JPH07145211A - Ethylene polymer and fuel tank using the same - Google Patents

Abstract

(57) [Summary] (Corrected) [Constitution] Ethylene homopolymer, or ethylene and charcoal
Α-Olephy consisting of α-olefins with a prime number of 3 to 20
Ethylene copolymer having a content of 10 wt% or less
I mean (1) Intrinsic viscosity [η] is 2 to 6 (dl / g) (2) Density is 0.945 to 0.970 (g / cm³ ) Formula (3) R value = σ₂ / Σ₁ (Σ₁, Σ² Is the elongation strain
Speed ε = 0.5sec ^-1Under the flow of 2 seconds,
The elongation stress in the strain amount in 4 sec is shown. ) Defined by
R value is 2.5 to 4 (4) High-speed impact strength measured at -30 ° C (HRI-IZ
OD) and melt index of 21.6 kg load (HL
MI) HRI-IZOD ≧ −logHLMI + 1.15 Is an ethylene-based polymer. [Effect] Excellent uniform stretchability, high rigidity and impact resistance
When an ethylene-based polymer with excellent mechanical properties such as
Both have excellent impact strength even with thinner wall thickness than before.
A light fuel tank can be obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel ethylene polymer and a fuel tank using the same. More specifically, the present invention relates to an ethylene-based polymer which is excellent in molding processability such as uniform stretchability, has high rigidity, and excellent impact resistance in hollow molding, particularly large-sized hollow molding. Further, the present invention relates to a fuel tank which has excellent impact resistance even when it is thinner than conventional products.

[0002]

2. Description of the Related Art In recent years, in the field of automobile industry, various automobile parts have been actively made plastic for the purpose of weight reduction and energy saving. As a plastic material, a polyolefin resin is generally used from the viewpoints of low cost, high strength, good weather resistance, good chemical resistance, and environmental problems.

Among the polyolefin resins, polyethylene is particularly suitable as a resin for blow molding, and generally polyethylene having a relatively wide molecular weight distribution, a large melt tension and a good uniform stretchability is used. In particular, in the large-sized hollow molding field, large-sized containers such as plastic fuel tanks and drums have recently attracted attention.
In particular, a plastic fuel tank made of high-molecular-weight high-density polyethylene has a high degree of freedom in shape as compared with a conventional steel-plate fuel tank, and is used in some vehicle models, for example, 4
It is mounted on vehicles such as WD (four-wheel drive) and 4WS (four-wheel steering).

[0004]

As a material suitable for such use, for example, an ethylene copolymer excellent in molding processability and environmental stress crack resistance (hereinafter referred to as ESCR) (Japanese Patent Laid-Open No. 2-53811). Have been proposed. However, with these high-density polyethylene, when an attempt is made to manufacture a fuel tank having a complicated shape, the wall thickness of the bent portion of the obtained fuel tank becomes thin and the strength of that portion decreases. Therefore, in order to increase the wall thickness in order to reinforce the strength of the curved portion, it is necessary to increase the thickness of the entire fuel tank, and as a result, the economy and the weight are insufficient.

Further, when copolymerization with α-olefin is carried out for the purpose of improving the mechanical strength such as impact resistance and ESCR of the product, rigidity is lowered because the copolymer has a relatively low density. Occurs. Especially product weight reduction,
When attempting to reduce the wall thickness, the reduction in rigidity causes problems such as bending when the fuel tank is used and deformation when the products are stacked.

An object of the present invention is to propose an ethylene polymer composition which has processing characteristics typified by excellent uniform stretchability, high rigidity and excellent impact resistance in such applications. An object of the present invention is to propose a fuel tank having a small wall thickness distribution, a thin wall, a light weight, an excellent economical efficiency, a high rigidity, and an excellent impact resistance.

[0007]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have made up an ethylene homopolymer, or a copolymer of ethylene and another α-olefin, HRI-IZOD, which has a specific range of intrinsic viscosity, a certain range of R value, which is a parameter relating to molding processing characteristics, and a parameter of impact resistance.
Is in a specific range with respect to HLMI, and the α-olefin content and density are in a specific range, and an ethylene polymer is excellent in molding processability such as uniform stretchability in hollow molding, particularly large-sized hollow molding. It has been found that an ethylene polymer composition having high rigidity and excellent impact resistance is provided. Further, it has been found that the fuel tank manufactured by the above ethylene polymer composition has excellent impact resistance even with a thinner wall thickness than conventional products.

That is, the present invention relates to ethylene homopolymerization.
Body or ethylene and α-olefins with 3 to 20 carbon atoms
And an α-olefin content of 10% by weight or less
An ethylene copolymer, which has (1) an intrinsic viscosity [η] of 2 to 6 (dl / g) (2) a density of 0.945 to 0.970 (g / cm)³ ) (3) Formula R value = σ₂ / Σ₁ (Σ₁ , Σ₂ Is the elongation strain
Speed ε = 0.5sec ^-1Under the flow of 2 seconds,
The elongation stress in the strain amount in 4 sec is shown. ) Defined by
R value is 2.5 to 4 (4) High-speed impact strength measured at -30 ° C (HRI-IZ
OD) and melt index of 21.6 kg load (HL
MI)

## EQU2 ## The present invention resides in an ethylene-based polymer characterized by HRI-IZOD ≧ -logHLMI + 1.15, and a fuel tank comprising the same.

The present invention will be described in detail below. The ethylene polymer of the present invention comprises an ethylene homopolymer or a copolymer with an α-olefin having 3 to 20 carbon atoms, and α-
An olefin content of 10% by weight or less, preferably 5% by weight or less is used. Examples of the α-olefin having 3 to 20 carbon atoms include propylene, butene-1, pentene-1, hexene-1, octene-1, decene-.
1, octadecene-1, and 4-methylpentene-
1,3-methylbutene-1,3-methylpentene-1,
Furthermore, vinyl cyclohexane, styrene, etc. may be mentioned. Further, if the α-olefin content is more than 10% by weight, the rigidity of the ethylene polymer is lowered, which is not preferable.

The ethylene polymer of the present invention has an intrinsic viscosity [η] of 2 to 6 dl / g, preferably 2.3 to 5.
It is necessary to set it to 5 dl / g, and more preferably 3 to 5 dl / g. When the intrinsic viscosity is less than 2 dl / g, the mechanical strength is lowered and the drawdown resistance is poor, which is not preferable. Further, when it exceeds 6 dl / g, the moldability is lowered, which is not preferable. Further, the ethylene polymer of the present invention has a density of 0.945 to 0.970 g / cm ³ , preferably 0.955 to 0.970 g / cm ³ , and more preferably more than 0.960 and 0. An ethylene homopolymer of not more than 0.970 is more preferable. Density is 0.945
When it is less than g / cm ³ , the rigidity is lowered, which is not preferable.

