amount of 0.2% by weight or less. For the same reason, solventless polymerization without using a solvent, that is, so-called gas phase polymerization, is not preferable.

As the saturated hydrocarbon having 6 or more carbon atoms, for example, a linear, branched or cyclic compound can be used. More specifically, a linear, branched, or cyclic compound of hexane, heptane, or octane may, for example, be mentioned.

Ethylene alone or ethylene and carbon number 3
The polymerization of α-olefins of from 20 to 20 is carried out batchwise or continuously at a polymerization temperature of 50 to 200 ° C. If the polymerization temperature is lower than this temperature range, the catalyst activity cannot be sufficiently exhibited, and very low molecular weight components such as by-produced wax cannot be sufficiently dissolved and removed by the polymerization solvent. Also, at polymerization temperatures higher than this temperature range,
Since the catalyst is deactivated by heat, it is difficult to sufficiently exert the catalyst activity.

The polymerization operation is preferably carried out in two or more stages of multistage polymerization. This means that in order to satisfy the desired density, HLMFR and melt elasticity, it is necessary to control the respective densities, molecular weights and proportions of the relatively low molecular weight components and the relatively high molecular weight components in each stage of the polymerization process. is necessary. In the two-stage polymerization method, (I) a low molecular weight ethylene homopolymer or a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms satisfying the following (a) and (b):
(A) ODCB, intrinsic viscosity (η1) at 140 ° C. of 0.6
1.5 dl / g (b) Density (JIS K6760-1981) is 0.9
5 to 0.98 g / cm ³ and (II) high molecular weight ethylene satisfying the following (c) and (d) and 3 to 20 carbon atoms
(C) ODCB, intrinsic viscosity (η2) at 140 ° C. of 4 to 1
5 dl / g (d) Density (JIS K6760-1981) is 0.8
A production method using a mixture consisting of ⁹ to 0.95 g / cm ³ is preferred. The method for obtaining the mixture and the polymerization order of the components (I) and (II) are not limited. The ethylene homopolymer or the copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms, which is the low molecular weight component (I), has (a) ODCB and an intrinsic viscosity (η1) at 140 ° C. of 0.6 to 1.5 dl / g, more preferably 0.6 to 1.3 dl / g is used. When η1 is less than 0.6 dl / g, the mechanical strength of the obtained mixture decreases, and when η1 exceeds 1.5 dl / g, the fluidity of the obtained mixture decreases. The component (I) having a density of 0.95 to 0.98 g / cm ³ is used. If the density is less than 0.95 g / cm ³ , the rigidity of the mixture will be insufficient, and if the density exceeds 0.98 g / cm ³ , the impact strength of the mixture will decrease. The above high molecular weight component (I
The copolymer (I) of ethylene and an α-olefin having 3 to 20 carbon atoms has (a) an ODCB and an intrinsic viscosity (η2) at 140 ° C. of 4 to 15 dl / g, more preferably 4 to 10 dl / g.
dl / g is used. When η2 is less than 4 dl / g, the melt elasticity of the obtained mixture decreases, and the ESCR
And mechanical strength such as impact strength are reduced, and η2 is 1
If it exceeds 5 dl / g, the molded article will be rough. The density of the component (II) is 0.89 to 0.95 g / cm.
³ , more preferably 0.90 to 0.94 g / cm ³ . If the density is less than 0.89 g / cm ³ , the rigidity of the mixture will be insufficient, and if the density exceeds 0.95 g / cm ³ , the ESCR will decrease. The mixing ratio of the low molecular weight component (I) and the high molecular weight component (II) is 35-
At 60% by weight, component (II) is 65 to 40% by weight. When the blending ratio of the component (I) is less than 35% by weight, the fluidity of the obtained mixture is reduced. When the blending ratio of the component (I) exceeds 60% by weight, the low-temperature drop strength is reduced.

