JPH1135745A - Polyethylene resin composition for blow molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition having excellent blow moldability by mixing an ethylene/α-olefin copolymer having a specified melt flow rate, a specified density and a specified weight-average molecular weight/number-average molecular weight ratio with a low-density polyethylene having a specified melt flow rate and a specified density in a specified ratio. SOLUTION: This composition comprises 5-80 wt.% ethylene/3-18C α-olefin copolymer (A) having a melt flow rate of 0.5-50 g/10 min (as measured at 190 deg.C under a load of 2.16 kg), satisfying the relationship of the formula (wherein WA is the amount (wt.%) of component added), having a density of 0.87-0.93 g/cm<3> and a weight-average molecular weight/number-average molecular weight ratio of 1.5-3.3 and 95-20 wt.% low-density polyethylene (B) having a melt flow rate of 0.01-10 g/min and a density of 0.915-0.94 g/cm<3> . Component A is a copolymer prepared by polymerization in the presence of a metallocene catalyst and comprising ethylene and 3-50 wt.% α-olefin, and component B is a polymer prepared by polymerization in the presence of a polymerization initiator such as an organic peroxide under high pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a polyethylene resin composition for hollow molding. More specifically,
An object of the present invention is to provide a polyethylene resin composition for hollow molding which is excellent in impact resistance, flexibility, chemical resistance, ESCR and surface tackiness, and has improved transparency and hollow moldability.

[0002]

2. Description of the Related Art Conventionally, products requiring flexibility obtained by hollow molding of a polyethylene resin include a bag-in-box of several liters to about 20 liters molded by direct blow, an infusion bag or a rotary blow. Specific examples include molded food containers such as mayonnaise, juice, ice confectionery, and sauce bottles. For these products, high-pressure low-density polyethylene (LDPE) is generally used from the viewpoints of flexibility, heat sealability, high-speed processability, and hollow moldability, but further flexibility, impact resistance, ESCR
Are not always satisfactory. As a means for solving this problem, an ethylene / vinyl acetate copolymer (EVA) may be used. However, problems remain with respect to oxidative deterioration during molding, vinyl acetate odor, and the like. Regarding such problems of oxidative deterioration and odor during molding, the use of a titanium-based Ziegler-Natta catalyst or a chromium-based catalyst, flocculated low-density polyethylene (LLDPE) or ultra-low-density polyethylene (VLDPE) alone, Or LDP
It is effective to use it in a blend with E. However, since high molecular components are contained in the molecular structure, transparency is likely to be deteriorated and a gel is easily generated. In applications where design is required, problems remain. ,
Problems still remain in terms of surface stickiness due to bleeding of low crystal components.

In recent years, ethylene and α-olefin have been copolymerized using a homogeneous catalyst typified by a so-called metallocene catalyst described in Japanese Patent Application Laid-Open No. It has become possible to produce an ethylene / α-olefin copolymer having an extremely narrow distribution. Polyethylene (metallocene PE) produced by such a catalyst has excellent molecular properties such as impact resistance, flexibility, chemical resistance, ESCR, etc. due to narrow molecular weight distribution and composition distribution. Because it does not contain low crystalline components, it has excellent transparency, gel, stickiness and extractability. However, although the metallocene PE has a great advantage due to the extremely narrow molecular weight distribution and composition distribution as described above, it has a problem that the moldability is extremely poor. Specifically, because the molecular weight distribution is extremely narrow, the extrusion load in the extruder increases,
At the die exit, fine irregularities on the parison surface, called melt fracture, occur. In particular, at the time of hollow molding, a drawdown phenomenon in which the parison extruded from the die is stretched by its own weight and hangs down easily occurs.

As a method for solving this problem, it has been proposed to broaden the molecular weight distribution by means such as using a plurality of reactors or using several kinds of metallocene catalysts in combination. JP-A-3-234717 discloses a method for improving the melting characteristics of a polymer by a multi-stage polymerization method using an olefin polymerization catalyst comprising a transition metal compound and an organoaluminum oxy compound. In addition, JP
In Japanese Patent Publication No. 0-35008, a method is disclosed in which at least two transition metal compounds are mixed and used to broaden the molecular weight distribution. However, even when such a method of expanding the molecular weight distribution is used, processability comparable to that of LDPE cannot be obtained, and the improvement effect is low, and excellent physical properties based on the narrow molecular weight distribution of metallocene PE are offset. And so on.

