JPH1112320A - Ethylene (co)polymer, laminate and blow molded product using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an ethylene (co)polymer excellent in drawdown and puncture resistances, parison control responsiveness and pinch-off characteristics by overcoming disadvantages possessed by a conventional polyethylene. SOLUTION: This ethylene (co)polymer satisfies the following requirements (1) to (4): (1) 0.94-0.98 g/cm<3> density, (2) 25-50 molecular weight distribution (Mw /Mn ), (3) the value of (a) is (a)<=0.05 and the value of (b) is (b) <=1.45 when determined by the relational expression DS=a*Ln(γ)+b between the die swell(DS) in a region of shearing rate (γ) (6.08-24.8 sec<-1> ) and the shear rate (γ) at 230 deg.C and (4) >=2.1 ratio (σmax/σ) of the maximal stress (σ max) to the stress (σ) at 1.0 strain in a stress-strain curve by uniaxial extension at 0.1 sec<-1> measured at 170 deg.C. The laminate and blow molded product use the (co)polymer and may be a fuel tank.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel ethylene (co) polymer, a laminate using the (co) polymer, and a hollow molded article. More specifically, an ethylene (co) polymer having excellent mechanical strength such as impact resistance, moldability, and the like, and which can be applied to extrusion molding, injection molding, hollow molding, and the like,
Large hollow containers (fuel tanks, drums, etc.) that require draw-down resistance, puncture resistance, parison thickness controllability (paricon response), pinch-off characteristics, durability, etc.
The present invention relates to an ethylene (co) polymer exhibiting superiority for hollow molding, such as a hollow molded article, a laminate, a hollow multilayer molded article, and the like using the (co) polymer.

[0002]

2. Description of the Related Art Generally, food containers such as detergent bottles, beverage bottles, edible oil bottles, large containers such as drums and industrial cans, kerosene cans, fuel containers such as gasoline tanks, spoilers and bumpers are manufactured by a hollow molding method. Have been. In this hollow molding method, a parison extruded into a cylindrical shape made of a melt-softened resin is sandwiched between molds, and air is blown into the parison to expand (blow-up) the parison.
After being deformed and shaped into a mold cavity shape, it is cooled. Such hollow molding methods include large-sized gasoline tanks with complex shapes, including hollow molded products such as bottles,
It is widely used because it can be widely applied to drums and even panel-shaped molded products, is simple in molding, and has low molding costs including molds.

In general, when a large product is formed by hollow molding, the parison hangs down by its own weight (drawdown).
Tends to occur. In order to reduce the drawdown, it is known to use a resin having sufficiently high viscosity and melt tension. Further, in the molding of a hollow molded article having a complicated shape, the blow ratio locally increases, and there is a tendency that puncture of the parison and local thinning occur. In order to prevent puncture and local thinning, it is known to control the thickness of the parison (parison control), to increase the thickness of the required parts, or to change the equipment such as changing the mold shape. I have.

Conventionally, if the molecular weight is increased and the viscosity is increased in order to improve the drawdown resistance of polyethylene, the extrusion characteristics (extrusion amount, parison surface state) deteriorate,
Further, there has been a problem that the fusion property of the parison is poor and the pinch-off shape is deteriorated. As a method for solving this problem, for example, a multi-stage polymerization method using a Ziegler catalyst (Japanese Patent Application Laid-Open No. 55-152735), a method in which a small amount of a radical generator and a crosslinking assistant are added to a polyethylene resin (particularly, Fairness 2-
There is known a method of mixing two-component polyethylene at a certain ratio (JP-A-6-299009).

[0005] However, in recent years, large hollow molded products have been used.
As the complexity increases and a heavy parison is extruded longer and more stably, further improvement in drawdown resistance of the resin is required. Further, in order to improve the effect of preventing permeation of various fuels in the fuel tank, a fuel tank using a saponified ethylene-vinyl acetate copolymer (hereinafter referred to as EVOH) or the like having low thermal stability as a barrier material is required. I have. In these moldings, instead of the accumulator-type hollow molding machine conventionally used for large-sized hollow molding, a continuous extrusion-type hollow molding machine with a small staying portion and a small amount of EVOH pyrolysis is replaced by a hollow large-sized fuel tank. It has begun to be used for molding. Compared to the accumulator method, the continuous extrusion method of the hollow molding machine takes a long time to extrude the parison, and the drawdown of the parison is likely to occur,
There is a demand for a resin having more excellent drawdown resistance.
For this reason, the polyethylene improved by the above-mentioned conventional method or the like has insufficient drawdown resistance to obtain a large hollow molded product.