Further, in order to produce the large-sized blow-molded polyethylene resin of the present invention, it is preferable to subject the mixture of the two-stage polymerized product to a crosslinking treatment. Cross-linking treatment is a method of melt-kneading the mixture in the presence of oxygen, a method of heat-treating or melt-kneading the mixture at or above the decomposition temperature of the organic peroxide by adding an organic peroxide, and irradiating the mixture with radiation. And the like. Among these methods, particularly, a method of melt-kneading the mixture in the presence of oxygen and a method of adding an organic peroxide to the mixture and melt-kneading the mixture at a temperature equal to or higher than the decomposition temperature of the organic peroxide are economical and operationally efficient. It is more preferable than the nature.
When an organic peroxide is used, not only the organic peroxide but also a crosslinking aid may be added.

As the organic peroxide, for example, di-t-
Butyl peroxide, dicumyl peroxide, t-
Butyl cumyl peroxide, 2,5-dimethyl-2,
5-bis (t-butylperoxy) hexane, 2,5-
Dialkyl peroxides such as dimethyl-2,5-bis (t-butylperoxy) hexyne-3, α, α′-bis (t-butylperoxy) diisopropylbenzene, and 2,5-dimethyl-2,5- Peroxyesters such as bis (benzoylperoxy) hexane, t-hexylperoxybenzoate, t-butylperoxy-m-toluylbenzoate, t-butylperoxybenzoate, bis (t-butylperoxy) isophthalate, 1,1-bis (t-butylperoxy) 3,
3,5-trimethylcyclohexane, 1,1-bis (t
-Hexylperoxy) cyclohexane, 1,1-bis (t-hexylperoxy) 3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy)
Cyclohexane 1,1-bis (t-butylperoxy)
Peroxy ketals such as cyclododecane and n-butyl 4,4-bis (t-butylperoxy) valerate are exemplified. Among them, dialkyl peroxides, especially α, α'-bis (t-butylperoxy)
Diisopropylbenzene, 2,5-dimethyl-2,5-
It is preferable to use bis (t-butylperoxy) hexyne-3.

The oxygen concentration and the organic peroxide concentration at the time of the crosslinking treatment are determined by the HLM of the ethylene polymer after the crosslinking treatment.
FR and melt elasticity are LogMT ≧ −0.455 × Log
There is no particular limitation as long as the concentration falls within a range satisfying HLMFR + 1.64. When oxygen is used, the gas atmosphere in the granulator is set to 100 ppm to 10 ppm in oxygen concentration depending on the granulation speed and the supply speed of the oxygen-containing gas sent to the granulator.
%, Preferably 0.1 to 5%. When an organic peroxide is used, it depends on the kneading temperature, but it is 1 to 1000 PPM, preferably 5 to 200 PPM, based on the polyethylene resin.
It is desirable to use PPM. When the amount of the organic peroxide is larger than this range, the crosslinking proceeds, and a molded article with good skin is not obtained due to poor elongation of the copolymer during molding, or a gel is easily generated by local crosslinking. Become. In extreme cases, oxidative degradation may occur. When the amount of the organic peroxide is less than this range, the melt elasticity is low, and the thickness tends to be uneven.

The polyethylene resin for large blow molding of the present invention has a density, a melt flow rate, a molecular weight distribution (Mw / Mn), a melt tension and an HLMF as shown below.
It specifies the relationship between R and melt tension, the amount of boiling normal hexane extracted, and the environmental stress cracking time (ESCR).

That is, the density of the polyethylene resin (JIS
K6760-1981) is 0.94 to 0.97 g / c.
m ³ and less than 0.94 g / cm ³ , the rigidity of the container is inferior. On the other hand, when the density exceeds 0.97 g / cm ³ , the strength of the container is reduced due to a decrease in chemical resistance.

The polyethylene resin is heated at 190.degree.
Melt flow rate of Kg load (JIS K7210-
1976, condition 7, HLMFR) is 1 to 15 g /
When the HLMFR is less than 1 g / 10 minutes, the fluidity is reduced. If the HLMFR exceeds 15 g / 10 minutes, the drop strength decreases.

