JPH04224385A - Tube for fuel piping - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD The present invention relates to a tube for fuel piping, for example, a tube suitable for the fuel piping itself or for connecting the same, and is particularly lightweight, rust-free, and suitable for ordinary gasoline fuel. Of course, the present invention relates to a fuel piping tube that exhibits excellent fuel barrier properties even for mixed fuel containing methanol.

0002

[Background Art] Various materials have been used for fuel piping tubes used as fuel piping itself or for connecting fuel piping in automobiles, etc., and mainly metal tubes and , polyamide resin tubes made of nylon 11, nylon 12, etc. are used.

However, although metal tubes provide excellent fuel barrier properties (fuel impermeability), they have the problem of rust and are extremely heavy, making it difficult to reduce the weight of vehicles. It cannot cope with the current situation.

On the other hand, polyamide tubes
It is lightweight, does not rust, and has good fuel barrier properties against ordinary gasoline, so it can be said that it has all the characteristics required of a fuel piping tube. However, such polyamide tubes have an extremely low barrier property against mixed gasoline containing methanol, and the amount of permeation of such mixed gasoline is 50 to 60 times that of normal gasoline. However, if future demand is considered, it may become difficult to use.

[0005] This is because in the future, in preparation for the depletion of gasoline resources, it is conceivable that a mixed fuel containing gasoline and methanol will be used. This is because it is increasingly required to exhibit effective barrier properties even for mixed fuels.

[0006]

[Problem to be solved] The present invention has been made against the background of the above-mentioned circumstances, and the problem to be solved is to provide excellent light weight and rust prevention properties such as polyamide tubes, and metal It is an object of the present invention to provide a tube for fuel piping that has excellent fuel barrier properties like a tube made of aluminum.

[0007]

[Solution] In order to solve the above problems, the present invention provides a fuel piping tube characterized in that at least one layer of the single-layer tube or the multi-layer tube is formed of a polyacetal resin material. This is its gist.

[0008] In the present invention, if the fuel piping tube is a multilayer tube, preferably:
The innermost layer will be formed of a polyacetal resin material. Further, in the present invention, a polymer having -CH2O- as a basic skeleton is usually used as the polyacetal resin material.

[0009]

[Specific Structure] That is, as a result of studying various resin materials, the present inventors found that polyacetal resin material is more suitable than polyamide resin material, which is currently considered to be a material for forming fuel piping tubes. They discovered that it has even better fuel barrier properties. Based on this knowledge, they conducted further studies and completed the present invention.

By the way, the polyacetal resin material is
As is well known, the acetal bond (-O-CR
2 -O-) in the main chain, and generally,
It is obtained by cationic or anionic polymerization of aldehydes. In the present invention, polyacetal resin materials having the required properties are appropriately selected from various known polyacetal resin materials, but in particular -CH2O-
A polymer having a basic skeleton of is preferably selected. Also,
If necessary, by blending other polymers or elastomer components with the above polyacetal resin material, or adding various property-imparting agents and additives, the polyacetal resin material can be made into a tube-forming material. It is also possible to prepare

More specifically, the aldehydes that provide such polyacetal resin materials include, for example,
Formaldehyde, acetaldehyde, propionaldehyde, etc. can be used, and trioxane, which is a cyclic trimer of formaldehyde, can be used. Then, they are usually made to have a high molecular weight through a polymerization reaction in the presence of a catalyst.

[0012] In addition to the above-mentioned homopolymers of aldehydes and trioxanes, the polyacetal resin materials used in the present invention include those having at least two adjacent carbon atoms in such aldehydes and trioxanes. It is also possible to use a copolymer obtained by combining predetermined amounts of cyclic ethers and increasing the molecular weight by a copolymerization reaction in the presence of a catalyst. Incidentally, specific examples of such cyclic ethers include ethylene oxide and 1,3-dioxane, and the amount added is usually 0.0 of the amount in the case of aldehydes.
3 to 5 mol% is suitable, and in the case of trioxane,
0.1 to 15 mol% of that amount is suitable. Note that a copolymer can be obtained in the same manner by combining aldehydes or trioxane with a vinyl compound.

Furthermore, it is also possible to esterify the terminal hydroxyl group (-OH) of the homopolymer or copolymer thus obtained, if necessary, and such modification improves the effects of the present invention. There will be no hindrance.

Furthermore, in the present invention, it is also possible to use a blend of two or more different polyacetal resin materials, or it is possible to use a predetermined elastomer component as long as the barrier properties against methanol-mixed gasoline are not deteriorated. By melting and kneading, it is also possible to improve the sealing performance between the tube and the joint. Furthermore, it goes without saying that there is no problem in adding various property-imparting agents and additives such as heat stabilizers and antioxidants as appropriate.

