JP5365396B2 - Foamed hollow molding - Google Patents

Description

  The present invention relates to a foamed hollow molded article composed of a composition of an ethylene polymer and a low density polyethylene, which has an excellent balance between melt tension and melt draw ratio. More specifically, it comprises a composition of an ethylene copolymer and a low density polyethylene, which has a good balance between melt tension and melt stretch ratio, compared to the conventionally known foamed hollow molding made of an ethylene polymer, The present invention relates to a foamed hollow molded article having a high expansion ratio, light weight, excellent heat insulation, rigidity and heat resistance.

  In recent years, plastic pipes, films, and hollow molded articles have been actively used in various industrial fields. In particular, hollow molded bodies made of polyethylene resins are used in various applications because they are inexpensive and lightweight, and have excellent molding processability, chemical resistance, and recyclability. Attempts to improve the processing characteristics in these various hollow molding methods are carried out in a molten state of polyethylene, so various melting characteristics such as melt flowability (easy extrudability), melt stretchability, melt tension, etc. An intensive study has been made with an emphasis on improvement.

  Also, from the viewpoints of weight reduction, heat insulation, sound insulation, etc., by melting and kneading a polyethylene resin and a foaming agent with an extruder, the foamed molten resin film (parison) is extruded from a die and sandwiched between molds A foamed hollow molded body to be molded has been studied. In such a foamed hollow molded body, the above-mentioned melting characteristics are important, and in order to obtain a foam having a high expansion ratio, both the melt tension and the melt stretchability are good, that is, the melt tension and the melt. It is necessary that the balance of stretchability is excellent.

  As an ethylene polymer having a high melt tension, low density polyethylene (LDPE) produced by a high pressure radical method is known. Although LDPE is excellent in foamability, since the density range that can be produced is limited, the foamed hollow molded product lacks rigidity and heat resistance, so its use is limited.

  On the other hand, ethylene polymers obtained with a Ziegler catalyst or a metallocene catalyst are known as high-density ethylene polymers, but these have a low melt tension, break bubbles, etc. It was not obtained.

  Further, an ethylene polymer produced using a Cr-based catalyst (Phillips catalyst) is known as an ethylene-based polymer having a high density and a high melt tension. However, the ethylene-based polymer produced using a Cr-based catalyst has insufficient melt stretchability, and a good foamed molded product could not be obtained.

  Thus, it was difficult to obtain a foamed hollow molded article of polyethylene having a high density and a high foaming ratio.

  Therefore, a method of blending LDPE with high-density polyethylene (for example, see Patent Document 1) has been proposed. However, in this method, if the blend ratio of high-density polyethylene is increased, the melt tension of high-density polyethylene is low, and the foamability is reduced. In addition, since the balance between melt tension and melt stretchability is not good, problems such as draw-down and uneven thickness tend to occur in foam blow molding. On the other hand, when the blend ratio of low-density polyethylene is increased, a decrease in melt stretchability, a decrease in rigidity and heat resistance cannot be avoided.

  Moreover, although the method (patent document 2) etc. which add a thickener is proposed, since the expensive thickener is used, the improvement on the cost side was desired.

  Moreover, the inventor has proposed an uncrosslinked polyethylene foamed molded article having a good foamed state made of a polyethylene resin having specific properties (see, for example, Patent Document 3). Although this polyethylene-based resin is excellent in foaming properties, it has been necessary to improve blow molding properties in order to be used for foam blow molding.

JP 2006-305793 A Japanese Patent Laid-Open No. 2007-160582 Japanese Patent Laid-Open No. 2006-96910

  The present invention relates to a foamed hollow molded article made of a composition of an ethylene polymer and a low density polyethylene, which solves the above-described problems and has an excellent balance between melt tension and melt draw ratio. More specifically, compared to the conventionally known foamed hollow molding made of an ethylene polymer, a resin having an excellent balance between melt tension and melt drawing ratio and excellent blow moldability is used. It is an object of the present invention to provide a foamed hollow molded article that is high in weight, lightweight, has high heat insulation, has little unevenness, has a good molded body skin, has high density, and is excellent in rigidity and heat resistance.

  As a result of intensive studies on the above-mentioned purpose, the present inventor uses an ethylene-based polymer excellent in the balance between melt tension and maximum melt stretch ratio as a main component, so that the foaming ratio is high, light weight, and heat insulating properties. It is a foamed hollow molded body that is excellent in blow molding, and because it uses a resin that is excellent in blow moldability, it is excellent in blow moldability, and has a high density, high rigidity, and excellent heat resistance. As a result, the present invention has been completed.

That is, the present invention comprises an ethylene satisfying the following (A) to (D), comprising a repeating unit derived from ethylene, or a repeating unit derived from ethylene and a repeating unit derived from an α-olefin having 3 to 8 carbon atoms. The density (d) measured by the density gradient tube method in accordance with JIS K6760 and (E) JIS K6760 is from 890 kg / m ^{3 to} 940 kg / m ³ , (F) 190 ° C. It consists of low density polyethylene (2) satisfying a melt flow rate (MFR) measured at 16 kg load of 0.05 g / 10 min or more and 10 g / 10 min or less, and the proportion of the ethylene polymer of (1) is 50 wt. % Or less and less than 100% by weight, and the low density polyethylene of (2) is composed of an ethylene polymer composition of more than 0% by weight and 50% by weight or less. It relates hollow molded body.

(A) The density (d) measured by the density gradient tube method in accordance with JIS K6760 is 940 kg / m ³ or more and 970 kg / m ³ or less.
(B) The melt flow rate (MFR) measured at 190 ° C. and a 2.16 kg load is 0.05 g / 10 min or more and 10 g / 10 min or less.
(C) The relationship between the melt tension (MS (mN)) measured at 190 ° C. and MFR satisfies the following formula (1).

MS> 40-40 × log (MFR) (1)
(D) The relationship between the maximum melt drawing ratio (DR) at 190 ° C. and the melt flow rate (MFR) measured at 190 ° C. under a 2.16 kg load satisfies the following formula (2).

