JPH08127089A - Multi-layer plastic fuel tank - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a fuel tank made of a multi-layered plastic, which has excellent fuel impermeability and impact resistance and can be suitably recycled. [Structure] A fuel tank in which a high-density polyethylene and a polyamide layer are laminated via a high-density polyethylene layer modified with an unsaturated carboxylic acid or a derivative thereof.
The polyamide layer contains 100 parts by weight of a polyamide resin and 0.2 to 5 parts by weight of a layered silicate having a side length of 0.002 to 1 μm and a thickness of 6 to 20 Å. The layered silicate is uniformly dispersed in the polyamide resin and dispersed at intervals of 20 Å or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel tank made of a multi-layered plastic, and more particularly, it has excellent hollow molding characteristics and a small fuel permeation amount, and has excellent performance as a multi-layered plastic fuel tank. Further, the present invention relates to a fuel tank made of a multi-layer plastic, which is easy to recycle burrs generated during hollow molding.

[0002]

2. Description of the Related Art Conventionally, metal fuel tanks and resin fuel tanks have been known. However, metal fuel tanks have come to be used as road antifreezing agents and particularly in recent years. Due to the problem of rust caused by alcohol / gasoline mixed fuels, plastic fuel tanks have recently been attracting attention because they have the advantages of weight saving, fuel cost improvement, freedom of shape, and reduction of the number of manufacturing processes. Metal fuel tanks are being replaced by this. Known plastic fuel tanks include a single layer of high-density polyethylene and a multi-layer hollow molded article having a polyamide resin as a barrier layer.

[0003]

However, in such a conventional plastic fuel tank, the fuel permeation is required for clearing the exhaust gas regulations of each country not only in the case of a single layer but also in the case of a multilayer. It is necessary to reduce the amount, and in the case of a single layer, the high density polyethylene and in the case of a multilayer, the polyamide resin layer must have a considerable thickness. Therefore, not only the material cost and productivity become high, but also not only the weight becomes heavy, but also the tank becomes hard, and the shock absorption at the time of collision is bad, and it may be damaged and cause a serious accident. There was a problem.

In the case of a multi-layer, if the wall thickness of the polyamide resin is increased in order to improve the barrier property, the burr generated at the time of molding is mixed into the high-density polyethylene for recycling, and when the polyamide resin in the high-density polyethylene is recycled. Dispersibility deteriorates and impact resistance of the multilayer plastic fuel tank deteriorates. On the other hand, if kneading is performed with a strong shearing force in order to improve the dispersibility, the temperature of the resin rises too much due to the shear heat insulation generated at this time and the high-density polyethylene deteriorates or crosslinks. Therefore, there is a problem that the impact resistance of the multi-layered plastic fuel tank is deteriorated. The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a multi-layer plastic fuel tank which is excellent in fuel impermeability and impact resistance and can be suitably recycled. To provide.

[0005]

DISCLOSURE OF THE INVENTION As a result of intensive studies aimed at achieving the above object, the present inventors have found that the above object can be achieved by mixing a specific layered silicate into a polyamide layer as a barrier layer. Heading out, the present invention has been completed. Therefore, the multi-layered plastic fuel tank of the present invention is a fuel tank made of multi-layered plastic in which a high-density polyethylene layer and a polyamide layer are laminated via a high-density polyethylene layer modified with an unsaturated carboxylic acid or a derivative thereof. , The polyamide layer,
Polyamide resin or resin mixture containing polyamide resin 1
00 parts by weight, uniformly dispersed in the polyamide resin or resin mixture, and having a side length of 0.002 to 1 μm and a thickness of 6 to
A layered silicate having a flat plate shape of 20 angstroms, in which each silicate is dispersed at intervals of 20 angstroms or more.
And 5 parts by weight.

