JP2018083298A - Fuel container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel container having excellent fuel barrier properties even when a fuel with a high lower-alcohol content, such as ethanol, is used.SOLUTION: The present invention provides a fuel container for storing a fuel with a lower alcohol content of 20 mass% or more. The fuel container is formed from a multilayered structure with a fuel barrier layer disposed between thermoplastic resin layers. The fuel barrier layer contains resin composition containing a saponified ethylene/vinyl ester copolymer and an inorganic laminar compound.SELECTED DRAWING: None

Description

  The present invention relates to a fuel container for containing a fuel having a lower alcohol content of 20% by mass or more.

  In recent years, lower alcohols such as methanol and ethanol have been used to improve the octane number of gasoline and to reduce the amount of unburned hydrocarbons in exhaust gas from the viewpoint of tightening regulations on environmental pollution, preventing air pollution and saving gasoline consumption. Blended gasoline is used mainly in the United States.

  Biomass produced by fermenting and distilling biomass such as sugar cane and corn as a gasoline fuel substitute because it is renewable natural energy and does not increase the amount of carbon dioxide in the atmosphere due to its combustion. Ethanol is attracting attention. Biomass ethanol is used without being mixed with gasoline, or is blended at a high ratio even when mixed and used.

  However, in the fuel container used in conventional gasoline, when using a fuel having a high content of lower alcohol such as ethanol as described above, the fuel barrier property of the container is not sufficient, and there is room for improvement. there were.

  Therefore, in order to solve the above problems, for example, in Patent Document 1, a high-density polyethylene (a) layer is provided via an adhesive resin (b) layer on the inner and outer layers of an ethylene-vinyl alcohol copolymer (c) layer. And (c) the thickness of each layer inside the layer is I, and (c) the thickness of each layer outside the layer is O, the thickness ratio (I / O) is 50. A fuel container smaller than / 50 is disclosed.

JP-A-9-29904

  However, in Patent Document 1, the permeation preventing performance of the fuel container is evaluated when gasoline containing 15% by weight of ethanol is used as the fuel, but in the case of gasoline containing more ethanol, the fuel container The permeation prevention performance of is unknown.

  The present invention has been made in view of the above-described conventional situation, and solves the problem of providing a fuel container having an excellent fuel barrier property even when a fuel having a high content of lower alcohol such as ethanol is used. It is an issue that should be done.

As a result of intensive studies, the inventor has a multilayer structure in which a fuel barrier layer is disposed between thermoplastic resin layers, and the fuel barrier layer is a saponified ethylene-vinyl ester copolymer and an inorganic layered compound. It has been found that the above-mentioned problems can be solved by a fuel container that is a layer having a resin composition containing, and the present invention has been completed.
That is, the present invention relates to the following <1> to <2>.
<1> A fuel container for containing a fuel having a lower alcohol content of 20% by mass or more, wherein the fuel barrier layer is formed of a multilayer structure in which a fuel barrier layer is disposed between thermoplastic resin layers. A fuel container comprising a resin composition containing a saponified ethylene-vinyl ester copolymer and an inorganic layered compound.
<2> The fuel container according to <1>, wherein the inorganic layered compound has an average particle size of 1 to 30 μm.

  According to the present invention, a fuel container having excellent fuel barrier properties can be provided even when a fuel having a high content of lower alcohol such as ethanol is used.

  Hereinafter, although this invention is explained in full detail, these show an example of a desirable embodiment, and this invention is not specified by these content.

[Fuel container]
The fuel container of the present invention is formed from a multilayer structure in which a fuel barrier layer is disposed between thermoplastic resin layers. Further, the fuel barrier layer is made of a resin composition containing an ethylene-vinyl ester copolymer saponified product (hereinafter sometimes referred to as “EVOH resin”) and an inorganic stratiform compound.