[0005] In addition, there has been proposed a method of imparting the processability of metallocene PE by blending with LDPE, for example. JP-A-7-26079 discloses a laminating resin composition containing LDPE having a specific property,
Japanese Patent Application Laid-Open No. 9-3262 proposes a polyethylene resin composition for an extruded tube containing 30 to 95% by weight of LDPE having a specific property. However, since these lamination molding or extrusion tube molding and hollow molding differ greatly in molding method, molding temperature, molding speed, and the like, these findings do not necessarily correspond to hollow molding. Specifically, in the case of hollow molding, metallocene P
When the metallocene PE is added in an amount of 30% by weight or more in order to obtain the characteristics of E, if the MFR of the metallocene PE is too low, melt fracture easily occurs, and the MFR
If the ratio is too high, a draw-down easily occurs, so that a good molding area is very narrow. Furthermore, conventionally, according to the molding temperature, molding speed, product size, etc., the MFR is 0.05 to
Generally, LDPE of about 10 g / 10 minutes is used for the hollow molding.
Even if a small amount of about 10% by weight of the metallocene PE having the same MFR as that of E was added, there was a possibility that the melt fracture phenomenon would occur. The melt fracture phenomenon is
In general, the occurrence can be suppressed by changing the molding conditions such as raising the molding temperature, lowering the molding speed, etc., but when metallocene PE is blended, there is a problem that drawdown is rather induced. . Therefore, in the field of blow molding, although the excellent physical properties of metallocene PE are attractive, at present, their industrial applications have not been developed.

[0006]

As described above, in the prior art, impact resistance, flexibility, chemical resistance, ESCR,
A polyethylene resin for hollow molding excellent in transparency, mechanical properties such as gel, stickiness and the like and product performance and also excellent in hollow moldability has not been obtained. The problem to be solved by the present invention is to provide a polyethylene resin composition for hollow molding and a hollow molded article having excellent mechanical properties, product performance and hollow moldability.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to obtain a polyethylene resin composition having excellent mechanical properties and product properties as well as excellent hollow moldability. The object of the present invention has been achieved by blending a high-pressure low-density polyethylene having a specific property with an ethylene copolymer having a specific property produced by a production method, and adjusting the blending ratio of the specific ethylene copolymer. They have found that they can do this and have completed the present invention.

That is, the present invention relates to a polyethylene resin composition for hollow molding, comprising the following components A and B: Component A 5-80% by weight of an ethylene-C3-C18 α-olefin copolymer produced by a high-pressure ion polymerization method and having the following properties: MFR at 190 ° C. and 2.16 kg load is 0.5 to
In 50 g / 10 min, and _{0.009W A -0.344 ≦ log (MFR)} ≦ satisfy the following relation -
0.003W _A +1.699 Here, W _A indicates the mixing ratio of component A (% by weight: weight of component A in resin composition / weight of resin composition × 100). The density is 0.87 to 0.93 g / cm ³ The ratio of weight average molecular weight / number average molecular weight (Mw / Mn) measured by GPC method is 1.5 to 3.3. Component B at 190 ° C. under a load of 2.16 kg MFR of 0.01 to 1
0 g / 10 min, density 0.915-0.94 g / cm ³
High-pressure low-density polyethylene, 95 to 20% by weight.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION

[I] Raw materials (1) Constituent components (essential components) (A) Component A (ethylene-C 3-18 α-olefin copolymer) (a) Physical properties Ethylene / carbon number of component A used in the present invention 3-18
As the α-olefin copolymer, those produced by a high-pressure ionic polymerization method and having the following physical properties are used.

MFR (Melt Flow Rate) The α-olefin copolymer of ethylene and C 3-18 used as the component A in the present invention has a temperature of 190 ° C.
2. The MFR under a load of 16 kg is 0.5 to 50 g / 10.
Min, preferably 3.1 to 40 g / 10 min, more preferably 11 to 30 g / 10 min. If the MFR is less than the above range, melt fracture tends to occur during blow molding. If the MFR is larger than the above range, drawdown tends to occur, so that the content of the component A is limited, and characteristics such as extremely good mechanical properties and product properties are impaired.

Further, the α-olefin copolymer having 3 to 18 ethylene atoms and carbon atoms used as the component A in the present invention has an MFR satisfying the following relational expression according to the mixing ratio of the component A. is there. 0.009W _A -0.344 ≦ log (MFR) ≦ −
More preferably _{0.003W A +1.699, 0.009W A -0.086 ≦} log (MFR) ≦ -
0.003W _A +1.699, particularly preferably a shear rate of 4 at the die exit.
When the ^{value is} less than 00 sec ⁻¹ , 0.009W _A −0.086 ≦ log (MFR) ≦ −
0.007W _A +1.734 at a shear rate of at die exit is 400 sec ^-1 or _{more, 0.014W A -0.086 ≦ log (MFR} ) ≦ -
0.003W _A +1.699. Here, W _A is the polyethylene blend ratio of the component A in the resin composition: shows a (wt% weight × 100 / weight of the resin composition of component A in the resin composition). log (MF
In R) is less than 0.009W _A -0.344, extrusion load during blow molding is high, problems in workability such as melt fracture occurs. log (MFR) is-
If it is larger than 0.003W _A +1.699, drawdown tends to occur at the time of hollow molding, and workability deteriorates.