The ratio Mw / weight average molecular weight (Mw) of the polyethylene resin determined by gel permeation chromatography (GPC) to the number average molecular weight (Mn)
Mn is from 8 to 15, and when it is less than 8, the molecular weight distribution is narrow and the fluidity is poor, and the deterioration of the resin is promoted. The Mw
If / Mn exceeds 15, the impact strength decreases. Also,
If the Mw / Mn exceeds 15, the shape of the pinch-off portion of the parison joint becomes inferior, and the drop strength decreases.

The polyethylene resin has a melt tension at 190 ° C. (MT, unit g) of 15 to 65 g, preferably 1 to 65 g.
The amount is 5 to 60 g, and if it exceeds 65 g, the fluidity decreases. If the weight is less than 15 g, the melt tension that supports the weight of the parison decreases, and it becomes difficult to perform large-size blow molding. Also, MT
If it is less than 15 g, uneven wall thickness occurs and the drop strength decreases.

In large-size blow molding, in order to make the thickness of each part of the molding container uniform and to improve the drop strength, the polyethylene resin at 190 ° C. Melt tension (MT,
The unit g) is a melt flow rate (JIS K7210-1976, condition 7, HLM) at 190 ° C. under a load of 21.6 kg.
FRMT) LogMT ≧ −0.455 × LogHLMFR + 1.6
4 It is necessary to satisfy the following relationship.

The boiling normal hexane extractable amount of the polyethylene resin is 0.2% by weight or less. If the content exceeds 0.2% by weight, the amount of polymer components eluted into the contents such as chemicals will increase, and the quality (taste and odor) of the contents will be reduced and dust will be generated.

The polyethylene resin has an environmental stress cracking resistance (ESCR) of 350 hours or more. ESCR is 35
If the time is less than 0 hours, the chemicals to be contained and the residual strain of the molded container are susceptible to influence, and the reliability for storing the contents for a long period of time or for repeated use is low.

The amount of ash contained in the polyethylene resin is preferably 150 PPM or less. If the amount of ash contained in the polyethylene resin exceeds 150 PPM, the ash elutes in the chemical, so that the concentration of metal impurities in the chemical increases. The ash content indicates the ratio of complete ash to the total resin by weight PPM. Completely incinerated is obtained by complete incineration in an electric furnace, and includes Al, Mg, Ti, Si
And the like, metal-containing additives such as neutralizing agents, and metal oxides of impurities and deposits during the production of polyethylene resins.

The amount of chlorine contained in the polyethylene resin as measured by a fluorescent X-ray apparatus is 1 to the total polyethylene resin.
It is preferably at most 5 PPM. If the total polyethylene resin exceeds 15 PPM, chlorine will corrode the metal of the molding machine and the mold, and cause discoloration of the molded product. The used neutralizing agent causes metal impurities.

Further, the polyethylene resin used in the present invention may contain additives and additives such as known antioxidants, light stabilizers, and neutralizers. here,
Neutralizing agents are fatty acid metal salts represented by calcium stearate, magnesium stearate and zinc stearate, and hydrotalcites.

The polyethylene resin used in the present invention is the same as the polyethylene resin for large blow molding described above.
0 parts by weight of high-pressure LDPE (low-density polyethylene)
It may be mixed in a range of 0 parts by weight or less. High pressure method L
When DPE is mixed, the melt elasticity and the skin of the molded article are improved. On the other hand, if LDPE is mixed in an amount exceeding 40 parts by weight, the mechanical strength decreases. The high-pressure LDPE is produced under a polymerization pressure of 800 atm or more in the presence of air or an organic peroxide as a radical source. This LDP
E has a density of 0.91 to 0.94 g / cm ³ , preferably 0.915 to 0.935 g / cm ³ ,
MFR (JIS K7210-1976, conditions 4, 19
0 ° C., 2.16 kg load) 0.1 to 10 g / 10 min.
It is preferable to use one having a concentration of 0.1 to 4 g / 10 minutes.

Further, other polyolefins may be added as long as the effects of the present invention are not impaired.