The multi-layer plastic fuel tank of the present invention will be described in detail below. First, as the high-density polyethylene that constitutes the high-density polyethylene layer in the fuel tank of the present invention, one having a density of 0.935 g / cm ² or more is preferable, and its melt index (MI
190 ℃, 2.16kg load), drawdown resistance,
Considering the moldability, impact resistance and dispersibility of the polyamide resin at the time of recycling burrs, the lower limit is HLMI (190
℃, 21.6kg load) 1g / 10 minutes, the upper limit is MI
It is preferably 2 g / 10 minutes at (190 ° C., 2.16 load). Further, in the present invention, as the high-density polyethylene constituting the high-density polyethylene layer, all unnecessary portions (so-called “burrs”) generated during molding of the fuel tank of the present invention, particularly blow molding, or the above-mentioned high-density polyethylene is used. It can be used by being mixed with polyethylene.

In the fuel tank of the present invention, the innermost layer on the fuel side or the outermost layer on the outside air side is composed of the high density polyethylene layer. Also, the high-density polyethylene layer is
Not only the innermost layer or the outermost layer but also the other intermediate layer may be arranged.

Next, the polyamide layer functions as a barrier layer of the fuel tank, and preferably has an average thickness of 10 to 500 μm, more preferably 30 to 200 μm. When the average thickness of the polyamide layer is less than 10 μm, the fuel permeability is not sufficient, and the polyamide layer in the portion that is thinly stretched by blow molding or the like is likely to be cut, which is not preferable. Further, when the average thickness of the polyamide layer exceeds 500 μm, the characteristics required for the fuel tank, particularly stability against impact, are deteriorated due to the influence of the polyamide resin, which is more rigid than high-density polyethylene, and the burr is recycled. Since a strong shearing force is required to disperse the thick polyamide layer even when hitting the
Recycling temperature rises due to heat generated by shearing, which causes deterioration and crosslinking of high-density polyethylene, reduces impact of the fuel tank, and changes the melt viscosity of the high-density polyethylene of the main layer during blow molding, which is a stable product. Is difficult to obtain, which is not preferable.

Further, the above-mentioned polyamide layer is composed of (A) a polyamide resin or a resin mixture 100 containing a polyamide resin.
Parts by weight, and (B) 0.2 to 5 parts by weight of the layered silicate uniformly dispersed in the resin or resin mixture.
When the layered silicate of the component (B) is less than 0.2 parts by weight,
The effect of suppressing fuel permeation is not sufficient, and if it exceeds 5 parts by weight, the polyamide layer becomes rigid and the impact resistance of the multilayer plastic fuel tank decreases, which is not preferable because it does not satisfy the specifications for automobiles.

The above polyamide resin means, as monomers, ε-caprolactam, 6-aminocaproic acid, ω-
Enanthlactam, 7-aminoheptanoic acid, α-pyrrolidone, α-piperidone, 11-aminoundecanoic acid, undecanelactam, 12-aminododecanoic acid, dodecalactam, etc., and also hexamethylenediamine, nonamethylenediamine, undecamethylenediamine. , A polymer having an acid amide bond (—CONH—) polymerized from a diamine such as dodecamethylenediamine and a dicarboxylic acid such as terephthalic acid, isophthalic acid, adipic acid, and sebacic acid.

As described above, the polyamide resin may be used alone, or may be used in the form of a mixture with the polyamide resin polymerized from different monomers. It is also possible to use a mixture with a polymer other than the polyamide resin, and as the other polymer in this case, polyethylene, polypropylene, ABS resin, polyphenylene oxide, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, EPR, EPDM,
Examples thereof include ionomer resins, SEP resins, SEPS resins and the like. Thus, when the component (A) is used in the form of a mixture, the content of the polyamide resin is 6
It is preferably 0% by weight or more.

