Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reexamination Certificate
1997-12-11
2004-04-20
Nolan, Sandra M. (Department: 1772)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C138S137000, C428S036910, C428S419000
Reexamination Certificate
active
06723400
ABSTRACT:
TECHNICAL FIELD
The present invention relates to electroconductive, multilayered hollow moldings with good and well-balanced heat resistance, hot water resistance, chemical resistance, gasohol permeation resistance, outward appearance, interlayer adhesion and low-temperature stiffness.
BACKGROUND ART
For producing hollow moldings of thermoplastic resins, widely known are various techniques. For example, known is a technique of blow molding of polyamide resins to produce ducts to be in the car engines, and a technique of extrusion molding of saturated polyester resins, polyamide resins, polyolefin resins and thermoplastic polyurethanes to produce tubes.
However, since conventional, single-layered hollow moldings of polyamide resins, saturated polyester resins, polyolefin resins or thermoplastic resins such as polyurethane resins have poor heat resistance, hot water resistance and chemical resistance, their applications are limited. Therefore, products with improved heat resistance, hot water resistance and chemical resistance are desired.
For fuel tubes for cars, generally used are polyamide resins, in particular, soft polyamide resins such as polyamide 11 and polyamide 12. However, it is said that tubes made from only such polyamide resins do not have good alcohol-gasoline permeation resistance, which is required for preventing environmental pollution and for lowering fuel expenses. Some improvements in those tubes are required.
Where hollow blow moldings or tube moldings are used as tubes and where non-conductive liquids such as fuel are run therein, those moldings are often charged. In those cases, therefore, it is desired to prevent the moldings from being charged.
On the other hand, polyphenylene sulfide resins (hereinafter referred to as PPS resins) are engineering plastics with good heat resistance, hot water resistance, chemical resistance and flame resistance, while having good electric characteristics. There is increasing a great demand for the applications of those PPS resins to electric and electronic parts and also to car parts. Recently, Japanese Patent Publication No. 2-200415 has disclosed tubular moldings comprising PPS resins, referring to the characteristics of the resins.
Hollow moldings of such PPS resins could solve the problems in poor heat resistance, hot water resistance, chemical resistance and gas permeation resistance such as those mentioned above, but are often still unsatisfactory in stiffness, especially low-temperature stiffness that is often required for use in cars. Therefore, the applications of those hollow moldings are limited.
Japanese Patent Application Laid-Open No. 7-299855 discloses multilayered tubes comprising a PPS layer, in which is referred to a method for improving the interlayer adhesion of those multilayered tubes by activating the surface of the PPS layer through corona processing. However, secondary processing such as corona processing is disadvantageous in view of its cost, and is, therefore, unfavorable. In addition, nothing is referred to in the laid-open specification with respect to the stiffness of the multilayered tubes.
On the other hand, various studies have heretofore been made for making PPS resins electroconductive. For example, Japanese Patent Application Laid-Open No. 60-53560 discloses electroconductive PPS resin compositions comprising PPS resin and electroconductive carbon black; and Japanese Patent Application Laid-Open No. 1-272665 discloses electroconductive PPS mixtures comprising PPS resin, electroconductive carbon black, and graphite. However, no disclosure is given in any of those laid-open specifications with respect to hollow moldings of electroconductive PPS resins, and, in addition, nothing is referred to therein with respect to any specific resin characteristics and any specific resin compositions that may target the improvements in the blow moldability and the tube moldability of the resin compositions and in the interlayer adhesion of the moldings of the resin compositions. Needless to say, no disclosure is given in those laid-open specifications with respect to multilayered hollow moldings to be prepared by laminating electroconductive PPS resin layers.
It is known to incorporate an electroconductive filler into thermoplastic resins, for example, as in Japanese Patent Application Laid-Open No. 54-113640. However, our studies have revealed that such known resin compositions could be molded in injection molding or the like in which the moldings being produced are pressed against molds under high pressure. However, these bring about some problems when applied to hollow molding such as blow molding or tube molding, in which any high pressure is not applied to the surface of the molding being produced. Specifically, when the known resin compositions are applied to such hollow molding, the surfaces of the resulting moldings are often roughened so that the moldings do not have good surface smoothness. In addition, the extrusion molding conditions for the known resin compositions are narrowly limited, and even the extrusion molding devices applicable to them are also limited. For these reasons, we have found that the known resin compositions could not be simply applied to such hollow molding. Moreover, we have further found that the surface roughness of the moldings have some negative influences on the strength of the moldings.
Given this situation, we have conducted further studies in order to solve the problems with those conventional, multilayered hollow moldings. As a result, we have achieved the present invention. Specifically, the invention is to provide electroconductive, multilayered hollow moldings with good and well-balanced heat resistance, hot water resistance, chemical resistance, alcohol-gasoline permeation resistance, stiffness, low-temperature stiffness, surface smoothness and interlayer adhesion.
DISCLOSURE OF THE INVENTION
The invention provides the following moldings and compositions.
1. An electroconductive, multilayered hollow molding comprising at least two thermoplastic resin layers, in which at least one layer is a layer of (a) a thermoplastic resin composition consisting essentially of a polyphenylene sulfide resin, at least one layer is a layer of (b) a thermoplastic resin composition consisting essentially of a thermoplastic resin other than a polyphenylene sulfide resin, and at least one layer is a layer of an electroconductive resin composition comprising an electroconductive filler and/or an electroconductive polymer, and a thermoplastic resin.
2. An electroconductive, multilayered hollow molding comprising at least three thermoplastic resin layers, in which at least one layer is a layer of (a) a polyphenylene sulfide resin composition, at least one layer is a layer of (b) a thermoplastic resin composition consisting essentially of a thermoplastic resin other than a polyphenylene sulfide resin, and at least one layer is a layer of (c) an electroconductive, thermoplastic resin composition comprising an electroconductive filler and/or an electroconductive polymer.
3. An electroconductive, multilayered hollow molding composed of two thermoplastic resin layers, in which one layer is a layer of (a′) an electroconductive resin composition consisting essentially of a polyphenylene sulfide resin, and the other layer is a layer of (b) a thermoplastic resin other than a polyphenylene sulfide resin.
4. The electroconductive, multilayered hollow molding of 2, which is composed of three layers, an interlayer of (a) a polyphenylene sulfide resin composition, an outermost layer of (b) a thermoplastic resin composition consisting essentially of a thermoplastic resin other than a polyphenylene sulfide resin, and an innermost layer of (c) an electroconductive, thermoplastic resin composition comprising an electroconductive filler and/or an electroconductive polymer.
5. The electroconductive, multilayered hollow molding of 2, which is composed of three layers, an innermost layer of (a) a polyphenylene sulfide resin composition, an outermost layer of (b) a thermoplastic resin compositio
Ishio Atsushi
Kobayashi Kazuhiko
Shimasaki Norio
Tateyama Masaru
Nolan Sandra M.
Piper Rudnick LLP
Toray Industries Inc.
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