DR> 120 × (MFR) ^0.75 (2)

  First, an ethylene polymer (1) composed of a repeating unit derived from ethylene, or a repeating unit derived from ethylene and a repeating unit derived from an α-olefin having 3 to 8 carbon atoms will be described.

The ethylene polymer (1) of the present invention has a density of 940 kg / m ³ or more and 970 kg / m ³ or less measured by a density gradient tube method in accordance with (A) JIS K6760. When the density is less than 940 kg / m ³ , the rigidity becomes low and sufficient heat resistance cannot be obtained. On the other hand, if the density exceeds 970 kg / m ³ , the impact strength becomes weak.

  The ethylene polymer (1) has (B) a melt flow rate (hereinafter referred to as MFR) measured at 190 ° C. and a load of 2.16 kg of 0.1 g / 10 min or more and 10 g / 10 min or less. It is. Here, when the MFR is less than 0.1 g / 10 min, the load on the extruder increases during the molding process, and the productivity is lowered. Moreover, when MFR exceeds 10 g / 10min, melt tension becomes small and the drawdown at the time of shaping | molding becomes large.

  In the ethylene polymer (1), (C) the relationship between the melt tension (MS (mN)) measured at 190 ° C. and MFR satisfies the following formula (1), more preferably satisfies the formula (4). To do.

  MS> 40-40 × log (MFR) (1)

  MS> 50-50 × log (MFR) (4)

  A resin having a high melt tension such that MFR and MS satisfy the formula (1), more preferably the formula (3) can hold the generated bubbles at the time of foam blow molding, and the foam has a high foaming ratio. It is possible to produce a foamed molded product.

  In the ethylene polymer (1), (D) the relationship between the maximum melt stretch ratio (DR) measured at 190 ° C. and the MFR measured at 190 ° C. under a 2.16 kg load satisfies the following formula (2). More preferably, the expression (5) is satisfied.

DR> 120 × (MFR) ^0.75 (2)

DR> 130 × (MFR) ^0.85 (5)

  A resin excellent in melt stretchability in which MFR and DR satisfy the formula (2), more preferably the formula (4) is a foamed hollow molded body that is difficult to generate giant bubbles, has a uniform bubble diameter, and has high strength. Can be manufactured.

  Since the ethylene polymer constituting the present invention has a high melt tension (MS) and a melt draw ratio (DR), a foamed hollow molded body having a high expansion ratio and a uniform cell diameter can be obtained.

  In the ethylene polymer of the present invention, (E) the ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) is preferably 2 or more and 8 or less, more preferably 2.5 or more and 5 or less. When Mw / Mn is 2 or more, the load on the extruder is small at the time of molding, the skin of the molded body is good, and when Mw / Mn is 8 or less, the melt drawing ratio is high and the expansion ratio is good. It is. Mw / Mn can be calculated by measuring the weight average molecular weight (Mw) and the number average molecular weight (Mn), which are standard polyethylene equivalent values, by gel permeation chromatography (GPC).

  (A) to (D) constituting the foamed hollow molded article of the present invention, and preferably the ethylene polymer (1) satisfying (H), as long as it belongs to the category of the ethylene polymer. Any method may be used, and it may be obtained by any method. For example, the manufacturing conditions of the present embodiment to be described later or the condition factors can be arbitrarily adjusted.

  As a specific method for producing an ethylene polymer (1), for example, in the presence of a macromonomer described in JP-A No. 2004-346304, JP-A No. 2005-248013, and JP-A No. 2006-321991. Alternatively, a method such as a method of polymerizing ethylene and optionally an olefin having 3 or more carbon atoms can be exemplified simultaneously with the synthesis of the macromonomer. For example, two types of transition metal compounds (hereinafter referred to as components (a) and (b)) as main components, and clay minerals and clay minerals treated with organic compounds (hereinafter referred to as components (c)). Ethylene polymerized in the presence of a catalyst comprising a component selected from aluminoxane, protonate, Lewis acid salt, metal salt, and alkylaluminum (hereinafter referred to as component (d)), or ethylene And a method of copolymerizing an α-olefin having 3 to 8 carbon atoms.

  Although there is no particular limitation regarding the method for producing the macromonomer, for example, JP 2005-281676 A, JP 2006-28326 A, JP 2006-315999 A, JP 2007-246433 A, JP 2008-50278 A. The method etc. which are described in the gazette can be illustrated.

  By using the ethylene polymer production method and macromonomer production method described above, it is possible to produce an ethylene polymer having a high melt tension that satisfies the formula (1) or (3). The ethylene polymer constituting the present invention is further characterized by a high melt draw ratio. In order to produce such an ethylene polymer, the weight average molecular weight and number It is desirable to select a production method capable of producing an ethylene polymer having a narrow molecular weight distribution with an average molecular weight ratio (Mw / Mn) of 2 or more and 8 or less.

  When producing the ethylene polymer (1) constituting the hollow molded article of the present invention, it is preferably carried out at a polymerization temperature of −100 to 120 ° C., particularly preferably 20 to 120 ° C. in consideration of productivity. Is preferably performed in the range of 60 to 120 ° C. The polymerization time is preferably in the range of 10 seconds to 20 hours, and the polymerization pressure is preferably in the range of normal pressure to 300 MPa. As a monomer used for polymerization, ethylene alone or ethylene and an α-olefin having 3 to 8 carbon atoms, and ethylene and an α-olefin having 3 to 8 carbon atoms, ethylene and 3 to 8 carbon atoms As a supply ratio of α-olefin, a supply ratio of ethylene / C3-C8 α-olefin (molar ratio) of 1 to 200, preferably 3 to 100, more preferably 5 to 50 can be used. It is also possible to adjust the molecular weight using hydrogen during polymerization. The polymerization can be carried out by any of batch, semi-continuous and continuous methods, and can be carried out in two or more stages by changing the polymerization conditions. In addition, the ethylene copolymer can be obtained by separating and recovering from the polymerization solvent by a conventionally known method after the completion of the polymerization and drying.