[0006] Further, as the shape of the hollow molded article becomes more complicated, the phenomenon that the parison punctures during expansion and shaping, and the local thinning of corners of the product, etc., have become problems. As a method of preventing these problems, a method of controlling the thickness of the parison using a parison controller has been generally performed. However, in the case of a conventional polyethylene resin or a resin composition thereof, the thickness controllability of the parison (Paricon response) ) Is also becoming inadequate, and there is a demand for improved paricon responsiveness. In addition, as a method to enable molding of products with complex shapes with deep drawing by improving with equipment, a method of splitting a mold (Plastics vol.42, No.5,
p64-71) and a method using a hollow molding machine with a mold tilting mechanism (Plastics Vol. 41, No. 10, p59-69) are known. However, the above method has a problem that the cost of the apparatus and the mold is high.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to overcome the drawbacks of the conventional polyethylene and to provide an ethylene (co) polymer having excellent drawdown resistance, puncture resistance, paricon response and pinch-off characteristics. It is to provide coalescence. Another object of the present invention is to reduce the phenomenon that the parison of a hollow molded article having a complicated shape is punctured during expansion and shaping by the use of the ethylene (co) polymer or a composition thereof, and to locally reduce the thickness of corners of the product. An object of the present invention is to provide an improved hollow molded article. Still another object of the present invention is to provide a multilayer hollow molded body without permeation preventing performance of various fuels and without local thinning.

[0008]

The first aspect of the present invention is (a).
(B) a molecular weight distribution (Mw / Mn) of 25 to 50, and (c) 230 ° C. The density is 0.94 to 0.98 g / cm ^3.
And the following equation (1) between the die swell (DS) and the shear rate (γ) measured in the shear rate (γ) region (6.08 to 24.8 sec ^-1 ).

## EQU2 ## DS = a * Ln (γ) + b (1) The value of the slope a obtained from the equation (1) is a ≦ 0.05, and the value of the intercept b is b ≦ 1.
(D) Stress at a strain of 1.0 in a stress-strain curve due to uniaxial elongation at 0.1 sec ^-1 measured at 170 ° C. (σ) of 45
Is an ethylene (co) polymer that satisfies the requirement that the stress ratio between the maximum stress (σmax) and σmax / σ ≧ 2.1, and more preferably (e) HLMFR ≦ 10 g / 1
An ethylene (co) polymer satisfying the requirement of 0 min, wherein the content of the α-olefin having 3 to 20 carbon atoms is 10 mol% or less.

A second aspect of the present invention is a hollow molded article comprising the above-mentioned ethylene (co) polymer or a composition thereof. Preferably, the superiority of the copolymer of the present invention or the composition thereof is exhibited. It is a fuel tank.

A third aspect of the present invention is a laminate comprising the above-mentioned layer of ethylene (co) polymer or its composition, a barrier layer and, if desired, an adhesive layer, wherein the barrier layer comprises a polyamide resin, ethylene-acetic acid. A laminate using at least one selected from a saponified vinyl copolymer, a polyester resin, a polyvinylidene chloride resin, or a composition thereof is desirable. Further, it is desirable to use, as the adhesive layer, an adhesive resin composed of a copolymer of an unsaturated carboxylic acid or a derivative thereof and an olefin or a polyolefin resin modified with an unsaturated carboxylic acid or a derivative thereof.

A fourth aspect of the present invention is a hollow multilayer container comprising a laminate comprising the above-mentioned layer of ethylene (co) polymer or its composition, an adhesive layer and a barrier layer, and is preferably superior in a hollow multilayer fuel tank. The character is exhibited. A fifth aspect of the present invention is selected from a recycled resin composed of the laminate, a composition containing the resin with the ethylene (co) polymer of the first invention, or a composition containing them with a polyolefin-based resin. A hollow multilayer container comprising a laminate including at least one resin layer, a barrier layer, and, if desired, an adhesive layer. Preferably, the hollow multilayer fuel tank exhibits superior physical and economic advantages.

Hereinafter, the present invention will be described in more detail. The present invention relates to an ethylene homopolymer or ethylene and
An ethylene (co) polymer comprising the above α-olefin, wherein the density, molecular weight distribution, relationship between die swell (DS) and shear rate (γ), and stress ratio are adjusted to specific ranges. It has been achieved based on the finding that it has excellent drawdown resistance, puncture resistance, paricon response, pinch-off shape characteristics, and the like.

