JP2000079928A - Fuel tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel tank which is effective for attaining an energy saving of a vehicle due to its high rigidity and high impact strength as well as a superior fuel barrier characteristic (anti-fuel through-pass characteristic), anti-environmental stress cracking, superior processability, superior recycling characteristics and light weight. SOLUTION: This fuel tank has at least partially an elastomer layer comprised of a thermoplastic elastomer composition including a continuous phase composed of either a copolymer of ethylene and vinyl alcohol or a polyamide resin and a dispersion phase comprised of a rubber composition at least partially cross linked in a dynamic manner. The rubber component of this rubber composition is at least one kind of rubber selected from an acrylonitrile-butadiene rubber, an acrylic rubber, a chloroprene rubber, a urethane rubber, an ethylene- acrylic rubber, a fluororubber and a hydrin rubber and it is preferable to employ material having its glass transition point (Tg) of -20 deg.C or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel tank, and more particularly to a fuel tank having high impact strength, excellent fuel barrier properties (fuel permeation resistance), environmental stress crack resistance, moldability and recyclability, and light weight. Therefore, the present invention relates to a fuel tank that is effective for saving energy of a vehicle.

[0002]

2. Description of the Related Art In general, fuel tanks for automobiles are required to have high impact strength, excellent resistance to environmental stress cracking and excellent fuel barrier properties (resistance to fuel permeation) from the viewpoint of safety. From the viewpoint, excellent moldability is required. Conventionally, most of the fuel tank has a steel plate as a main material. However, in recent years, from the viewpoint of energy saving, the weight of automotive components has been reduced, and the use of plastic fuel tanks has been promoted. As a result, consideration has been given to low cost, high strength, weather resistance, chemical resistance and environmental issues. From such a viewpoint, a polyolefin resin has been used.

[0003] Therefore, as a material made of polyolefin resin, for example, a material made of high-density polyethylene has been proposed. From the viewpoint of fuel permeation resistance, it has been proposed to use a polyamide resin such as nylon as a material. Further, Japanese Patent Application Laid-Open No. 7-138322
The publication discloses an ethylene homopolymer or an ethylene copolymer comprising ethylene and an α-olefin having 3 to 20 carbon atoms and having an α-olefin content, an intrinsic viscosity, a density and the like in a specific range. Further, there is disclosed a fuel tank having a multilayer structure in which a polyethylene layer made of the ethylene copolymer and a barrier layer made of a polyamide resin or the like are laminated via an adhesive layer.

[0004]

However, those made of high-density polyethylene as described above have insufficient fuel permeation resistance, which is an important characteristic required for a fuel tank. In addition, those made of a polyamide resin had insufficient impact strength. Furthermore, the above-mentioned multi-layered fuel tank requires equipment costs for forming the multi-layered structure, and the debris and defective molding generated during the manufacturing are difficult to recycle because of the multi-layered structure. ,
This has led to an increase in waste, making it difficult to save resources.

Therefore, an object of the present invention is to provide high impact strength, excellent fuel barrier properties (fuel permeation resistance), excellent environmental stress cracking resistance and moldability, as well as excellent recyclability and light weight. An object of the present invention is to provide a fuel tank which is effective for saving energy of a vehicle.

[0006]

Means for Solving the Problems In order to solve the above problems, the present inventors have made intensive studies and found that a continuous phase composed of a polyamide resin and a dispersed phase composed of a dynamically crosslinked rubber component were used. It has been found that a fuel tank having an elastomer layer composed of a thermoplastic elastomer composition containing the above can achieve the above object, and have arrived at the present invention.
Further, they have found that a material in which a barrier resin for suppressing fuel permeation is dispersed in a layer in the elastomer layer is more effective for improving fuel permeation resistance.

That is, the present invention provides a thermoplastic elastomer composition comprising a continuous phase comprising an ethylene / vinyl alcohol copolymer or a polyamide resin and a dispersed phase comprising a rubber composition at least partially dynamically crosslinked. The present invention provides a fuel tank having at least a part of an elastomer layer composed of:

It is preferable that the fuel tank has a single-layer structure composed of only an elastomer layer.

The rubber composition is at least one rubber selected from acrylonitrile-butadiene rubber, acrylic rubber, chloroprene rubber, urethane rubber, ethylene acrylic rubber, fluorine rubber and hydrin rubber;
Further, it is preferable that the glass transition point (Tg) is -20 ° C or lower.

[0010] The elastomer layer may be made of ethylene.
A thermoplastic elastomer composition comprising a continuous phase composed of a vinyl alcohol copolymer or a polyamide resin and a dispersed phase composed of a rubber component at least partly dynamically crosslinked, and a barrier resin dispersed in a layered form. Is preferable.

