JPH05293916A - Multilayer fuel tube for automobile - Google Patents

Abstract

PURPOSE:To prevent fuel from being permeated through a wall surface and also to enhance impact properties at low temperature by providing a layer having composition consisting of both the specified polyamide resin and phyllosilicate wherein a plane having specified length and thickness forms a layer and the layer-to-layer distance is regulated to the specified value and forming the title tube. CONSTITUTION:In a fuel tube made of resin through which fuel for an automobile especially mixed fuel of alcohol/gasoline is passed, an internal layer 1 is formed by providing the layer having composition containing (A) 100 pts.wt. polyamide 11 resin and/or polyamide 12 resin and (B) 1.5-10 pts.wt. phyllosilicate described below in a range within 20-80% wall thickness of the tube. In the phyllosilicate, a plane having 0.002-1mum length of one side and 6-12 angstrom thickness is formed and the layer-to-layer distance thereof is >=20 angstrom on the average. The layer (an intermediate layer 2 and an external layer 3) excepting the layer of the above composition are formed of resin obtained by blending a plasticizer with fluororesin, high density polyethylene resin, polyamide 11 resin or polyamide 12 resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer fuel tube for an automobile, which has a small amount of permeation of alcohol / gasoline mixed fuel on a wall surface and is excellent in characteristics such as low temperature impact resistance.

[0002]

2. Description of the Related Art Conventionally, as fuel tubes for automobiles, those made of metal or resin have been known, but recently, there have been problems of rusting due to antifreezing agents on roads and vehicle weights aimed at improving fuel efficiency. In order to reduce the demand, metal tubes are being replaced by resin tubes.

However, the resin tube has a larger amount of fuel permeation through the wall surface than the metal tube, and the conventionally used polyamide 11 resin or polyamide 12 is used.
The resin tube has a drawback that the amount of alcohol permeation is particularly large. Therefore, in order to make the tube usable also for the alcohol / gasoline mixed fuel which has recently been used, it is necessary to increase the wall thickness, so that there is a drawback that the tube becomes inflexible or heavy. However, there is a problem that the cost becomes high in terms of materials and productivity. In addition, although various materials having fuel barrier properties have been proposed, as fuel tubes for automobiles, which have insufficient fuel barrier properties and are used under severe conditions, the tube performance such as low temperature impact resistance and bending stiffness is unsatisfactory. Was enough.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel tube for an automobile, which can significantly prevent fuel from penetrating the wall surface and is excellent in tube performance such as low temperature impact resistance and bending stiffness. Especially.

[0005]

The multilayer fuel tube for automobiles of the present invention is a tube having a composition layer containing the following (A) and (B), and the thickness of the composition layer is the tube wall thickness. Of 20 to 80%.

(A) Polyamide 11 resin and / or polyamide 12 resin 100 parts by weight (B) One side length 0.002-1 μm, thickness 6-20 Å
Slabs form a layer and the interlayer distance between them is 20 Å or more on average 1.5 to 10 parts by weight

The present invention will be described in detail below. The component (A) polyamide 11 resin used in the present invention has the following formula having an acid amide bond (-CONH-): (-CO-
A polyamide represented by (CH ₂ ) ₁₀ —NH—) _n is a typical one, and can be obtained by polymerizing 11-aminoundecanoic acid or undecane lactam.

The polyamide 12 resin as the component (A) has the following formula having an acid amide bond (-CONH-): (-
CO- (CH _{2) 11} -NH-) polyamide represented by _n is one typical, 12-aminododecanoic acid or can be obtained by polymerizing dodecane lactam.

The polyamide 11 resin and the polyamide 12 resin may be a copolymer containing the above-mentioned monomer as a main component (50% or more).

Other monomers used in the case of copolymers include ε-caprolactam, 6-aminocaproic acid, ε
-Enanthlactam, 7-aminoheptanoic acid, α-pyrrolidone, α-piperidone, diamines such as hexamethylenediamine, nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine, and terephthalic acid, isophthalic acid, adipic acid, sebacic acid, etc. And the like. Polyamide 1
It may be a copolymer of monomers of 1 resin and polyamide 12 resin.

The component (A) used in the present invention may be a mixture with another polyamide resin containing polyamide 11 resin or polyamide 12 resin as a main component or other polymer. The content of the polyamide 11 resin and / or the polyamide 12 resin in the mixture is preferably 40% by weight or more.

Examples of other polyamide resins to be mixed include polyamide 6, polyamide 66, polyamide 6/10, polyamide 6/12, polyamide 12/12, polyamide 6/66 copolymer, polyamide 6/12 copolymer and the like. .. Examples of other polymers include polypropylene, ABS resin, polyphenylene oxide, polycarbonate, polyethylene terephthalate, and polybutylene terephthalate.