Further, the ethylene polymer of the present invention has the formula
R = σ₂ / Σ₁ (Here, R value means that
Is an index showing the increase rate of elongation stress over time, and σ
₁ , Σ ₂ Is elongation strain rate ε = 0.5 sec^-1Under the flow of
Of the strain at 2 sec and 4 sec respectively
Power. ) Defined R value is 2.5-4.0, preferably
Preferably 2.6-3.8, more preferably 2.7-3.
It must be in the range of 5.

Generally, a resin having a large R value is used in blow molding at a portion having a large strain amount such as a mold corner portion.
Strain hardening due to material deformation
It is considered that the resin has a good property (uniform stretchability) of suppressing excessive elongation at that portion,
When the R value is less than 2.5, the uniform stretchability is poor, and particularly when molding a container having a complicated shape, the wall thickness of the curved portion is thin and the strength of the portion is reduced. Therefore, in order to reinforce the strength of the curved portion, it is necessary to increase the thickness of the entire container in order to increase the wall thickness. As a result, there is a disadvantage in terms of economical efficiency and light weight. Further, if the R value exceeds 4, it is not preferable because the moldability is deteriorated due to breakage of stretching and the like.

The ethylene polymer of the present invention is -30.
The relationship between HRI-IZOD and HLMI measured at

HRI-IZOD ≧ −logHLMI + 1.15 Preferably

## EQU4 ## It is necessary that HRI-IZOD≥-logHLMI + 1.4. When the HRI-IZOD is lower than the above relationship, the impact resistance is poor, which is not preferable. R
The value and HRI-IZOD can be controlled by, for example, using a specific catalyst, performing polymerization under specific conditions, or specifying polymerization conditions in multistage polymerization. next,
An example of the method for producing the ethylene polymer of the present invention will be shown, but the present invention is not limited to the following production method.

The ethylene polymer of the present invention can be produced by polymerizing under specific conditions using a specific catalyst or by specifying the polymerization conditions in multistage polymerization. Specific catalysts include, for example, Mg compounds, Ti compounds,
Examples thereof include a solid catalyst component (A) containing halogen as an essential component and a catalyst containing an organoaluminum compound (B) as a main component. Specifically, for example, (A) general formula Mg
Mg compound represented by (OR ¹ ) _m X ¹ _2-m (wherein R ¹ represents an alkyl, aryl, or cycloalkyl group, X ¹ represents a halogen atom, and m is 1 or 2). (A) and the general formula Ti (OR ² ) _n X ² _4-n (wherein R ² represents an alkyl, aryl, or cycloalkyl group, X ² represents a halogen atom, and n is 4 ≧ n ≧ 1. Compound represented by the formula (I) and a general formula (I) shown below.

[0015]

[Chemical 1]

(Where R³ Is alkyl, aryl or si
It represents a chloroalkyl group and may be the same or different.
p indicates 20 ≧ p ≧ 2. ) Polyalkylchi
The tannate (c) and, if necessary, the general formula R^Four OH (formula
Medium R^Four Is an alkyl, aryl or cycloalkyl group
Show. ) Uniform carbonization containing alcohol compounds
Carbonization obtained by treating a hydrogen solution with a halogenating agent
Hydrogen-insoluble solid catalyst component and (B) organoaluminum compound
Ethylene alone using a catalyst system consisting of
Polymerization or ethylene and α-olefin having 3 to 20 carbon atoms
It can be produced by copolymerization with. More concrete
Is a Mg compound used in the production of solid catalyst components.
General formula Mg (OR of (a)¹ )_mX¹ _2-m(R in the formula¹ Is
Represents an alkyl, aryl, or cycloalkyl group,
X¹ Represents a halogen atom, and m is 1 or 2. )
Specific examples of the compound represented by¹ Is methyl,
Ethyl, propyl, butyl, pentyl, hexyl, octa
C1 such as chill, tolyl, xylyl, cyclohexyl
Up to about 5 alkyl, aryl, cycloalkyl groups
Yes, X¹ Where is chlorine, bromine, or iodine
Compounds such as dimethoxymagnesium, diethoxymag
Nesium, ethoxy magnesium chloride, dipheno
Examples include xymagnesium. M of the general formula
Are preferred. Ti compound (b)
The general formula of Ti (OR² )_nX² _4-n(R in the formula ² Is Archi
Represents an alkyl group, an aryl group or a cycloalkyl group, and X² Is
It represents a halogen atom, and n represents 4 ≧ n ≧ 1. )
The Ti compound used is R² , X²As above R¹ ,
X¹ The same examples can be given as examples. Specifically, n
4 as a compound of tetraethoxy titanium, tetrapro
Poxytitanium, tetra-n-butoxytitanium, etc.
Triethoxy monochlorotitanium and tripro as compounds
Poxy monochloro titanium, tri-n-butoxy monochloro
Compounds in which n is 2, such as titanium, are diethoxydichloro
Titanium, dipropoxydichlorotitanium, di-n-butoxy
Ethoxyt as a compound in which n is 1 such as dichlorotitanium
Lichlor titanium, propoxy trichlor titanium, n-bu
Examples include toxytrichlorotitanium and the like. Especially when n is 4
And 3 are preferred. Above all, n is a compound of 4.
Tetra-n-butoxytitanium, a compound in which n is 3
N-butoxymonochlorotitanium and the like are preferable. Polyal
Conversion of the quiltitanate (c) represented by the above general formula (I)
Compound (R in the formula³ Is alkyl, aryl or cycloal
It represents a kill group and may be the same or different. p is 20
Indicates ≧ p ≧ 2. ) Is R in the above general formula.³ Is before
Note R¹ The same examples can be given as examples. Materialization
Tetraethoxy titanium 2 to 20 mer as a compound, tet
2 to 20-mer of lapropoxy titanium, tetrabutoxy
2-20 mer of tan, tetrakis (2 ethylhexyl
Xy) 2-20 mer of titanium, tetrastearyloxy
2-20 mer of titanium etc. are mentioned. Among them, Tetra
2-4 Tetrabutoxytitanium and Tetrapropoxytita
The dimers to dimers are preferred. In addition, Tetraalkoki
A small amount of H for titanium etc.₂ Tetraa obtained by reacting O
It is also possible to use a condensate of lucoxytitanium. Well
Of the alcohol compound (d) used as necessary
General formula R^Four OH (R in the formula^Four Is alkyl, aryl or
Indicates a cycloalkyl group. ) As R^Four Is the R ¹ 
The same examples can be given as examples. Specifically ethyl
Alcohol, n-propyl alcohol, isopropyl alcohol
Rucol, n-butyl alcohol, n-octyl alcohol
And the like.