  Polymerization can be carried out in a slurry state, a solution state, or a gas phase state. In particular, when the polymerization is performed in a slurry state, an ethylene-based copolymer having a powder particle shape is efficiently and stably produced. Can do. Further, the solvent used for the polymerization may be any organic solvent that is generally used, and specific examples include benzene, toluene, xylene, propane, isobutane, pentane, hexane, heptane, cyclohexane, gasoline, and the like, propylene, Olefin itself such as 1-butene, 1-hexene and 1-octene can also be used as a solvent.

The foamed hollow molded article of the present invention has the above-mentioned ethylene polymer (1) and (E) a density (d) measured by a density gradient tube method in accordance with JIS K6760 of 890 kg / m ³ or more and 940 kg / m ^3. A composition comprising: (F) low density polyethylene (2) having a melt flow rate (MFR) measured at 190 ° C. and a load of 2.16 kg of 0.05 g / 10 min or more and 5 g / 10 min or less. Used.

The low density polyethylene (2) of the present invention has a density (d) of 890 kg / m ³ or more and 940 kg / m ³ or less measured by a density gradient tube method in accordance with (E) JIS K6760 manufactured by a high pressure radical method. It is a low-density polyethylene and (F) has a melt flow rate (MFR) measured at 190 ° C. and a load of 2.16 kg of 0.05 g / 10 min or more and 5 g / 10 min or less.

Here, when the MFR of the low density polyethylene (2) is less than 0.05 g / 10 min, the load on the extruder increases during the molding process, and fish tends to be generated. Moreover, when MFR exceeds 5 g / 10min, melt tension becomes small and the drawdown at the time of shaping | molding becomes large.
In the composition of the ethylene-based resin (1) and the low-density polyethylene (2), the proportion of the ethylene-based polymer (1) is 50 wt% or more and less than 100 wt%, and the low-density polyethylene (2) is 0 % And 50% by weight or less. If the proportion of the ethylene resin (1) is less than 50% by weight, the rigidity and heat resistance are lowered, which is not preferable. When the low density polyethylene exceeds 50% by weight, the rigidity and heat resistance are similarly lowered, which is not preferable. From such a viewpoint, the proportion of the ethylene-based resin (1) is more preferably 70% by weight or more, and further preferably 80% by weight or more. Similarly, the low density polyethylene (2) is preferably 30% by weight or less, more preferably 20% by weight or less.

  When the low density polyethylene (2) exceeds 0%, the drawdown resistance is improved, and a foam blow molded article having a uniform thickness and cell diameter can be obtained.

  Any method may be used as a method for obtaining the composition of the ethylene polymer (1) and the low density polyethylene (2). For example, the ethylene polymer (1) and the low density polyethylene (2) are previously obtained from a Henschel mixer. , V-blender, ribbon blender, tumbler blender, etc., mixing the composition mixed in a blow molding machine, polyethylene-based polymer (1) and low-density polyethylene (2) single screw extrusion Examples thereof include a method of melt-mixing in advance at a melt kneading temperature of 100 to 300 ° C. with an extruder such as a granulator or a twin screw extrusion granulator.

  The composition comprising the ethylene polymer (1) and the low density polyethylene (2) thus obtained has the following relationship between (G) melt tension (MS (mN)) measured at 190 ° C. and MFR: It is preferable that the composition satisfies the formula (3).

MS> 60-70 × log (MFR) (3)
When the melt tension does not satisfy the above formula, the resin is difficult to hold bubbles, so that the generated bubbles are liable to break and the expansion ratio is difficult to increase. Moreover, the drawdown property at the time of shaping | molding becomes large and shaping | molding becomes difficult.

Next, the manufacturing method of the foaming hollow molding of this invention is demonstrated.
The foamed hollow molded article of the present invention is obtained by melt-kneading the ethylene polymer composition of the present invention and a foaming agent with an extruder, extruding a foamed molten resin film (parison) from a die, and sandwiching it with a mold. Can be manufactured. As a molding machine at that time, a known blow molding machine such as an accumulator type and a direct mold, a foam blow molding machine having a device capable of injecting a foaming agent in the middle of an extruder, or the like can be used.

  Examples of the foaming agent include inorganic gas foaming agents such as carbon dioxide, nitrogen, argon, and air; and volatile foaming agents such as propane, butane, pentane, hexane, cyclobutane, cyclohexane, trichlorofluoromethane, and dichlorodifluoromethane. be able to. Also, azodicarbonamide, barium azodicarboxylate, N, N-dinitrosopentamethylenetetramine, 4,4′-oxybis (benzenesulfonylhydrazide), diphenylsulfone that is liquid or solid at room temperature and generates gas upon heating. Examples thereof include chemical blowing agents such as -3,3'-disulfonylhydrazide, p-toluenesulfonyl semicarbazide, trihydrazinotriazine, biurea, zinc carbonate, and sodium bicarbonate (sodium bicarbonate). A plurality of foaming agents can be used in combination. The addition amount of the foaming agent is preferably 1 to 20 parts by weight, particularly preferably 2 to 8 parts by weight, based on 100 parts by weight of the polyethylene resin composition of the present invention.

  The foamed hollow molded article of the present invention is not only a foamed hollow molded article using a gas foaming agent that requires a blow molding machine accompanied by a gas injection facility, but also a chemical foamable foaming in a normal blow molding machine. The foamed hollow molded article using the agent also has a feature that the expansion ratio is high.

  As a method of blending these foaming agents into the composition of the ethylene polymer (1) and the low density polyethylene (2), any method may be used as long as a foamed hollow molded body is obtained. A composition in which one or both of coalescence (1) and low-density polyethylene and a foaming agent are mixed in advance by a mixer represented by a Henschel mixer, a V-blender, a ribbon blender, a tumbler blender, etc. is put into a blow molding machine. The method of foaming, the composition of the ethylene polymer (1) and the low density polyethylene (2) and the foaming agent are separately introduced into an extruder, and the method of melt mixing in the extruder is exemplified. Can do.