The ethylene (co) polymer of the present invention is an ethylene homopolymer or ethylene and α-α having 3 to 20 carbon atoms.
It is a copolymer composed of olefins. Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 4-methylpentene-1, 1-octene, 1-decene and the like. The content of these α-olefins is 10 mol% or less. If the content of the α-olefin exceeds 10% by weight, the rigidity may decrease.

The ethylene (co) polymer of the present invention has a density (a) of 0.94 to 0.98 g / cm ³ , preferably 0.945 to 0.97 g / cm ³ .
cm ³ , and 0.95 g /
cm ³ or more is desirable. When the density is less than 0.94 g / cm ³ , the rigidity decreases. On the other hand, when the density exceeds 0.98 g / cm ³ , the impact strength decreases.

The (b) molecular weight distribution (Mw / Mn) of the ethylene (co) polymer of the present invention is 25 to 50, preferably 27 to 50.
-50, more preferably in the range of 30-50. When the molecular weight distribution is less than 25, the drawdown resistance and extrusion characteristics are inferior, and when the molecular weight distribution exceeds 50, the die swell (DS) and the slope (a) of the formula (1) described later become large. Paricon responsiveness is reduced, and smoke is increased during parison extrusion.

The ethylene (co) polymer of the present invention comprises (c)
230 ° C, shear rate (γ) region (6.08 ~ 24.8se
The following equation (1) of the die swell (DS) and the shear rate (γ) measured in c ^-1 )

DS = a * Ln (γ) + b (1) (where Ln (γ) is the natural logarithm of the shear rate (γ))

It is necessary that the value of the slope a obtained from the above is a ≦ 0.05 and the value of the intercept b is within the range of b ≦ 1.45, preferably a ≦ 0.03, b ≦ 1.35. The value of the slope a is a ≦ 0.05
When the value of the intercept b is b> 1.45 or the value of the gradient a is a> 0.05, it is difficult to control the thickness of the parison (paricon response).

(D) 1 of the ethylene (co) polymer of the present invention
Stress (σ) and maximum stress (σmax) at a strain of 1.0 in a stress-strain curve due to uniaxial elongation at 0.1 sec ⁻¹ measured at 70 ° C.
Is required to be within a range of σmax / σ ≧ 2.1, preferably 2.5 or more. Stress ratio (σmax / σ)
Is less than 2.1, the puncture resistance decreases.

(E) H of the ethylene (co) polymer of the present invention
LMFR (High Load Melt Flow Rate) is 10.0g / 10
min, particularly 5.0 (g / 10 mi) for large hollow molded articles such as fuel tanks.
n) or less, more preferably 4.0 (g / 10 min) or less. HLMFR is 10.0 (g / 10
min) or more, drawdown resistance may not be improved.

The ethylene (co) polymer of the present invention has excellent moldability, rigidity and mechanical properties, and can be formed by extrusion molding, injection molding,
It is applied to hollow molding and the like. The requirements (a) to (d) above,
In the case of large or complex molded products such as tanks, by further satisfying the requirements of (e), the drawbacks of the conventional polyethylene for hollow molding can be overcome, and the drawdown resistance, puncture resistance, It has superiority in paricon response and pinch-off characteristics.

The method for producing the ethylene (co) polymer of the present invention is not particularly limited as long as the requirements (a) to (d), and preferably the requirement (e), are satisfied. It is produced by a gas phase polymerization method, a slurry polymerization method, a solution polymerization or the like in the presence of a catalyst such as a system catalyst, a Phillips system catalyst, a metallocene catalyst or the like. The polymerization conditions are not particularly limited, but the polymerization temperature is usually 15 to 350 ° C, preferably 2 to 350 ° C.
0-200 ° C., more preferably 50-120 ° C., and when the polymerization pressure is low / medium pressure, it is usually from normal pressure to 70K.
gG / cm ² , preferably normal pressure to 50 KgG / cm ² , and in the case of the high-pressure method, usually 1500 kg / cm ² G or less. The polymerization method is not particularly limited, and it can be prepared not only by one-stage polymerization but also by two or more multi-stage polymerization methods in which polymerization conditions such as hydrogen concentration, monomer concentration, polymerization pressure, polymerization temperature, and catalyst are different from each other. It can also be prepared by blending multiple components.