Examples of the layered silicate of the component (B) used in the present invention include a layered phyllosilicate composed of a layer of magnesium silicate or aluminum silicate, and one side length is 0. 0.002 to 1 μm and a thickness of 6 to
A 20Å flat plate is a layer. The layered silicate as the component (B) is polyamide 11 resin or polyamide 1
2 Gives excellent fuel barrier properties to resin.

Specific examples of the layered phyllosilicate include montmorillonite, saponite, beidellite,
Examples thereof include smectite-based clay minerals such as nontronite, hectorite, and stevensite, vermiculite, and halosite. These may be natural products or synthetic products.

When the layered silicate is dispersed in the composition, the layered silicate maintains an average interlayer distance of 20 Å or more and is uniformly dispersed. Here, the interlayer distance means a distance between the centers of gravity of the flat silicate slabs, and the term “uniformly distributed” means that the flat silicate slabs have an average of 5 layers or less, and the multi-layered products are parallel to each other, or It means a state in which 50% by weight or more, preferably 70% by weight or more is dispersed without forming local lumps in a random state or in a state where parallel and random are mixed.

The blending amounts of the components (A) and (B) are
The amount of the component (B) is 1.5 per 100 parts by weight of the component (A).
10 to 10 parts by weight. When the amount of the component (B) is less than 1.5 parts by weight, the effect of suppressing fuel permeation is not sufficient, and when it exceeds 10 parts by weight, even if the composition layer of the tube is thinned,
It is not preferable because it is difficult to mold the tube, and the impact strength and the elongation rate decrease, and the tube standard for automobiles is not met.

The composition layer used in the present invention has the above-mentioned (A).
In addition to the components and the component (B), those containing a plasticizer are preferable. Examples of the plasticizer include benzenesulfonic acid butylamide, p-hydroxybenzoic acid, and 6 to 2 carbon atoms.
An ester with one straight or branched chain alcohol (eg,
2-ethylhexyl p-hydroxybenzoate) and the like.

The blending amount of the plasticizer is preferably 0 to 30 parts by weight with respect to 100 parts by weight of the component (A). When the compounding amount of the plasticizer exceeds 30 parts by weight, the breaking pressure of the tube is lowered and the problem of bleeding out occurs, which is not preferable.

The composition layer used in the present invention has a thickness of 20 to 80%, preferably 30 to 70% of the wall thickness of the tube. When the thickness of the composition layer exceeds 80%, the flexibility and low temperature impact resistance of the tube are impaired, and when it is less than 20%, the effective fuel permeation preventive property is impaired, which is not preferable.

The outer diameter of the multi-layer fuel tube for automobiles can be designed in consideration of the flow rate of fuel gasoline, and the wall thickness is
Gasoline permeability does not increase, and the thickness is such that the normal tube breaking pressure can be maintained, and it is possible to maintain flexibility with a good degree of ease of tube assembly work and vibration resistance during use. It can be designed to be thin, but the outer diameter is preferably 4 mm to 15 mm, and the wall thickness is 0.5
mm to 2 mm is preferable.

Layers other than the above composition layers (hereinafter referred to as other resin layers) used in the multilayer fuel tube for automobiles of the present invention include fluororesins, high-density polyethylene resins,
A layer made of a resin obtained by mixing the polyamide 11 resin or the polyamide 12 resin with the plasticizer is preferable. As the outermost layer or a layer which is a main skeleton of the other layers, it is preferable to use polyamide 11 resin, polyamide 12 resin, or a material obtained by adding a plasticizer thereto.

As the fluororesin, polytetrafluoroethylene (PTEF), polyvinylidene fluoride (PVD)
F), polyvinyl fluoride (PVF), etc. can be mentioned. In addition, polychlorofluoroethylene (PCTF
It may be a resin partially containing chlorine as in E) or a copolymer with ethylene or the like.

As the high-density polyethylene resin, one having an average molecular weight of about 200,000 to 300,000 is preferable in consideration of gasoline resistance. The high-density polyethylene resin has a low-temperature embrittlement temperature of −80 ° C. or lower and is excellent in low-temperature impact resistance.

If the resin layer has poor adhesion to the composition layer, another resin layer may be provided via the adhesive layer. The other resin layer does not have to be a single layer and may be a stack of several layers.

The multilayer fuel tube for automobiles of the present invention preferably contains conductive carbon black in at least one of the constituent layers thereof in an amount of 3 to 30% by weight based on the composition of the layer.

Examples of the conductive carbon black include acetylene black and Ketjen black. Among them, those having a good chain structure and a large aggregation density are preferable.