  The expansion ratio of the foamed hollow molded article of the present invention thus produced is 1.5 to 10 times, more preferably 2.0 to 8 times.

  The ethylene-based polymer constituting the foamed hollow molded article of the present invention may be blended with other optional blending components according to various purposes without departing from the object of the present invention. As a compounding component, it may be used as a normal polyolefin additive or compounding material, such as a crystallization nucleating agent, an antioxidant, a neutralizing agent, a weather resistance improving agent, a dispersing agent, an antistatic agent, a lubricant, Molecular weight regulators (peroxides, etc.), heat stabilizers, light stabilizers, UV absorbers, lubricants, antifogging agents, antiblocking agents, slip agents, flame retardants, conductivity-imparting agents, crosslinking agents, crosslinking aids And various auxiliary agents such as metal deactivators, antibacterial agents and fluorescent brighteners, other various resins and elastomers, fillers, colorants and the like.

  The foamed hollow molded article of the present invention is uniformly foamed and has a high foaming ratio, so it is lightweight, has high heat insulation properties, and has high density, so it has excellent rigidity and heat resistance. It can be used for various purposes.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, commercially available reagents were used.

  Preparation of the clay mineral (c) treated with the organic compound, preparation of the ethylene polymer production catalyst, production of the ethylene polymer and solvent purification were all carried out in an inert gas atmosphere. Preparation of clay minerals (component (c)) treated with organic compounds, preparation of catalysts for ethylene polymer production, solvents used for ethylene polymer production, etc. are all purified, dried, What used oxygen was used. Components (a) and (b) were synthesized and identified by known methods. Toso Finechem Co., Ltd. was used as the hexane solution (0.714 mol / l) of triisobutylaluminum.

  Furthermore, various physical properties of the ethylene-based polymer in the examples were measured by the following methods.

~ Measurement of density ~
The density (d) was measured by a density gradient tube method in accordance with JIS K6760 (1995).

-Measurement of molecular weight and molecular weight distribution-
The weight average molecular weight (M _w ), the number average molecular weight (M _n ), and the ratio of the weight average molecular weight to the number average molecular weight (M _w / M _n ) were measured by gel permeation chromatography (GPC). Tosoh Co., Ltd. HLC-8121GPC / HT is used as the GPC apparatus, Tosoh Co., Ltd. TSKgel GMHhr-H (20) HT is used as the column, the column temperature is set to 140 ° C., and 1 is used as the eluent. Measurement was performed using 2,4-trichlorobenzene. A measurement sample was prepared at a concentration of 1.0 mg / ml, and 0.3 ml was injected and measured. The calibration curve of molecular weight is calibrated using a polystyrene sample having a known molecular weight. In addition, _Mw and _Mn were calculated | required as a value of linear polyethylene conversion.

The ethylene polymer (1) and the composition comprising the ethylene polymer (1) and the low density polyethylene (2) used for the measurement of the melt tension (MS) and the maximum melt draw ratio (DR) are preliminarily heat resistant stabilizers. Irganox 1010 ^TM (manufactured by Ciba Japan Co., Ltd.) 1,500 ppm and Irgafos 168 ^TM (manufactured by Ciba Japan Co., Ltd.) 1,500 ppm were added as a 20 mmφ single-screw extruder (Toyo Seiki Co., Ltd.) A product manufactured by Seisakusho Co., Ltd., trade name: Labo Plast Mill, screw compression ratio 3) was used, which was kneaded at 200 ° C. and rotation speed 30 rpm under a nitrogen stream.

~ Measurement of melt tension (MS) ~
Melt tension was measured on a capillary viscometer with a barrel diameter of 9.55 mm (trade name: Capillograph, manufactured by Toyo Seiki Seisakusho Co., Ltd.) with a die having a length of 8 mm and a diameter of 2.095 mm and an inflow angle of 90 °. It was mounted on and measured. The temperature was set to 190 ° C., the piston lowering speed was set to 10 mm / min, the stretch ratio was set to 47, and the load (mN) required for take-up was taken as the melt tension.

~ Measurement of maximum melt draw ratio (DR) ~
The maximum melt drawing ratio is a capillary viscometer with a barrel diameter of 9.55 mm (trade name: Capillograph, manufactured by Toyo Seiki Seisakusho Co., Ltd.), and a die with a length of 8 mm and a diameter of 2.095 mm has an inflow angle of 90 °. It was mounted and measured. The temperature is set to 190 ° C, the piston descending speed is 10 mm / min, the take-up speed is 5 m / min (drawing ratio is 24), and the take-up speed is accelerated by 40 m / min for 1 minute. The maximum melt draw ratio was calculated from the speed.

-Foam molded body of 1000ml container and its evaluation-
Using a single-layer blow molding machine (made by Plako Co., Ltd.) having a 65 mmφ extrusion screw, a 0.2 μm filter was attached to the blowing air port, a cylinder temperature of 220 ° C., a thickness of 1.5 mm, and a container volume of 1000 ml. The container was molded, and the expansion ratio and storage elastic modulus (heat resistance index) at 80 ° C. were measured.

~ Measurement of foaming ratio ~
The apparent density of the foamed molded product was measured with a hydrometer (manufactured by Shinko Denshi Co., Ltd., trade name: DME-220H), and the expansion ratio was determined from the ratio to the density of the composition.

~ Measurement of storage modulus at 80 ℃ ~
The storage elastic modulus at 80 ° C. of the foamed molded product was measured using a melt viscoelasticity measuring apparatus (trade name DVE-V4, manufactured by UBM Co., Ltd.). A test piece having a width of 3 mm and a length of 25 mm was cut out from the foamed molded article, given a sine strain of 10 Hz in the tensile direction, heated from a starting temperature of 30 ° C. at a heating rate of 2 ° C./min, and a storage elastic modulus at 80 ° C. Was measured.

