JPH0740998A - Fire-retardant multi-layer plastic fuel tank - Google Patents

Abstract

PURPOSE:To obtain a plastic fuel tank improved in fire resistance without using thermal insulation plate in the bottom part of the fuel tank by covering the outermost shell layer of the fuel tank with a fire-retardant foam layer. CONSTITUTION:A fire-retardant multi-layer plastic fuel tank 1 consists of a fire-retardant plastic foam layer formed on an outermost shell layer 5 and a HDPE layer 4 or HDPE/adhesive agent/PA/HDPE layer. The foam layer is formed of plastic foam and polyethylene foam in combination with halogen containing organic compound, chloric halogen containing organic compound and halogen free inorganic compound as flame retardant. By using azo and nitroso organic foaming agent and through blow molding process, a fire- retardant plastic foam layer is formed on the outermost shell layer 5 simultaneously and then foaming treat is effected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flame-retardant multi-layer plastic fuel tank having a flame-retardant foam plastic layer as the outermost shell layer of a single-layer or multi-layer plastic fuel tank.

[0002]

2. Description of the Related Art As a plastic fuel tank, a single-layer or multi-layer structure is known. These fuel tanks are mainly formed by blow molding.As a constituent material, a fuel tank with a single-layer structure has a high density, a high polymer and a high polymer, considering drawdown, impact resistance, gasoline permeability, etc. High density polyethylene (HDPE) having a molecular weight of, for example, about 200,000 to 300,000 is used. Further, a fuel tank having a multi-layer structure has a structure for passing the SHED method (US gasoline permeation regulation), and is disclosed in Japanese Patent Laid-Open No. 61-104952.
There is known a tank of three types and five layers, which is formed of a specific blown moldable modified polyamide (PA) layer as an intermediate layer and an adhesive layer for bonding the layer to an HDPE layer.

[0003]

However, in the conventional single-layer or multi-layer plastic fuel tank, the outermost shell layer is the HDPE layer. Therefore, the Ministry of Transport standard "Plastic Fuel Tank Technical Standard for Passenger Vehicles" is adopted. For the fire resistance test, a 1 minute direct contact with flame and a 1 minute indirect contact with the flame were conducted for a total of 2 minutes. As shown in FIG. Was required to be shielded by the heat shield plate 6, for example, a steel plate having a thickness of 0.5 mm. For this reason, the total weight of the fuel tank becomes heavy, and there is a problem that it goes against the tendency of weight reduction of the vehicle body. Therefore, it is an object of the present invention to provide a plastic fuel tank having improved fire resistance without using the heat shield plate.

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventor has found that the outermost shell layer of a fuel tank is coated with a foam layer having flame retardancy.
The present invention has been achieved by finding that the above problems can be solved.

Therefore, the flame-retardant multi-layer plastic fuel tank of the present invention is characterized in that the outermost shell layer of the single-layer or multi-layer plastic fuel tank is provided with the flame-retardant foaming plastic layer.

In the present invention, the expandable plastic layer applied as the outermost shell layer of a single-layer or multi-layer fuel tank can be formed of any expandable plastic, but the covered layer is formed of HDPE. Therefore, it is preferable to use expandable polyethylene.
Therefore, the flame-retardant multi-layered plastic tank according to the preferred embodiment of the present invention comprises the outermost shell flame-retardant foamed plastic layer, H
DPE layer or HDPE / adhesive / PA / adhesive / HD
It consists of a PE layer.

In the present invention, the foaming layer comprises a foaming resin, preferably a foaming polyethylene, containing a halogen-containing organic compound as a flame retardant, preferably 2% by weight or more of a chlorine-based halogen-containing organic compound, and a halogen-free inorganic compound of 1. 5% by weight or more is used in combination, and an azo or nitroso organic foaming agent is preferably used as the foaming agent.

The fuel tank of the present invention is formed by blow molding a foamable plastic layer having flame retardancy into the outermost shell layer at the same time by a usual blow molding method as in the conventional tank, and then performing a foaming treatment. can do.