[Thermoplastic resin layer]
As the thermoplastic resin used in the thermoplastic resin layer of the fuel container of the present invention, linear low density polyethylene, low density polyethylene, ultra-low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, Ionomer, ethylene-propylene copolymer, ethylene-acrylic acid ester copolymer, polypropylene, propylene-α-olefin (α-olefin having 4 to 20 carbon atoms) copolymer, olefin such as polybutene and polypentene Polymers, or polyolefin resins such as those obtained by graft-modifying these olefins alone or copolymers with unsaturated carboxylic acids or esters thereof, polyesters, polyamides, copolymerized polyamides, polyvinyl chloride, polyvinylidene chloride, Acrylic resin, polystyrene, Examples thereof include vinyl ester resins, polyester elastomers, polyurethane elastomers, chlorinated polyethylene, chlorinated polypropylene, aromatic or aliphatic polyketones, and polyalcohols obtained by reducing these.

  Among these, polyolefin resins are preferable from the viewpoint of practicality such as moldability and strength of the fuel container, and among these, high density polyethylene (HDPE) is particularly preferable.

  In addition, various additives, modifiers, other resins, and the like may be blended with the thermoplastic resin as long as the object of the present invention is not impaired.

[Fuel barrier layer]
The fuel barrier layer of the fuel container of the present invention is characterized by comprising a resin composition containing a saponified ethylene-vinyl ester copolymer (“EVOH resin”) and an inorganic layered compound.

(EVOH resin)
The EVOH resin used in the present invention is usually a resin obtained by saponifying a copolymer of ethylene and a vinyl ester monomer (ethylene-vinyl ester copolymer), and is a water-insoluble thermoplastic resin. It is.

As the polymerization method, any known polymerization method such as solution polymerization, suspension polymerization, and emulsion polymerization can be used. Generally, solution polymerization using methanol as a solvent is used.
Saponification of the obtained ethylene-vinyl ester copolymer can also be performed using a known method.
The EVOH resin produced in this way is mainly composed of ethylene-derived structural units and vinyl alcohol structural units, and contains a slight amount of vinyl ester structural units remaining without saponification.

As the vinyl ester monomer, vinyl acetate is typically used from the viewpoint of market availability and good impurity treatment efficiency during production.
Examples of other vinyl ester monomers include vinyl formate, vinyl propionate, vinyl valelate, vinyl butyrate, vinyl isobutyrate, vinyl pivalate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl versatate, etc. Examples include aliphatic vinyl esters and aromatic vinyl esters such as vinyl benzoate, and usually use aliphatic vinyl esters having 3 to 20 carbon atoms, preferably 4 to 10 carbon atoms, and more preferably 4 to 7 carbon atoms. Can do.
These vinyl ester monomers are usually used alone, but a plurality of them may be used simultaneously if necessary.

The content of the ethylene structural unit in the EVOH resin is a value measured based on ISO 14663, and is usually 10 to 50 mol%, preferably 15 to 40 mol%, and more preferably 20 to 30 mol%.
When the content is too low, melt moldability tends to be reduced, and when it is too high, gasoline permeability tends to be insufficient.

The saponification degree of the vinyl ester component in the EVOH resin is a value measured based on JIS K6726 (however, the EVOH resin is a solution uniformly dissolved in water / methanol solvent) and is usually 90 to 100 mol%, preferably It is 95-100 mol%, More preferably, it is 99-100 mol%.
If the degree of saponification is too low, gas barrier properties, thermal stability, moisture resistance and the like tend to be reduced.

The melt flow rate (MFR) (210 ° C., load 2,160 g) of EVOH resin is usually 0.5 to 100 g / 10 minutes, preferably 1 to 50 g / 10 minutes, more preferably 3 to 35 g / 10 minutes. It is.
When the MFR is too large, the film forming property tends to be unstable, and when it is too small, the viscosity becomes too high and melt extrusion tends to be difficult.

  In addition to ethylene structural units and vinyl alcohol structural units (including unsaponified vinyl ester structural units), EVOH resins may further contain structural units derived from the following comonomer.