Density The α-olefin copolymer having 3 to 18 ethylene carbon atoms used in the present invention has a density of 0.87 to 0.93.
g / cm ³ , preferably 0.87 to 0.92 g / cm ³ ,
More preferably, it shows 0.87 to 0.91 g / cm ³ . If the density is less than the above range, the surface of the hollow molded article is likely to be sticky. When the density is larger than the above range, characteristics such as good flexibility, impact strength, transparency, and ESCR are impaired.

Weight average molecular weight / number average molecular weight (Mw
/ Mn) The α-olefin copolymer having 3 to 18 carbon atoms of ethylene used in the present invention has a Mw / Mn measured by GPC method of 1.5 to 3.3, preferably 1.5 to 3.3. 3.
It indicates 0. When Mw / Mn is less than the above range,
Since the molecular weight distribution is extremely narrow, even if it is added to component B in a small amount, melt fracture and drawdown are liable to occur, resulting in poor processability. If Mw / Mn is larger than the above range, characteristics such as good impact strength, ESCR and transparency are impaired.

(B) Production Method The α-olefin copolymer of ethylene / C 3-18 of component A is usually produced by a high pressure ion polymerization method using a metallocene catalyst. By producing using the metallocene catalyst, Mw / Mn in the above physical properties satisfies 1.5 to 3.3, and ethylene and α having 3 or more carbon atoms
-It is preferable because copolymerizability with an olefin can be improved and mechanical strength, flexibility, transparency, ESCR and the like can be exhibited.

As a method for producing the component A, Japanese Patent Application Laid-Open No.
19309, JP-A-59-95292, JP-A-60-95292
-35005, JP-A-60-35006, JP-A-6
Nos. 0-35007, JP-A-60-35008, JP-A-60-35009, JP-A-61-130314, JP-A-3-163030, and European Patent Application Publication No. 420,436. U.S. Pat.
5,438, and International Publication WO091 / 04
No. 257, or a metallocene catalyst, a metallocene / alumoxane catalyst, or a metallocene compound as disclosed in, for example, International Publication WO09 / 07123 and the like, and a metallocene catalyst described below. Examples of the method include a method of copolymerizing ethylene as a main component and an α-olefin having 3 to 18 carbon atoms as a main component using a catalyst comprising a compound which reacts to form a stable ion.

Metallocene Catalyst The compound which reacts with the metallocene catalyst to form a stable ion is an ionic compound or an electrophilic compound formed from an ion pair of a cation and an anion, and reacts with the metallocene compound to form a stable ion. Ion to form polymerization active species. Among them, the ionic compound is represented by the following formula (I). [Q] ^{m +} [Y] ^m- (m is an integer of 1 or more) (I) a cation component of the Q ionic compound in the formula, which is a carbonium cation, a tropylium cation, an ammonium cation, an oxonium cation, or a sulfonium cation , Phosphonium cations and the like, and further, cations of metals and cations of organic metals which are easily reduced by themselves.

These cations are described in JP-T-1-5019.
Not only a cation capable of giving a proton as disclosed in Japanese Patent Publication No. 50 and 50, but also a cation not providing a proton may be used. Specific examples of these cations include triphenylcarbonium, diphenylcarbonium, cycloheptatrienium, indenium, triethylammonium, tripropylammonium, tributylammonium, N, N-dimethylammonium, dipropylammonium, dicyclohexylammonium, Phenylphosphonium, trimethylphosphonium, tri (dimethylphenyl) phosphonium, tri (methylphenyl) phosphonium, triphenylsulfonium, triphenyloxonium, triethyloxonium, pyrylium, silver ion, gold ion, platinum ion, palladium ion, mercury Ion, ferrocenium ion and the like.