The polyethylene resin for large-size blow molding of the present invention is suitable for large-size blow molding because the melt tension is large and the thickness is hard to be uneven. When used as large industrial parts such as gasoline tanks, large industrial chemical cans, drums and container containers, it has excellent low-temperature drop strength, good molded product skin, and can be used repeatedly for a long period of time. In addition, since low molecular weight components and metal impurity components eluted in the drug are small and the inner skin is good, it can be used for large containers of high-purity drugs, pharmaceuticals, and foodstuffs. Molded using the polyethylene resin for large blow molding of the present invention, the shape of the large container is not specified,
The container has an inner volume of 50 liters or more, preferably,
100 liters or more. Further, it can be used as an inner container of a 1 to 4 ton container container whose outside is surrounded by FRP and metal.

Depending on the type of chemicals, it is necessary to use a light-shielding container. A multilayer container having the polyethylene resin of the present invention as an inner layer and at least one layer containing a light-shielding material such as an organic pigment or an inorganic pigment, Organic pigments or inorganic pigments may be added to the polyethylene resin of the present invention as long as the degree of cleanliness can be maintained.

[0033]

EXAMPLES The present invention will be described below with reference to examples, but is not limited to these examples.

The test method was as follows.

Density: According to JIS K6760-1981, a test piece which was immersed in hot water at 100 ° C. for 1 hour and then cooled slowly to room temperature was measured with a density gradient tube kept at 23 ° C.

Mw / Mn: 150C manufactured by Waters
ALC / GPC (column: GMHHR-H manufactured by Tosoh)
(S), solvent; 1,2,4-trichlorobenzene), and Mw and Mw / Mn were calculated by GPC method. The column elution volume was calibrated by the universal calibration method using standard polystyrene manufactured by Tosoh Corporation.

Melt tension (MT): Using a melt tension tester manufactured by Toyo Seiki Co., Ltd., resin temperature 190 ° C.
Was measured.

The amount of boiling normal hexane extracted (n-
C ₆ ): Using a Soxhlet extractor, 2 g of the resin was extracted with 400 ml of normal hexane solvent for 2 hours. It is shown as a percentage by weight of the extractables relative to the total resin.

Low temperature drop test: [Preparation of large container] Using a MB80 / P115 type blow molding machine manufactured by Nippon Steel Works, large blow molding was performed at a molding temperature of 210 ° C, and the diameter was 440.
mmφ, cylindrical shape of height 800mm, average thickness 4mm,
A large container having an inner volume of 100 liters and a container weight of 7.0 kg was prepared. [State adjustment] 100 liters of a 50% aqueous solution of ethylene glycol is placed in a large container, and left in a low temperature chamber at -18 ° C for 24 hours or more. [Drop test] After the liquid content reaches -18 ° C, the container is dropped from a height of 1 m so that the body of the container comes into contact with the concrete ground horizontally, and the state of damage of the large container is checked. If it does not break, increase the drop height up to a maximum of 3.2 m at 20 cm intervals and break it. The height at which the container is broken is defined as the drop strength (m). ESCR: Polyethylene test method (JIS K676)
0-1981) based on the constant strain environmental stress crack test. 5
Using a thermostat at 0 ± 0.5 ° C., the time required for 10 samples to crack in a 10% by weight solution of Nonion NS210. F50 values are shown in hours.

Molded skin: MB80 / P manufactured by Japan Steel Works
Using a 115-type blow molding machine, large blow molding was performed at a molding temperature of 210 ° C., with a diameter of 440 mmφ and a height of 800 m.
A large container having a cylindrical shape of m, an average thickness of 4 mm, an internal volume of 100 liters, and a container weight of 7.0 kg was prepared. The inner surface of the obtained large container was visually observed. Judgment (○, △, ×)
Followed the following.

：: The skin on the inner surface is smooth and clean.

Δ: It cannot be said that the skin on the inner surface is smooth or rough.

×: The inner skin is rough.