[0015] Such a polyacetal resin material is then uniformly kneaded using a normal twin screw extruder or the like in a melting temperature range to prepare a tube forming material. By molding according to the tube extrusion molding method, the desired fuel piping tube can be obtained. The thickness of the tube layer formed from such a polyacetal resin material can be freely set depending on the desired fuel barrier properties, but is usually 0.5 to 1.
Approximately 5 mm is preferable.

Further, in the present invention, the thin single-walled tube thus formed can be used as a product as it is, but it can also be applied as one layer of a multi-layered tube. In that case, the tube layer made of polyacetal resin material is preferably used as the innermost layer in order to effectively obtain fuel barrier properties, and the layer located outside (outer layer) is preferably used with various other forming materials. so that it forms. For example, by forming this outer layer from a polyamide resin such as nylon 11 or nylon 12, it is possible to advantageously reduce the weight of the tube while suppressing deterioration in fuel barrier properties. Note that the outer layer is usually formed with a thickness of about 0.5 to 1.5 mm, although it varies depending on the forming material used.

Furthermore, depending on the usage environment, a tube protective layer made of a specified rubber material, soft resin, thermoplastic elastomer, or the like may be provided on the outside of the single-layer or multi-layer tube. This protective layer may be formed of a foam as well as a solid body, and is usually 0.5 to 2 m long.
It is formed with a wall thickness of about m. An adhesive can also be applied between the protective layer and the tube, if necessary.

[0018]

[Examples] Below, typical examples of the present invention will be shown to clarify the present invention more specifically. However, the present invention is not limited in any way by the description of such examples. Needless to say, it is not something that can be accepted. In addition to the following examples and the above-mentioned specific description, the present invention includes various changes, modifications, and changes based on the knowledge of those skilled in the art, as long as they do not depart from the spirit of the present invention. It should be understood that improvements and the like may be made.

First, as a polyacetal resin material,
Delrin 100 (USA: DuPont, homopolymer)
Alternatively, using Duracon U10-01 (manufactured by Polyplastics Co., Ltd., copolymer), according to the layer structure shown in Table 1 below, a single layer with an inner diameter of 6 mmφ and an outer diameter of 8 mmφ or Various resin tubes (No. 1 to 3) having a two-layer structure were produced.

[0020] Regarding the obtained various tubes,
The weight was measured, and the fuel barrier properties and rust prevention properties were also measured using the methods shown below, and the results are shown in Table 1 below. For comparison, inner diameter: 6mmφ
An iron tube (No. 4) and a nylon tube (No. 5) with an outer diameter of 8 mm were prepared, their weights were similarly measured, and their fuel barrier properties and rust prevention properties were measured. The results are shown in Table 1 below.

[0021] Gasoline for fuel barrier property test or gasoline for test and methanol
One of the mixed gasolines mixed at a ratio of 0:50 (volume %) was sealed in each tube, left at a temperature of 40°C, and the amount of weight loss (g/m2 ・day) was measured. did.

[0022] Rust prevention A salt spray test was conducted in accordance with JIS-Z-0103, and the state of surface corrosion was observed after 300 hours. Those with no corrosion were marked with ○, while those with corrosion were marked with ×. It was shown in

[0023]

[Table 1]

As is clear from the results shown in Table 1, No. 1 according to the present invention. Tubes 1 to 3 are comparative example No. It is as light as the nylon tube in No. 5, has no rust, and has extremely good fuel barrier properties not only against regular gasoline but also against mixed gasoline containing methanol.

On the other hand, comparative example No. In the case of No. 4, the iron tube is heavy and has rust. Also, No. It can be seen that the nylon tube No. 5 has extremely low barrier properties against mixed gasoline containing methanol.

[0026]

[Effects of the Invention] As is clear from the above explanation, the fuel piping tube according to the present invention is lightweight, does not rust, and has extremely excellent fuel barrier properties, so it will be useful in the future. It is also extremely useful as a highly practical fuel piping tube.

[0027] Therefore, such a tube can be suitably used as a fuel piping tube for automobiles, etc., and can advantageously reduce the weight of the product.
There is no risk of rust and the parts have a long service life. Furthermore, since it has good fuel barrier properties not only against ordinary gasoline but also against methanol-mixed gasoline, it can satisfactorily meet future needs.

Claims (3)

[Claims] 1. A fuel piping tube, wherein at least one layer of the single-layer tube or the multi-layer tube is formed of a polyacetal resin material. 2. The fuel piping tube according to claim 1, wherein the innermost layer of the multilayer tube is made of a polyacetal resin material. 3. The polyacetal resin material is -
The fuel piping tube according to claim 1 or 2, which is a polymer having CH2O- as a basic skeleton.