If necessary, the polyamide resin or resin mixture as the component (A) may contain dyes, pigments, plasticizers, antioxidants, heat stabilizers, heat-resistant materials and the like in appropriate amounts. be able to. In particular, as described above, in the case of recycling burrs generated during blow molding, burrs are kneaded by a kneader in the same manner as a polymer alloy. At that time, high-density polyethylene has a very high melt viscosity. Shear heat may be generated and the resin temperature may rise. In that case, a processing stabilizer is added according to the situation, but as the processing stabilizer, 2 parts by weight or less of a hindered phenolic antioxidant and / or a phosphorus processing stabilizer and / or
Alternatively, it is preferable to add a copper-based processing stabilizer. If the processing stabilizer is added in an amount of more than 2 parts by weight, not only a further effect cannot be expected but also the toughness of the resin is lowered, which is not preferable.

Next, the component (B), which is another component constituting the polyamide layer, will be described. The component (B) is the layered silicate as described above, and is a fuel excellent for the polyamide layer and eventually for the fuel tank. It is a component that imparts barrier properties. This layered silicate has a thickness of 0.002 to 1 μm (side length).
It is preferable to form a flat plate having a size of 6 to 20 angstroms (thickness). Further, the layered silicate is preferably one in which, when dispersed in the component (A), each tabular grain maintains an average interparticle distance of 20 Å or more and is uniformly dispersed. Here, the "distance between particles" means the distance between the centers of gravity of the layered silicate particles forming a flat plate, and "is uniformly dispersed".
Means that each tabular grain or a multi-layered article having an average number of layers of 5 or less exists in a parallel and / or random state,
It is assumed that 50% by weight or more, preferably 70% by weight or more of the layered silicate particles are dispersed without forming local lumps.

Examples of such a raw material for the layered silicate include a layered phyllosilicate mineral composed of a layer of magnesium silicate or aluminum silicate. Specifically, montmorillonite, saponite, beidellite,
Examples thereof include smectite-based clay minerals such as nontronite, hectorite, and stevensite, vermiculite, halosite, and the like. These may be natural or synthetic.

Next, the modified high-density polyethylene layer interposed between the high-density polyethylene layer and the polyamide layer will be described. The modified polyethylene layer is composed of high density polyethylene modified with unsaturated carboxylic acid or its derivative. This modification is performed in order to impart adhesiveness (reactivity) to the high-density polyethylene and the polyamide, and the modified polyethylene obtained by this modification has adhesiveness to both the high-density polyethylene and the polyamide.

Due to the above properties, the modified polyethylene layer is disposed between the high-density polyethylene layer and the polyamide layer, and is present on both surfaces of the polyamide layer with a thickness of 0.1 times or more that of the polyamide layer. Is preferred. Also,
This thickness is a necessary thickness at the portion in contact with the polyamide layer even when the thickness becomes non-uniform due to the difference in stretch ratio during blow molding.

Here, the reason why it is preferable to have the above-mentioned thickness is as follows. That is, the modified polyethylene layer has a function of adhering the high-density polyethylene layer and the polyamide layer, but in addition to this,
When the polyamide is dispersed in the high-density polyethylene in the above-described recycling of burrs, it functions as a compatibilizing agent in the polymer alloy between the high-density polyethylene and the polyamide having no affinity. Therefore, if this modified polyethylene layer does not have a thickness of 0.1 times or more that of the polyamide layer, it cannot sufficiently function as a compatibilizing agent quantitatively in the recycling of burrs, and the polyamide is stably dispersed in high-density polyethylene. This is because, as a result of making it difficult, the characteristics of the multi-layer plastic fuel tank obtained by recycling burrs, particularly the physical properties against impact, deteriorate.

In the modified polyethylene constituting the modified polyethylene layer, the modification amount is modified in consideration of the above-mentioned adhesion (reactivity) by modification and the function as a compatibilizing agent of the resulting modified polyethylene. 0.1-5 wt% based on high density polyethylene before
It is preferred that If the amount of modification is less than 0.1% by weight, sufficient adhesion (reactivity) with the polyamide cannot be obtained, and as a result, the impact resistance of the fuel tank is particularly reduced. In addition, since the content of polyamide also increases in the recycling of burrs, it is difficult to disperse the polyamide in high-density polyethylene, which makes recycling difficult, and the impact resistance of the fuel tank obtained by recycling decreases, which is not preferable. On the other hand, even if the modification is performed in an amount of more than 5% by weight, no further effect can be expected, and the toughness of the modified high-density polyethylene is decreased, so that the impact resistance of the fuel tank is particularly decreased, which is not preferable. .

