JPH05193061A - Molded container - Google Patents

Abstract

PURPOSE:To obtain a molded container having excellent barrier capacity against methanol mixed gasoline and effectively utilized as a tank for a gas hole by forming a wall part by mutually bonding and laminating a polyethylene layer, an adhesive layer and a specific barrier layer in this order from the outside. CONSTITUTION:A wall part is constituted by mutually bonding a polyethylene layer, an adhesive layer and a polyphenylene sulfide layer (PPS layer) in this order from the outside. Herein, polyphenylene sulfide is a polymer containing 70mol% or more, pref., 90mol% or more of a specified repeating unit. When the repeating unit is below 70mol%, unpreferable effect is obtained because the heat resistance of PPS is damaged. By constituting the outermost layer of the wall part of the polyethylene layer, the resistance against a cracking from the outside is enhanced and, since the PPS layer does not directly come into contact with the open air, the deterioration of PPS and the lowering of the durability of a container based on said deterioration can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic molded container used for a vehicle fuel tank or the like. Particularly, it relates to a plastic molded container suitable for a tank for methanol-mixed gasoline.

[0002]

2. Description of the Related Art Recently, fuel tanks for vehicles have been formed by blow molding using plastics such as polyethylene from the viewpoints of flexibility in shape design and weight reduction. However, this polyethylene plastic tank has a problem that it permeates gasoline, that is, the gasoline in the tank seeps out.

As a means for preventing gasoline permeation, it has been proposed to manufacture a tank by blow molding with a multilayer parison in which a polyamide layer effective for preventing gasoline permeation is laminated on the above-mentioned polyethylene layer. That is,
The multi-layer parison has a multi-layer structure including a polyethylene layer, an adhesive layer and a polyamide layer, and this is blow-molded in a molding die. (JP-A-58-220738)

[0004]

In recent years, there has been an increasing demand in the world for gasoline blended with methanol. Since the polyamide layer is less effective as a barrier layer for methanol-mixed gasoline, a conventional plastic gasoline tank having a polyamide layer as a barrier layer is insufficient.
For example, a container using polyamide as a barrier layer has an excellent barrier performance for 100% gasoline, but the barrier performance is significantly deteriorated for a mixed gasoline containing 15% methanol.

The present invention provides a molded plastic container having excellent barrier properties against methanol-blended gasoline.

[0006]

A feature of the present invention is that a polyphenylene sulfide resin is used as a barrier layer in order to prevent the permeation of methanol-blended gasoline. That is, the present invention relates to a molded container in which the wall portion is composed of a polyethylene layer, an adhesive layer, and a polyphenylene sulfide layer, which are mutually adhered in this order from the outside.

In the present invention, the wall portion means a portion forming the container body, and includes the bottom portion. In this invention,
As long as the wall portion of the container is formed from the outside in the above-mentioned order, it may be formed of three or more layers. Among them, a molded container in which the wall portion is composed of five layers in which the polyethylene layer, the adhesive layer, the polyphenylene sulfide layer, the adhesive layer and the polyethylene layer are adhered in this order from the outside is preferable. By forming the outermost layer of the wall portion with a polyethylene layer, a container resistant to external scratches can be obtained. Further, since the PPS layer does not come into direct contact with the outside air, it is possible to prevent deterioration of durability of the container due to deterioration and aging of PPS.

The polyethylene constituting the wall of the container of the present invention is, for example, a homopolymer of ethylene, or ethylene mainly composed of ethylene and other α-olefins such as propylene, 1-butene, 1-pentene,
It is a copolymer of 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene or the like alone or with two or more kinds, and has a melt flow rate (JIS K7210,
190 ° C., 2160 g) is 0.01 to 1 g / 10 min, preferably 0.03 to 0.4 g / 10 min, density (JIS
K7112, 23 ° C) is 0.910 to 0.970 g /
cm ³ , preferably 0.931 to 0.960 g / cm ³
The ones are listed.

The polyphenylene sulfide (hereinafter abbreviated as PPS) constituting the wall of the container of the present invention has the following structural formula.

[0010]

[Chemical 1]

70 mol% or more of the repeating unit represented by
More preferably, it is a polymer containing 90 mol% or more. If the repeating unit content is less than 70 mol%, heat resistance is impaired, which is not preferable. In addition, PPS has a repeating unit of 30
Less than mol% can be composed of repeating units having the following structural formula.

[0012]

[Chemical 2]

These PPS are disclosed, for example, in Japanese Examined Patent Publication No.
Although it can be obtained by the method described in Japanese Patent No. 3368 or Japanese Patent Publication No. 52-12240, essentially linear PPS having a relatively high molecular weight is preferably used in the present invention. Further, in the present invention, PPS subjected to deionization treatment by acid treatment after polymerization, hot water treatment or washing with an organic solvent is preferably used.