As the solid catalyst component (A), a uniform hydrocarbon solution containing the Mg compound (a), the Ti compound (b), the polyalkyl titanate (c) and, if necessary, the alcohol (d) is prepared. As the hydrocarbon used as a solvent, hexane, an aliphatic hydrocarbon such as heptane,
Alicyclic hydrocarbons such as cyclohexane and aromatic hydrocarbons such as benzene, toluene and xylene are used. To prepare the hydrocarbon solution, a Mg compound, a Ti compound, and a polyalkyl titanate may be contacted in advance to prepare a uniform liquid material. Alternatively, a Mg compound and a Ti compound may be contacted in advance to form a uniform liquid material. After preparation, polyalkyl titanate may be contacted.

A uniform liquid material can be achieved by mixing and heating the above-mentioned three components or two components depending on the kind of the compound used, but when it is difficult to form a uniform liquid material, an alcohol is present. Is preferred. There is no particular limitation on the order of addition. After mixing, preferably 100 ° C to 1
By heating to 70 ° C., a uniform liquid material or a uniform alcohol solution can be obtained. Then, a hydrocarbon solvent is added to form a hydrocarbon solution. When alcohol is used, the hydrocarbon solvent may be added after distilling off the alcohol. Alternatively, a polyalkyl titanate may be added after preparing a liquid material composed of two components of a Mg compound and a Ti compound and then adding a hydrocarbon solvent to form a uniform hydrocarbon solution.

Next, the homogeneous hydrocarbon solution obtained as described above is treated with a halogenating agent to obtain a solid catalyst component (A). The halogenating agent is not particularly limited as long as it has a halogenating action, and a compound in which halogen is covalently bonded is usually used. Specifically, boron trichloride, titanium tetrachloride, silicon tetrachloride, tin tetrachloride, vanadium tetrachloride, chlorides such as aluminum chloride, chlorine-containing compounds such as hydrogen chloride, thionyl chloride, chlorosulfonic acid, or chlorine, bromine. , Iodine and the like. Of these, titanium tetrachloride and silicon tetrachloride are preferable.

The method of treating with these halogen-containing compounds is not particularly limited, but it is usually preferable to perform the treatment at a temperature of room temperature to 200 ° C. The halogenation treatment may be performed once or may be repeated twice or more. The degree of halogenation is within the following range with respect to the above Mg compound, Ti compound, polyalkyl titanate and alcohol compound.

[0021]

[Equation 5] Is preferred. More preferably

[0022]

[Equation 6]

The range is (Where X is halogenated
Indicates the number of moles of halogen atoms in the agent, X¹ , X² , R
¹ , OR² , OR³ , OR^Four In the general formula of the compound
The number of moles of each group is shown. ) After the solid catalyst component is obtained as described above, the solid is separated.
Separate and wash with hydrocarbon solvent. Then, the Mg compound
(A), Ti compound (b), polyalkyl titanate
The amount of each component used in (c) is the molar ratio of each component.

## EQU7 ## 0.1 ≦ (b) / (a) ≦ 5 0.3 ≦ (c) / (a) ≦ 8 Preferably

## EQU8 ## Used in the range of 0.2 ≦ (b) / (a) ≦ 2 0.5 ≦ (c) / (a) ≦ 4.

Outside the above range, molding processability such as uniform stretchability and impact resistance tend to be inferior, which is not preferable. The alcohol compound (d) is used in an amount necessary for obtaining the above-mentioned uniform liquid material. Next, as an organoaluminum compound used as a cocatalyst, a compound represented by the general formula AlR ⁵ _q (OR ⁶ ) _r X ⁵ _{3- (q + r)} (wherein R ⁵ , R ^5
6 represents an alkyl, aryl or cycloalkyl group, X
⁵ shows a halogen atom, q shows 2-3 and r shows the number of 0-1. ). Specific examples include triethyl aluminum, triisobutyl aluminum, diethyl aluminum monochloride, diisobutyl aluminum monochloride, diethyl aluminum monoethoxide and the like. It is also possible to use the reaction product of a trialkylaluminum and water.
As these organoaluminum compounds, a single compound may be used, or two or more compounds may be used.

The proportion of the organoaluminum compound (B) used is the concentration of the organoaluminum compound and the ratio of the organoaluminum compound to the solid catalyst component, that is, the product of Al / Ti atomic ratio [Al] (mmol / l) × (Al / Ti) is used in the range of 1.2 to 0.02, preferably 1.0 to 0.03, and more preferably 0.5 to 0.05. If it is less than the above range, the polymerization activity is lowered, and if it is more than the above range, the molding properties such as uniform stretchability are deteriorated and the impact resistance is lowered, which is not preferable.

Polymerization of ethylene or copolymerization with the α-olefins exemplified above is carried out using the above catalyst system, and the polymerization reaction is carried out in an inert solvent such as slurry polymerization, solution polymerization, or gas phase polymerization. Done by. As the inert solvent, aliphatic hydrocarbons such as butane, hexane and heptane, alicyclic hydrocarbons such as cyclohexane, and aromatic hydrocarbons such as benzene and toluene are used. The polymerization reaction is usually selected from the range of normal temperature to 200 ° C. and normal pressure to 100 atm. Further, by introducing hydrogen in the polymerization reaction, a polymer having a desired molecular weight can be easily obtained.

Further, in producing the ethylene-based polymer of the present invention, not only a one-step polymerization method but also a multi-step polymerization method can be adopted. As an example of the multi-stage polymerization method, (a) the polymerization reaction is carried out in two stages, that is, a method of further polymerizing in the second reaction zone in the presence of the reaction product obtained by polymerizing in the first reaction zone, (B) Homopolymerization of ethylene is carried out in either one of the first and second reaction zones, and the polymer A having a viscosity average molecular weight of 60 to 150,000 is added to the total amount of produced polymer of 6 or less.
0% to 90% by weight, and (c) homopolymerization of ethylene in the other reaction zone or the above α-
Copolymerization with olefin, α-olefin content 1
40 wt% to 10 wt% of a polymer B having a viscosity average molecular weight of 500,000 to 4,000,000 is produced at 0 wt% or less, and (d)
A method of polymerizing so that the molecular weight ratio of the polymer B and the polymer A is in the range of 3 to 50 can be mentioned.