Examples of the unsaturated carboxylic acid or its derivative used for the above modification include monocarboxylic acids such as acrylic acid and methacrylic acid, dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid, maleic anhydride, itaconic anhydride and ene. Examples thereof include dicarboxylic acid anhydrides such as Dick acid anhydride (hymic acid anhydride), and dicarboxylic acid or its anhydride is particularly preferable.

Examples of the method for modifying the modified polyethylene include a melt kneading method and a solution method, and any method can be preferably used. In the case of the melt kneading method, high-density polyethylene, unsaturated carboxylic acid (or acid anhydride) used for modification, and a catalyst are put into an extruder, a twin-screw kneader, or the like and heated to a temperature of 150 to 250 ° C. And kneading while melting. On the other hand, in the case of the solution method, the above substance is dissolved in an organic solvent such as xylene to prepare a solution of 80 to 140
Denature with stirring at a temperature of ° C. In either case,
Usual catalysts for radical polymerization can be used as the catalyst, for example, benzoyl peroxide, lauroyl peroxide, di-tert-butyl peroxide, acetyl peroxide, tert-butyl peroxybenzoic acid, dicumyl peroxide, peroxybenzoic acid. Preferably, peroxides such as peroxyacetic acid, tert-butylperoxybivalate, 2,5-dimethyl-2,5-di-tert-butylperoxyhexyne, and diazo compounds such as azobisisobutylnitrile are used. You can The catalyst is preferably added in an amount of 1 to 100 parts by weight with respect to 100 parts by weight of the unsaturated carboxylic acid for modification or its anhydride.

Next, a multi-layer plastic obtained by laminating the high-density polyethylene, the polyamide layer and the modified polyethylene will be described. The total thickness of the multi-layer plastic is preferably 10 times or more the thickness of the polyamide layer. By making the ratio of the thickness of the high-density polyethylene layer and the thickness of the polyamide layer, which provides impact resistance to the fuel tank, about 10 times or more, it has sufficient impact resistance as a fuel tank and is suitable for recycling burr. Also facilitates dispersion of the polyamide, and can give practically sufficient characteristics to impact, especially in a fuel tank in which burrs are recycled. When the thickness is 10 times or less, the polyamide layer becomes too thick with respect to the total thickness of the multilayer plastic, and the impact resistance of the polyamide is stiffer than that of high-density polyethylene, so that the impact resistance of the fuel tank is particularly lowered. In addition, since the content of polyamide also increases in the recycling of burrs, the dispersibility of polyamide in high-density polyethylene decreases,
This is not preferable because the impact resistance of the fuel tank is reduced by recycling.

Next, the recycling of unnecessary portions such as burrs that occur when the fuel tank of the present invention is molded, particularly blow molded, will be described. As described above, the high-density polyethylene layer may contain such burr in an amount of 0 to 100% by weight based on the high-density polyethylene layer. That is, as the high-density polyethylene layer, of course, it does not include burrs, but burrs themselves (100% burrs) can be used as the raw material, and even in that case, the impact resistance required for the fuel tank is high. And characteristics such as fuel impermeability are satisfied,
Moreover, the characteristics of the plastic fuel tank, which are lightweight and have a high degree of freedom in shape, can be fully utilized. In addition,
The recycling material such as burrs is mixed into the high density polyethylene layer forming the innermost and outermost layers, but if the high density polyethylene layer is also present in other parts, it can be mixed in that part as well. .