[0011] Further, the thermoplastic elastomer composition wherein the elastomer layer comprises a continuous phase comprising an ethylene / vinyl alcohol copolymer or a polyamide resin and a dispersed phase comprising at least a part of a dynamically crosslinked rubber component. With respect to the following formulas (a) and (b)
It is preferable that they have the relationship represented by η _d / η _m > 3.0 (a) α = Φ _d / Φ _m × η _m / η _d <1.0 (b) (where, η _d : melt viscosity of the barrier resin (poise) η _m : heat Melt viscosity (poise) of the thermoplastic elastomer composition Φ _d : volume fraction of the barrier resin Φ _m : volume fraction of the thermoplastic elastomer composition

Further, it is preferable that the barrier resin is at least one selected from a polyamide resin, a polyester resin, a polyvinyl resin and a polyvinyl chloride resin.

[0013]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the fuel tank of the present invention will be described in detail.

The fuel tank of the present invention has at least one part of an elastomer layer made of a thermoplastic elastomer composition. The fuel tank of the present invention may have a single-layer structure composed of an elastomer layer composed of a thermoplastic elastomer composition, or may have a multilayer structure composed of the elastomer layer and a layer composed of other components. Further, the fuel tank of the present invention may be configured such that only part or all of the fuel tank has a single-layer structure composed of the elastomer layer or a multi-layer structure having the elastomer layer and a layer composed of other components. Good. In particular, a single-layer fuel tank composed of an elastomer layer composed of the thermoplastic elastomer composition does not require a complicated molding device when molding the fuel tank, and is effective in reducing equipment costs.
In addition, since it is composed of a single component, there is an advantage that recycling is easy and excellent in recyclability.

In the present invention, the thermoplastic elastomer composition, which is a main component of the elastomer layer, comprises a continuous phase composed of an ethylene / vinyl alcohol copolymer or a polyamide resin and a rubber composition at least partially dynamically crosslinked. And a dispersed phase composed of a solid phase, wherein the dispersed phase is uniformly dispersed in the continuous phase.

In this thermoplastic elastomer composition, the ethylene / vinyl alcohol copolymer, which is a main component of the continuous phase, is a copolymer of ethylene and polyvinyl alcohol. In the present invention, by changing the polymerization ratio of the components in the ethylene / vinyl alcohol copolymer, heat stability, gas barrier properties, and moldability differ. As specific examples of the ethylene / vinyl alcohol copolymer, those having a grade in which the ethylene polymerization ratio is changed in the range of 27 to 47% are commercially available.
From the viewpoint of gasoline permeability, flexibility and moldability, those having an ethylene polymerization ratio of about 40% are preferred. The polyamide resin is made of a linear polymer having an amide group in the molecule. Specific examples of the polyamide resin include nylon 6, nylon 66, nylon 46, nylon 11, nylon 12, nylon 610, and nylon 61.
2, nylon 6/66 copolymer, nylon 6/66/6
10 copolymer, nylon MXD6, nylon 6T, nylon 6 / 6T copolymer, nylon 66 / PP copolymer,
Nylon 66 / PPS copolymer and the like. These may be used alone or in combination of two or more. Among them, nylon, nylon 6 and nylon 66 are used in terms of gasoline permeability, moldability and versatility, and nylon 11 and nylon 1 are used in terms of flexibility.
2 is preferred.

Further, the continuous phase may contain other thermoplastic resins as required in addition to the ethylene / vinyl alcohol copolymer or the polyamide resin as long as the object of the present invention is not impaired. Other thermoplastic resins include, for example, high density polyethylene (HDPE), low density polyethylene (LDPE), ultra high molecular weight polyethylene (UHMWPE), isotactic polypropylene,
Polyolefin resins such as ethylene propylene copolymer resin; polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), polyester copolymer, PET /
Polyester resins such as PEI copolymer, polyarylate (PAR), polybutylene naphthalate (PBN), liquid crystalline polyester, aromatic polyester such as polyoxyalkylenediimidic acid / polybutylate terephthalate copolymer; polyacetal (POM) , Polyphenylene oxide (PPO), polysulfone (PSF), polyether-based resins such as polyetheretherketone (PEEK); polyacrylonitrile (PAN), polymethacrylonitrile, acrylonitrile / styrene copolymer (AS), methacrylonitrile / Polystyrenes such as styrene / styrene copolymer and methacrylonitrile / styrene / butadiene copolymer; polymethyl methacrylate (PMM
A), polymethacrylate resins such as polyethyl methacrylate; vinyl acetate (EVA), polyvinyl alcohol (PVA), polyvinylidene chloride (PVDC), polyvinyl chloride (PVC), vinyl chloride / vinylidene chloride copolymer, chloride Polyvinyl resins such as vinylidene / methyl acrylate copolymer; cellulose resins such as cellulose acetate and cellulose acetate butyrate; polyvinylidene fluoride (P
VDF), fluororesins such as polyvinyl fluoride (PVF), polychlorofluoroethylene (PCTFE), and tetrafluoroethylene / ethylene copolymer (ETFE);
An imide-based resin such as aromatic polyimide (PI); polyacetal, and the like. Among them, polyolefin-based resins, polyester-based resins, polyether-based resins, and fluorine-based resins can be appropriately used from the viewpoint of the coefficient of friction and the like.