As the method for producing the multi-layer fuel tube for automobiles of the present invention, for example, a molten resin extruded from the extruder in the number corresponding to the number of layers or the number of materials constituting the molten resin is used to form one multi-layer tube die. Introduced into the die, each layer is bonded in or immediately after leaving the die, and then manufactured in the same manner as normal tube molding, or after molding a single-layer tube once, outside or inside the tube. And the like.

[0028]

EXAMPLES The present invention will be described in more detail below by showing Examples and Comparative Examples. Example 1 100 g of montmorillonite having an average unit thickness of 9.5 Å and a side length of about 0.1 μm was dispersed in 10 liters of water, and 51.2 g of 12
-Aminododecanoic acid and 24 ml of concentrated hydrochloric acid were added, and the mixture was stirred for 5 minutes and then dried in vacuum to prepare a complex of ammonium 12-aminododecanoate ion and montmorillonite.

The layered silicate content in the obtained composite was 8
0% by weight, and the silicate interlayer distance of this composite is X
When measured by line diffraction, it was 18Å. next,
12-aminododecanoic acid (10 kg), water (1 liter) and the complex (526 g) were placed in a reaction vessel equipped with a stirring blade and heated to 100 ° C.
The mixture was stirred until the inside of the reaction system became uniform.

Further, the temperature was raised to 290 ° C. and 43 kg
The mixture was stirred for 1 hour or more under a pressure of / cm ² . Then release the pressure,
The reaction was carried out at 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 then cut to obtain a pellet made of polyamide 12 resin (average molecular weight 35,000) and montmorillonite, which was vacuum dried, A composition used as a material for the inner layer of the multilayer tube was obtained (layered silicate content: 4% by weight; hereinafter, this composition is referred to as resin 1). When the interlayer distance of the silicate of this composition was measured by X-ray diffraction, it was 100Å or more.

Further, as a material for the intermediate layer and the outer layer, a polyamide 12 resin (manufactured by Ube Industries, UBE) containing 13% by weight of a plasticizer (benzenesulfonic acid butylamide).
Nylon 3035 JU) was prepared.

As an apparatus for forming a multi-layer tube, an extruder for the inner layer, an extruder for the intermediate layer and an extruder for the outer layer are provided.
Using a device comprising a die for collecting resin discharged from an extruder of a stand by an adapter and forming it into a tube, a sizing die for cooling the tube and controlling the dimensions, and a take-up machine, and the above inner layer in the hopper of the inner layer extruder. Materials for
The material for the outer layer is charged into the hoppers of the extruder for the intermediate layer and the extruder for the outer layer, and the inner diameter of the cross section shown in FIG. 1 is 6 mm and the outer diameter is 8 mm.
A multi-layered tube was prepared. The inner layer of the tube had a thickness of 0.3 mm, and the intermediate layer and the outer layer had a total thickness of 0.7 mm.

Regarding the obtained multilayer tube, the following
Was evaluated. Tube tensile elongation at break (according to SAE J844). Tube low temperature impact resistance (SAE J844 compliant). Fuel permeability

A tube cut into 30 cm was sealed at one end, alcohol gasoline containing a mixture of commercial gasoline and methyl alcohol in a ratio of 1: 1 was placed inside, and the remaining one end was also sealed, and then the weight of the whole was measured, and then tested. Tube 6
It was placed in an oven at 0 ° C., and the weight change (g / 24 hours) was measured to evaluate the fuel permeability. The results are shown in Table 1.

Example 2 A composition used as the material for the inner layer in the same manner as in Example 1 except that the compounding amount of the composite was changed to 204 g (layered silicate content: 1.6% by weight; hereinafter, this composition Example 2 was prepared in the same manner as in Example 1 except that the thickness of the inner layer of the multilayer tube was 0.5 mm and the total thickness of the intermediate layer and the outer layer was 0.5 mm. The tube elongation at break, tube low temperature impact resistance and fuel permeability were evaluated in the same manner as in. The results are shown in Table 1.

Example 3 A composition obtained by further adding 13% by weight of a plasticizer (benzenesulfonic acid butylamide) to the composition used as the material for the inner layer of Example 1 (layered silicate content: 3.5% by weight, ,
A tube was prepared in the same manner as in Example 1 except that this composition was referred to as Resin 3) was used as the material for the inner layer.
The tube elongation at break, tube low temperature impact resistance and fuel permeability were evaluated in the same manner as in. The results are shown in Table 1.

Comparative Example 1 A tube was prepared in the same manner as in Example 1 except that the thickness of the inner layer of the multilayer tube was 0.05 mm and the total thickness of the intermediate layer and the outer layer was 0.95 mm. The tube tensile elongation at break, tube low temperature impact resistance and fuel permeability were evaluated. The results are shown in Table 1.