In the above formula, Y is an anionic component of an ionic compound, which is a component which reacts with a metallocene compound to form a stable anion, such as an organic boron compound anion, an organic aluminum compound anion, an organic gallium compound anion, or an organic compound. Examples thereof include a phosphorus compound anion, an organic arsenic compound anion, and an organic antimony compound anion, and specifically, tetraphenylboron, tetrakis (3,4,
5-trifluorophenyl) boron, tetrakis (3,
5-di (trifluoromethyl) phenyl) boron, tetrakis (3,5- (t-butyl) phenyl) boron, tetrakis (pentafluorophenyl) boron, tetraphenylaluminum, tetrakis (3,4,5-trifluorophenyl) ) Aluminum, tetrakis (3,5-
Di (trifluoromethyl) phenyl) aluminum, tetrakis (3,5-di (t-butyl) phenyl) aluminum, tetrakis (pentafluorophenyl) aluminum, tetraphenylgallium, tetrakis (3
4,5-trifluorophenyl) gallium, tetrakis (3,5-di (trifluoromethyl) phenyl) gallium, tetrakis (3,5-di (t-butyl) phenyl)
Gallium, tetrakis (pentafluorophenyl) gallium, tetraphenylphosphorus, tetrakis (pentafluorophenyl) phosphorus, tetraphenylarsenic, tetrakis (pentafluorophenyl) arsenic, tetraphenylantimony, tetrakis (pentafluorophenyl) antimony, decaborate, undeca Borate, carbado decaborate, decachloro decaborate and the like.

Among the above-mentioned electrophilic compounds, compounds known as Lewis acid compounds, which react with metallocene compounds to form stable ions to form polymerization active species, include various metal halide compounds. And metal oxides known as solid acids. Specific examples include magnesium halides and Lewis acidic inorganic compounds.

Α-olefin As the α-olefin used in the component A, an α-olefin having 3 to 18 carbon atoms, specifically, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene , 1-heptene, 4-methyl-pentene-1,4
-Methyl-hexene-1,4,4-dimethylpentene-
1 and the like. Among these α-olefins, preferably, an α-olefin having 4 to 12 carbon atoms, particularly preferably 3 to 50% by weight, preferably 8 to 45% by weight of one or more α-olefins having 6 to 10 carbon atoms. weight%,
More preferably, 12 to 40% by weight of ethylene and 97 to 50%
% By weight, preferably from 92 to 55% by weight, more preferably from 88 to 60% by weight.

(C) Copolymerization The above copolymerization is produced by a high pressure ionic polymerization method. still,
This high-pressure ionic polymerization method is described in JP-A-56-18607.
And JP-A-58-225106. Specifically, the pressure is 300 to 3000
kg / cm ² , preferably 1100 to 2000 kg / c
m ² , particularly preferably 1300 to 1800 kg / cm ² ,
This is a method for producing an ethylene-based polymer, which is carried out under a reaction condition at a temperature of 125 ° C or higher, preferably 130 to 250 ° C, particularly preferably 150 to 200 ° C.

(B) Component B (High-Pressure Low-Density Polyethylene) (a) Physical Properties As the high-pressure low-density polyethylene of Component B used in the polyethylene resin composition for blow molding of the present invention, those exhibiting the following physical properties are listed. It is important to use. MFR The high-pressure low-density polyethylene used as the component B in the present invention has a MFR of 190 ° C. under a load of 2.16 kg.
Is 0.01 to 10 g / 10 min, preferably 0.05 to 1
0 g / 10 min, more preferably 0.1 to 10 g / 10 min. When the MFR is less than the above range, the resin pressure at the time of the hollow molding is increased and the processability is deteriorated. In addition, the melt appearance is liable to occur, so that the appearance of the product is also deteriorated.
If the MFR is larger than the above range, drawdown tends to occur during blow molding, and workability deteriorates. Density The high-pressure low-density polyethylene used as the component B in the present invention has a density of 0.915 to 0.940 g / cm.
³ , preferably 0.918 to 0.930 g / cm ³ . If the density is less than the above range, the stickiness of the product surface increases. If the density is larger than the above range, characteristics such as flexibility, impact strength, ESCR, and transparency of the product are impaired.

(B) Production Method The high-pressure low-density polyethylene of the above component B is usually prepared by using a radical initiator such as an organic peroxide or oxygen as a polymerization initiator, at a polymerization temperature of about 130 to 350 ° C., and at a polymerization pressure of 500 to 500. 300
It is obtained by subjecting ethylene to radical polymerization under the condition of about 0 kg / cm ² .

(C) Blending Ratio The blending ratio of the α-olefin copolymer having 3 to 18 carbon atoms of ethylene (component A) and the low-density high-pressure polyethylene (component B) is 5 to 80% by weight of component A. Preferably 10
75% by weight, more preferably 21-60% by weight, component B
Is 95 to 20% by weight, preferably 90 to 25% by weight, more preferably 79 to 40% by weight. If the compounding ratio of the component A is less than the above range, extremely good characteristics such as mechanical properties and product properties are not exhibited. If the compounding ratio of the component A is larger than the above range, melt fracture or drawdown tends to occur during blow molding. Component A and Component B
As long as the above range is satisfied, each component may contain two or more kinds.