In the thermoplastic elastomer composition, the dispersed phase dispersed in the continuous phase is at least partially composed of a dynamically crosslinked rubber composition. Examples of the rubber component which is a main component of the dispersed phase include NR, IR, epoxidized natural rubber, SBR, BR
(High cis BR and low cis BR), acrylonitrile-
Butadiene rubber (NBR), hydrogenated NBR, hydrogenated SB
R and other diene rubbers and hydrogenated products thereof; ethylene propylene rubber (EPDM, EPM), maleic acid-modified ethylene propylene rubber (M-EPM), IIR, isobutylene and aromatic vinyl or diene monomer copolymer, acrylic rubber Olefinic rubbers such as (ACM); B
r-IIR, CI-IIR, bromide of isobutylene paramethylstyrene copolymer (Br-IPMS), chloroprene rubber (CR), hydrin rubber (CHR), chlorosulfonated polyethylene (CSM), chlorinated polyethylene (CM), Maleic acid-modified chlorinated polyethylene (M-
CM) and the like; silicone rubber such as methyl vinyl silicone rubber, dimethyl silicone rubber, and methylphenyl vinyl silicone rubber; sulfur-containing rubber such as polysulfide rubber; vinylidene fluoride rubber, fluorine-containing vinyl ether rubber, and tetrafluoroethylene rubber. Fluorine rubbers such as propylene-based rubber, fluorine-containing silicon-based rubber, and fluorine-containing phosphazene-based rubber; urethane rubber; and epichlorohydrin rubber. In the present invention,
These rubber components can be used alone or in combination of two or more. Among them, acrylonitrile-butadiene rubber (NBR), acrylic rubber (ACM), chloroprene rubber (CR), urethane rubber, ethylene acrylic rubber, fluorine are considered in consideration of fuel barrier properties (fuel permeation resistance) and fuel deterioration resistance. Gasoline-resistant rubbers such as rubber and hydrin rubber are preferred. In particular, among these gasoline-resistant rubbers, Tg is -2.
Those having a temperature of 0 ° C or lower are preferable, and those having a temperature of -40 ° C or lower are more preferable.

Further, in the rubber component constituting the dispersion layer, reinforcing materials, fillers, and the like generally compounded for the purpose of improving the dispersibility and heat resistance of the rubber component, and for other purposes.
A softening agent, a cross-linking agent, an antioxidant, a processing aid, and the like can be appropriately compounded as needed.

In the present invention, in the thermoplastic elastomer composition constituting the elastomer layer, the rubber component constituting the dispersed phase is dispersed in the continuous phase into particles having a size of 0.1 μm to several tens μm.

In the thermoplastic elastomer composition constituting the elastomer layer of the fuel tank of the present invention, an ethylene / vinyl alcohol copolymer or a polyamide resin as a main component of the continuous phase and a rubber as a main component of the dispersed phase are used. The combination of the components is not particularly limited, and one or more selected from the above-mentioned ethylene / vinyl alcohol copolymer or polyamide resin and one or more selected from the above-mentioned rubber components can be used in combination.

In this thermoplastic elastomer composition, the content ratio of the resin composition of the ethylene / vinyl alcohol copolymer or the polyamide resin constituting the continuous phase and the rubber composition constituting the dispersed phase is expressed as rubber composition / resin The ratio by weight of the composition is preferably 50/50 to 2/95,
In particular, a ratio of 30/70 to 10/90 is preferable.

Further, the elastomer layer of the fuel tank of the present invention comprises a continuous phase composed of an ethylene / vinyl alcohol copolymer or a polyamide resin, and a dispersed phase composed of a dynamically crosslinked rubber composition at least partially. It is preferable to include a thermoplastic resin composition containing the above-described thermoplastic elastomer composition and a barrier resin dispersed in a layered form, since a fuel tank having excellent fuel permeation resistance can be obtained. In the present invention, “dispersed in a layered form” means that the barrier resin is dispersed in the thermoplastic elastomer composition in a flat shape, and particularly, the layer shape has an aspect ratio of 10 to 5
00 (when the major axis length a and the minor axis length b, the aspect ratio:
a / b).

In the present invention, from the viewpoint of gasoline permeability and impact resistance, the barrier resin is preferably dispersed as a plate-like layer parallel to the fuel tank surface.