In the present invention, an antistatic agent, an antioxidant, a lubricant, an antiblocking agent, an antifogging agent, an organic or inorganic pigment, a filler, an ultraviolet ray inhibitor, Known additives such as an agent, a weathering agent, a crosslinking agent, a foaming agent, and a flame retardant can be added.

The hollow molded article of the present invention is a hollow molded article comprising the above ethylene (co) polymer or a composition thereof, and is used for food containers such as detergent bottles, beverage bottles, edible oil bottles, kerosene cans, Containers such as drums and bottles for chemicals, various types of fuel tanks and the like, various parts such as spoilers and bamboos, and panel-shaped structural parts constituting housings, simple toilets, pallets and the like for home electric appliances and OA equipment and the like are included. In the ethylene (co) polymer or the composition thereof, another polyolefin-based resin may be added to the ethylene (co) polymer of the present invention in an amount of 1 to 70% by weight. Further, as a method for producing the hollow molded body of the present invention, extrusion blow molding method, injection blow molding method, extrusion stretch blow molding method,
Examples include an injection stretch blow molding method, and the method is not particularly limited, such as a cold parison method or a hot parison method.

Another aspect of the present invention is a laminate comprising at least a layer comprising the ethylene (co) polymer or a composition thereof (hereinafter, referred to as the present resin layer) and a barrier layer. The laminate is not particularly limited as long as the above two types of layer configurations are present, and the lamination order is not particularly limited, but generally, the barrier layer is an intermediate layer, and the inner layer and / or It is preferable that the outer layer be the present resin layer and the inner layer or the outer layer be another polyolefin layer.

The barrier layer of the present invention includes polyamide resin, saponified ethylene-vinyl acetate copolymer, polyacrylonitrile resin, polymethacrylonitrile resin, polyacetal resin, polyester resin, and polyvinylidene chloride resin. And a resin layer composed of at least one selected from polycarbonate resins or a composition layer thereof. From the viewpoints of performance and physical properties, polyamide resins, ethylene-vinyl acetate copolymer saponified products, poly ( (Meth) acrylonitrile resin, polyester resin and polyvinylidene chloride resin are desirable.

The above-mentioned polyamide resin includes polyamide obtained by polycondensation of diamine and dicarboxylic acid, polyamide obtained by condensation with aminocarboxylic acid,
Examples thereof include polyamides obtained from lactams and copolymerized polyamides thereof, having a relative viscosity in the range of 1 to 6, a melting point of 170 to 280 ° C, and preferably 200 to 24 ° C.
Those in the range of 0 ° C are used. Specifically, nylon-6, nylon-66, nylon-610, nylon-
9, nylon-11, nylon-12, nylon-6 /
66, nylon-66 / 610, nylon-6 / 11, mixtures of these polyamide resins with polyolefin resins, polymer alloys, and the like. Of these, nylon-6 is preferable.

The saponified ethylene-vinyl acetate copolymer includes ethylene-vinyl acetate copolymers having a degree of saponification of 90% or more, preferably 95% or more and an ethylene content of 15 to 50 mol%. And saponified vinyl acetate copolymer.

The poly (meth) acrylonitrile-based resin is a polymer composed of methacrylonitrile units and / or acrylonitrile units or a copolymer containing these units and alkyl (meth) acrylate units.
The weight ratio is in the range of 95: 5 to 70:30,
It is a (co) polymer having a weight average molecular weight of 60,000 to 200,000 as measured by GPC.

As the polyester resin, polyethylene terephthalate, polybutylene terephthalate,
Examples include thermoplastic polyesters such as polyethylene terephthalate / isophthalate, polyethylene naphthalate, and benzoic acid polyester, mixtures of these with polyolefin, and polymer alloys.

The polyvinylidene chloride resin is, for example, one having a vinylidene chloride unit content of 70 to 99 mol%, preferably 80 to 98 mol%, and the comonomer of the polyvinylidene chloride resin is acrylonitrile, Examples include acrylic monomers such as methacrylonitrile, methyl methacrylate, ethyl methacrylate, propyl methacrylate, glycidyl methacrylate, glycidyl acrylate, hydroxyethyl acrylate, and hydroxypropyl acrylate, and vinyl monomers such as vinyl chloride.