When burr is contained in the high-density polyethylene layer, it is preferable to control the dispersed particle size of the above polyamide to 50 μm or less in the burr itself or in the layer composed of the burr and the high-density polyethylene. If the dispersed particle size of the polyamide exceeds 50 μm, the impact resistance of the fuel tank in which burrs are recycled is reduced, which is not preferable. The burr recycling method is not particularly limited and may be any method. Generally, crushed burr is made into a resin in which polyamide is dispersed using a kneader and then blended with virgin high-density polyethylene for blow molding, or a blow molding machine with a strong kneading screw is used. Examples thereof include a method in which a crushed product of burrs and a high-density polyethylene of virgin are directly filled and blended to be used for blow molding.

When the incompatible resin is kneaded as described above, the components that form the continuous layer (sea component) and the components that form the discontinuous layer (island component) are phase-separated. The dispersed particle size of the resin that becomes the island component (polyamide in the above) is
It is affected by various factors such as concentration ratio between components, viscosity ratio, interfacial tension, strength of mutual interaction, and mechanical external force. In the fuel tank of the present invention, the composition ratio of each layer laminated can be converted from the layer thickness ratio. Further, when a certain amount of mechanical external force (shearing force applied from a kneader or a screw at the time of blow molding) is applied at the time of recycling the burr, a state in which the polyamide having the above dispersed particle diameter is contained can be easily prepared.

The method for producing the resin composition for hollow molding of the multi-layer plastic for the fuel tank of the present invention is not particularly limited, and the following method can be applied, for example. When the raw material of the layered silicate as the component (B) is a multilayered clay mineral, the polyamide resin forming the polyamide layer as the barrier layer is contacted with a swelling agent to expand the layers in advance, and the monomer between the layers is used. Is incorporated, and then mixed with a polyamide monomer and polymerized (JP-A-62-
No. 74957). In addition, a polymer compound is used as a swelling agent, and 100
It is also possible to use a method in which it is spread over an angstrom or more, and this is melt-kneaded with a polyamide resin or a resin containing the same and uniformly dispersed.

Further, as the resin which can be used for other layers which can be added to the above-mentioned multi-layer plastic, the following resins can be mentioned. When these resins have no adhesiveness with the multilayer plastic, they may be used via an adhesive layer.
Note that the resin layer used as the other layer exemplified may not be a single layer, and some layers may be laminated. First, as a resin that can be used as the other layer, there is a fluororesin, and the fluororesin includes polytetrafluoroethylene (PTEF) and polyvinylidene fluoride (PVD).
F), polyvinyl fluoride (PVF), and the like, and also include a resin partially containing chlorine such as polychlorofluoroethylene (PCTFE) and a copolymer with ethylene.

Further, as a resin which can be used as another layer which does not form the innermost and outermost layer, a high density polyethylene resin can be mentioned. In this case, it is preferable to use a high-density polyethylene resin having an average molecular weight of about 200,000 to 300,000 in consideration of gasoline resistance. In particular, it does not have to be the same as the high-density polyethylene forming the innermost and outermost layers, and may be different. The reason for using the layer of high-density polyethylene resin is that the low-temperature embrittlement temperature is usually -80 ° C or lower and the low-temperature impact resistance is excellent. But,
Gasoline permeability is extremely poor.

The method for producing the multi-layered plastic fuel tank of the present invention is not particularly limited, but a molten resin extruded from an extruder corresponding to the number of layers or the number of materials is melted into one multi-layer hollow. Introduced in the forming die,
An example is a method of bonding in a die or immediately after leaving the die, and then producing by a method similar to ordinary blow molding.

Although the reason why the fuel tank of the present invention exhibits excellent barrier properties against fuel is not clear, the flow rate of fuel is improved because the layered silicate is uniformly and microscopically dispersed in the polyamide layer. It is thought that it acts to block the road.

[0030]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. (Example 1) First, a resin material used for a multi-layer structure of a multi-layer plastic fuel tank was prepared as follows. [Component (B) of Polyamide Resin] The average thickness of one unit of the layered silicate is 9.5 Å, and the side length is about 0.1 μm.
Of 100 g of montmorillonite was dispersed in 10 l of water, 51.2 g of 12-aminododecanoic acid and 24 ml of concentrated hydrochloric acid were added thereto, and the mixture was stirred for 5 minutes and then dried in vacuum. By this operation, a complex of ammonium 12-aminododecanoate ion and montmorillonite was prepared. The ratio of the layered silicate in the composite was 80% by weight. When this composite was analyzed by X-ray diffraction, the silicate interlayer distance was 18 Å.