Further, other catalysts used in the production of the ethylene copolymer of the present invention include, for example, (A) the general formula Mg (OR ¹ ) _m X ¹ _2-m (wherein R ¹ is alkyl). , Aryl, or a cycloalkyl group, X ¹ represents a halogen atom, and m is 1 or 2).
Compound (a) and the general formula Ti (OR ² ) _n X ² _4-n (wherein R ² represents an alkyl, aryl or cycloalkyl group, X ² represents a halogen atom, and n is 4 ≧ n ≧ 1. A Ti compound (b) represented by the formula ( ⁴ ) and optionally an alcohol (c) represented by the general formula R ⁴ OH (wherein R ⁴ represents an alkyl, aryl or cycloalkyl group). A hydrocarbon-insoluble solid catalyst component obtained by treating a homogeneous hydrocarbon solution with a solution containing titanyl chloride (TiOCl ₂ ) (d) and a halogen-containing compound (e) having no reducing ability, and (B) an organic compound. A catalyst system in combination with an aluminum compound may be mentioned. More specifically, as the Mg compound (a), the Ti compound (b), and the alcohol (c) used as necessary, which are used in the production of the solid catalyst component, the same compounds as the above-exemplified catalyst are used. It The solid catalyst (A) is the above Mg compound,
A homogeneous solution containing the Ti compound and optionally the alcohol is prepared. As the hydrocarbon used as the solvent, those exemplified above are used. To prepare the hydrocarbon solution, a Mg compound and a Ti compound are brought into contact with each other in advance to prepare a uniform liquid material. When it is difficult to form a uniform liquid, it is preferable to allow alcohol to be present. There is no particular limitation on the order of addition.

After mixing, heating to 100 ° C. to 170 ° C. is preferably performed to obtain a uniform liquid material or a uniform alcohol solution. Then, a hydrocarbon solvent is added to form a hydrocarbon solution. When alcohol is used, the hydrocarbon solvent may be added after distilling off the alcohol. Then, the homogeneous hydrocarbon solution obtained as described above is treated with a solution containing TiOCl ₂ and a halogen-containing compound having no reducing ability to obtain a solid catalyst component (A).

TiOCl₂ And halogens that have no reducing ability
The solution containing the compound is TiOCl₂ And has a reducing ability
By mixing with a halogen-free compound and heating
Obtained. As a halogen-containing compound that has no reducing ability
There is no particular limitation, but TiOCl ₂ Higher solubility
Compounds are preferred. Of these, titanium tetrachloride and silicon tetrachloride are preferred.
Good Particularly, titanium tetrachloride is preferable.

There is no particular limitation on the method of treating with a solution containing these TiOCl ₂ and a halogen-containing compound having no reducing ability, but the above solution is preferably a uniform solution. The treatment temperature is preferably room temperature to 200 ° C. After the solid catalyst component is obtained as described above, the solid is separated and washed with a hydrocarbon solvent. Therefore, Mg compound (a), Ti compound (b), TiOCl
₂ (d) The amount of each component used is the molar ratio of each component.

## EQU9 ## The range is 0.01 ≦ (b) / (a) ≦ 10 0.1 ≦ (d) / (a) ≦ 50. Further, the amount of the halogen-containing compound (c) having no reducing ability to be used is preferably within the following range with respect to the Mg compound (a), the Ti compound (b) and the alcohol (c).

[0032]

[Equation 10]

(Here, X represents the number of moles of the halogen atom in the halogen-containing compound having no reducing ability, and X ¹ , X
² , OR ¹ , OR ² and OR ⁴ represent the number of moles of each group in the general formula of the above compound. ) Outside the above range, the molding and processing characteristics such as uniform stretchability are inferior and the impact resistance is inferior, which is not preferable.

The alcohol (e) is used in an amount necessary to obtain the above-mentioned uniform liquid material. Next, as the organoaluminum compound (B) used as a cocatalyst, the same compounds as the above exemplified catalysts are used. The proportion of the organoaluminum compound (B) used is the concentration of the organoaluminum compound and the ratio of the organoaluminum compound (B) to the solid catalyst component, that is, the product of Al / Ti atomic ratio [Al] (mmol / l) × (Al / Ti) is 2.0
It is used in the range of 0.01 to 0.01, preferably 1.0 to 0.02.

If the amount is less than the above range, the polymerization activity may decrease,
On the other hand, when the content is in the above range or more, the molding properties such as uniform stretchability are deteriorated and the impact resistance is lowered, which is not preferable. Polymerization of ethylene or copolymerization with the above-mentioned α-olefin is carried out using the above catalyst system, and the polymerization reaction can be carried out in the same manner as in the above-mentioned polymerization example. Furthermore, in the present invention, not only the one-step polymerization method but also the above-described multi-step polymerization method can be carried out in the same manner.

The ethylene polymer of the present invention is characterized by excellent moldability such as uniform stretchability, high rigidity, and excellent impact resistance. In molding the ethylene polymer of the present invention, known additives such as fillers, pigments, light stabilizers, heat stabilizers, flame retardants, plasticizers, antistatic agents, release agents, foaming agents, nucleating agents, etc. You may mix | blend an agent.

The fuel tank of the present invention can be manufactured by a known blow molding method or the like. For example, the parylene is formed by passing the ethylene polymer of the present invention from an extruder through a die. The parison is manufactured by inflating the parison from the inside by air pressure in the molding die, bringing it into close contact with the die, and cooling at the same time. The ethylene-based polymer of the present invention has a strain hardening phenomenon (strain har) of a material.
Dening) is likely to occur and the excessive elongation of the part is suppressed, so that the parison is blown up in the curved part of the mold in a uniformed state. It is possible to mold a material having a larger wall thickness than the conventional one.