Example 1 (1) Preparation of solid catalyst component (A) A solid catalyst component (A) was prepared according to JP-A-7-41513. That is, 40 g of metallic magnesium powder was placed in a 3 liter glass flask sufficiently purged with nitrogen.
(1.65 mol) and titanium tetrabutoxide 225
g (0.66 mol), 256 g (3.5 mol) of n-butanol in which 2.0 g of iodine was dissolved was added at 90 ° C. over 2 hours, and under a nitrogen blanket while further removing generated hydrogen gas. Stirred at 140 ° C. for 2 hours. This is 11
After the temperature was reduced to 0 ° C., 37 g of tetraethoxysilane (0.1 g) was added.
8 mol) and 25 g (0.17 mol) of tetramethoxysilane, and the mixture was further stirred at 140 ° C. for 2 hours. Next, 2.1 liters of hexane was added to obtain a homogeneous solution.
This homogeneous solution was placed in a 10-liter stainless steel autoclave equipped with a stirrer, and while keeping the internal temperature at 45 ° C, 0.74 kg of a hexane solution containing 1.4 mol of diethyl aluminum chloride and 0.56 mol of i-butyl aluminum dichloride was added. Add over 1 hour and add 1 hour at 60 ° C
Stirred for hours. Next, 3.2 kg of a hexane solution containing 10.4 mol of i-butylaluminum dichloride was added, followed by stirring at 60 ° C. for 1 hour to obtain a solid catalyst component. The obtained solid catalyst component (A) was used as a hexane slurry after removing remaining unreacted substances and by-products using hexane.

(2) Production of polyethylene resin 110 liter / hour of hexane dehydrated and purified in a continuous polymerization vessel having an internal volume of 370 liters, 164 mmol / hour of triisobutylaluminum as the organoaluminum compound (B), A) at a temperature of 85 ° C., a total pressure of 30 kg / cm ² and an average residence time of 0.95 g / hour, 20.0 kg / hour of ethylene and hydrogen at an ethylene concentration ratio of 0.5 mol / mol. The first-stage polymerization was continuously performed under the conditions of 1.6 hours. The first-stage ethylene homopolymer (low molecular weight component (I)) has an intrinsic viscosity of 1.0 dl / g and a density of 0.974.
g / cm ³ .

After removing unreacted hydrogen and ethylene in a flash tank, the hexane slurry containing the first-stage polymer was introduced into another continuous polymerization vessel having an internal volume of 545 liters. While feeding additional 121 liters / hour of hexane to the polymerization vessel, ethylene 20.0 kg / hour, 1-butene 0.7 kg / hour, hydrogen to ethylene concentration ratio 0.04 mol / mol, 80 ° C. Pressure 20kg / c
The second stage polymerization was carried out under the conditions of m ² and an average residence time of 1.3 hours. The unreacted hydrogen, ethylene, and 1-butene are removed from the discharge from the second-stage polymerization tank in a flash tank, and then, through a drying step, an ethylene copolymer (low molecular weight component (I) and high molecular weight component ( II) mixture powder)
I got When the polymerization of only the second stage is separately performed, the component (I)
The ethylene / 1-butene copolymer of I) has an intrinsic viscosity of 5.
The density was 0.932 g / cm ³ at 8 dl / g. The polymerization ratio of the component (I) was 55% by weight, and the component (I)
The polymerization ratio of I) was 45% by weight.

The obtained mixture powder was mixed with 500 PPM of tetrakis- [methylene-3- (3 ′, 5′-di-tert-butyl-4′-hydroxyphenyl) propionate] methane as an antioxidant and tris (2 , 4-di-t
-Butylphenyl) phosphite 300 PPM, calcium stearate 500 PPM as a neutralizing agent, and α, α′-bis (t-butylperoxy) diisopropylbenzene as an organic peroxide at 50 PPM,
Pellets were obtained with a 50 mmφ granulator to obtain a polyethylene resin. The polyethylene resin has a density of 0.954 g / cm.
³ , the melt flow rate under a load of 21.6 Kg at 190 ° C. was 5.5 g / 10 min, the Mw / Mn determined by GPC was 13.2, the melt tension at 190 ° C. was 23 g, and boiling normal hexane was used. The extraction amount was 0.10%. (LogMT = 1.361, −0.455 × Lo
gHLMFR + 1.64 = 1.303) (3) ESCR Measurement and Production and Evaluation of Large Container ESCR measurement was performed on the granulated pellets. The large-size blow molding is performed at a molding temperature of 210 ° C. using a MB80 / P115 type hollow molding machine manufactured by Nippon Steel Works.
A large container of 0 liter and a container weight of 7.0 kg was prepared. Using the obtained large container, the above-mentioned low-temperature drop test and observation of the skin of the molded article were performed.