The adhesive layer of the present invention comprises at least one adhesive selected from the group consisting of a copolymer of an unsaturated carboxylic acid or a derivative thereof and olefin, and a modified polyolefin grafted with an unsaturated carboxylic acid or derivative thereof. It is composed of a resin or a resin composition that is a mixture of the adhesive resin and unmodified polyolefin.

Specific examples of the copolymer of the above unsaturated carboxylic acid or its derivative and olefin include ethylene-
(Meth) acrylic acid copolymer, ethylene-glycidyl (meth) acrylate copolymer, ethylene-glycidyl (meth) acrylate-vinyl acetate copolymer, ethylene-maleic anhydride copolymer, ethylene- (meth) Acrylic acid
Binary or multi-component copolymers such as a maleic anhydride copolymer, a styrene-maleic anhydride copolymer, and an ethylene-styrene-maleic anhydride copolymer are exemplified.

The polyolefin modified with the unsaturated carboxylic acid or a derivative thereof according to the present invention means that the polyolefin is kneaded with an unsaturated carboxylic acid or a derivative thereof in the presence of a radical generator such as an organic peroxide by using an extruder, a Henschel mixer or the like. Graft-modified in a solvent or a solvent such as a hydrocarbon.

Specific examples of the modified polyolefin of the present invention include maleic anhydride-modified high-density polyethylene, maleic anhydride-modified linear low-density polyethylene, maleic anhydride-modified ultra-low-density polyethylene, and maleic anhydride-modified polypropylene. Can be These can be used alone or as a modified polyolefin resin composition by blending the above-mentioned unmodified polyolefin and, if necessary, rubber.

The mixing ratio of the adhesive resin and the unmodified polyolefin is not particularly limited, but generally, the unmodified polyolefin can be mixed at a ratio of 1 to 99% by weight. The content of the unsaturated carboxylic acid or the derivative thereof in the adhesive resin or the composition is 1 to 1 g of the resin component.
It is desirably selected in the range of 0 ^-8 to 10 ^-3 mol, preferably 10 ^-7 to 10 ^-4 mol. If the content is less than 10 ^-8 mol, the adhesive strength is not sufficient, and if it exceeds 10 ^-3 mol, "burn" or "gel" may occur at the time of molding and it is not economical.

As the polyolefin resin, a high-
Medium-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, low-density polyethylene produced by high-pressure radical polymerization, ethylene-vinyl ester copolymers such as ethylene-vinyl acetate copolymer, and ethylene-ethyl (meth) acrylate Polyethylene resins such as ethylene and unsaturated carboxylic acid alkyl ester copolymers such as polymers, propylene homopolymer, random with propylene-α-olefin, block copolymers, α- such as 1-butene polymer
Examples thereof include olefin homopolymers and their mutual copolymers. Among them, high / medium density polyethylene, linear low density polyethylene, ultra low density polyethylene and the like are preferable.

The unsaturated carboxylic acids or derivatives thereof of the present invention include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid and their anhydrides and metal salts. Maleic acid is preferred.

Examples of the radical generator used for graft modification include organic peroxides and dicumyl compounds.
Organic peroxides are preferred from the viewpoint of reactivity and ease of handling, and specific examples thereof include dicumyl peroxide and 2,2.
5-dimethyl-2,5-bis (t-butylperoxy)
Hexane, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3,1,3-bis (2-t-
Butylperoxyisopropyl) benzene, benzoyl peroxide and the like. As the dicumyl compound, 2,3-dimethyl-2,3-diphenylbutane, 2,3-diethyl-2,3-diphenylbutane,
2,3-diethyl-2,3-di (p-methylphenyl)
Butane, 2,3-diethyl-2,3-di (p-bromophenyl) butane and the like are exemplified.
2,3-diphenylbutane is preferably used.

The hollow multilayer molded article of the present invention is obtained by hollow molding using a plurality of extruders to join the above resin layers from a multilayer die. In addition, large containers such as fuel tanks and drums require stricter drawdown resistance, and fuel tanks have more complicated shapes, such as baffles in the tank, and local thinning tends to occur. , Parison thickness controllability (paricon response), pinch-off shape characteristics, durability, etc. are required. In the present invention, by using the polymer of the present invention or the composition thereof, these required performances are reduced. It is possible to be satisfied.

In the hollow multilayer container of the present invention,
The copolymer of the present invention or a composition thereof, a molded article of a laminate including an adhesive layer and a barrier layer, a recycled material such as burrs or a recycled material and a copolymer of the present invention,
It is desirable in terms of economy to use a mixture with a general polyolefin resin as the outer layer of the hollow multilayer container. The blending amount of the recycled material and the polyolefin is not particularly limited.