(2) Additives (Optional Components) The polyethylene resin composition for blow molding of the present invention contains auxiliary additives generally used for resin compositions, such as antioxidants, heat stabilizers, and antioxidants. It may contain a blocking agent, a slip agent, an ultraviolet absorber, a neutralizing agent, an antistatic agent, a molecular weight regulator such as a peroxide, a coloring agent, a transparent nucleating agent, a filler, and the like. When these auxiliary additives are contained in the resin composition and used in a hollow molded article, the contents may be contaminated depending on the type of the additional components. Is preferable.

[II] Polyethylene Resin Composition for Hollow Molding The polyethylene resin composition for hollow molding of the present invention comprises the components A and B described above. Physical properties, product physical properties,
It is preferable because the hollow moldability is improved. Melt tension at 190 ° C. 190 ° C. of the polyethylene resin composition for hollow molding of the present invention
It is preferable that the melt tension (MT) satisfy the following relational expression. logMT ≧ 0.137 (logγ) ² −0.807 ·
logγ + 1.370, more preferably logMT ≧ 0.176 (logγ) ² −1.053 ·
logγ + 1.875. Here, MT is one of the polyethylene resin compositions.
The melt tension at 90 ° C. (g) and γ indicate the shear rate (sec ⁻¹ ) at the die exit during the hollow molding. If MT is less than the above relational expression, drawdown tends to occur at the time of blow molding, and workability deteriorates.

Differential Scanning Calorimetry of Component A (DS
Extrapolation melting end temperature (Tem) of the melting peak by C) The polyethylene resin composition for blow molding of the present invention includes:
Tem of the melting peak obtained by DSC of component A
However, preferably 60 to 130 ° C., more preferably 70 to 130 ° C.
120 ° C., preferably in the range of 80 ° C. to 110 ° C., and the relationship between Tem and density (D) is expressed by the following relational expression, preferably Tem ≦ 286D-137, more preferably Tem ≦ 429D-271. Satisfies Tem ≦ 571D-404. If the Tem of the melting peak is less than the above range, if the copolymer is blended at a high blending ratio, the product will be sticky and the mold releasability at the time of molding will deteriorate, or blocking will occur when the products are stacked. Easier to do.
When Tem is larger than the above range, characteristics such as flexibility, impact strength, and transparency of the product are impaired. Further, when Tem is out of the range of the above relational expression, transparency becomes poor, which is not preferable.

MFR The polyethylene resin composition for hollow molding according to the present invention has an MFR
(190 ° C., 2.16 kg load) 0.01 to 10 g /
It is preferable to show 10 minutes, more preferably 0.1 to 10 g / 10 minutes. If the MFR is less than the above range, the resin pressure at the time of the hollow molding is increased, and the workability is deteriorated such that melt fracture is easily generated. When the MFR is larger than the above range,
At the time of blow molding, drawdown easily occurs, and workability deteriorates. Density The polyethylene resin composition for hollow molding of the present invention has a density of preferably 0.88 to 0.94 g / cm ³ , more preferably 0.88 to 0.93 g / cm ³ , and desirably 0.8.
8 to 0.92 g / cm ³ . When the density is less than the above range, there are problems such as insufficient rigidity of the product, lack of rigidity, and stickiness of the product surface. If the density is larger than the above range, characteristics such as flexibility, impact strength, ESCR, and transparency of the product are impaired.

[III] Production of Polyethylene Resin Composition for Blow Molding (1) Blending The blending method of the component A and the component B includes melt mixing by a Banbury mixer method, an extrusion granulation method, a tumbler blender method, and a Henschel mixer method. , V blender method or the like, and can be mixed by a method such as dry blending.

(2) Molding The resin composition of the present invention is processed into a hollow product by blow molding. Examples of the method of the blow molding include direct blow molding using an extrusion blow molding machine, a ram blow molding machine, an accumulator blow molding machine, or the like. Among them,
In particular, molding using an extrusion hollow molding machine is preferable, and specifically, molding using an extrusion hollow molding machine such as a single head type, a double head type, a multiple head type, a cut-off type, and a rotary type is preferable. The hollow product using the resin composition of the present invention may be a single layer or a multilayer of two or more layers. Specifically, the resin composition is used only in the innermost layer in order to satisfy requirements such as chemical resistance and ESCR, and the resin composition is used in the intermediate layer in order to satisfy requirements such as impact strength and piercing strength. Examples of use are given. The obtained hollow product is used for several liters to 20 liters of industrial chemicals, beverages, food containers such as bag-in-box for infusion containers, infusion bags, mayonnaise, juice, ice confectionery, sauce bottles, etc. Can be.