Comparative Example 2 A tube was prepared in the same manner as in Example 1 except that the thickness of the inner layer of the multilayer tube was 0.85 mm and the total thickness of the intermediate layer and the outer layer was 0.15 mm. The tube tensile elongation at break, tube low temperature impact resistance and fuel permeability were evaluated. The results are shown in Table 1.

Comparative Example 3 A composition used as a material for the inner layer in the same manner as in Example 1 except that the compounding amount of the composite was changed to 102 g (layered silicate content: 0.8% by weight; hereinafter, this composition). Was prepared in the same manner as in Example 1, and the tube tensile elongation at break, tube low temperature impact resistance and fuel permeability were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 4 A single-layer tube having the same shape as that of Example 1 was produced using only the material used for the inner layer of Example 1, and the same evaluation as in Example 1 was performed. The results are shown in Table 1.

Comparative Example 5 A single-layer tube having the same shape as that of Example 1 was produced using only the material used for the outer layer of Example 1, and the same evaluation as in Example 1 was performed. The results are shown in Table 1.

Example 4 As the inner layer, a resin (Cefural Soft G180 manufactured by Central Glass Co., Ltd.) in which vinylidene fluoride resin and fluororubber main chain were grafted with vinylidene fluoride resin was used as 20 /
Polyamide containing a resin blended at a ratio of 100 and a resin (Cefural Soft G180 manufactured by Central Glass Co., Ltd.) in which vinylidene fluoride resin is grafted to the main chain of fluororubber and 13% by weight of a plasticizer as an intermediate layer. 12 resin (made by Ube Industries, UBE nylon 3035)
JU) was blended at a ratio of 1: 1 and the resin 1 of Example 1 was used as the outer layer, and the inner layer had a thickness of 0.2 m.
A multilayer tube having m, an intermediate layer having a thickness of 0.2 mm, and an outer layer having a thickness of 0.6 mm was prepared, and the tube tensile elongation at break, tube low temperature impact resistance and fuel permeability were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 5 As an inner layer, melt flow rate (JIS K676)
0) is 0.03 mg / 10 min high-density polyethylene (manufactured by Toyo Soda Kogyo Co., Ltd., polyolefin resin 8600A), and maleic acid-modified polyethylene (Ube Kosan Co., Ltd.) that has adhesiveness to the high-density polyethylene and polyamide resin as an intermediate layer. U-bond F1100 manufactured by Co., Ltd. is used, the resin 1 of Example 1 is used as the outer layer, and the thickness of the inner layer is 0.2 m.
A multilayer tube having m, an intermediate layer having a thickness of 0.2 mm, and an outer layer having a thickness of 0.6 mm was prepared, and the tube tensile elongation at break, tube low temperature impact resistance and fuel permeability were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Example 6 Polyamide 12 resin containing 8% by weight of conductive carbon black (Ketjenblack EC600DJ, manufactured by Lion Oil & Fats Co., Ltd.) was used as the inner layer, and Resin 1 of Example 1 was used as the intermediate layer. , Plasticizer 13 as outer layer
Polyamide 12 resin containing wt% (Ube Industries, Ltd.)
Manufactured by UBE Nylon 3035JU) to prepare a multi-layer tube having an inner layer thickness of 0.2 mm, an intermediate layer thickness of 0.4 mm and an outer layer thickness of 0.4 mm, and performing tube tension in the same manner as in Example 1. Elongation at break, low temperature tube impact and fuel permeability were evaluated. The results are shown in Table 1.

[0045]

[Table 1]

[0046]

INDUSTRIAL APPLICABILITY The multi-layer fuel tube for automobiles of the present invention can significantly prevent the fuel from penetrating the wall surface and is excellent in tube performance such as low temperature impact resistance and bending stiffness.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a multi-layer fuel tube manufactured in an example.

[Explanation of symbols]

 1 ... inner layer 2 ... intermediate layer 3 ... outer layer

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Ryuichi Deguchi, Ube City, Yamaguchi Prefecture Kogushi 1978-10 Ube Chemical Co., Ltd., Ube Chemical Factory (72) Inventor Takesumi Nishio 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Automobile Co., Ltd. (72) Akane Okada Akane, Aichi Prefecture, Nagakute Town, Aichi Prefecture 1-41, Yokomichi, Nagatoyo Toyota Central Research Institute Co., Ltd.

Claims (1)

[Claims] 1. A multilayer fuel tube for an automobile, which is a tube having a composition layer containing the following (A) and (B), wherein the composition layer has a thickness of 20 to 80% of the tube wall thickness. (A) Polyamide 11 resin and / or polyamide 12 resin 100 parts by weight (B) One side length 0.002-1 μm, thickness 6-20 Å
Slabs form a layer and the interlayer distance between them is 20 Å or more on average 1.5 to 10 parts by weight