Examples of resin components constituting the barrier resin include polyamide resins such as nylon 6, nylon 6, and aromatic nylon (MXD6), polyester resins such as polyethylene phthalate (PET), ethylene-vinyl alcohol (EVOH), Polyvinyl Alcote (P
VA) and the like, a polyvinyl resin, a polyvinyl chloride resin, a polyvinylidene chloride (PVDC)) resin, and the like.
In the present invention, the barrier resin may be composed of only one of these, or may be composed of a combination of plural kinds. Among these, aromatic nylon (MXD6) or ethylene-vinyl alcohol copolymer (EVOH) is particularly preferable from the viewpoint of fuel permeation resistance. When the elastomer layer of the fuel tank of the present invention contains the barrier resin, the content of the barrier resin is determined by the following formula (based on the melt viscosity and volume fraction of the thermoplastic elastomer composition and the barrier resin). It is appropriately determined so as to satisfy a) and (b). Usually, the weight ratio of the thermoplastic elastomer composition to the barrier resin is 90/10
A ratio of 50 to 50/50, particularly a ratio of 90/10 to 70/30 is preferred.

In the fuel tank of the present invention, the elastomer layer is composed of a thermoplastic elastomer composition containing a continuous phase composed of an ethylene / vinyl alcohol copolymer or a polyamide resin and a dispersed phase composed of a rubber composition. Even if this thermoplastic elastomer composition is simply kneaded in a molten state with an ethylene / vinyl alcohol copolymer or a polyamide resin and a rubber composition, it is not always possible to obtain a target dispersion structure. Therefore, in order to control the mixing ratio of both components and obtain a thermoplastic elastomer composition having a desired dispersed structure, a resin composition constituting a continuous phase including an ethylene / vinyl alcohol copolymer or a polyamide resin to be used. It is effective to adjust the value of α ₂ determined by the following formula (c) so as not to exceed 1 in accordance with the melt viscosity at the specific kneading temperature of each of the product and the rubber composition. α ₂ = (φ _R / φ _P ) × (η _P / η _R ) (c) (where, φ _R : volume fraction of rubber component φ _P : resin component constituting the continuous phase including polyamide resin) Volume fraction η _R : Melt viscosity (poise) of rubber composition under temperature and shear rate conditions during kneading of resin composition and rubber composition η _P : Temperature and shear rate during kneading of resin composition and rubber composition When the value of the melt viscosity (poise) this alpha ₂ of the resin composition in the condition is not 1 or more, dispersion structure of the compositions of the present invention, reversed, there is a fear that the rubber composition becomes the continuous phase.

In the fuel tank of the present invention,
A stomach layer comprising the thermoplastic elastomer composition;
In addition, when the above-mentioned barrier resin is contained, ethylene
Consists of nyl alcohol copolymer or polyamide resin
Continuous phase and at least partly dynamically crosslinked rubber composition
Elastomer composition containing a dispersed phase composed of a product
In contrast, the barrier resin is represented by the following formulas (a) and (b)
It needs to have the relationship expressed. η_d/ Η_m> 3.0  (A) α₁= Φ_d/ Φ_m× η_m/ Η_d<1.0 (b) (where η_d: Melt viscosity of barrier resin (poise) η_m: Melt viscosity (poise) of the thermoplastic elastomer composition Φ_d: Volume fraction of barrier resin Φ_m: Volume fraction of thermoplastic elastomer composition  In equation (a), η_d/ Η_mIs 3 or more,
The barrier resin has a thermoplastic elastomer composition during melt kneading.
They are finely dispersed in the object, and function as a barrier.
It will not help. Also, in equation (b), α₁Is 1 or more
Is, the barrier resin and the thermoplastic elastomer composition
The phase structure is reversed and the barrier resin becomes a matrix.
I will.

In the present invention, the melt viscosity means the melt viscosity of a component at an arbitrary temperature during kneading. Since the melt viscosity of the polymer component varies depending on temperature, shear rate (sec ⁻¹ ) and shear stress, generally, at any temperature in a molten state, particularly at a temperature range during kneading,
A value obtained by flowing a polymer component in a molten state through a thin tube and measuring the stress and the shear rate according to the following equation.

[0029]

(Equation 1)

The melt viscosity is measured, for example, using a capillary rheometer Capillograph 1C manufactured by Toyo Seiki Co., Ltd.
Can be used.

Further, the thermoplastic elastomer composition constituting the elastomer layer of the fuel tank of the present invention has improved properties such as fluidity, heat resistance, physical strength, and cost during molding of the resin component constituting the continuous phase. Therefore, as long as the object of the present invention is not impaired, a necessary amount of a compounding agent such as a reinforcing agent, a filler, a softening agent, an antioxidant, and a processing aid, which is added to a usual composition, can be added. Further, a pigment can be added to the resin component for the purpose of coloring or the like.