Further, in the case of manufacturing a multi-layer fuel tank, for example, the resin composition of each layer is individually plasticized from a plurality of extruders and extruded into the same die having the same circular flow path, and then in the die. The thickness of each layer is made uniform, and the layers are superposed to form a single parison, which is then molded in a molding die in the same manner as described above. As the multi-layer fuel tank, a three-kind five-layer structure in which a high-density polyethylene layer made of the ethylene polymer composition of the present invention is laminated on both sides of a barrier layer with an adhesive layer is particularly preferable. At that time, the thickness of the barrier layer is 0.01 to 0.5 mm,
The thickness of the adhesive layer is preferably 0.1 to 0.3 mm.
01-0.5 mm, preferably 0.3 mm, the thickness of the high-density polyethylene layer is 1-10 mm, preferably 1.5
It is selected from the range of up to 5 mm.

In the case of a multi-layer, it can be suitably used as a laminated fuel tank in which a polyethylene layer formed of an ethylene polymer composition is laminated on at least one side of a barrier layer with an adhesive layer interposed therebetween. The barrier layer is a thermoplastic polyester resin such as polyamide resin, polyethylene terephthalate or polybutylene terephthalate, an ethylene-vinyl acetate copolymer having a saponification degree of 93% or more, preferably 96% or more and an ethylene content of 25 to 50 mol%. It can be formed from a saponified ethylene-vinyl acetate copolymer.

In particular, a polyamide resin is preferable from the viewpoints of stability of formation and gas barrier property, and a polyamide obtained by polycondensation of diamine and dicarboxylic acid, a polyamide obtained by condensation of aminocarboxylic acid, a polyamide obtained from lactam, or these Copolymerized polyamide, etc., usually has a relative viscosity of about 1 to 6 and a melting point of 170 to 2
One having a temperature of 80 ° C., preferably 200 to 240 ° C. is used. Specifically, for example, nylon-6, nylon-6
6, nylon-610, nylon-9, nylon-1
1, nylon-12, nylon-6 / 66, nylon-
66/610, nylon-6 / 11 and the like.
Nylon-6 is particularly preferable.

In the present invention, the polyamide layer is preferably formed from a modified polyamide resin composition comprising the above polyamide resin and a maleic anhydride-modified ethylene-α-olefin copolymer, and maleic anhydride-modified ethylene-α. -The olefin copolymer has a crystallinity of 1
~ 35%, preferably 1-30%, melt index 0.01-50 g / 10 min, preferably 0.1-2
To ethylene-α-olefin copolymer at 0 g / 10 min,
Maleic anhydride is 0.05 to 1% by weight, preferably 0.1.
Grafted from 2 to 0.6% by weight is used. Examples of the α-olefin of the ethylene-α-olefin copolymer include propylene, butene-1, and hexene-1, and the amount of these α-olefins is 30% by weight or less, preferably 5 to 20% by weight. Copolymerized with ethylene.

The proportion of the maleic anhydride-modified ethylene-α-olefin copolymer used is selected from the range of 10 to 50 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the polyamide resin, for example, 200 to. It is used by kneading at a temperature of 280 ° C. with an extruder or the like. As the adhesive layer, a homopolymer or copolymer of α-olefin such as ethylene or propylene is grafted with an unsaturated carboxylic acid or a derivative thereof in an amount of 0.01 to 1% by weight, preferably 0.02 to 0.6% by weight. Modified polyolefins described above can be used. In particular, ethylene homopolymer having a density of 0.940 to 0.970 g / cm ³ or ethylene and 3% by weight or less, preferably 0.05 to 0.5% by weight of propylene and butene-1,
A modified product of a copolymer with an α-olefin such as hexene-1 is preferable. Examples of the unsaturated carboxylic acid or its derivative include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid and their anhydrides. Maleic anhydride is particularly preferable.

[0043]

EXAMPLES Next, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples unless it exceeds the gist thereof. In the following examples, various physical property tests were conducted according to the following methods. (1) Intrinsic viscosity [η] Measured in tetralin at 130 ° C. (2) Density The density was measured according to JIS K6760.

(3) Uniform Stretchability Index (R Value) The R value is an index showing the increase rate of the elongation stress over time under elongation flow, and is defined as R = σ ₂ / σ ₁ . Here, σ ₁ and σ ₂ are elongation strain rates ε = 0.5 se, respectively.
Under the flow of c ⁻¹ , it means the elongation stress when the elongation strain amounts ε = 1 and ε = 2. For σ ₁ and σ ₂ , σ = η _E × ε
(Η _E ; extensional viscosity, ε; extensional strain rate)

Σ ₁ = η _E (t = 2.0; ε = 0.5) × 0.5 σ ₂ = η _E (t = 4.0; ε = 0.5) × 0.5 (t ; Time). The elongation flow characteristic can be estimated by the following method. The extensional viscosity can be analytically obtained as in the equation by solving the Giesekus constitutive equation for uniaxial extensional stress at a constant strain rate.

[0045]

[Equation 12]

[0046]

[Equation 13]

Where T _i is

[0048]

[Equation 14]

It is Here, the relaxation spectrum H _i (τ
_i ) and the nonlinear parameter α were obtained as follows. Measurement A dynamic spectrometer RMS-800 manufactured by Rheometrics Inc. was used to measure the dynamic viscoelasticity required for obtaining the relaxation spectrum. The measuring jig was a cone-plate type, and had a diameter of 25 mm and an angle between the cone and the plate (hereinafter referred to as a cone angle) of 0.1 rad.
The measurement frequency range is 0.01 to 100 rad / sec.

For the measurement of a wide range of steady shear viscosities, RSR-M and RMS-800 manufactured by Rheometrics Co., Ltd. and an INTESCO2020 type capillary viscometer manufactured by Intesco Co. were used. The measuring jig of RSR-M has a diameter of 25 m.
m, and the cone angle was 0.1 rad. RMS-8
No. 00 measuring jig has a diameter of 7.9 mm and a cone angle of 0.1.
The one of rad was used. The INTESCO 2020 type capillary viscometer has a diameter of 1.0 mm and a tube length of 50.
It was 0 mm and had an inflow angle of 90 °. Rabinowitch correction was performed as a correction of the shear rate.

The RSR-M mainly has a shear rate γ = 10 ^-5.
Used for measurement at -10 ^-3 sec ^-1 , RMS-800 has γ
= 10 ^-3 to 10 ⁰ sec ^-1 , the INTESCO 2020 type capillary viscometer was used for measurement at γ = 10 ⁰ to 10 ³ sec ^-1 . All of the above measurements were performed at 190 ° C. For the measurement using RSR-M and RMS-800, a press-molded sample piece having a thickness of 1.0 mm was used. INT
A pellet-shaped sample was provided for the ESCO 2020 capillary viscometer.