[0031]

Embodiments of the present invention will be described below. The present invention is not limited by these examples. [I] Method of measuring physical properties (1) MFR: JIS-K7210 condition 4 (190
° C and a load of 2,16 kgf). (2) Density: Measured according to the method of JIS-K7112. (3) Ratio of weight average molecular weight / number average molecular weight (Mw / M
n): GPC is Waters's ISOC-ALC /
Using GPC, three columns of AD80M / S manufactured by Showa Denko KK were used for the column, the sample was dissolved in o-dichlorobenzene, and 200 μl of a 0.2% by weight solution was used.
C., at a flow rate of 1 m / min. Mw / Mn was measured using standard polystyrene (monodisperse polystyrene manufactured by Tosoh Corporation) with a known molecular weight, and converted into a number average molecular weight (Mn) and a weight average molecular weight (Mw) by a universal method.
The value of Mn is determined.

(4) Extrapolated melting end temperature (Tem): J
It was measured by the method of IS-K7121 using SSC5200 manufactured by Seiko Denshi Kogyo KK. (5) Melt tension (MT): Using Toyo Seiki Capillograph 1-B, capillary length 8.00 mm, inner diameter 2.095 mm, outer diameter 9.50 mm, test temperature 190
C., the tension at a molten resin extrusion speed of 1 cm / min and a take-off speed of 4 m / min were measured. (6) Tensile impact strength: Measured by the method of ASTM D1822. (7) Bending stiffness (Olsen): JIS-K7106
Was measured according to the method described above. (8) ESCR: Measured by the method of JIS-K6760 4.7 Constant strain environmental stress crack test method (ESCR). (9) Chemical resistance: Measured at a test temperature of 40 ° C. using 99% acetic acid as a test solution in accordance with JIS-K6760 4.7 Constant strain environmental stress cracking test method (ESCR).

(10) Surface Stickiness: Using a hollow molded article, the condition was adjusted at 23 ° C. for one day after molding, and the surface stickiness was evaluated by touch. ○ No stickiness or slippery △ Slightly sticky, but no problem in practical use × Large stickiness, unusable level (11) Transparency (haze): Tested from the body of molded article similar to (10) Cut out a piece to make two sheets, JIS-K
It was measured by the method of 7105.

[II] Examples and Comparative Examples Example 1 Preparation of Component A (Ethylene / C3-C18 α-Olefin Copolymer) The preparation of the catalyst is described in JP-A-61-130314. The method was performed in the following manner. That is, to 2.0 mmol of the ethylenebis (4,5,6,7-tetrahydroindenyl) zirconium dichloride complex, methylalumoxane manufactured by Toyo Stouffer Co., Ltd. was added at a 1000-fold molar amount to the above complex, and diluted to 10 liters with toluene. Thus, a catalyst solution was prepared, and polymerization was performed by the following method. A mixture of ethylene and 1-hexene was added to a 1.5-liter stirred autoclave-type continuous reactor in which the
3% by weight and the pressure in the reactor was 160
The reaction was carried out at a temperature of 180 ° C. while maintaining the pressure at 0 kg / cm ² . After completion of the reaction, ethylene / 1-hexene copolymer having an MFR of 16.5 g / 10 min, a density of 0.895 g / cm ³ , Mw / Mn of 2.0, and an extrapolated melting end temperature (Tem) of 100 ° C. A coalescence was obtained. Irganox 1076 (manufactured by Ciba-Geigy) is used as an antioxidant in the obtained copolymer.
And P-EPQ (Sand).

Production of Pellets As the component B, a commercially available high-pressure low-density polyethylene LF122 (MFR 0.25 g / 10 min, density 0.923 g / cm ³ ) manufactured by Nippon Polychem Co., Ltd. was used.
Were mixed at a ratio of 50:50, melt-mixed at a cylinder temperature of 190 ° C. using a 40 mmφ single screw extruder, and then granulated to obtain a resin composition pellet comprising the components A and B. Evaluation Using the resin composition pellets comprising the components A and B produced by the above method, hollow molding was performed under the following conditions, and the hollow moldability, the product properties of the hollow molded article, and the physical properties of the composition were evaluated. Table 1 shows the evaluation results.