Further, in the present invention, when the above-mentioned resin composition and the rubber composition have different chemical compatibility, it is preferable to compatibilize the two by using an appropriate compatibilizer as the third component. . By mixing the compatibilizer into the system,
The interfacial tension between the resin composition and the rubber composition decreases, and as a result, the particle diameter of the rubber composition forming the dispersed phase becomes finer, so that the properties of both compositions are more effectively expressed. become. As the compatibilizer, generally, a resin component,
A copolymer having a structure of both or one of the rubber components, or a copolymer having an epoxy group, a carboxyl group, a carbonyl group, a halogen group, an amino group, an oxazoline group, a hydroxyl group, etc. which can react with the resin component or the rubber component. One having the following structure: These can be selected according to the types of the resin component and the rubber component to be mixed.
As general-purpose products, styrene / ethylene / butylene / styrene block copolymer (SEBS) and its maleic acid-modified product, EPDM, EPM and their maleic acid-modified product, EPDM / styrene or EPDM / acrylonitrile graft copolymer and The maleic acid modified product, styrene / maleic acid copolymer, reactive phenoxine and the like can be mentioned. When the compatibilizing agent is blended with the thermoplastic elastomer composition, the blending amount is not particularly limited, and preferably, the total amount of the resin composition and the rubber composition is 1%.
The amount is 0.5 to 20 parts by weight with respect to 00 parts by weight.

In the present invention, the vulcanizing agent, vulcanization aid, vulcanization conditions (temperature, time) and the like used for the dynamic crosslinking of the rubber component may be appropriately determined according to the composition of the rubber component used. Is not particularly limited. As the vulcanizing agent, a general rubber vulcanizing agent (crosslinking agent) can be used.

Specific examples of the sulfur vulcanizing agent used as the rubber vulcanizing agent include powdered sulfur, precipitated sulfur, highly dispersible sulfur, surface-treated sulfur, insoluble sulfur, dimorpholine disulfide, alkylphenol disulfide and the like. Is exemplified. When this sulfur-based vulcanizing agent is used, its amount is preferably, for example, 0.5 to 4 phr (parts by weight per 100 parts by weight of the rubber component, the same applies hereinafter).

The organic peroxide-based vulcanizing agents include:
Benzoyl peroxide, t-butyl hydroperoxide, 2,4-dichlorobenzoyl peroxide,
Examples thereof include 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and 2,5-dimethylhexane-2,5-di (peroxylbenzoate). When this organic peroxide-based vulcanizing agent is used, the amount used is preferably, for example, an amount of 1 to 15 phr.

Further, as a phenol resin-based vulcanizing agent, bromide of alkylphenol resin, tin chloride,
A mixed crosslinking system containing a halogen donor such as chloroprene and an alkylphenol resin is exemplified. When this phenolic resin-based vulcanizing agent is used, the amount used is preferably, for example, an amount of 1 to 20 phr.

As another vulcanizing agent, zinc white (5
phr), magnesium oxide (about 4 phr), litharge (about 10 to 20 phr), p-quinonedioxime, p-dibenzoylquinonedioxime, tetrachloro-p-benzoquinone, poly-p-dinitrosobenzene (2- 10 phr), methylin dianiline (0.2
To about 10 phr).

Further, the thermoplastic elastomer composition includes:
If necessary, a vulcanization accelerator may be added. Examples of the vulcanization accelerator used include general vulcanization accelerators such as aldehyde / ammonia, guanidine, thiazole, sulfenamide, thiuram, dithioate and thiourea. About 5 to 2 phr may be used.

Specific examples of the aldehyde / ammonia vulcanization accelerator include hexamethylenetetramine;
Examples of the guanidine vulcanization accelerator include diphenylguanidine and the like; examples of the thiazole vulcanization accelerator include dibenzothiazyl disulfide (DM), 2-mercaptobenzothiazole and its Zn salt, cyclohexylamine salt; As amide vulcanization accelerators, cyclohexylbenzothiazylsulfenamide (CB)
S), N-oxydiethylenebenzothiazyl-2-sulfenamide, Nt-butyl-2-benzothiazolesulfenamide, 2- (thymolpolynyldithio)
Benzothiazole and the like; tetramethylthiuram disulfide (TMT) as a thiuram-based vulcanization accelerator;
D), tetraethylthiuram disulfide, tetramethylthiuram monosulfide (TMTM), dipentamethylenethiuram tetrasulfide, and the like; as dithioate-based vulcanization accelerators, Zn-dimethyldithiocarbamate, Zn-diethyldithiocarbamate, Zn -Ji-
n-butyldithiocarbamate, Zn-ethylphenyldithiocarbamate, Tc-diethyldithiocarbamate, Cu-dimethyldithiocarbamate, Fe-dimethyldithiocarbamate, pipecoline pipecolyldithiocarbamate, etc .; as thiourea-based vulcanization accelerators, Ethylenethiourea, diethylthiourea and the like; each disclosed. As a vulcanization accelerator, a general rubber auxiliary agent can be used in combination.
hr), stearic acid, oleic acid, and Zn salts thereof (about 2 to 4 phr) can be used.