~ Drawdown resistance during molding ~
When the resin is extruded at a rotation speed of 30 rpm by a 65 mmφ extruder used for molding a 1000 ml container, it is necessary for the molten resin film (parison) discharged from the die outlet of the molding machine to hang down to 12 cm from the die outlet. The ratio of time to the time required to hang down to 60 cm (t _{60 cm} / t _{12 cm} ) was measured. The greater this _t60cm / _t12cm , the better the drawdown resistance.

Example 1
[Preparation of Clay Mineral {Component (d)} Treated with Organic Compound]
After adding 60 ml of ethanol and 2.0 ml of 37% concentrated hydrochloric acid to 60 ml of water, 6.6 g (0.022 mol) of N, N-dimethyl-octadecylamine was added to the resulting solution and heated to 60 ° C. A hydrochloride solution was prepared. To this solution was added 20 g of hectorite. The suspension was stirred at 60 ° C. for 3 hours, the supernatant was removed, and then washed with 1 L of 60 ° C. water. Then, the modified hectorite (component (m)) with an average particle diameter of 5.2 micrometers was obtained by drying at 60 degreeC and 10 < ^-3 > torr for 24 hours, and grind | pulverizing with a jet mill. As a result of elemental analysis, the amount of ions per gram of modified hectorite was 0.85 mmol.

[Preparation of ethylene polymer production catalyst]
62 mg (160 μmol) of dimethylsilanediyl [(cyclopentadienyl) (2-methylindenyl)] zirconium dichloride (component (a)) was suspended in 17.6 ml of hexane, and triisobutylaluminum (component (c)) 22.4 ml of hexane solution (0.714M) was added to obtain a contact product of component (a) and component (c). 4.0 g of the modified hectorite (component (l)) prepared in Example 1 [Preparation of clay mineral {component (d)} treated with an organic compound]) was added to the contact product, and the mixture was heated at 60 ° C. for 3 hours. After stirring, the solution was left to stand to remove the supernatant, and washed with a hexane solution (0.03M) of triisobutylaluminum. Further, a hexane solution (0.15 M) of triisobutylaluminum was added to form a catalyst slurry (100 g / L).

  To the catalyst slurry prepared above, 3 mol% of isopropylidene (1-cyclopentadienyl) (2,7-didiyl) with respect to dimethylsilanediyl [(cyclopentadienyl) (2-methylindenyl)] zirconium dichloride. A solution consisting of 2.7 mg (4.8 μmol) of tert-butyl-9-fluorenyl) zirconium dichloride (component (b)), 6.7 ml of hexane and 1.18 ml of a hexane solution of triisobutylaluminum (0.714 M) was added. And stirred at room temperature for 6 hours. Let stand and remove the supernatant, wash with hexane solution of triisobutylaluminum (0.03M), add hexane solution of triisobutylaluminum (0.15M) and finally add 100g / L catalyst slurry. Obtained.

[Production of ethylene polymer (1)]
To a 50 L autoclave, 30 L of hexane and 25.0 ml of a hexane solution of triisobutylaluminum (0.714 M) were introduced, and the internal temperature of the autoclave was raised to 85 ° C. To this autoclave, 1.875 ml of the catalyst slurry was added, and an ethylene / hydrogen mixed gas (hydrogen: containing 800 ppm) was introduced until the partial pressure reached 1.2 MPa to initiate polymerization. During the polymerization, an ethylene / hydrogen mixed gas was continuously introduced so that the partial pressure was maintained at 1.2 MPa. The polymerization temperature was controlled at 85 ° C. After 90 minutes from the start of the polymerization, the internal pressure of the autoclave was released, and the contents were suction filtered. After drying, 2400 g of polymer was obtained. Table 1 shows the density, MFR, Mw, Mw / Mn, melt tension, and melt stretch ratio of the resulting ethylene polymer.

[Molding of foamed hollow moldings]
80 parts by weight of the obtained ethylene polymer, 20 parts by weight of low density polyethylene (trade name Petrocene 175, manufactured by Tosoh Corporation) and 3 parts by weight of sodium bicarbonate-based foaming agent masterbatch (product name: EE-275F) Using a single layer blow molding machine (manufactured by Plako Co., Ltd.), a foamed container having a cylinder temperature of 220 ° C., a thickness of 1.5 mm and a container volume of 1000 ml was molded. There was little surface roughness of the container, and the corners were not thinned.

The expansion ratio and storage modulus (80 ° C.) of this container were measured. Further, the ratio of the time required for the molten resin film (parison) discharged from the die outlet of the molding machine to hang down to 12 cm from the die outlet and the time required to hang down to 60 cm (t _{60 cm} / t _{12 cm} ) was measured. The results are shown in Table 2. It can be seen that the foaming property and heat resistance are excellent, and the drawdown resistance during molding is excellent.

Comparative Example 1
[Molding of foamed hollow moldings]
80 parts by weight of commercially available high-density polyethylene (trade name Nipolon Hard 5700, manufactured by Tosoh Corporation) and 20 parts by weight of low-density polyethylene (trade name: Petrocene 170R, manufactured by Tosoh Corporation) and a baking soda-based foaming agent masterbatch (manufactured by Eiwa Kasei, trade name EE) -275F) 3 parts by weight of the mixture was dry blended, and a foamed container having a container volume of 1000 ml was molded in the same manner as in Example 1. Unlike Example 1, the corner portion of the container had a thin-walled portion and had a hole.