[0009]

EXAMPLES The present invention will be further described below with reference to examples and comparative examples. Example 1 SHOREX 4551H (produced by Showa Denko KK, trade name) was used as the high-density polyethylene (HDPE), and the foamed polyethylenes A and B shown in Table 1 below were used as the expandable polyethylene, and the thickness was obtained by coextrusion molding. H of 3 mm
A laminate of DPE and expandable polyethylene A or B having a thickness of 500 μm was obtained, and a test piece having a size of 15 mm × 15 mm was prepared. For each test piece, the foam tip was placed on the Bunsen burner with the expandable polyethylene on the lower side, and the temperature of the test piece was set to 800 ° C, and the temperature was set to 800 ° C. . Table 1 also shows the results obtained by performing a fire resistance test on HDPE test pieces of the same size.

[0010]

[Table 1]

Next, the above HDPE and expandable polyethylene A
Was used to mold a two-layer fuel tank (tank capacity 50 liters) having an outer layer made of expandable polyethylene A by a blow molding machine. The film thickness of HDPE was 3 mm, and the film thickness of the expandable polyethylene A layer was 500 μm.

The tank and HD thus obtained
A fire resistance test (within the "Plastic Fuel Tank Technical Standard for Passenger Vehicles" established by the Ministry of Transport) of a tank made of PE only and a heat shield plate as shown in Fig. 2 placed below the tank made of HDPE Direct contact with flame for 1 minute and indirect contact for 1 minute for a total of 2 minutes. In the tank made of expandable polyethylene A or B and HDPE, after the fire resistance test, the wall thickness was the same as the tank using the heat shield. Although there was no decrease, tank deformation was observed in the HDPE single layer tank.

Example 2 and Comparative Example Showlex 455 used in Example 1 as HDPE
1H, modified polyethylene as adhesive, trade name F
Using T61AR1 Showa Denko KK, trade name CM1061Y Toray Co., Ltd. as the polyamide, and using the expandable polyethylene A described in Example 1 as the expandable polyethylene in a multilayer blow molding machine, (A)
A four-kind seven-layer multi-layer plastic fuel tank (tank capacity 50 liters) shown in (1) was obtained.

In FIG. 1 (b), 1 is a fuel tank, 2 is a polyamide layer having a thickness of 100 μm, 3 is a modified polyethylene layer having a thickness of 100 μm, 4 is an HDPE layer having a thickness of 3 mm, 5
Indicates a 500 μm expandable polyethylene layer. For comparison, a 3-kind 5-layer multi-layer plastic fuel tank was obtained in the same manner except that the expandable polyethylene layer 5 as the outermost shell layer was not provided. A heat shield plate was provided at the bottom of this tank, and the fire resistance test described in Example 1 was performed. The results are shown in Table 2.

[0015]

[Table 2] As can be seen from Table 2, the multi-layer tank of the example shows a deformation amount almost equal to that of the multi-layer tank of the comparative example,
Passed the fire resistance test.

[0016]

As described above, the multi-layer structure plastic fuel tank of the present invention does not require a heat shield plate having a flame-retardant foam layer as the outermost shell layer, is lightweight, and has the fire resistance test described above. To pass.

[Brief description of drawings]

FIG. 1 (a) is a side view of a flame-retardant multi-layered plastic fuel tank according to an example of the present invention, and FIG. 1 (b) is an enlarged view of a portion A of FIG. 1 (a).

FIG. 2 is a side view of an example of a conventional plastic fuel tank.

[Explanation of symbols]

 1 Fuel Tank 2 Polyamide Layer 3 Modified Polyethylene Layer 4 HDPE Layer 5 Foamable Polyethylene Layer 6 Heat Shield

Claims (1)

[Claims] 1. A flame-retardant multi-layered plastic fuel tank, wherein the outermost shell layer of the single-layer or multi-layered plastic fuel tank comprises a flame-retardant foamed plastic layer.