[Polyamide Resin Mixture] 10 kg of ε-caprolactam, 1 kg of water and 200 g of the above complex were placed in a reaction vessel equipped with a stirring blade and stirred at 100 ° C. until the inside of the reaction system became uniform. . Then the temperature is raised to 26
The temperature was raised to 0 ° C., and the mixture was stirred under a pressure of 15 kg / cm ² for 1 hour or more. Then, the pressure was released, and the reaction was carried out under atmospheric pressure for 3 hours while vaporizing water. After completion of the reaction, the reaction product taken out in a strand form from the lower nozzle of the reaction vessel was water-cooled and cut to obtain pellets composed of polyamide 6 resin (average molecular weight 30,000) and montmorillonite. The pellets were immersed in hot water to extract and remove unreacted monomer (about 10%) and then dried in vacuum to obtain a polyamide resin mixture used in the adhesive layer of the present invention. When this mixture was analyzed by X-ray diffraction, the interparticle distance of the layered silicate was 100 angstroms or more.

[High Density Polyethylene (HDPE) and Modified High Density Polyethylene] As the high density polyethylene constituting the outer layer and the inner layer of the fuel tank, HDPE (HLM)
I; 4.0), a modified HDPE modified with 0.6 part by weight of maleic anhydride was prepared as an adhesive layer between the HDPE layer and the polyamide layer.

[Manufacture of Fuel Tank] Next, using the resin materials shown above, HDPE (outer layer) / modified HDPE (adhesive layer) / polyamide resin composition (barrier layer) / modified H
A fuel tank composed of a multilayer plastic having a structure of DPE (adhesive layer) / HDPE (inner layer) of three types and five layers was prepared by molding with a blow molding machine of three types and five layers. In this fuel tank, the average thickness of the barrier layer is 1
00μm, adhesive layer 0.5 times 50μm, HDPE
The average thickness of the entire multi-layer plastic including the layers is 5000 μm, which is 50 times the thickness of the barrier layer, and the dimensions are 690 mm × 350 mm × 190 mm and the volume is 4
It is 0l. The following performance evaluation was performed on the obtained multilayer plastic fuel tank.

Low temperature impact resistance (non-destructive height). 40 kg of ethylene glycol was injected into the obtained fuel tank, which was hermetically sealed and left in an atmosphere of −40 ° C. for 12 hours or more, and then taken out. The tank was evaluated by whether or not the tank was naturally dropped in the vertical direction from a height of 6 m to cause cracking or deformation. If there is no cracking or deformation, replace it with a new tank, raise the height by 0.5m, and perform the same evaluation.
m or more, ○, 8 m or more and less than 10 m, Δ, 8
Those less than m were marked with x. The results are shown in Table 1.

Gasoline permeability. Fill the fuel tank with 20 liters of gasoline and seal it to 40
After being left in a nitrogen atmosphere at ℃ for 60 days, the weight of the entire tank was measured as an initial value. Next, the weight of the whole tank after being left for 30 days in a nitrogen atmosphere at 40 ° C. is measured,
The weight reduction was derived from the difference from the initial value and divided by 30 days which is the measurement period to obtain an average gasoline permeation amount per day. If the gasoline permeation amount per day calculated in this way is less than 0.1 g / day, it is ◯, 0.1 g / d
Those with ay or higher were marked with x. The results are shown in Table 1.

Recyclability of Burrs Burrs generated during fuel tank molding were crushed and melt-kneaded in a biaxial kneader of the same direction, and the burrs were mixed at a ratio of 40% by weight to 60% by weight of HDPE. The obtained resin mixture was used in place of HDPE as a material for the innermost and outermost layers of a multilayer plastic fuel tank, and a multilayer plastic fuel tank was molded in the same manner as above. With respect to the obtained recycled fuel tank, the dispersion state of the above polyamide resin composition in HDPE and the low temperature impact resistance of the tank were evaluated.