Calculation of relaxation spectrum H (τ) Among the measurement data of dynamic viscoelasticity, the storage elastic modulus G ′
(Ω) was subjected to least squares approximation with a regression curve of an arbitrary order (normally quadratic regression), and the relaxation spectrum was calculated by the following formula (Tchoegl quadratic approximation).

[0053]

[Equation 15]

(Ω is the angular frequency and τ is the relaxation time.)
Although the relaxation spectrum obtained by the equation is given as a continuous function, it is necessary to use a discontinuous line spectrum when actually applying it to a multimode constitutive equation and performing various calculations. Therefore, the relaxation spectrum curve is changed from 10 ⁻³ sec on the short time side to 10 ³ to 10 ⁵ se on the long time side.
The histogram was plotted as the isothermic melting point on the natural logarithmic axis in the range of c. Here, in order to confirm that the range of the relaxation time τ selected when performing the line spectrum conversion is appropriate, the obtained line spectrum is measured G ′ by the following equation.
It was confirmed that (ω) was reproduced.

[0055]

[Equation 16]

Further, in determining the boundary value on the long time side, it was determined that the zero shear viscosity η ₀ is reproduced by the combination of the obtained line spectra by the following equation.

[0057]

[Equation 17]

The range of the relaxation spectrum obtained directly from the actually measured dynamic viscoelasticity is τ = √2 × 10 ^{-2 to} √2 × 10 ^2.
Although it is sec, those that deviate from this range were extrapolated from the regression curve of the relaxation spectrum within the measurement range. The order of the regression curve here was the same as that used when the relaxation spectrum was obtained from the storage elastic modulus. When the equation for determining the non-linear parameter α is solved for steady shear flow, the steady shear viscosity η is expressed as the following equation as an analytical solution.

[0059]

[Equation 18]

The relaxation spectrum determined in (1) was substituted into the equation, and the value of α was determined so as to reproduce the measured steady shear viscosity curve. (4) Bending stiffness (stiffness) Measured in accordance with ASTM D747. (5) High-speed impact strength (HRI-IZOD) <Preparation of sample> According to JISK7110, width: 6.0
mm, thickness: press piece of 9.55 mm, length 63.5 m
It cut to m and cut the notch part. <Measurement> Model GRC8250 manufactured by Dynatap was used, and measurement was performed at -30 ° C and 7.7 m / sec. (6) Melt Index (HLMI) Based on ASTM-D-1238-57T, 190 ° C,
It was measured under a load of 21.6 kg.

Example 1 (1) Preparation of Solid Catalyst Component A 3 liter flask equipped with a condenser was thoroughly dried and purged with nitrogen, and then 66.5 g of Mg (OEt) ₂ was added.
(0.58 mol), 98.7 g of Ti (OBu) ₄ .
(0.29 mol) was charged, the temperature was raised to 130 ° C. with stirring, and heat treatment was performed. A uniform viscous liquid was obtained after 4 hours. After cooling to about 80 ° C., 1.0 liter of toluene was added to form a uniform solution. Fully dried and replaced with nitrogen 2
The entire amount of the above solution was transferred to a 4-liter autoclave. To this toluene solution was added 1272 g (1.31 mol) of tetrabutoxytitanium tetramer, and
4.5 l of toluene was added. 40 ° C under stirring
4.24 liters (38.6 mol) of TiCl ₄ was diluted with toluene to a concentration of 4.55 mol / l and added over 3 hours. Subsequently, the temperature was raised to 105 ° C. over 30 minutes and kept for 1 hour. Then, after cooling, it was washed with normal hexane to obtain a solid catalyst component. The Ti content in the solid catalyst component was 34.9% by weight.

(2) Prepolymerization of ethylene In a reactor for prepolymerization having a capacity of 300 liters, 220 liters of normal hexane were charged, and then 360 g of the solid catalyst component obtained in Example 1 was introduced. 2 kg / cm of hydrogen
^After introducing ² and raising the temperature to 80 ° C., 0.36 mol of triethylaluminum was fed together with ethylene to start prepolymerization. Ethylene was continuously introduced and prepolymerized for 0.5 hours to obtain 10 g of polyethylene per 1 g of the solid catalyst component. After the completion of prepolymerization, the mixture was cooled and washed with normal hexane.

(3) Polymerization of ethylene Using a continuous polymerization apparatus equipped with a reactor having a capacity of 500 liters, ethylene 27 kg / hr, normal hexane 63
kg / hr and hydrogen were continuously fed so that polyethylene having an intrinsic viscosity shown in Table 1 was obtained, and 2.5 g / h of the prepolymerized catalyst prepared in Example 1 was supplied.
r and triethylaluminum were introduced at a rate of 1.5 g / hr, and homopolymerization of ethylene was carried out under the conditions of 80 ° C., total pressure 25 kg / cm ² , and average residence time 3 hours.
Polyethylene in the reactor was introduced into the degassing tank at a rate of 25 kg / hr, and the polymer powder was obtained through the rough separation and drying steps. 0.1 part by weight of Irganox 1010 (trade name, manufactured by Ciba Geigy), which is a hindered phenol stabilizer, and 100 parts by weight of obtained polyethylene, and Irgafos 168 (trade name, manufactured by Ciba Geigy), which is a phosphite stabilizer. ) And 0.1 parts by weight of calcium stearate were added to form pellets, which were then subjected to various physical property tests and molding tests. The results are shown in Table-1.

Example 2 (1) Preparation of Fixed Catalyst Component A 3 liter flask equipped with a condenser was thoroughly dried and purged with nitrogen, and then 133 g of Mg (OEt) ₂ was added.
(1.16 mol), 197 g of Ti (OBu) ₄ .
(0.58 mol) was charged, the temperature was raised to 130 ° C. with stirring, and heat treatment was performed. A uniform viscous liquid was obtained after 4 hours. After cooling to about 80 ° C., 1.0 liter of toluene was added to form a uniform solution. Fully dried and replaced with nitrogen 2
The entire amount of the above solution was transferred to a 4-liter autoclave. Tetrabutoxytitanium tetramer (957 g, 0.986 mol) was added to the toluene solution, and
5.8 liters of toluene were added. 40 ° C under stirring
1.99 liters (18.13 mol) of TiCl ₄
Was diluted with toluene to a concentration of 4.55 mol / l and 3
Added over time. Continue to 105 ℃ for 30 minutes
The temperature was raised to and held for 1 hour. Then, after cooling, 12.5 liters of the supernatant liquid was extracted by decantation,
Further, it was washed with 10 liters of toluene. afterwards,
Add 4.0 liters of toluene, 4.55 mol
A TiCl ₄ / toluene solution having a concentration of 1 / l was added again so that the amount of TiCl ₄ was 18.13 mol. Subsequently, heat treatment was carried out at 105 ° C. for 1 hour, cooling and washing with normal hexane were carried out to obtain a fixed catalyst component. The Ti content in the solid catalyst component was 33.8% by weight.