Example 2
[Production of ethylene polymer (1)]
To a 50 L autoclave, 30 L of hexane and 25.0 ml of a hexane solution of triisobutylaluminum (0.714 M) were introduced, and the internal temperature of the autoclave was raised to 85 ° C. To this autoclave, 1.875 ml of the catalyst slurry described in [Preparation of ethylene polymer production catalyst] in Example 1 and 50 g of 1-butene were added, and an ethylene / hydrogen mixed gas (hydrogen: 1800 ppm included) had a partial pressure. The polymerization was started by introducing it until the pressure reached 1.2 MPa. During the polymerization, an ethylene / hydrogen mixed gas was continuously introduced so that the partial pressure was maintained at 1.2 MPa. The polymerization temperature was controlled at 85 ° C. After 90 minutes from the start of the polymerization, the internal pressure of the autoclave was released, and the contents were suction filtered. After drying, 2,250 g of polymer was obtained. Table 1 shows the density, MFR, Mw, Mw / Mn, melt tension, and melt stretch ratio of the resulting ethylene polymer.

[Molding of foamed hollow moldings]
Dry 70 parts by weight of the obtained ethylene polymer, 30 parts by weight of low-density polyethylene (trade name Petrocene 172, manufactured by Tosoh Corporation) and 3 parts by weight of a baking soda-based foaming agent master batch (trade name EE-275F, manufactured by Eiwa Kasei). After blending, a foam container having a container volume of 1000 ml was molded in the same manner as in Example 1. Although the surface of the container was not very rough, the corner part was considerably thinned.

The expansion ratio and storage modulus (80 ° C.) of this container were measured. Moreover, _t60cm / _t12cm was measured. The results are shown in Table 2. It can be seen that the foaming property and heat resistance are excellent, the drooping time is long, and the drawdown resistance during molding is excellent.

Comparative Example 2
[Molding of foamed hollow moldings]
Dry blend of 100 parts by weight of the ethylene polymer obtained in [Production of ethylene polymer (1)] of Example 1 and 3 parts by weight of a baking soda-based foaming agent masterbatch (trade name: EE-275F, manufactured by Eiwa Kasei) A foamed container having a container volume of 1000 ml was molded in the same manner as in Example 1 except that was used. The expansion ratio and storage modulus (80 ° C.) of this container were measured. Moreover, _t60cm / _t12cm was measured. The results are shown in Table 2, and it can be seen that t _{60 cm} / t _{12 cm} is small and inferior in draw-down resistance during molding as compared to Example 2.

Example 3
[Production of ethylene polymer (1)]
To a 50 L autoclave, 30 L of hexane and 25.0 ml of a hexane solution of triisobutylaluminum (0.714 M) were introduced, and the internal temperature of the autoclave was raised to 85 ° C. To this autoclave, 1.875 ml of the catalyst slurry described in [Preparation of ethylene polymer production catalyst] in Example 1 and 50 g of 1-butene were added, and an ethylene / hydrogen mixed gas (hydrogen: 1800 ppm included) had a partial pressure. The polymerization was started by introducing it until the pressure reached 1.2 MPa. During the polymerization, an ethylene / hydrogen mixed gas was continuously introduced so that the partial pressure was maintained at 1.2 MPa. The polymerization temperature was controlled at 85 ° C. After 90 minutes from the start of the polymerization, the internal pressure of the autoclave was released, and the contents were suction filtered. After drying, 2,100 g of polymer was obtained. Table 1 shows the density, MFR, Mw, Mw / Mn, melt tension, and melt stretch ratio of the resulting ethylene polymer.

[Molding of foamed hollow moldings]
Dry 70 parts by weight of the obtained ethylene polymer, 30 parts by weight of low density polyethylene (trade name Petrocene 173, manufactured by Tosoh Corporation) and 3 parts by weight of a baking soda-based foaming agent masterbatch (manufactured by Eiwa Kasei, trade name EE-275F). After blending, a foaming container having a container volume of 1000 ml was molded in the same manner as in Example 1. There was little surface roughness of the container, and the corners were not thinned.

The expansion ratio and storage modulus (80 ° C.) of this container were measured. Moreover, _t60cm / _t12cm was measured. The results are shown in Table 2. It can be seen that the foamability, heat resistance, and resistance to drawdown during molding are excellent.

Comparative Example 3
[Preparation of ethylene polymer production catalyst]
[Preparation of clay minerals treated with organic compounds]
After adding 60 ml of ethanol and 2.0 ml of 37% concentrated hydrochloric acid to 60 ml of water, 11.7 g (0.022 mol) of N-methyldioleylamine was added to the resulting solution and heated to 60 ° C. A methyldioleylamine hydrochloride solution was prepared. To this solution was added 20 g of hectorite. The suspension was stirred at 60 ° C. for 3 hours, the supernatant was removed, and then washed with 1 L of 60 ° C. water. Then, it dried at 60 degreeC and 10 < ^-3 > torr for 24 hours, and the modified | denatured hectorite with an average particle diameter of 5.2 micrometers was obtained by grind | pulverizing with a jet mill. As a result of elemental analysis, the amount of ions per gram of modified hectorite was 0.85 mmol.

[Preparation of catalyst for macromonomer production]
8.0 g of the above modified hectorite is suspended in 29 ml of hexane, 46 ml of a hexane solution of triisobutylaluminum (0.714M) is added, and the mixture is stirred at room temperature for 1 hour, whereby contact formation of the modified hectorite and triisobutylaluminum occurs. I got a thing. On the other hand, 14.0 mg (40 μmol) of dimethylsilanediylbis (cyclopentadienyl) zirconium dichloride dissolved in toluene was added and stirred overnight at room temperature to obtain a catalyst slurry (100 g / L). .

[Manufacture of macromonomer]
To a 10 L autoclave, 6,000 ml of hexane and 12 ml of a hexane solution of triisobutylaluminum (0.714 mol / L) were introduced, and the internal temperature of the autoclave was raised to 85 ° C. To the autoclave, 3 ml of the catalyst slurry was added, and ethylene was introduced until the partial pressure reached 1.2 MPa to initiate polymerization. During the polymerization, ethylene was continuously introduced so that the partial pressure was kept at 1.2 MPa. The polymerization temperature was controlled at 85 ° C. 53 minutes after the start of polymerization, the internal temperature was lowered to 50 ° C. and the internal pressure of the autoclave was depressurized to 0.1 MPa, and then nitrogen was introduced into the autoclave until the pressure became 0.6 MPa and depressurized. This operation was repeated 5 times to produce a macromonomer having an _Mn of 10,950.