As shown in Table 1, the ESCR was excellent at 900 hours. The drop strength was 3.2 m or more, and the skin was good, and no merfura, shark skin, and bruise were observed.

Example 2 (1) Production of polyethylene resin The same solid catalyst component (A) as in Example 1 and a continuous polymerization vessel 2
Using a table, a mixed powder was obtained. However, the first stage ethylene homopolymer (low molecular weight component (I)) had an intrinsic viscosity of 0.9 dl / g and a density of 0.973 g / cm ³ . When the polymerization of only the second stage is separately performed, the ethylene / 1-butene copolymer of the component (II) has an intrinsic viscosity of 5.3 dl.
/ G and a density of 0.935 g / cm ³ . The polymerization ratio of the component (I) was 50% by weight, and the polymerization ratio of the component (II) was 50% by weight.

The same additives and organic peroxide as in Example 1 were added and pelletized. The obtained polyethylene resin has a density of 0.953 g / cm ³ ,
Melt flow rate of 1.6 kg load is 5.0 g / 10
Mw / Mn determined by GPC is 12.7
The melt tension at 190 ° C. was 24 g, and the boiling normal hexane extraction amount was 0.10%. (LogMT =
1.380, -0.455 x Log HLMFR + 1.6
(4 = 1.322) (2) ESCR measurement and production and evaluation of large container ESCR measurement was performed on granulated pellets, and the above-mentioned low-temperature drop test was performed using a large container obtained by molding in the same manner as in Example 1. And the skin of the molded article were observed.

As shown in Table 1, the ESCR was excellent at 500 hours. The drop strength was 3.2 m or more, and the skin was good, and no merfura, shark skin, and bruise were observed.

Example 3 (1) Production of polyethylene resin The same solid catalyst component (A) as in Example 1 was used.
Using two continuous polymerization reactors, the solid catalyst component (A) was used in an amount of 0.4 g / hour, and in the first stage, hydrogen was fed to an ethylene concentration ratio of 0.30 mol / mol in a ratio of 0.30 mol / mol. C., the total pressure was 30 kg / cm ² , and the average residence time was 3.4 hours. The first-stage polymerization was carried out while continuously supplying the raw materials. In the second stage, 1-butene was 0.8 kg. / H, hydrogen was fed to the ethylene in a ratio of 0.04 mol / mol, 80 ° C., total pressure was 20 kg / cm ² , and the average residence time was 3.3 hours. Was polymerized. The effluent from the second-stage polymerization vessel is subjected to a flash tank to remove unreacted hydrogen, ethylene and 1-butene, and then subjected to a drying step to obtain an ethylene copolymer (low molecular weight component (I)).
And a high molecular weight component (II). First stage ethylene homopolymer (low molecular weight component (I))
Has an intrinsic viscosity of 0.9 dl / g and a density of 0.973 g / cm
^{Was 3} . When the polymerization of only the second stage was separately performed, the ethylene / 1-butene copolymer of the component (II) had an intrinsic viscosity of 4.8 dl / g and a density of 0.935 g / cm ³ .
The polymerization ratio of the component (I) was 45% by weight, and the component (I)
The polymerization ratio of I) was 55% by weight.

The same additives and organic peroxide as in Example 1 were added and pelletized. The obtained polyethylene resin has a density of 0.952 g / cm ³ ,
Melt flow rate of 1.6 kg load is 6.5 g / 10
Mw / Mn determined by GPC is 10.5
The melt tension at 190 ° C. was 21 g, and the amount of boiling normal hexane extracted was 0.10%. (LogMT =
1.322, -0.455 x Log HLMFR + 1.6
(4 = 1.270) (3) ESCR measurement and production and evaluation of large container ESCR measurement was performed on granulated pellets, and the above-mentioned low temperature drop test was performed using a large container obtained by molding in the same manner as in Example 1. And the skin of the molded article were observed.