The layer structure of the hollow multilayer container is as follows: high-density polyethylene (HDPE) layer / adhesive layer / polyamide resin (PA) of the present invention, HDPE layer / adhesive layer /
Saponified ethylene-vinyl acetate copolymer (EVOH), HDPE layer / adhesive layer / polyester resin (PE
T), HDPE layer / adhesive layer / PA / adhesive layer / HDPE layer of the present invention, HDPE layer / adhesive layer / EV of the present invention
OH / adhesive layer / HDPE layer of the present invention, HDPE of the present invention
Layer / adhesive layer / PET / adhesive layer / HDPE layer of the present invention, HDPE layer of the present invention + HDPE / adhesive layer / PA / adhesive layer /
HDPE layer of the present invention, recycled layer / adhesive layer / PA / adhesive layer / recycled layer, recycled layer / adhesive layer / PA / adhesive layer / HDPE layer of the present invention, recycled layer / adhesive layer / P
A / adhesive layer / HDPE layer, recycled layer + HDPE / adhesive layer / PA / adhesive layer / HDPE layer, HDPE layer / adhesive layer / EVOH layer / adhesive layer / recycle layer / HDPE + carbon black layer.

The thickness of each layer of the hollow molded article is not particularly limited. In the case of a multilayered article, the thickness of the barrier layer is generally 0.001 to 1.0 mm, preferably 0.01 to 0.5 mm, and the thickness of the adhesive layer is generally 0.001 to 1.0 mm, preferably 0.01 mm to 0.
It is selected in the range of 5 mm. The thickness of the (co) polymer of the present invention or its composition layer, and other polyolefin layers is
It is selected in the range of about 0.5 to 10 mm, preferably about 1.0 to 7 mm.

[0043]

The present invention will be described in more detail with reference to Examples and Comparative Examples. The physical properties of the polyethylene and polyethylene resin compositions of Examples 1 and 2 and Comparative Examples 1 to 3 were measured by the following test methods. <Test Method> (1) Density: Based on JIS K6760. (2) HLMFR: based on JIS K6760. (3) Molecular weight distribution measurement (GPC): Waters (Wa)
ters) 150 type GPC, two Shodex HT-806M columns, sample amount 0.8 mg / ml, temperature 140 ° C, flow rate 1
The measurement was performed under the condition of ml / min using 1,2,4-trichlorobenzene (TBC) to which 0.05% by weight of 2,6-di-t-butyl-4-methylphenol (BHT) was added as a solvent. .

(4) Die swell measurement: "Capillograph 1C" manufactured by Toyo Seiki was used. A strand melted at 230 ° C. from an orifice having a diameter of 1 mm, a length of 40 mm and an inflow angle of 90 °, and a strand diameter when the strand length reaches 75 mm in a range of a shear rate (γ) of 6.08 to 24.32 sec ^−1. Was measured with the attached laser diameter measuring device (distance between capillary exit and die swell detecting device: 10 m)
m). The die swell ratio (DS) was calculated as the ratio of the strand diameter Ds to the orifice diameter Do, Ds / Do. The slope a and the intercept b are represented by a relational expression between DS and Ln (γ): DS
= A * Ln (γ) + b by the least square method.

(5) Measurement of stress ratio: Preparation of sample "Capillograph 1C" manufactured by Toyo Seiki was used. 21
A sample melted at 0 ° C. has a constant piston speed of 10 m from an orifice having a diameter of 3 mm, a length of 15 mm and an inflow angle of 90 °.
Extrusion was performed at m / min to obtain a sample. Stress ratio measurement "Molten rheometer" manufactured by Toyo Seiki was used. 170
After annealing the sample at 1000C for 1000 seconds, the sample was clamped, and the extensional viscosity was measured at a strain rate of 0.1 sec- ¹ . Distortion amount
The stress ratio “σmax / σ1.0” was calculated with the stress at 1.0 as “σ1.0” and the maximum stress value generated until the sample was broken as “σmax”.

(6) Extrusion characteristics: "NB3" manufactured by Japan Steel Works, Ltd.
Using a “0” multilayer blow molding machine (main material extruder: 90 mm), the extruded amount at 60 RPM was measured.