As the pigment, an inorganic pigment and an organic pigment can be used. Examples of the inorganic pigment include zinc white, titanium oxide, red iron oxide, chromium oxide, iron black, and complex oxides (eg, titanium yellow, zinc-iron brown, titanium / cobalt green, cobalt green, cobalt blue, copper Oxides such as chromium black and copper-iron black); chromates such as graphite and molybdate orange; ferrocyanides such as dark blue; sulfides such as cadmium yellow, cadmium red and zinc sulfide; barium sulfate Sulfates such as ultramarine blue; silicates such as calcium carbonate; phosphates such as manganese violet; hydroxides such as yellow iron oxide; carbon such as carbon black; metal powders such as aluminum powder and bronze powder; And titanium-coated mica.

As the organic pigment, for example, monoazo lakes (for example, Lake Red C, Permanen Red 2)
B, brilliant carmine 6B), monoazo type (for example, toluidine red, naphthol red, fast yellow G, benzimidalone bordeaux, benzimidazolone brown), disazo type (for example, disazo yellow A)
Azo pigments such as AA, disazo yellow HR, pyrazolone red), condensed azo type (for example, condensed azo yellow, condensed azo red, condensed azo brown), and metal complex salt azo type (for example, nickel azo yellow); copper phthalocyanine blue, copper phthalocyanine green Phthalocyanine pigments such as brominated copper phthalocyanine green; dyed pigments such as basic dye lakes (eg, rhodamine 6 lake); anthraquinones (eg, flavanthrone yellow, diansuraquinolyl red, indanthrene blue) Thioindigos (eg, thioindigo bordeaux), perinones (eg, perinone orange), perylenes (eg, perylene scarlet, perylene red, perylene maroon), quinacridones (eg, quinacridone red, quinacridone) Quinacridone scarlet), dioxazine (eg, dioxazine violet), isoindolinone (eg, isoindolinone yellow), quinophthalone (eg, quinophthalone yellow), isoindoline (eg, isoindolin yellow), pyrrole Condensed polycyclic pigments such as a pigment (for example, pyrrole red); metal complex salts azomethine such as copper azomethine yellow; aniline black; and daylight fluorescent pigments.

The thermoplastic elastomer composition is prepared by previously kneading a resin component containing an ethylene / vinyl alcohol copolymer or a polyamide resin and other resins with an unvulcanized rubber composition using a twin-screw kneader or the like. The rubber composition is dispersed in a resin composition forming a continuous phase (matrix phase) as a dispersed phase (domain) in a resin composition forming a continuous phase (matrix phase). Next, a vulcanizing agent is added under kneading to dynamically crosslink the rubber composition, whereby a thermoplastic elastomer composition can be produced. Further, the addition of various compounding agents to the resin composition or the rubber composition may be performed during the above-mentioned kneading operation, but it is preferable to mix them before kneading. At this time, the vulcanizing agent may also be mixed in the rubber composition in advance, and the rubber composition may be simultaneously cross-linked while the resin composition and the rubber composition are being kneaded. The prepared thermoplastic elastomer composition is extruded from a kneading extruder into a strand, cooled with water or the like, and then pelletized with a resin pelletizer. By supplying the pellets to a blow molding machine and blowing air into a tubular extrudate or an injection-molded parison, a fuel tank having a desired shape and dimensions having an elastomer layer composed of the thermoplastic elastomer composition is formed. Can be provided.

The kneading machine used for kneading the resin composition and the rubber composition is not particularly limited, and for example, a screw extruder, a kneader, a Banbury mixer, a twin-screw kneading extruder and the like can be used. In particular, it is preferable to use a twin-screw kneading extruder for kneading the resin composition and the rubber composition and for dynamically cross-linking the rubber composition. In addition, two or more kinds of kneading machines may be used to knead sequentially.

As the conditions for the melt-kneading, the temperature may be at least the temperature at which the thermoplastic resin melts. Further, the shear rate at the time of kneading is preferably from 500 to 7500 sec ^-1 . The total time of kneading is preferably 30 seconds to 10 minutes, and the vulcanization time after addition is preferably 15 seconds to 5 minutes.