[Method for producing ethylene polymer]
In a 10 L autoclave containing the macromonomer produced above, 12 ml of a hexane solution (0.714 mol / L) of triisobutylaluminum and diphenylmethylene (1-cyclopentadienyl) (2,7-di-t-butyl-9 -Fluorenyl) Zirconium dichloride 7 µmol was introduced, and the internal temperature of the autoclave was raised to 60 ° C. Polymerization was initiated by introducing an ethylene / hydrogen mixed gas (hydrogen 28,500 ppm) until the partial pressure reached 0.2 MPa. During the polymerization, an ethylene / hydrogen mixed gas was continuously introduced so that the partial pressure was maintained at 0.3 MPa. The polymerization temperature was controlled at 90 ° C. After 173 minutes from the start of polymerization, the internal pressure of the autoclave was released, and the contents were suction filtered. After drying, 865 g of polymer was obtained. Table 1 shows the density, MFR, Mw, Mw / Mn, melt tension, and melt draw ratio of the obtained ethylene polymer of the obtained ethylene polymer.
[Molding of foamed hollow moldings]
Next, 70 parts by weight of the obtained ethylene-based polymer, 30 parts by weight of low-density polyethylene (trade name Petrocene 173, manufactured by Tosoh Corporation), and 3 parts by weight of a baking soda-based foaming agent masterbatch (manufactured by Eiwa Kasei, trade name: EE-275F) And a foamed container having a container volume of 1000 ml was molded in the same manner as in Example 1. There was little surface roughness of the container, and the corners were not thinned.

The expansion ratio and storage modulus (80 ° C.) of this container were measured. Moreover, _t60cm / _t12cm was measured. The results are shown in Table 2. It can be seen that the foamability, drawdown resistance and heat resistance are inferior to those of Example 3.

  Comparative Example 4

[Manufacture of macromonomer]
To a 10 L autoclave, 6,000 ml of hexane and 12 ml of a hexane solution of triisobutylaluminum (0.714 mol / L) were introduced, and the internal temperature of the autoclave was raised to 85 ° C. To the autoclave, 3 ml of the catalyst slurry was added, and ethylene was introduced until the partial pressure reached 1.2 MPa to initiate polymerization. During the polymerization, ethylene was continuously introduced so that the partial pressure was kept at 1.2 MPa. The polymerization temperature was controlled at 85 ° C. 53 minutes after the start of polymerization, the internal temperature was lowered to 50 ° C. and the internal pressure of the autoclave was depressurized to 0.1 MPa, and then nitrogen was introduced into the autoclave until the pressure became 0.6 MPa and depressurized. This operation was repeated 5 times to produce a macromonomer having an _Mn of 10,950.

[Method for producing ethylene polymer]
In a 10 L autoclave containing the macromonomer produced above, 12 ml of a hexane solution (0.714 mol / L) of triisobutylaluminum and diphenylmethylene (1-cyclopentadienyl) (2,7-di-t-butyl-9 -Fluorenyl) Zirconium dichloride 7 µmol was introduced, and the internal temperature of the autoclave was raised to 60 ° C. Polymerization was initiated by introducing an ethylene / hydrogen mixed gas (hydrogen 20,200 ppm) until the partial pressure reached 0.2 MPa. During the polymerization, an ethylene / hydrogen mixed gas was continuously introduced so that the partial pressure was maintained at 0.3 MPa. The polymerization temperature was controlled at 90 ° C. 210 minutes after the start of polymerization, the internal pressure of the autoclave was released, and the contents were suction filtered. After drying, 1020 g of polymer was obtained. Table 1 shows the density, MFR, Mw, Mw / Mn, melt tension, and melt draw ratio of the obtained ethylene polymer of the obtained ethylene polymer.
[Molding of foamed hollow moldings]
Next, 70 parts by weight of the obtained ethylene-based polymer, 30 parts by weight of low-density polyethylene (trade name Petrocene 173, manufactured by Tosoh Corporation), and 3 parts by weight of a baking soda-based foaming agent masterbatch (manufactured by Eiwa Kasei, trade name: EE-275F) And a foamed container having a container volume of 1000 ml was molded in the same manner as in Example 1. There was little surface roughness of the container, and the corners were not thinned.

The expansion ratio and storage modulus (80 ° C.) of this container were measured. Moreover, _t60cm / _t12cm was measured. The results are shown in Table 2, and it can be seen that the foamability is inferior.

Example 4
[Preparation of ethylene polymer production catalyst]
68 mg (160 μmol) of dimethylsilanediyl [(cyclopentadienyl) (4,7-dimethylindenyl)] zirconium dichloride (component (a)) was suspended in 17.6 ml of hexane, and triisobutylaluminum (component (c)) ) In 22.4 ml of a hexane solution (0.714M) was obtained to obtain a contact product of component (a) and component (c). 4.0 g of the modified hectorite (component (l)) prepared in Example 1 [Preparation of clay mineral {component (d)} treated with an organic compound]) was added to the contact product, and the mixture was heated at 60 ° C. for 3 hours. After stirring, the solution was left to stand to remove the supernatant, and washed with a hexane solution (0.03M) of triisobutylaluminum. Further, a hexane solution (0.15 M) of triisobutylaluminum was added to form a catalyst slurry (100 g / L).

  To the catalyst slurry prepared above, 5 mol% of diphenylmethylene (1-cyclopentadienyl) (9-fluorenyl) with respect to dimethylsilanediyl [(cyclopentadienyl) (4,7-dimethylindenyl)] zirconium dichloride. ) A solution consisting of 4.5 mg (8.0 μmol) of zirconium dichloride (component (b)), 6.7 ml of hexane, and 1.18 ml of a hexane solution of triisobutylaluminum (0.714 M) was added and stirred at room temperature for 6 hours. . Let stand and remove the supernatant, wash with hexane solution of triisobutylaluminum (0.03M), add hexane solution of triisobutylaluminum (0.15M) and finally add 100g / L catalyst slurry. Obtained.