  Examples of the comonomer include α-olefins such as propylene, isobutene, α-octene, α-dodecene, α-octadecene; 3-buten-1-ol, 4-penten-1-ol, 3-butene-1, 2- Hydroxyl group-containing α-olefins such as diols and hydroxy group-containing α-olefin derivatives such as esterified products and acylated products thereof; 2-methylenepropane-1,3-diol, 3-methylenepentane-1,5-diol, etc. Hydroxyalkylvinylidenes; hydroxyalkylvinylidene diacetates such as 1,3-diacetoxy-2-methylenepropane, 1,3-dipropionyloxy-2-methylenepropane, 1,3-dibutyronyloxy-2-methylenepropane Unsaturated carboxylic acid or salt thereof, partial alkyl ester, complete alkyl ester Ether, nitrile, amide or anhydride; unsaturated sulfonic acids or salts thereof; vinylsilane compounds; vinyl chloride; styrene.

  Further, post-modified EVOH resins such as urethanization, acetalization, cyanoethylation, oxyalkyleneation and the like can also be used. Among the above modified products, EVOH resin in which a primary hydroxyl group is introduced into the side chain by copolymerization is preferable in terms of good secondary formability such as stretching treatment and vacuum / pressure forming, and in particular, 1,2-diol. EVOH resin having a structure in the side chain is preferred.

  In the EVOH resin, as long as the effects of the present invention are not impaired, a compounding agent generally incorporated into the EVOH resin, for example, a heat stabilizer, an antioxidant, an antistatic agent, a colorant, an ultraviolet absorber, a lubricant, a plasticizer, Light stabilizer, surfactant, antibacterial agent, drying agent, antiblocking agent, flame retardant, crosslinking agent, curing agent, foaming agent, crystal nucleating agent, antifogging agent, biodegradation additive, silane coupling agent, oxygen An absorbent or the like may be blended.

  The EVOH resin may be a mixture with other different EVOH resins. Examples of other EVOH resins include those having different ethylene contents, those having different saponification degrees, those having different polymerization degrees, and other common resins. Examples include those having different polymerization components and those having different contents of 1,2-diol structural units.

(Inorganic layered compound)
The inorganic layered compound used in the present invention forms a sheet-like material in which atoms are strongly bonded by a covalent bond or the like to form a dense arrangement, for example, a tetrahedral sheet-like material such as silicon oxide, or a metal hydroxide such as aluminum An octahedral sheet-like material such as, etc., which is an inorganic compound having a structure in which these sheet-like materials are stacked almost in parallel by van der Waals force, electrostatic force or the like. Generally, it is also called layered silicate.

Such an inorganic layered compound is, for example, a 1: 1 type having a crystal structure in which one octahedral sheet shares the apex oxygen of one tetrahedral sheet, and the two apexes of one tetrahedral sheet. A 2: 1 type having a crystal structure shared by the face sheet is exemplified.
For example, specific examples of the 1: 1 type include kaolinites such as kaolinite, serpentine, dickite, nacrite, halloysite, chrysotile, lizarite, halloysite, and the like, and the 2: 1 type specific examples include talc and pyrophyll. Examples include talc such as light, mica such as illite, muscovite, biotite, smectite such as montmorillonite, beidellite, nontronite, saponite, hectorite, stevensite, and vermiculite.
The inorganic layered compound may be a natural product or a synthetic product.

  Among the inorganic layered compounds, kaolinites and smectites are preferably used, and kaolinite and montmorillonite are particularly preferably used from the viewpoint of availability.

The average particle diameter (μm) of the inorganic layered compound is usually 1 to 30 μm, preferably 2 to 20 μm, and more preferably 3 to 10 μm.
When the average particle size is too large, the dispersion stability in the aqueous dispersion deteriorates and the appearance of the molded product tends to deteriorate.

  Such an average particle diameter can be obtained by a laser scattering method. For example, an inorganic layered compound aqueous dispersion having a concentration of 0.1% by mass is prepared using distilled water, and the dispersion is analyzed by a laser scattering particle size distribution analyzer ( It is obtained by analyzing using LA-950) manufactured by HORIBA.

The BET specific surface area (m ² / g) of the inorganic layered compound is not particularly limited, but is usually 1 m ² / g or more, preferably 3 m ² / g or more, more preferably 5 m ² / g or more.
When the BET specific surface area is too small, the dispersion stability in the aqueous dispersion tends to deteriorate.