In the elastomer layer of the fuel tank of the present invention, a dynamically crosslinked rubber composition constitutes a dispersed phase in a resin composition constituting a continuous phase.
That is, in the above-described production process, crosslinking of the rubber composition proceeds while kneading the resin composition and the rubber composition, and the obtained composition is a crosslinked rubber as a dispersed phase in the resin composition to be a continuous phase. Exist in a finely dispersed state.

Further, in the present invention, a thermoplastic elastomer composition comprising a continuous phase composed of an ethylene / vinyl alcohol copolymer or a polyamide resin and a dispersed phase composed of a rubber composition at least partly dynamically crosslinked. When,
Further, in the elastomer layer containing the barrier resin dispersed in a layered form, the pellets of the thermoplastic elastomer composition prepared as described above and the pellets of the barrier resin are mixed and blended at a predetermined ratio. The method of dry blending using a conventional blender etc. for mixing of both pellets,
Each pellet may be supplied to the kneader from an independent feeder at a predetermined ratio according to any method.

Next, the mixture of the two pellets is melt-kneaded with the thermoplastic elastomer composition and the barrier resin in a single screw extruder at a low shear rate (for example, 30 or more and less than 300). Extrude from the extruder tip,
Alternatively, injection molding may be performed, and the melt-kneaded material may be directly supplied to a molding machine to be used for production of a fuel tank, or may be extruded into a strand shape from the tip of the extruder, pelletized, and subjected to molding. .

During the melt kneading, the mixing ratio of the thermoplastic elastomer composition and the barrier resin is adjusted so that the melt viscosity ratio and α value shown in the above formulas (a) and (b) are obtained.
By adjusting the molecular weight and the like of the barrier resin, a continuous phase composed of an ethylene / vinyl alcohol copolymer or a polyamide resin, and a thermoplastic elastomer composition composed of a rubber composition, the barrier resin is added and finely dispersed. Without this, it is possible to obtain a dispersion form of a continuous flat layered dispersion structure. Furthermore, at the time of molding,
When the elastomer layer is greatly stretched, the barrier layer further increases the area and contributes to fuel permeation resistance.

In the fuel tank of the present invention, ethylene
A continuous phase made of a vinyl alcohol copolymer or a polyamide resin, and a thermoplastic elastomer composition made of a rubber composition, and an elastomer layer having a structure in which a barrier resin is further dispersed in a layer form can further improve fuel permeation resistance. It is advantageous because it can.

The fuel tank of the present invention can be formed by extrusion molding, injection molding, or the like using the thermoplastic elastomer composition or a kneaded product obtained by kneading a barrier resin into the thermoplastic elastomer composition and dispersing it in a layered form. Since it can be manufactured by a usual molding method, it can be manufactured at low cost.

In the fuel tank of the present invention, the shape, dimensions and the like are not particularly limited, and can be appropriately selected based on the location of the fuel tank.

[0052]

EXAMPLES Examples and comparative examples of the present invention will be described below.
The present invention will be described more specifically. In the following Examples and Comparative Examples, the recyclability, low-temperature impact resistance and gasoline permeability of the manufactured fuel tank were evaluated according to the following methods.

1. Preparation of Thermoplastic Elastomer Composition In each mixing ratio of Examples 1 to 7 shown in Table 1, rubber, an antioxidant and a processing aid were put into a Banbury mixer, kneaded, and then released at 150 ° C. Thereafter, the rubber was pelletized with a rubber pelletizer. Next, after melt-kneading, a vulcanizing system was added from an intermediate charging port to perform dynamic vulcanization. The temperature of the twin-screw kneader at this time is 230 ° C.
The shear rate was set at 1000 s ^-1 . The thermoplastic elastomer composition extruded in a strand form from the twin-screw kneader was cooled with water, cooled, and then pelletized with a resin pelletizer.

2. Production of Fuel Tank The thermoplastic elastomer composition prepared by the above method was molded into a fuel tank shape by a blow molding machine. In Examples 5 and 6, a fuel tank was manufactured by blow molding by dry blending the previously prepared thermoplastic elastomer composition with a barrier resin. In Comparative Examples 1 and 2, blow molding was performed using nylon 6 or HDPE alone. In Comparative Example 3, a two-type and three-layer fuel tank in which the inner layer and the outer layer were HDPE and the barrier layer was formed of nylon 6 was used. Manufactured. The average thickness of each fuel tank is 5 mm and the dimensions are 700 mm x 350 mm x 2
00 mm.

The recyclability, low temperature impact resistance and gasoline permeability of the obtained fuel tank were evaluated. Table 1 shows the results.