Another preferred example of PPS is PPS modified with a polyfunctional isocyanate. Further, as a preferred example of PPS, an epoxy group-containing olefin polymer, a maleic anhydride-modified ethylene-propylene copolymer or an ethylene-α, β unsaturated acid alkyl ester-maleic anhydride copolymer is used as an island component, and PPS is used.
PPS-elastomer alloy having sea component as a sea component.

The adhesive layer constituting the wall of the container of the present invention is for adhering the polyethylene layer and the PPS layer to each other. The adhesive used is an epoxy group-containing olefin polymer or anhydrous maleic acid. Acid-modified ethylene-propylene copolymer, ionomer, ethylene-α, β unsaturated acid alkyl ester-acid anhydride copolymer, carboxylic acid group-containing olefin polymer, maleic anhydride-modified hydrogenated styrene-butadiene block copolymer Examples thereof include coalesce and maleic anhydride-modified polyethylene. Particularly preferred is an epoxy group-containing olefin polymer, ethylene to
It is an α, β unsaturated acid alkyl ester-acid anhydride copolymer.

The epoxy group-containing olefin polymer has a side chain of glycidyl ester, glycidyl ether,
Examples thereof include an olefin polymer having a glycidyl group such as glycidyl amine and a double bond-containing olefin polymer obtained by epoxy-oxidizing a double bond. In the present invention, among these epoxy group-containing olefin-based polymers, α
A copolymer composed of an olefin and a glycidyl ester of an α, β-unsaturated acid is preferably used. Α here
-Olefins include ethylene, propylene, butene-1 and the like. Further, the glycidyl ester of α, β-unsaturated acid is represented by the following general formula

[0017]

[Chemical 3]

(R represents a hydrogen atom or a lower alkyl group), and specific examples thereof include glycidyl acrylate, glycidyl methacrylate and glycidyl ethacrylic acid. The content of the epoxy group in the epoxy group-containing olefin polymer is 0.1 to 30.
%, Especially 0.2 to 20% by weight is preferred. Epoxy group-containing olefin polymer, other olefin monomers such as methyl acrylate, methyl methacrylate, acrylonitrile, within a range that does not impair the effects of the present invention,
Styrene, vinyl acetate and vinyl ether may be copolymerized.

The ethylene-α, β unsaturated acid alkyl ester-maleic anhydride copolymer has an ethylene content of 50-95.
% By weight, preferably 60-80% by weight, α-β unsaturated acid alkyl ester 5-49% by weight, preferably 7-4
5% by weight, maleic anhydride 0.5 to 10% by weight, preferably 1 to 8% by weight. The α, β unsaturated acid alkyl ester is an unsaturated carboxylic acid having 3 to 8 carbon atoms, for example, an alkyl ester such as acrylic acid or methacrylic acid, and specific examples thereof include methyl acrylate and ethyl acrylate. , N-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate. , T-butyl methacrylate, isobutyl methacrylate, and the like, and among these, ethyl acrylate, n-butyl acrylate, and methyl methacrylate are particularly preferable.

The molded container of the present invention can be molded by injection molding, blow molding, etc., but blow molding is preferable.
An example of a molding method by blow molding will be described below with reference to the drawings. FIG. 1 is a sectional view showing a method of blow molding. The parison 1 extruded from the parison die 2 is sandwiched between the molds 3 and 3 ', and the upper and lower end portions of the parison 1 are bonded together to form a pinch-off portion. It is supplied and molded into a predetermined shape.

FIG. 2 is a partially enlarged sectional view of the parison 1. The parison 1 is adhered to the polyethylene layer 1A, the adhesive layer 1B, and the PPS layer 1C in this order from the outside. In the case of blow molding, if the innermost layer of the container is formed of a polyethylene layer, the pinch-off portion swells due to the strong adhesive force of the polyethylene layer, so that the inner surface of the pinch-off portion is V-shaped.
This is preferable because no mold groove is generated.

[0022]

The present invention will be further described with reference to the following examples.

[0023]

[Example 1] As polyethylene, Suntech B680 (melt flow rate: 0.05 g /
10 minutes, density 0.953 g / cm ³ ), ethylene / glycidyl methacrylate copolymer (88/1) as an adhesive
2 weight ratio), using a linear polyphenylene sulfide resin that has been subjected to deionization treatment as PPS, and by the blow molding method shown in FIG. 1, the wall portion of the container has three layers of a polyethylene layer, an adhesive layer, and a PPS layer from the outer surface. A container made of was prepared.

The resulting containers were filled with 100% gasoline and gasoline containing 15% of methanol, and a gasoline permeation test was carried out at 60 ° C. for 2000 hours. The results of determining the gasoline permeation amount (relative value) from the weight reduction amount are shown in Table 1.

[0025]

Example 2 A container having a three-layer structure was produced in the same manner as in Example 1 except that maleic anhydride-modified polyethylene was used as the adhesive. The results of a gasoline permeation test conducted in the same manner as in Example 1 are shown in Table 1.