The inorganic layered compound may be surface-treated with a reactive agent such as a silane coupling agent.
A conventionally known silane coupling agent can be used. The silane coupling agent is represented by the general formula RSiX ₃ , where R is an organic functional group such as vinyl group, styryl group, epoxy group, glycidyl group, glycidoxy group, methacryl group, amino group, mercapto group, and X is Mainly chlorine and alkoxy groups.

  Specifically, vinyltrimethoxysilane, vinyltriethoxysilane, p-styryltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycid Xylpropylmethyldiethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, etc. Can be mentioned.

(Mixing method)
The fuel barrier layer of the fuel container of the present invention is composed of a resin composition containing an EVOH resin and an inorganic layered compound (hereinafter sometimes referred to as “EVOH resin composition”).

  In the present invention, the EVOH resin composition can be obtained by melt-kneading or solution mixing the EVOH resin and the inorganic layered compound. Among these, melt kneading is preferable from the viewpoint of productivity. Hereinafter, melt kneading will be described.

The blending ratio of the EVOH resin and inorganic layered compound used for kneading is preferably 0.1 to 100 parts by weight (solid content) of the inorganic layered compound with respect to 100 parts by weight (solid content) of the EVOH resin, More preferably, it is 0.1-50 mass parts (solid content), More preferably, it is 1-20 mass parts (solid content), Most preferably, it is 5-15 mass parts (solid content).
If the blending ratio is too low, the gasoline permeability improving effect tends to be small, and if the blending ratio is too high, the appearance of the molded product may be deteriorated, which tends to be undesirable.

  In kneading the EVOH resin and the inorganic layered compound, there are no particular limitations on the apparatus and method used, and for example, using a known kneading apparatus such as an extruder, kneader, mixing roll, Banbury mixer, plast mill, Brabender, etc. A known method can be used. These kneading apparatuses may be used alone or in combination of two or more apparatuses.

  Moreover, the apparatus to be used may be appropriately selected depending on the type, nature, shape, etc. of the EVOH resin and the inorganic layered compound, and usually an extruder such as a single screw extruder or a twin screw extruder which is widely used industrially is suitable. From the viewpoint of dispersibility of the inorganic compound in the resin, a twin screw extruder is preferred.

Although it does not specifically limit as a twin-screw extruder, Preferably the screw internal diameter is 20 mm or more, More preferably, it is 30-150 mm.
When the screw inner diameter is too small, productivity is poor, which is not preferable.

The L / D of the twin screw extruder {ratio of the effective length (L) of the screw of the twin screw extruder to the screw inner diameter (D)} is preferably 20 or more, more preferably 30 or more.
When the L / D is too small, the kneading time is short, and the dispersibility of the inorganic compound in the EVOH resin is lowered, which is not preferable.

  When the EVOH resin and the inorganic layered compound are supplied to the twin screw extruder, there is no particular limitation, but from the viewpoint of uniform dispersion of the inorganic layered compound in the EVOH resin, an aqueous dispersion of the inorganic layered compound is prepared in advance. Then, it is preferable to blend into EVOH resin.

For example, (1) a method in which a mixture obtained by previously blending an EVOH resin and an inorganic compound aqueous dispersion is supplied to the hopper of the extruder, and (2) an EVOH resin and an inorganic compound aqueous dispersion are directly supplied to the hopper of the extruder. And (3) a method of supplying EVOH resin to the hopper of the extruder and supplying an inorganic compound aqueous dispersion from a part of the barrel of the extruder (that is, side-feeding).
In carrying out the method (3), the aqueous dispersion of the inorganic stratiform compound can be supplied from the vent port using gravity, or can be supplied under pressure.
Among these, the method (3) is preferable from the viewpoint of productivity.