(2) Prepolymerization of Ethylene The same prepolymerization conditions as in Example 1 were used except that 730 g of the above solid catalyst component was used and 0.52 mol of triethylaluminum was used. (3) Polymerization of ethylene Polymerization was carried out in the same manner as in Example 1 except that the prepolymerization catalyst was introduced at a rate of 2.5 g / hr and triethylaluminum was introduced at a rate of 1.5 g / hr. The results are shown in Table-1.

(Example 3) (1) Preparation of solid catalyst component A 3-liter flask equipped with a condenser was thoroughly dried and purged with nitrogen, and then 133 g of Mg (OEt) ₂ was added.
(1.16 mol), 197 g of Ti (OBu) ₄ .
(0.58 mol) was charged, the temperature was raised to 130 ° C. with stirring, and heat treatment was performed. A uniform viscous liquid was obtained after 4 hours. After cooling to about 80 ° C., 1.0 liter of toluene was added to form a uniform solution. Fully dried and replaced with nitrogen 2
The entire amount of the above solution was transferred to a 4-liter autoclave. To this solution was added 5.89 liters of toluene. Next, TiOCl ₂ prepared in advance
A heated solution of (0.99 mol) and TiCl ₄ (11.6 mol) was added over 3 hours. Subsequently, the temperature was raised to 105 ° C. over 30 minutes and kept for 1 hour.
Then, it was cooled and washed with normal hexane to obtain a solid catalyst component. The Ti content in the solid catalyst component was 33.5% by weight.

(2) Preliminary Polymerization of Ethylene The same prepolymerization conditions as in Example 1 were used except that 730 g of the above solid catalyst component was used and 0.52 mol of triethylaluminum was used. (3) Polymerization of ethylene The prepolymerization catalyst was introduced at a rate of 2.5 g / hr and triethylaluminum at a rate of 1.75 g / hr, and hydrogen and butene-1 had the intrinsic viscosity and density shown in Table 1. Polymerization was carried out in the same manner as in Example 1 except that polyethylene was continuously fed so as to obtain polyethylene. The results are shown in Table-1.

Example 4 (1) Preparation of Solid Catalyst Component The amount of tetrabutoxytitanium tetramer used was 844.
A solid catalyst component was prepared in the same manner as in Example 1 except that g (0.87 mol) was changed. The Ti content in the solid catalyst component was 31.2% by weight. (2) Prepolymerization of ethylene The same procedure as in Example 1 was carried out. (3) Polymerization of ethylene Using the same continuous polymerization apparatus as in Example 1, ethylene 27
kg / hr, 63 kg / hr of normal hexane, and hydrogen are continuously fed so that polyethylene having an intrinsic viscosity shown below can be obtained, and 1.7 g / hr of the prepolymerization catalyst component and 1 g of triethylaluminum are added. Introduced at a rate of 0.75 g / hr, 90 ° C, total pressure 25
Polymerized under the condition of kg / cm ² and the viscosity average molecular weight is 1
20,000 ethylene homopolymers were polymerized at 75% by weight of the total polymer. The polyethylene in the reactor was introduced into a degassing tank at a predetermined rate, hydrogen was separated, and then introduced into a second-stage reactor having a capacity of 500 liters. Ethylene 9 kg / h in the second reactor
r, 21 kg / hr of normal hexane were continuously supplied, polymerization was carried out at 50 ° C. for an average residence time of 1.5 hours, and a second stage ethylene homopolymer having a viscosity average molecular weight of 1.3 million was polymerized at 25% by weight of all the polymers. did. After the reaction was completed, the viscosity average molecular weight of the polymer was measured and found to be 340,000. The following operations were performed in the same manner as in Example 1. The results are shown in Table-1.

(Comparative Example 1) Polymerization of ethylene Polymerization was carried out in the same manner as in Example 1 except that the prepolymerized catalyst prepared in Example 1 was introduced at a rate of 1.3 g / hr and triethylaluminum was introduced at a rate of 5.3 g / hr. did. Table of results
Shown in 1.

Comparative Example 2 (1) Preparation of Solid Catalyst Component A 24-liter autoclave was thoroughly dried and purged with nitrogen.
And then Mg (OEt) ₂133g (1.16mo
l), Ti (OBu)₃160g of Cl (0.53mo
l), Zr (OBu)₃138g of Cl (0.40mo
l) was charged, the temperature was raised to 130 ° C. with stirring, and heat treatment was performed.
went. A uniform viscous liquid was obtained after 4 hours. About 80
After cooling to ℃, add 3.5 liters of toluene to obtain a uniform solution.
It was a liquid. Then EtAlCl at 40 ° C₂210 g
Was added over 1.5 hours and the remaining EtAlCl₂4
90 g was added over 1.5 hours. Stir at 80 ° C for 2 hours
After stirring, cool and wash with normal hexane.
A medium component was obtained. The Ti content in the solid catalyst component is 10.1.
% By weight. (2) Polymerization of ethylene Use a continuous polymerization device equipped with a reactor with a capacity of 500 liters.
, Ethylene 13 kg / hr, normal hexane 32
It has an intrinsic viscosity of kg / hr and hydrogen as shown below.
When continuously fed so that polyethylene can be obtained,
And 1.7 g / hr of the above solid catalyst component, and
Chill aluminum was introduced at a rate of 4.4 g / hr, and 9
0 ℃, total pressure 25kg / cm² Polymerized under the conditions of
An ethylene homopolymer having an average molecular weight of 60,000 is 6% of the total polymer.
0 weight% polymerized. Move the polyethylene in the reactor to the specified speed.
Degassing tank at a temperature of 500 liters after hydrogen separation
To the second reactor of Le. The second stage reactor has ethyl
11 kg / hr, normal hexane 21 kg / hr
It is continuously fed and polymerized at 50 ° C, and the viscosity average molecular weight is
640,000 second-stage enylene homopolymer was added to the total weight of 40
Polymerized in an amount of%. After completion of the reaction, the viscosity average molecular weight of the polymer
It was 270,000 when measured. The following operation is performed in Example 1.
I went the same way. The results are shown in Table-1.