(Molding conditions) Hollow molding machine: JB105, 45 mm, manufactured by Japan Steel Works, Ltd.
φ hollow molding machine (double-head type direct blow molding machine) Molding temperature: 180 ° C. Extrusion speed: 27 rpm Molded product size: 500 cc cylindrical bottle, body thickness 0.
The 75 mm hollow moldability was evaluated for drawdown and the occurrence of melt fracture by the following method. Drawdown: ○ Not generated at all △ Generated slightly, but at a level that can be molded × Drawdown is large, level at which molding is not possible Melt fracture: ○ Not generated at all △ Some slightly generated in this evaluation, rotary hollow component Level that is not a problem depending on the molding method such as shape × Melt fracture occurs, and the appearance of molded products is extremely deteriorated

Examples 2 and 3 Using the component A used in Example 1 and the high-pressure low-density polyethylene having the physical properties shown in Table 1 as the component B, the components were blended in the proportions shown in Table 1, respectively. A pellet was prepared in the same manner as described above. Using the pellets, the hollow moldability, the product properties of the hollow molded article, and the properties of the composition were evaluated in the same manner as in Example 1 except that the hollow molding conditions were changed. Table 1 shows the evaluation results.

Example 4 Component A was prepared in the same manner as in Example 1 except that the supply amount of 1-hexene and the temperature in the reactor were changed to 140 ° C.
The MFR shown in Table 1 is 3.5 g / 10 min, and the density is 0.89.
An ethylene / 1-hexene copolymer having 7 g / cm ³ , Mw / Mn of 2.1, and an extrapolated melting end temperature (Tem) of 105.5 ° C. was obtained. Using this component A, a high-pressure low-density polyethylene having the physical properties shown in Table 1 was used as the component B, and the components were blended at the ratio shown in Table 1. Pellets were produced in the same manner as in Example 1. Using the pellets, the hollow moldability, the product properties of the hollow molded article, and the properties of the composition were evaluated in the same manner as in Example 1 except that the hollow molding conditions were changed. Table 1 shows the evaluation results.

Examples 5 and 6 Component A was prepared in the same manner as in Example 1 except that the supply amount of 1-hexene and the temperature in the reactor were changed to 120 ° C.
The MFR shown in Table 1 is 2.5 g / 10 min and the density is 0.89
An ethylene / 1-hexene copolymer having 1 g / cm ³ , Mw / Mn of 1.9, and an extrapolated melting end temperature (Tem) of 95 ° C. was obtained. Using this component A, a high-pressure low-density polyethylene having the physical properties shown in Table 1 was used as the component B, and the components were blended at the ratio shown in Table 1. Pellets were produced in the same manner as in Example 1. Using the pellets, the hollow moldability, the product properties of the hollow molded article, and the properties of the composition were evaluated in the same manner as in Example 1 except that the hollow molding conditions were changed. Table 1 shows the evaluation results.

[0040]

[Table 1]

Comparative Example 1 A high-pressure low-density polyethylene LF122 (MFR0.
25 g / 10 min, density 0.923 g / cm ³ )
Except for changing the hollow molding conditions, the hollow moldability, the product properties of the hollow molded article, and the properties of the composition were evaluated in the same manner as in Example 1. Table 2 shows the evaluation results.

COMPARATIVE EXAMPLE 2 A commercially available ethylene-vinyl acetate copolymer LV121 (MFR) manufactured by Nippon Polychem Co., Ltd.
0.5 g / 10 min, vinyl acetate content 5% by weight)
Except for changing the hollow molding conditions, the hollow moldability, the product properties of the hollow molded article, and the properties of the composition were evaluated in the same manner as in Example 1. Table 2 shows the evaluation results.

Comparative Example 3 Ethylene / 1 obtained with a chromium-based catalyst as component A
-Butene copolymer (MFR 0.7 g / 10 min, density 0.
922 g / cm ³ ), and the hollow moldability, the product properties of the hollow molded article and the physical properties of the composition were evaluated in the same manner as in Example 1 except that the component B was not used and the conditions for the hollow molding were changed. . Table 2 shows the evaluation results.

Comparative Example 4 The MFR used in Example 4 as Component A was 3.5 g / 10
Min, density 0.897 g / cm ³ , Mw / Mn 2.
1. The same as Example 1 except that an ethylene / 1-hexene copolymer having an extrapolated melting end temperature (Tem) of 105.5 ° C. was used, component B was not added, and the hollow molding conditions were changed. The method was used to evaluate the hollow moldability, the product properties of the hollow molded article, and the physical properties of the composition. Table 2 shows the evaluation results.