(7) Drawdown resistance: "NB30" multilayer blow molding machine manufactured by Nippon Steel Works was used. Resin temperature 230
A parison having a temperature of 8.5 ° C., a weight of 8.5 kg and a length of 1600 cm was extruded, and after the completion of the extrusion, a change in the length of the parison with time was measured. After the extrusion is completed, the parison is reduced in length by shrink-back, then hangs down by a drawdown due to its own weight, and becomes longer. The length at the time of completion of the parison injection is defined as L _0, and the measurement is started from that point. The parison shortened by the shrinking is the holding time Tp when the parison length becomes L ₀ again by the drawdown.
Was evaluated for drawdown resistance.

(8) Pinch-off shape characteristics: Using the above-mentioned hollow molding machine and mold, the resin layer of Example or Comparative Example
A 40-liter multilayer tank (weight 6 kg) having a layer structure of adhesive layer (maleic anhydride-modified high-density polyethylene) / nylon 6 / adhesive layer / resin layer of Example or Comparative Example was molded. The pinch-off portion of the obtained molded product was cut perpendicularly to the pinch-off fusion line. The pinch-off characteristic was evaluated from the thickness distribution on the cut surface as shown in FIG. The thickness of the fused portion at the center of the pinch-off was set to t, and the thick portions on both sides were set to T, and the pinch-off characteristics were evaluated by the ratio t / T between t and T.

(9) Tank Drop Test A drop test was performed using the above-mentioned multilayer tank. The drop test was performed by filling a 70% aqueous solution of 50% ethylene glycol and performing a vertical drop test at −40 ° C. and 6 m.

(10) Puncture resistance "NB30" hollow molding machine manufactured by Nippon Steel Works (screw diameter: 90 mm, die diameter: 120 mm) was used, and the mold entrance dimensions (W1 = 200, W2 = 300) were the same. Then, using a mold having a different depth D (100, 150, 200, 250 mm), forming a box-shaped hollow molded product, and evaluating the deep drawing ratio (D / W1) at which a puncture of parison occurs. The molding limit (puncture resistance) was evaluated.

(11) Paricon responsiveness: A parison controller is set at a constant setting so that the thickness of a part of the central part of the molded article is increased at the time of molding using the above-mentioned hollow molding machine and mold, and the box is formed. A hollow molded article was obtained. As the parison controller, a parison controller attached to the above molding machine and set at 25 points by MOOG was used. By measuring the thickness distribution of the obtained hollow molded article, the thickness control characteristic (paricon response) of the parison with respect to the parison controller was measured. The thickness of the central portion where the thickness was increased by the parison controller was defined as Tp, and the thickness at the reference point where the thickness was not increased was defined as Ts, and the ratio Tp / Ts was calculated as an index of the paricon response.

Example 1 Component 1 polymerized with a Philips catalyst, Component 2 and Component 3 polymerized with a MgCl-supported Ziegler catalyst were blended in a twin-screw extruder (Kobe Steel, KTX-90).
Created a sample. Table 1 shows detailed data and blend ratios of each component. In addition, physical properties were measured, and data are shown in Table 4.

[0053]

[Table 1]

Example 2 Component 1 polymerized with a Phillips catalyst, Component 2 and Component 3 polymerized with a MgCl-supported Ziegler catalyst were blended in a twin screw extruder (Kobe Steel, KTX-90).
Created a sample. Table 2 shows the detailed data and blend ratio of each component. In addition, physical properties were measured, and data are shown in Table 4.

[0055]

[Table 2]

[0056] Comparative Example 1 Component 1 polymerized with Phillips catalyst, component 3 was polymerized with MgCl supported Ziegler catalyst were blended in a biaxial extruder (Kobe Steel, KTX-90), create a sample of Comparative Example 1 did. Table 3 shows the detailed data and blend ratio of each component. In addition, physical properties were measured, and data are shown in Table 4.

[0057]

[Table 3]

Comparative Example 2 Commercially available high-density polyethylene for hollow molding (density = 0.947 g)
/ Cm ³ , HLMFR = 4.6, J-LEX HD455
Extrusion characteristics and the like were evaluated using 1H, manufactured by Japan Polyolefin Co., Ltd.). Table 4 shows the results.

Comparative Example 3 Commercially available high-density polyethylene for hollow molding (density = 0.951 g)
/ Cm ³ , HLMFR = 5.6, Hyzex 8200
B, manufactured by Mitsui Petrochemical Co., Ltd.) to evaluate extrusion characteristics and the like. Table 4 shows the results.