As shown in Table 1, the ESCR was as excellent as 450 hours. The drop strength was 3.2 m or more, and the skin was good, and no merfura, shark skin, and bruise were observed.

Comparative Example 1 (1) Production of Polyethylene Resin A powder produced using a Philips-based catalyst containing Cr and SiO ₂ as main components was used as an antioxidant, tetrakis- [methylene-3- (3 ′, 5). '-Di-t-butyl-4'-hydroxyphenyl) propionate] methane was added at only 500 PPM to obtain a polyethylene resin. The polyethylene resin has a density of 0.946 g / cm ³ , a melt flow rate at 190 ° C. under a load of 21.6 Kg of 5.2 g / 10 min, and a Mw determined by GPC.
/ Mn is 9.2, the melt tension at 190 ° C. is 33 g,
The amount of boiling normal hexane extracted was 0.11%.
(LogMT = 1.519, −0.455 × LogHL
(MFR + 1.64 = 1.314) (2) ESCR measurement and production and evaluation of large container ESCR measurement was performed using granulated pellets, and the above-described low temperature was obtained using a large container obtained by molding in the same manner as in Example 1. A drop test and observation of the skin of the molded article were performed.

As shown in Table 1, the ESCR was inferior at 150 hours. The drop strength is 3.2m or more,
In addition, the skin was good, and no merfura, shark skin, bruising, etc. were observed.

Comparative Example 2 (1) Production of polyethylene resin Except that the mixture powder of Example 3 was used and α, α'-bis (t-butylperoxy) diisopropylbenzene as an organic peroxide was not added. Was pelletized by adding the same additives as in Example 1. The resulting polyethylene resin has a density of 0.952 g / cm ³ ,
Melt flow rate of 21.6Kg load is 7.5g / 1
0 min, and Mw / Mn determined by GPC is 10.
The melt tension at 190 ° C. was 16 g, and the boiling normal hexane extraction amount was 0.10%. (LogMT =
1.204, -0.455 x Log HLMFR + 1.6
(4 = 1.242) (2) ESCR measurement and production and evaluation of large container ESCR measurement was performed on granulated pellets, and the above-mentioned low temperature drop test was performed using a large container obtained by molding in the same manner as in Example 1. And the skin of the molded article were observed.

As shown in Table 1, the ESCR was excellent at 480 hours. The drop strength was 1.9 m, and a crack was generated from the pinch-off portion, which was broken, and the content liquid flowed out. In addition, there was a little rough skin.

Comparative Example 3 (1) Production of polyethylene resin The same solid catalyst component (A) as in Example 1 and a continuous polymerization vessel 2
Using a table, a mixture powder was obtained. However, the first-stage ethylene homopolymer (low molecular weight component (I)) has an intrinsic viscosity of 0.65 dl / g and a density of 0.974 g / cm ³ , and the second-stage ethylene (II) The 1-butene copolymer has an intrinsic viscosity of 5.3 dl / g and a density of 0.935 g
/ Cm ³ . The polymerization ratio of the component (I) is 45
By weight, the polymerization rate of component (II) was 55% by weight. The mixture powder was pelletized by adding the same additives as in Example 1. The obtained polyethylene resin has a density of 0.952 g / cm ³ and a temperature of 190 ° C. and 21.6 kg.
The melt flow rate of the load is 6.0 g / 10 min,
Mw / Mn determined by GPC is 16.0, and 1
The melt tension at 90 ° C. was 19 g, and the boiling normal hexane extraction amount was 0.15%. (LogMT = 1.279,
-0.455 x Log HLMFR + 1.64 = 1.28
6) (2) ESCR Measurement and Production and Evaluation of Large Container The ESCR measurement was performed on the granulated pellets, and the above-described low-temperature drop test and the molding of the molded product were performed using the large container obtained by molding in the same manner as in Example 1. The skin was observed and the ESCR was evaluated.