Comparative Example 5 As the component A, the MFR was 0.8 g / 10 min, and the density was 0.
Using an ethylene / 1-butene copolymer obtained with a titanium-based catalyst having 911 g / cm ³ , Mw / Mn of 3.5, and an extrapolated melting end temperature (Tem) of 124.9, component B
The high-pressure low-density polyethylene having the physical properties shown in Table 2 was blended in the proportions shown in Table 2, and pellets were prepared in the same manner as in Example 1. Using the pellets, except that the hollow molding conditions were changed, the hollow moldability was the same as in Example 1,
The product properties of the hollow molded article and the properties of the composition were evaluated. Table 2 shows the evaluation results.

Comparative Example 6 Component A was prepared in the same manner as in Example 1 except that the supply amount of 1-hexene and the temperature in the reactor were changed to 120 ° C.
The MFR shown in Table 2 is 1.0 g / 10 min, and the density is 0.90
An ethylene / 1-hexene copolymer having 0 g / cm ³ , Mw / Mn of 2.0, and an extrapolated melting end temperature (Tem) of 102 ° C. was obtained. Using this component A, a high-pressure low-density polyethylene having the physical properties shown in Table 2 was used as the component B, and the components were blended at the ratio shown in Table 2 to produce pellets in the same manner as in Example 1. Using the pellets, the hollow moldability, the product properties of the hollow article, and the properties of the composition were evaluated in the same manner as in Example 1 except that the hollow molding conditions were changed. Table 2 shows the evaluation results.

Comparative Example 7 A component A was prepared in the same manner as in Example 1 except that the supply amount of 1-hexene was changed, and the MFR shown in Table 2 was 38 g /
An ethylene / 1-hexene copolymer having a density of 0.882 g / cm ³ , Mw / Mn of 2.0, and an extrapolated melting end temperature (Tem) of 78 ° C. for 10 minutes was obtained. Using this component A, a high-pressure low-density polyethylene having the physical properties shown in Table 2 was used as the component B, and the components were blended at the ratio shown in Table 2 to produce pellets in the same manner as in Example 1. Using the pellets, the hollow moldability, the product properties of the hollow molded article, and the properties of the composition were evaluated in the same manner as in Example 1 except that the hollow molding conditions were changed. Table 2 shows the evaluation results.

[0048]

[Table 2]

[0049]

As described above, the present invention relates to a polyethylene resin composition for hollow molding, which has impact resistance, flexibility,
An object of the present invention is to provide a polyethylene resin composition for hollow molding, which is excellent in chemical resistance, ESCR, surface tackiness, and transparency, and has improved hollow moldability which cannot be achieved by conventional techniques. This makes it possible to mold a hollow molded product, and therefore has a large industrial value.

Claims (4)

[Claims] 1. A polyethylene resin composition for hollow molding comprising the following components A and B: Component A 5-80% by weight of an ethylene-C3-C18 α-olefin copolymer produced by a high-pressure ion polymerization method and having the following properties: MFR at 190 ° C. and 2.16 kg load is 0.5 to
In 50 g / 10 min, and _{0.009W A -0.344 ≦ log (MFR)} ≦ satisfy the following relation -
0.003W _A +1.699 Here, W _A indicates the mixing ratio of component A (% by weight: weight of component A in resin composition / weight of resin composition × 100). The density is 0.87 to 0.93 g / cm ³ The ratio of weight average molecular weight / number average molecular weight (Mw / Mn) measured by GPC method is 1.5 to 3.3. Component B at 190 ° C. under a load of 2.16 kg MFR of 0.01 to 1
0 g / 10 min, density 0.915-0.94 g / cm ³
High-pressure low-density polyethylene, 95 to 20% by weight. 2. The polyethylene resin composition for hollow molding according to claim 1, wherein the melt tension (MT) at 190 ° C. satisfies the following relational expression. logMT ≧ 0.137 (logγ) ² −0.807 ·
Here, MT represents the melt tension (g) of the polyethylene resin composition at 190 ° C., and γ represents the shear rate (sec ⁻¹ ) at the die outlet during hollow molding. 3. The α of the ethylene / carbon 3 to 18 of the component A.
The polyethylene resin composition for hollow molding according to claim 1 or 2, wherein the olefin copolymer is produced using a metallocene catalyst and has the following properties. The extrapolated melting end temperature (Tem) of the melting peak obtained by DSC is 60-1.
30 ° C., and the relationship between Tem and density (D) satisfies the following relational expression. Tem ≦ 286D-137 4. The method according to claim 1, which has the following properties.
4. The polyethylene resin composition for hollow molding according to any one of items 3 to 3. MFR at 190 ° C, 2.16 kg load is 0.01
-10 g / 10 min. Density 0.88-0.94 g / cm ³