  The EVOH resin composition obtained as described above has a conventionally known plasticizer, heat stabilizer, light stabilizer, ultraviolet absorber, anti-aging agent at the time of mixing or kneading raw materials or at the time of molding depending on the purpose. , Pigments, colorants, natural fibers, various inorganic particles, various fillers, antistatic agents, mold release agents, plasticizers, fragrances, lubricants, crosslinking (vulcanizing) agents, crosslinking (vulcanizing) accelerators, crystal nucleating agents, Various lacquering agents such as a crystallization accelerator, a flame retardant, a foaming agent, a softening agent, an antiseptic, an antibacterial / drug resistance agent, and the like may be blended.

In producing the EVOH resin composition, the moisture content of the EVOH resin is usually 60% by mass or less, preferably 40% by mass or less, more preferably 20% by mass or less, still more preferably 5% by mass or less, and particularly preferably 0%. .5% by mass or less.
The lower limit of the moisture content is not particularly limited, but if the moisture content is too high, the dehydration becomes insufficient, the backflow of steam to the hopper part of the extruder occurs due to foaming, the resin adheres in the hopper, and the supply is poor. Tend to occur.

The method of adding water to the EVOH resin is not particularly limited. However, the method of precipitating the EVOH resin solution in water, washing it thoroughly with water to remove the solvent and containing water, and adding EVOH resin in pressurized hot water 1 There are known methods such as a method of treating for about 3 hours, a method of precipitating a paste after saponification in the production of EVOH resin in water and containing water (see, for example, JP-A-2002-003611).
Among these, the method of precipitating the paste after saponification in water during EVOH resin production is particularly preferably used.

[Fuel container manufacturing method]
In manufacturing the fuel container of the present invention, that is, the fuel container having a layer structure such as thermoplastic resin layer / EVOH resin composition layer / thermoplastic resin layer, the EVOH resin composition and the thermoplastic resin are injected into an injection molding machine. In addition to the direct blow molding machine (continuous type, accumulator type), injection blow molding machine, etc., in addition to the method of directly obtaining the fuel container of the present invention, multilayer obtained by co-extrusion of EVOH resin composition and thermoplastic resin A method of vacuum forming a sheet, a method of vacuum forming a laminated sheet obtained by co-extrusion lamination of an EVOH resin composition / thermoplastic resin to a thermoplastic resin film, and using a thermoplastic resin film and an EVOH resin composition film as an adhesive And a method of vacuum forming a multilayer sheet obtained by dry laminating, preferably direct blow, injection blow, etc. Low molding method is adopted.
For example, the fuel container of the present invention can be obtained by blow-molding a parison obtained by co-extrusion of an EVOH resin composition and a thermoplastic resin with a mold and blowing air.

  In the present invention, when the EVOH resin composition layer is a and the thermoplastic resin layer is b, not only the layer configuration of b / a / b but also b / b / a / b / b, b / b / R / a / b, b / R, where R is a regrind layer made of a / b / a / b or the like, or at least a mixture of EVOH resin composition and thermoplastic resin (recycled product). / A / R / b, b / a / R / a / b, b / R / a / R / a / R / b, etc. are also possible.

Preferably, layer configurations of b / a / b, b / b / a / b / b, b / R / a / b, b / R / a / R / b are adopted, and these layer configurations are also used. If necessary, the mixture used in the regrind layer and an adhesive resin described later can be blended in b.
Further, in these laminates, an adhesive resin is used between the layers as necessary.

  The adhesive resin contains a carboxyl group obtained by chemically bonding an unsaturated carboxylic acid or its anhydride to an olefin polymer (the above-mentioned polyolefin resin in the broad sense) by an addition reaction or a graft reaction. And modified olefin polymers.

  Specifically, maleic anhydride graft-modified polyethylene, maleic anhydride graft-modified polypropylene, maleic anhydride graft-modified ethylene-propylene (block or random) copolymer, maleic anhydride graft-modified ethylene-ethyl acrylate copolymer, anhydrous One type or a mixture of two or more types selected from maleic acid graft-modified ethylene-vinyl acetate copolymer and the like are preferable.

At this time, the content of the unsaturated carboxylic acid or anhydride thereof contained in the modified olefin polymer is preferably 0.001 to 3% by mass, more preferably 0.01 to 1% by mass, and still more preferably. It is 0.03-0.5 mass%.
If the amount of modification in the modified olefin polymer is too small, the interlaminar adhesion, moldability and impact resistance may be insufficient, and if too large, a crosslinking reaction may occur and the moldability may deteriorate. It is not preferable.