Comparative Example 3 The same as Example 1 except that triethylaluminum was introduced at a rate of 1.65 g / hr during the polymerization of ethylene and the hydrogen amount was changed so as to obtain the intrinsic viscosity shown in Table 1. Polymerized to. The results are shown in Table-1.

(Comparative Example 4) A commercially available ethylene polymer ("Showrex 4551H" manufactured by Showa Denko KK) was used.

[0073]

[Table 1]

(Example 5 and Comparative Example 5) Each HDPE produced in the Examples and Comparative Examples shown in Table 1 was melted by an extruder (cylinder set temperature: 185 to 215 ° C), and a die (die temperature) was used. 235 ° C through diameter 530
mm parison was formed. Adjust the drawdown with the parison controller so that the thickness of the parison just before molding becomes constant in the injection direction.
It is a saddle type and has 40R corners. After sandwiching it at a temperature of 20 ° C. and pressurizing air (pressure: 6 kg / cm ² ), a fuel tank (product weight: 7 kg and 10 kg) having a capacity of 60 liters was obtained at a product removal temperature of 80 ° C.

With respect to each of the obtained fuel tanks, the drop test and the wall thickness at the 40R corner were measured. Table of the results
2 shows. The drop impact strength was evaluated by filling the fuel tank with antifreeze and dropping it from a height of 16 m at -40 ° C to check for cracks. Also, in Example 5-1, the 40R corner portion wall thickness is 2.2 m.
When molded to m, the product weight is 5.9 kg
Thus, it was possible to obtain a 1.1 kg lighter fuel tank per product. The drop impact strength of this fuel tank was measured, but no damage was observed. Further, the product take-out temperature can be lowered by 12 ° C. in the same cooling time, and the cooling time can be shortened by about 24 seconds per one product.

[0076]

[Table 2]

(Example 6) The HDPE produced in the examples shown in Table 3 and the raw material resins for the respective layers of the adhesive resin (a) and the barrier resin (b) shown below were individually prepared using separate extruders. It was melted and extruded into the same die having concentric flow paths, and layers were superposed in the die (die temperature: 230 ° C.) and coextruded to form a parison with a diameter of 530 mm. Thereafter, in the same manner as in Example 5, a multi-layer (5 layers of 3 types 5) fuel tank (7 kg) having a capacity of 60 liters was obtained. No damage was observed in the container in the drop impact strength test of the container. In addition, the wall thickness of the 40R corner was measured to be 2.9 m.
It was m.

[0078]

[Table 3] Table-3 ───────────────────────── Layer composition Resin used Thickness (μm) ───────── ──────────────── Outer layer Example 1 2600 Adhesive layer (a) APO 100 Barrier layer (b) MPA 100 Adhesive layer (b) APO 100 Inner layer Example 1 2600 ─ ────────────────────────

(A) Modified polyethylene (APO) A modified polyethylene obtained by grafting maleic anhydride (0.4% by weight) on high density polyethylene having a density of 0.960 g / cm ³ . Melt index (MI); 0.1 g / 1
0 minutes. (B) Modified polyamide resin composition (MPA) 80 parts by weight of nylon-6 having a relative viscosity of 4.0 and 20% by weight of maleic anhydride (0.3% by weight) modified ethylene-butene-1 copolymer (ethylene ~ Butene-1 (13 mol
%) Crystallinity of copolymer is 20%, MI is 3.5 g / 1
0 min).

[0080]

According to the present invention, uniform stretchability is excellent,
An ethylene-based polymer having high rigidity and excellent mechanical properties such as impact resistance can be obtained, and a light fuel tank having excellent impact resistance even with a thinner wall thickness than before can be obtained. In addition, it is possible to manufacture the fuel tank in which the cooling time and the injection time are shortened and the manufacturing cycle is shortened.

Front page continuation (72) Inventor Nobuyuki Shimizu 3-10-10 Shiodo, Kurashiki-shi, Okayama Mitsubishi Kasei Co., Ltd.Mizushima Plant (72) Motonori Ueda 3-10-3 Shiodo, Kurashiki, Okayama Mitsubishi Kasei Co., Ltd. Mizushima factory

Claims (8)

[Claims] 1. An ethylene homopolymer or ethylene
And α-olefin having 3 to 20 carbon atoms
Ethylene copolymer having a fin content of 10% by weight or less
And (1) the intrinsic viscosity [η] is 2 to 6 (dl / g) (2) the density is 0.945 to 0.970 (g / cm)³ ) (3) Formula R value = σ₂ / Σ₁ (Σ₁ , Σ₂ Is the elongation strain
Speed ε = 0.5sec ^-1Under the flow of 2 seconds,
The elongation stress in the strain amount in 4 sec is shown. ) Defined by
R value is 2.5 to 4 (4) High-speed impact strength measured at -30 ° C (HRI-IZ
OD) and melt index of 21.6 kg load (HL
The ethylene-based polymer is characterized in that the relationship of MI) is HRI-IZOD ≧ -logHLMI + 1.15. 2. A hollow molded article made of the ethylene polymer according to claim 1. 3. A fuel tank comprising a hollow molded article made of the ethylene polymer according to claim 2. 4. The fuel tank according to claim 3, wherein the hollow molded article is a laminate having a barrier layer and a polyethylene layer made of the ethylene polymer according to claim 1. 5. A laminate comprising a barrier layer and a polyethylene layer comprising the ethylene polymer according to claim 1, which is present on at least one side of the barrier layer with an adhesive layer interposed therebetween. The fuel tank according to claim 4. 6. The fuel tank according to claim 4, wherein the barrier layer is made of a polyamide resin. 7. The polyamide resin has a crystallinity of 1 to 35.
%, Ethylene with a melt index of 0.01 to 50
Maleic anhydride is added to the α-olefin copolymer in an amount of 0.05 to
1 wt% grafted maleic anhydride modified ethylene ~ α
The fuel tank according to claim 6, wherein the fuel tank is formed from a composition of an olefin copolymer and a polyamide resin. 8. The fuel tank according to claim 5, wherein the adhesive layer is a high-density polyethylene graft-modified with 0.01 to 1% by weight of an unsaturated carboxylic acid or a derivative thereof.