(1) Recyclability The burrs generated during the production of the fuel tank are removed from the virgin material by 50%.
A fuel tank is formed using the raw material mixed by weight%,
A sample was cut out from the fuel tank into a strip of 80 mm × 10 mm, and a tensile test was performed. A specimen whose strength was reduced by 20% or more compared with the virgin material was evaluated as “×”. In addition, the case of less than 20% was evaluated as ○.

(2) Low-Temperature Impact Resistance A full ethylene glycol was poured into the obtained fuel tank, which was sufficiently cooled in an atmosphere of -40 ° C., and then the tank was dropped from a height of 10 m onto a concrete surface. I let it. At this time, も の indicates that no cracking or deformation occurred, △ indicates that cracking did not occur but deformation occurred, and × indicates cracking.
Was evaluated.

(3) Gasoline Permeability Gasoline was charged into the obtained fuel tank, left for one month in a nitrogen atmosphere at 40 ° C., and the daily gasoline permeation amount was calculated from the total weight change. As a result, those having permeated 2 g / day or more were evaluated as x, those permeating 0.1 to 2 g / day as Δ, and those less than 0.1 g / day as ○.

[0059]

[Table 1]

[0060]

[Table 2]

Resins Ethylene-vinyl alcohol copolymer (EVOH): EVAL EP-H101, Kuraray Nylon 6: CM1001, Toray Nylon 666: CM6001, Toray Nylon 11: BESN O TL, Atochem HDPE : Ace Polyeth S6002, rubber component manufactured by Nippon Polyolefin Co., Ltd. NBR: Perbutin NT2865, manufactured by Bayer Co., Ltd. Hydrogenated NBR: Zetpol 1020, manufactured by Zeon Corporation ACM: Nipol AR54, manufactured by Zeon Corporation Barrier resin: MXD6: Reny 6001, Mitsubishi Gas Chemical Company Ethylene / vinyl alcohol copolymer (EVOH): EVAL EP-F101, Kuraray Co., Ltd. vulcanizing compound Sulfur: Powdered sulfur, Karuizawa Seirensho Co., Ltd. Zinc flower: Zinc flower No. 3, Seido Chemical stearic acid ： Beads Phosphoric acid, manufactured by NOF Corporation butane tetracarboxylic acid: BTC, Mitsui Toatsu Fine Co., Ltd. Antioxidant: Irganox 1010, Ciba-Geigy Japan Co., Ltd. processing aids: Armin D18, manufactured by Lion Akzo Co., Ltd.

[0062]

The fuel tank of the present invention has high rigidity and impact strength, is excellent in fuel barrier properties (fuel permeation resistance), environmental stress crack resistance and moldability, and is excellent in recyclability and light weight. Therefore, it is effective for energy saving of automobiles. In addition, since the elastomer layer composed of a single material can be recycled without being disposed of as waste, it is excellent in recyclability and, furthermore, equipment costs required for molding can be reduced. Is of great value.

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Claims (6)

[Claims] 1. An elastomer layer comprising a thermoplastic elastomer composition comprising a continuous phase comprising an ethylene / vinyl alcohol copolymer or a polyamide resin and a dispersed phase comprising a rubber composition at least partly dynamically crosslinked. A fuel tank having at least a part of the fuel tank. 2. The fuel tank according to claim 1, wherein said fuel tank has a single-layer structure comprising said elastomer layer. 3. The rubber component of the rubber composition is at least one rubber selected from acrylonitrile-butadiene rubber, acrylic rubber, chloroprene rubber, urethane rubber, ethylene acrylic rubber, fluorine rubber and hydrin rubber, and has a glass transition. The fuel tank according to claim 1, wherein a point (Tg) is −20 ° C. or lower. 4. A thermoplastic elastomer composition, wherein said elastomer layer comprises a continuous phase comprising an ethylene / vinyl alcohol copolymer or a polyamide resin and a dispersed phase comprising a rubber composition at least partly dynamically crosslinked. Things and
The fuel tank according to any one of claims 1 to 3, further comprising a barrier resin dispersed in a layer. 5. A thermoplastic elastomer composition, wherein said elastomer layer comprises a continuous phase composed of an ethylene / vinyl alcohol copolymer or a polyamide resin, and a dispersed phase composed of a dynamically crosslinked rubber composition. The fuel tank according to claim 4, wherein the barrier resin has a relationship represented by the following formulas (a) and (b) with respect to the object. η _d / η _m > 3.0 (a) α ₁ = φ _d / φ _m × η _m / η _d <1.0 (b) (where η _d : melt viscosity (poise) of barrier resin η _m : Melt viscosity (poise) of thermoplastic elastomer composition Φ _d : volume fraction of barrier resin Φ _m : volume fraction of thermoplastic elastomer composition 6. The fuel tank according to claim 4, wherein the barrier resin is at least one selected from a polyamide resin, a polyester resin, a polyvinyl resin, and a polyvinyl chloride resin.