[0026]

Example 3 As the adhesive, ethylene-acrylic acid ester-maleic anhydride copolymer (Sumitomo CDF Chemical Co., Ltd.), Bondine AX8390, acrylic acid ester content 32%, maleic anhydride content 1.75%) are used. And modified PPS of polyphenylene sulfide / diphenylmethane diisocyanate (100/2) as PPS
A container having a three-layer structure was produced in the same manner as in Example 1 except that was used. The results of a gasoline permeation test conducted in the same manner as in Example 1 are shown in Table 1.

[0027]

Example 4 A container having a three-layer structure was produced in the same manner as in Example 1 except that PPS alloy containing 20% by weight of ethyleneglycidyl methacrylate in polyphenylene sulfide as an PPS alloy was used. The results of a gasoline permeation test conducted in the same manner as in Example 1 are shown in Table 1.

[0028]

Example 5 As a PPS, a maleic anhydride-modified ethylene-propylene copolymer is contained as an island component in an amount of 20% by weight.
3 except that the PPS alloy was used
A container having a layered structure was produced. The results of a gasoline permeation test conducted in the same manner as in Example 1 are shown in Table 1.

[0029]

EXAMPLE 6 As PPS, PP comprising 80 parts by weight of modified PPS of polyphenylene sulfide / diphenylmethane diisocyanate (100/2) and 20 parts by weight of ethylene-acrylic acid ester-maleic anhydride copolymer.
A three-layered container was produced in the same manner as in Example 3 except that S alloy was used. The results of a gasoline permeation test carried out in the same manner as in Example 1 are also shown in Table 1.

[0030]

[Comparative Example 1] The same operation as in Example 1 was carried out except that nylon 6 was used instead of PPS, and a container having a three-layered structure including a polyethylene layer, an adhesive layer, and a nylon 6 layer was formed from the outside of the container wall. It was made. The results of a gasoline permeation test conducted in the same manner as in Example 1 are shown in Table 2.

A container having a nylon 6 layer as a barrier layer is
It has good gasoline permeation preventive ability against 100% gasoline, but its permeation preventive ability against gasoline containing 15% methanol is significantly lower than that using PPS, and it is suitable for methanol mixed gasoline. I know there isn't.

[0032]

[Comparative Example 2] The same operation as in Example 2 was carried out except that nylon 66 was used instead of PPS, and a container having a three-layered structure including a polyethylene layer, an adhesive layer, and a nylon 66 layer was formed from the outside of the container wall. It was made. The results of a gasoline permeation test conducted in the same manner as in Example 1 are shown in Table 2.

[0033]

Comparative Example 3 A container having a three-layer wall was produced in the same manner as in Example 3 except that nylon 6/66 copolymer was used as the barrier layer instead of PPS. The results of a gasoline permeation test conducted in the same manner as in Example 1 are shown in Table 2.

[0034]

Example 7 The same polyethylene used in Example 1,
Using an adhesive and PPS, blow molding was performed to prepare a container in which the wall portion of the container was composed of five layers of a polyethylene layer, an adhesive layer, a PPS layer, an adhesive layer and a polyethylene layer from the outside.
A gasoline permeation test was conducted on the obtained container in the same manner as in Example 1 and the results are shown in Table 3.

[0035]

Example 8 A container having a 5-layer structure was produced in the same manner as in Example 7 except that the same adhesive material as that used in Example 2 was used. The results of a gasoline permeation test performed on the obtained container in the same manner as in Example 1 are shown in Table 3.

[0036]

Example 9 The same adhesive and PPS used in Example 3
A container having a five-layer structure was produced in the same manner as in Example 7 except that was used. The results of a gasoline permeation test performed on the obtained container in the same manner as in Example 1 are shown in Table 3.

[0037]

Example 10 A container having a five-layer structure was produced in the same manner as in Example 7, except that the same PPS as used in Example 4 was used. The results of a gasoline permeation test performed on the obtained container in the same manner as in Example 1 are shown in Table 3.

[0038]

Example 11 A container having a five-layer structure was produced in the same manner as in Example 7 except that the same PPS as used in Example 5 was used. The results of a gasoline permeation test performed on the obtained container in the same manner as in Example 1 are shown in Table 3.

[0039]

Example 12 A container having a five-layer structure was produced in the same manner as in Example 9 except that the same PPS as used in Example 6 was used. The results of a gasoline permeation test conducted on the obtained container in the same manner as in Example 1 are shown in Table 3.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

[Table 3]

[0043]

INDUSTRIAL APPLICABILITY The molded container of the present invention has an excellent barrier performance against methanol-blended gasoline and is therefore useful as a tank for gasohol.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a blow molding method.

FIG. 2 is a partially enlarged cross-sectional view of a parison used in Example 1.

[Explanation of symbols]

 1 parison 2 parison die 3 mold 4 air inlet

Claims (1)

[Claims] 1. A molded container, wherein the wall portion is composed of a polyethylene layer, an adhesive layer, and a polyphenylene sulfide layer, which are mutually adhered in this order from the outside.