These modified olefin polymers can be blended with EVOH resin compositions, other EVOH, polyisobutylene, rubber / elastomer components such as ethylene-propylene rubber, and other thermoplastic resins.
In particular, the incorporation of an olefin polymer different from the base olefin polymer of the modified olefin polymer is useful because the adhesiveness may be improved.

  In addition, the thickness of each layer cannot be generally specified depending on the application, container form, required physical properties, etc., but for example, when used for a fuel tank of an automobile, the thickness of the EVOH resin composition layer is preferably It is 30-500 micrometers, More preferably, it is 50-400 micrometers, More preferably, it is 80-300 micrometers.

The thickness of the thermoplastic resin layer is preferably 100 to 10,000 μm, more preferably 200 to 5000 μm, and still more preferably 300 to 3000 μm.
The thickness of the regrind layer is preferably 100 to 10,000 μm, more preferably 200 to 5000 μm, and still more preferably 300 to 3000 μm.
The thickness of the adhesive resin layer is preferably 30 to 500 μm, more preferably 50 to 400 μm, and still more preferably 80 to 300 μm.
The thickness of the entire fuel container is preferably 300 to 10,000 μm, more preferably 1000 to 8000 μm, and still more preferably 2000 to 6000 μm.

[fuel]
The fuel container of the present invention obtained above is for containing a fuel having a lower alcohol content of 20% by mass or more, and has excellent barrier properties against the fuel.
Here, the lower alcohol refers to alcohols having 1 to 4 carbon atoms such as methanol, ethanol, propanol, and butanol, and mixtures thereof. Among these, ethanol is preferable from the viewpoint of danger and environmental load.

The content of the lower alcohol in the fuel used in the fuel container of the present invention is 20% by mass or more, preferably 50% by mass or more, more preferably 80% by mass or more.
When a fuel having a lower alcohol content of less than 20% by mass is used, no significant improvement in fuel barrier properties as in the fuel container of the present invention is observed.

  Usually, since EVOH has an affinity for the lower alcohol, the lower alcohol interacts with EVOH, the mobility of the amorphous portion of EVOH is increased, and the mobility of the amorphous portion is increased, thereby increasing the fuel barrier. Sex is reduced.

  In the fuel container of the present invention, by mixing the inorganic layered compound and EVOH, the inorganic layered compound and EVOH interact with each other, weakening the interaction between EVOH and the lower alcohol and improving the mobility of the amorphous portion. It is estimated that it can be suppressed. Thus, in the fuel container of the present invention, it is presumed that the fuel barrier property in the fuel having a high content of lower alcohol can be obtained particularly remarkably.

  As long as the above fuel is used, the fuel container of the present invention includes fuel tanks for automobiles such as gasoline for automobiles, motorcycles, ships, aircraft, generators, fuel containers mounted on industrial and agricultural equipment, and these fuels. It is useful as a portable container for replenishment of fuel, and various containers such as bottles, tanks and drums for transporting, storing and storing these fuels.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the examples, “part” refers to a mass standard unless otherwise specified.

[Preparation of multilayer film 1]
EVOH resin (ethylene content 25 mol%, saponification degree 99.7 mol%, MFR 4.0 g / 10 min) 100 parts was added to a twin screw extruder (L / L) equipped with a dispersion press-fitting part, side feeder and vacuum vent. D = 56, screw inner diameter = 32 mm) was charged from the raw material supply unit, and the EVOH resin was melted at a temperature of 230 ° C., and then kaolinite (manufactured by Imerys, (Al ₂ O ₃ .SiO ₂ .2H ₂ O 16 parts of an aqueous dispersion (solid content concentration: 73% by mass)} having an average particle diameter of 6.0 μm was continuously pressed from the dispersion press-fitting part and kneaded.