(I) The dispersed state was such that the tank cross section was dyed with a polyamide dyeing solution, and the polyamide resin composition dyed in the inner and outer HDPE layers was observed with a magnifying glass. ． The case where 50 μm or more was observed was designated as x. The results are shown in Table 1. (Ii) Low temperature impact resistance was evaluated by the same method as above. The results are shown in Table 1. In the following examples and comparative examples, the low temperature impact during recycling was evaluated using the multilayer plastic fuel tank having the layer structure of the first example. This is to exclude the influence of the layer structure in the evaluation of recyclability.

Example 2 When preparing the polyamide resin mixture of Example 1, 10 kg of ε-caprolactam,
7. Instead of 1 kg of water and 200 g of the above complex.
The same operation as in Example 1 was carried out except that 2 kg of ε-caprolactam, 0.9 kg of hexamethylenediamine, 0.9 kg of adipic acid, 2 kg of water and 200 g of the above complex were used, and the results were obtained. Is shown in Table 1.

Example 3 The same operation as in Example 1 was carried out except that the amount of modification of the modified HDPE of the adhesive layer with maleic anhydride was changed to 0.1 part by weight. The results are shown in Table 1.

Example 4 The same operation as in Example 1 was carried out except that the total thickness of the multilayer plastic constituting the fuel tank was set to 1000 μm, which was 10 times the thickness of the barrier layer. The results are shown in Table 1.

Example 5 Example 1 was repeated except that the thickness of the adhesive layer was 10 μm, which was 0.1 times the thickness of the barrier layer.
The same operation was performed. The results are shown in Table 1.

Example 6 The thickness of the adhesive layer was set to 0.1 μm, which is 0.1 times the thickness of the barrier layer, and 10 μm, which was 10 times the thickness of the barrier layer.
The same operation as in Example 1 was performed except that the thickness was changed to μm. The results are shown in Table 1.

Example 7 The same operation as in Example 1 was carried out except that 27 g of the above composite was used in preparing the polyamide resin mixture. The results are shown in Table 1.

Example 8 In preparing a polyamide resin mixture, instead of 10 kg ε-caprolactam, 1 kg water and 200 g of the above complex, 8.2 kg ε was used.
-Caprolactam, 0.9 kg hexamethylenediamine, 0.9 kg adipic acid, 2 kg water and 400 g
The same operation as in Example 1 was carried out except that the above complex of was used. The results are shown in Table 1.

(Embodiment 9) In the recycling of burrs of Embodiment 1, after crushing the burrs produced at the time of molding the fuel tank, the burrs are melted and kneaded by a biaxial kneader in the same direction, and the whole amount is put inside and outside the fuel tank. The same operation as in Example 1 was performed, except that HDPE was used as the material for the layer. Table 2 shows the results.

(Embodiment 10) In the recycling of the burr of the embodiment 2, after burr generated at the time of molding the fuel tank is ground and melted and kneaded by a biaxial kneader in the same direction, the whole amount of the burr is removed from the fuel tank. The same operation as in Example 2 was performed, except that HDPE was used as the material for the inner and outer layers. Table 2 shows the results.

(Comparative Example 1) The barrier layer has a thickness of 5 μm.
The same operation as in Example 1 was performed, except that the thickness of the adhesive layer was 5 μm, which was one time the thickness of the barrier layer, and the total thickness of the multilayer plastic was 2500 μm, which was 500 times the thickness of the barrier layer. Table 2 shows the results.

(Comparative Example 2) The thickness of the barrier layer was 600 μm.
m, except that the thickness of the adhesive layer was 300 μm, which is 0.5 times the thickness of the barrier layer, and the total thickness of the multilayer plastic was 6000 μm, which was 10 times the thickness of the barrier layer.
The same operation as in Example 1 was performed. Table 2 shows the results.