As shown in Table 1, the ESCR was 1000 hours or more. The drop strength was 2.4 m, and a crack was generated from the pinch-off portion, which was broken, and the content liquid flowed out. In addition, there was a little rough skin.

Comparative Example 4 (1) Production of polyethylene resin The same solid catalyst component (A) as in Example 1 and a continuous polymerization vessel 2
Using a table, a mixture powder was obtained. However, the first-stage ethylene homopolymer (low molecular weight component (I)) has an intrinsic viscosity of 0.9 dl / g and a density of 0.973 g / cm ³ , and the second-stage ethylene (Component (II)) 1-butene copolymer has an intrinsic viscosity of 6.7 dl / g and a density of 0.930 g
/ Cm ³ . The polymerization ratio of the component (I) is 60
By weight, the polymerization rate of component (II) was 40% by weight. The mixture powder was pelletized by adding the same additives as in Example 1. The obtained polyethylene resin has a density of 0.956 g / cm ³ and a temperature of 190 ° C. and 21.6 kg.
The melt flow rate of the load is 5.1 g / 10 min,
Mw / Mn determined by GPC is 15.5, and 1
The melt tension at 90 ° C. was 22 g, and the boiling normal hexane extraction amount was 0.12%. (LogMT = 1.342,
-0.455 x Log HLMFR + 1.64 = 1.31
8) (2) ESCR Measurement and Production and Evaluation of Large Container The ESCR measurement was performed on the granulated pellets, and the low-temperature drop test and the molding of the molded product were performed using the large container obtained by molding in the same manner as in Example 1. The skin was observed.

[0062] As shown in Table 1, the ESCR was over 1000 hours. The drop strength was 1.8 m, and a crack was generated from the pinch-off portion, which was broken and the content liquid flowed out. The skin was good.

[0063]

[Table 1]

[0064]

The polyethylene resin for large-size blow molding of the present invention has a large melt tension and is hard to be uneven, so that it is suitable for large-size blow molding. It has excellent strength, good molded product skin, and can be used repeatedly for a long time.

[0065]

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B29K 23:00 B29L 22:00

Claims (3)

[Claims] 1. It has the following characteristics (1) to (6):
Polyethylene resin for large blow molding. (1) Density (JIS K6760-1981) is 0.9
4-0.97 g / cm ³ , (2) 190 ° C., 21.6K
Melt flow rate of g load (JIS K7210-1)
976, condition 7, HLMFR) is 1 to 15 g / 10 min,
(3) Gel permeation chromatography (G
PC) the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is 8 to 15, (4)
Melt tension at 190 ° C. (MT, unit g) is 15 to 6
5 g and a melt flow rate at 190 ° C. under a load of 21.6 kg (JIS K7210-1976, condition 7, H
LMFR) is as follows: LogMT ≧ −0.455 × LogHLMFR + 1.6
(5) Boiling normal hexane extraction amount is 0.2% by weight or less, (6) Environmental stress cracking time (ES
CR) is 350 hours or more 2. (I) 35-60% by weight of an ethylene homopolymer or a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms satisfying the following (a) and (b): (a) o- The intrinsic viscosity (η1) at 140 ° C. using a dichlorobenzene solvent is 0.6 to 1.5 dl / g. (B) The density (JIS K6760-1981) is 0.9.
5 to 0.98 g / cm ³ and (II) a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms that satisfies the following (c) and (d): 65 to 40% by weight (c) o-dichlorobenzene The intrinsic viscosity (η2) at 140 ° C using a solvent is 4 to 15 dl / g. (D) The density (JIS K6760-1981) is 0.8.
The method for producing a polyethylene resin for large-size blow molding according to claim 1, wherein a mixture comprising ⁹ to 0.95 g / cm3 is subjected to a crosslinking treatment. 3. A large-size blow-molded container comprising the polyethylene resin for large-size blow-molding having an inner volume of 50 liters or more according to claim 1.