  The average particle size of the kaolinite is such that a water dispersion having a concentration of 0.1% by weight of kaolinite is prepared using distilled water, and this dispersion is subjected to a laser scattering particle size distribution analyzer (LA-950 manufactured by HORIBA). It is the value obtained by analyzing using.

The EVOH resin composition after kneading was extruded into a water tank in a strand shape and cut with a pelletizer to produce EVOH resin composition pellets.
A side feeder with L / D = 8.3 and screw inner diameter = 28 mm was used at 25 ° C. in an open air state. The rotation speed of the side feeder screw was 100 rpm.

  The obtained EVOH resin composition pellets are introduced into a three-kind five-layer cast film forming machine (extruder: L / D = 28, screw inner diameter = 40 mm, full flight type screw, extrusion temperature: 220 ° C.), and high density A multilayer film 1 of polyethylene / polyolefin adhesive resin / EVOH resin composition / polyolefin adhesive resin / high density polyethylene (80/10/20/10/80 μm) was produced.

As high-density polyethylene, “NOVATEC HD HB431” manufactured by Nippon Polyethylene Co., Ltd. was used. In addition, “MODIC-AP H511V” manufactured by Mitsubishi Chemical Corporation was used as the polyolefin-based adhesive resin.
The take-up speed was 2.5 m / min.

[Preparation of multilayer film 2]
A multilayer film 2 was produced in the same manner as the multilayer film 1 except that kaolinite was not used when the multilayer film 1 was produced.

[Example 1]
The obtained multilayer films 1 and 2 were each cut into two pieces of 11 cm × 11 cm to obtain two pouches containing 15 cc of 100% ethanol fuel. The pouch was heat-sealed 5 mm from the end to make a 10 cm square. The pouch was allowed to stand for 20 days at 40 ° C. and 0% Rh.

When the multilayer films 1 and 2 were used, the fuel permeability (g · 20 μm / m ² · day) of 100% ethanol fuel was measured. The results are shown in Table 1.

  The fuel permeability is calculated by calculating from the 21st day to the 63rd day after the pouch is allowed to stand for 20 days, and the fuel permeation from the 21st day to the 63rd day. The average value was obtained by dividing the fuel permeation amount per day by the unit area.

  Also, the mass reduction improvement rate of 100% ethanol fuel by using the multilayer film 1 having kaolinite in the fuel barrier layer (1-fuel permeability of multilayer film 1 / fuel permeability of multilayer film 2 × 100) is calculated. did. The results are shown in Table 1.

[Comparative Examples 1 and 2]
In Comparative Example 1, Fuel C (toluene / isooctane = 50/50 volume ratio) was sealed in the pouch, and in Comparative Example 2, E10 (Fluel C / ethanol = 90/10 volume ratio) was sealed in the pouch. Evaluation was performed in the same manner. The results are shown in Table 1.

  From the above results, when the multilayer film 1 using the fuel barrier layer in which EVOH is mixed with kaolinite is used compared to the conventional pouch using the multilayer film 2 using EVOH as the fuel barrier layer, the ethanol 100% fuel In Example 1 which used No., the mass reduction improvement rate was 58%.

  On the other hand, when Fluor C and E10 were used as fuels (Comparative Examples 1 and 2), the mass reduction improvement rate remained at 33% and 43%, and no significant difference was observed in the value of fuel permeability.

From this result, a fuel container is formed of a multilayer structure in which a fuel barrier layer is disposed between thermoplastic resin layers, and the fuel barrier layer is made of a resin composition containing EVOH and an inorganic layered compound. It can be seen that the fuel barrier property with respect to the fuel rich in lower alcohol is remarkably excellent.
Therefore, the fuel container of the present invention is particularly useful as a fuel container having abundant lower alcohols.

Claims (2)

A fuel container for containing a fuel having a lower alcohol content of 20% by mass or more,
Formed from a multilayer structure in which a fuel barrier layer is disposed between thermoplastic resin layers,
The fuel barrier layer is made of a resin composition containing a saponified ethylene-vinyl ester copolymer and an inorganic layered compound.   The fuel container according to claim 1, wherein the inorganic layered compound has an average particle size of 1 to 30 μm.