Comparative Example 3 The barrier layer has a thickness of 600 μm.
m, the thickness of the adhesive layer was 300 μm, which is 0.5 times the thickness of the barrier layer, and the thickness of the entire multilayer plastic was 12000 μm, which is 20 times the thickness of the barrier layer. went. Table 2 shows the results.

(Comparative Example 4) The same operation as in Example 1 was carried out except that the thickness of the entire multilayer plastic was 500 μm, which was five times the thickness of the barrier layer. Table 2 shows the results.

Comparative Example 5 The same operation as in Example 1 was carried out except that the modified amount of the modified HDPE of the adhesive layer with maleic anhydride was changed to 0.02 part by weight. Table 2 shows the results.

(Comparative Example 6) HDPE without modifying the adhesive layer
The same operation as in Example 1 was performed except for the above. Table 2 shows the results.

Comparative Example 7 The same operation as in Example 1 was carried out except that the modified amount of the modified HDPE of the adhesive layer with maleic anhydride was changed to 6.0 parts by weight. The results are shown in Table 3.

Comparative Example 8 Example 1 was repeated except that the thickness of the adhesive layer was 5 μm, which was 0.05 times the thickness of the barrier layer.
The same operation was performed. The results are shown in Table 3.

(Comparative Example 9) The same operation as in Example 1 was carried out except that when the polyamide resin mixture was prepared, the polymerization was carried out without blending the above composite. The results are shown in Table 3.

(Comparative Example 10) The same operation as in Example 2 was carried out except that when the polyamide resin mixture was prepared, the polymerization was carried out without blending the above composite. The results are shown in Table 3.

(Reference Example) For reference, when molding the multi-layer gasoline tank of Example 1, a single-layer gasoline tank molded of HDPE single layer without any barrier layer and adhesive layer was evaluated. The results are shown in Table 3.

[0058]

[Table 1]

[0059]

[Table 2]

[0060]

[Table 3]

[0061]

[Table 4]

[0062]

As described above, according to the present invention,
Since a specific layered silicate is mixed in the polyamide layer as the barrier layer, it is possible to provide a multi-layer plastic fuel tank which has a small fuel permeability and a small wall thickness, is excellent in impact resistance, and can be suitably recycled. .

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location B32B 27/34 9349-4F B60K 15/03 B65D 90/02 L C08K 3/34 KKT 7/00 KLC C08L 77/00 (72) Inventor Katsuyuki Miura 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. (72) Inventor Kajiro Iriyama 1 Toyota-cho, Toyota-shi, Aichi (72) Invention Toshio Yokoi 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Ritsuya Matsumoto 3-1, Chidori, Kawasaki-ku, Kawasaki-shi, Kanagawa Tonen Kagaku Co., Ltd. Technical Development Center

Claims (3)

[Claims] 1. A fuel tank comprising a multi-layer plastic in which a high-density polyethylene layer and a polyamide layer are laminated via a high-density polyethylene layer modified with an unsaturated carboxylic acid or a derivative thereof, wherein the polyamide layer is a polyamide. 100 parts by weight of a resin mixture containing a resin or a polyamide resin, uniformly dispersed in the polyamide resin or the resin mixture, and having a side length of 0.00
2-1 μm × thickness 6-20 angstroms in the form of a flat plate,
A multi-layered plastic fuel tank, characterized in that each silicate contains 0.2 to 5 parts by weight of a layered silicate dispersed at intervals of 20 angstroms or more. 2. The modified high-density polyethylene layer comprises 0.1% of the polyamide layer on both sides of the polyamide layer.
The multi-layered plastic fuel tank according to claim 1, wherein the multi-layered plastic fuel tank is present with a thickness of at least twice, and the total thickness of the multi-layered plastic is 10 times or more the thickness of the polyamide layer. 3. The high-density polyethylene layer includes an unnecessary portion generated during molding of a multilayer fuel tank, or is formed only from the unnecessary portion.
The described multi-layer plastic fuel tank.