[Production of ethylene polymer]
To a 50 L autoclave, 30 L of hexane and 25.0 ml of a hexane solution of triisobutylaluminum (0.714 M) were introduced, and the internal temperature of the autoclave was raised to 85 ° C. To this autoclave, 1.875 ml of the catalyst slurry and 50 g of 1-butene were added, and an ethylene / hydrogen mixed gas (containing hydrogen: 1600 ppm) was introduced until the partial pressure reached 1.2 MPa to initiate polymerization. During the polymerization, an ethylene / hydrogen mixed gas was continuously introduced so that the partial pressure was maintained at 1.2 MPa. The polymerization temperature was controlled at 85 ° C. After 90 minutes from the start of the polymerization, the internal pressure of the autoclave was released, and the contents were suction filtered. After drying, 2,100 g of polymer was obtained. Table 1 shows the density, MFR, Mw, Mw / Mn, melt tension, and melt stretch ratio of the resulting ethylene polymer.

[Molding of foamed hollow moldings]
80 parts by weight of the obtained ethylene polymer, 20 parts by weight of low density polyethylene (trade name Petrocene 172, manufactured by Tosoh Corporation) and 3 parts by weight of sodium bicarbonate-based foaming agent master batch (trade name EE-275F, manufactured by Eiwa Kasei) After blending, a foaming container having a container volume of 1000 ml was molded in the same manner as in Example 1. There was little surface roughness of the container, and the corners were not thinned.

The expansion ratio and storage modulus (80 ° C.) of this container were measured. Moreover, _t60cm / _t12cm was measured. The results are shown in Table 2. It can be seen that the foamability, heat resistance, and resistance to drawdown during molding are excellent.

  Example 5

[Production of ethylene polymer]
To a 50 L autoclave, 30 L of hexane and 25.0 ml of a hexane solution of triisobutylaluminum (0.714 M) were introduced, and the internal temperature of the autoclave was raised to 85 ° C. To this autoclave, 1.875 ml of the catalyst slurry and 50 g of 1-butene were added, and an ethylene / hydrogen mixed gas (containing hydrogen: 1000 ppm) was introduced until the partial pressure reached 1.2 MPa to initiate polymerization. During the polymerization, an ethylene / hydrogen mixed gas was continuously introduced so that the partial pressure was maintained at 1.2 MPa. The polymerization temperature was controlled at 85 ° C. After 90 minutes from the start of the polymerization, the internal pressure of the autoclave was released, and the contents were suction filtered. After drying, 1,900 g of polymer was obtained. Table 1 shows the density, MFR, Mw, Mw / Mn, melt tension, and melt stretch ratio of the resulting ethylene polymer.

[Molding of foamed hollow moldings]
80 parts by weight of the obtained ethylene polymer, 20 parts by weight of low density polyethylene (trade name Petrocene 172, manufactured by Tosoh Corporation) and 3 parts by weight of sodium bicarbonate-based foaming agent master batch (trade name EE-275F, manufactured by Eiwa Kasei) After blending, a foaming container having a container volume of 1000 ml was molded in the same manner as in Example 1. There was little surface roughness of the container, and the corners were not thinned.

The expansion ratio and storage modulus (80 ° C.) of this container were measured. Moreover, _t60cm / _t12cm was measured. The results are shown in Table 2. It can be seen that the foamability, heat resistance, and resistance to drawdown during molding are excellent.

  The foamed hollow molded body of the present invention can be used, for example, as a container, a bath tub, a duct, an automobile member, an electrical product member, a building member, or the like.

Claims (3)

Ethylene polymer (1) satisfying the following (A) to (D) from a repeating unit derived from ethylene, or a repeating unit derived from ethylene and a repeating unit derived from an α-olefin having 3 to 8 carbon atoms And (E) a density (d) measured by a density gradient tube method in accordance with JIS K6760 is 890 kg / m ³ or more and 940 kg / m ³ or less, and (F) a melt measured at 190 ° C. and a load of 2.16 kg. The low-density polyethylene (2) satisfying a flow rate (MFR) of 0.05 g / 10 min or more and 10 g / 10 min or less, and the proportion of the ethylene polymer (1) is 50 wt% or more and less than 100 wt% And the low density polyethylene of (2) comprises a polyethylene resin composition comprising an ethylene polymer composition of more than 0% and not more than 50% by weight, and foamed. Expanded hollow molded expansion ratio determined from the density ratio of the apparent density and composition is characterized in that 1.5 to 10 times.
(A) The density (d) measured by the density gradient tube method in accordance with JIS K6760 is 940 kg / m ³ or more and 970 kg / m ³ or less.
(B) Melt flow rate (MFR) measured at 190 ° C. and 2.16 kg load is 0.1 g / 10 min or more and 10 g / 10 min or less (C) Melt tension (MS (mN)) measured at 190 ° C. and MFR The following relationship (1) is satisfied.
MS> 40-40 × log (MFR) (1)
(D) The relationship between the maximum melt drawing ratio (DR) at 190 ° C. and the melt flow rate (MFR) measured at 190 ° C. under a 2.16 kg load satisfies the following formula (2).
DR> 120 × (MFR) ^0.75 (2) A foamed hollow molded article, wherein the composition comprising the ethylene-based polymer (1) according to claim 1 and the low-density polyethylene (2) satisfies the following (G).
(G) The relationship between melt tension (MS (mN)) measured at 190 ° C. and MFR satisfies the following formula (3).
MS> 60-70 × log (MFR) (3) The foamed hollow molded article, wherein the ethylene polymer according to claim 1 or 2 is an ethylene polymer satisfying the following (H).
(H) The ratio of the weight average molecular weight to the number average molecular weight (Mw / Mn) is 2 or more and 8 or less.