[0060]

[Table 4]

[0061]

According to the (co) polymer of the present invention described above, the drawdown resistance, the puncture resistance, the paricon response, the pinch-off shape are excellent, and there is no local thinning.
A hollow molded body having excellent mechanical strength such as impact resistance and rigidity is provided. The (co) polymer of the present invention can be suitably used as a large hollow molding material for gasoline tanks and drums having complicated shapes such as baffles.

[Brief description of the drawings]

1 (a) is a vertical cross-sectional view of a pinch-off fusion line of a hollow molding according to the present invention, and (b) and (c) are partial enlarged views of a pinch-off central portion (M) in FIG. 1 (a). (B) shows a state where the fused portion is good,
(C) shows a state where the fused portion is defective.

[Explanation of symbols]

 1 Mold 2 Resin

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // B29K 23:00 B29L 22:00 (72) Inventor Koichi Ogawa 2-3-2 Night Light, Kawasaki-ku, Kawasaki-shi, Kanagawa Japan Polyolefin Kawasaki Laboratory Co., Ltd. (72) Inventor Satoshi Kanazawa 2-3-2, Yakko, Kawasaki-ku, Kawasaki City, Kanagawa Prefecture, Japan Kawasaki Laboratory, Polyolefin Co., Ltd.

Claims (13)

[Claims] 1. An ethylene (co) polymer satisfying the following requirements (a) to (d): (a) a density of 0.94 to 0.98 g / cm ³ , (b) a molecular weight distribution (Mw / Mn) Is 25 to 50, (c) 23
At 0 ° C., the following equation (1) of the die swell (DS) and the shear rate (γ) measured in the shear rate (γ) region (6.08 to 24.8 sec ⁻¹ ): DS = a * Ln (γ) ) + B (1) The value of the slope a obtained from (1) is a ≦ 0.05, and the value of the intercept b is b ≦ 1.
(D) Stress at a strain of 1.0 in a stress-strain curve due to uniaxial elongation at 0.1 sec ^-1 measured at 170 ° C. (σ) of 45
And the maximum stress (σmax) is σmax / σ ≧ 2.1. 2. The ethylene (co) polymer according to claim 1, wherein the ethylene (co) polymer further satisfies the requirement of (e) HLMFR ≦ 10 g / 10 min. 3. The ethylene (co) polymer has 3 carbon atoms.
The ethylene (co) polymer according to claim 1 or 2, wherein the content of the α-olefin of from 20 to 20 is 10 mol% or less. 4. A hollow molded article comprising the ethylene (co) polymer or a composition thereof according to claim 1. 5. The hollow molded article according to claim 4, wherein the hollow molded article is a fuel tank. 6. A laminate comprising at least a layer comprising the ethylene (co) polymer or a composition thereof according to claim 1 and a barrier layer. 7. The laminate according to claim 6, comprising at least a layer, an adhesive layer, and a barrier layer comprising the ethylene (co) polymer or a composition thereof according to any one of claims 1 to 3. 8. The method according to claim 1, wherein the barrier layer comprises a polyamide resin, a saponified ethylene-vinyl acetate copolymer, a poly (meth) acrylonitrile resin, a polyacetal resin, a polyester resin, a polyvinylidene chloride resin or a composition thereof. The laminate according to claim 6, comprising at least one member selected from the group consisting of: 9. The adhesive layer, wherein the adhesive layer is at least one adhesive resin selected from the group consisting of a copolymer of an unsaturated carboxylic acid or a derivative thereof and olefin, a modified polyolefin grafted with an unsaturated carboxylic acid or a derivative thereof, or 9. The laminate according to claim 7, wherein the laminate is a mixture of the adhesive resin and unmodified polyolefin. 10. A layer comprising the ethylene (co) polymer or a composition thereof according to any one of claims 6 to 9,
A hollow multilayer container comprising a laminate comprising a barrier layer and, if desired, an adhesive layer. 11. The hollow multilayer container according to claim 10, wherein the hollow multilayer container is a fuel tank. 12. A recycled resin comprising the laminate according to any one of claims 6 to 9, or a composition of the resin and the ethylene (co) polymer according to claim 1 or 2, or a combination thereof. A hollow multilayer container comprising a laminate including at least one resin layer selected from a composition with a polyolefin resin, a barrier layer, and, if desired, an adhesive layer. 13. The hollow multilayer container according to claim 12, wherein the hollow multilayer container is a fuel tank.