Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Reexamination Certificate
2001-03-30
2003-07-15
Nolan, Sandra M. (Department: 1772)
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
C428S036910, C428S475800, C428S476100
Reexamination Certificate
active
06592957
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to piping parts for an automobile cooling system, which are made of novel materials. More particularly, it relates to a multi-layer hose for an automobile cooling system, which is made of thermoplastic materials and is light in weight, flexible and excellent in endurance.
The piping parts for automobile cooling system, such as radiator hoses, cooling pipes and heater pipes, have hitherto been made using metals or crosslinked rubbers, and demands for weight saving, flexibilization and improvement of moldability have been increased, and improvement in materials is desired.
Hoses made of thermoplastic resins or thermoplastic elastomers are expected as meeting the above demands. However, it is necessary that the hoses be excellent in oil resistance, heat resistance and water resistance, and it is difficult to meet all of the above demands with hoses composed of one material such as olefin resins, styrene resins or polyamide resins. Thus, development of hoses made of a plurality of the materials in combination has been attempted.
Recently, olefin thermoplastic elastomers are used in a wide variety of fields as substitutes for crosslinked rubbers since they have water resistance, are high in flexibility, can be subjected to various molding processing and can be recycled.
Among them, so-called dynamically crosslinked thermoplastic elastomers obtained by crosslinking an olefin elastomer having radical-crosslinkability and a thermoplastic resin having no radical-crosslinkability such as polypropylene in the presence of a crosslinking agent under melt-kneading in a kneading machine are now being used for applications such as automobile parts and others because they can be markedly improved in heat resistance, oil resistance, permanent compression set and others by crosslinking the elastomer component.
On the other hand, JP-A-4-290691 and JP-A-8-100873 disclose multi-layer hoses composed of an inner layer comprising a polyolefin and an outer layer comprising a polyamide, but these are insufficient in flexibility and still have room for improvement in endurance.
SUMMARY OF THE INVENTION
Under the circumstances, the object of the present invention is to provide a multi-layer hose for automobile cooling systems which is light in weight, flexible and, besides, excellent in endurance.
Here, the piping parts for automobile cooling systems in the present invention mean piping hoses used for circulating engine cooling water, and an anti-freeze of high temperature is circulated therethrough.
That is, the inner layer of these hoses directly contacts with an aqueous anti-freeze, and, hence, is required to have hydrolytic resistance, heat resistance, water vapor permeation resistance, and the like. On the other hand, the outer layer of the hoses is required to have oil resistance, heat resistance, and the like. In order to meet the different requirements of the inner and outer layers, it is effective to use multi-layer hoses whose inner layer and outer layer are made of different materials, respectively. Specifically, olefin materials are most suitable for the inner layer and polyamide materials are most suitable for the outer layer. Furthermore, when the inner layer and the outer layer of hoses are made of different materials, the material of the inner layer and the material of the outer layer must closely adhere to each other at their interface. Moreover, the piping hoses for automobile cooling systems, per se, which comprise the material for the outer layer and the material for the inner layer must be flexible to satisfy piping performance and be able to withstand vibrations.
The inventors have found that the above object can be attained by using a composition comprising a polymer having a specific polar group and a thermoplastic elastomer as essential components and by molding the composition to a specific multi-layer structure. That is, the multi-layer hose for automobile cooling systems of the present invention has been accomplished by using suitable materials which comprise a thermoplastic elastomer as the material for the inner layer and a polyamide thermoplastic resin as the material for the outer layer flexibility to the hose, per se, and furthermore impart to the thermoplastic elastomer a strong adhesive property to bind the materials for the inner and outer layers.
That is, the present invention relates to a multi-layer hose for automobile cooling systems comprising at least two layers of inner layer and outer layer wherein:
(1) the material for inner layer comprises a composition which contains a polymer having a carboxyl group and/or its derivative group in the molecule and a thermoplastic elastomer, the content of the polymer having a carboxyl group and/or its derivative group in the molecule being 5-50% by weight based on the total weight of the composition, and
(2) the material for outer layer comprises a polyamide thermoplastic resin,
said thermoplastic elastomer being a dynamically crosslinked olefin thermoplastic elastomer which comprises (A) 10-90 parts by weight of an ethylene-&agr;-olefin copolymer comprising ethylene and an &agr;-olefin of 3-12 carbon atoms produced using a metallocene catalyst and (B) 90-10 parts by weight of a propylene resin [total amount of (A) and (B) being 100 parts by weight].
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be explained in detail below.
In the present invention, the multi-layer hose basically has a structure of the inner layer and the outer layer as adhered together side by side, but the multi-layer hose may have such a structure that an intermediate layer, which has adhesion to both of the inner layer and the outer layer, is put between the inner layer and the outer layer. For example, the intermediate layer composed of polypropylene modified with maleic anhydride may be used.
First, the materials used for inner layer of the multi-layer hose for automobile cooling systems according to the present invention will be explained.
The materials for inner layer comprise a composition which contains a polymer having a carboxyl group and/or its derivative group in the molecule and a thermoplastic elastomer. These components will be specifically explained.
1. Polymer Having a Carboxyl Group and/or Its Derivative Group in the Molecule
In the present invention, for developing adhesiveness at the interface with the polyamide material as a material for outer layer, a dynamically crosslinked olefin thermoplastic elastomer in combination with a polymer having a carboxyl group and/or its derivative group in the molecule are used as the material for inner layer.
The term “derivative group” means a group which is obtained by a chemical reaction of a carboxyl group and has adhesion to polyamide materials. For example, an anhydride group, a glycidyl ester group, an amide group and an imide group may be mentioned.
Here, the polymer having a carboxyl group and/or its derivative group in the molecule of the present invention has no limitation, and any polymers can be used as far as a carboxyl group and/or its derivative group are introduced into the polymers. Preferred are polyolefin resins having a carboxyl group and/or its derivative group. Examples thereof are (a) polymers which are modified so that they have a carboxyl group and/or its derivative group, preferably olefin polymers modified with an ethylenically unsaturated carboxylic acid and/or a derivative thereof, and (b) polymers containing an ethylenically unsaturated carboxylic acid and/or a derivative thereof as a copolymer component or a graft component, preferably olefin polymers containing an ethylenically unsaturated carboxylic acid and/or a derivative thereof as a copolymer component or a graft component.
The polymers of type (a) or (b) mentioned above may be used directly or by diluting those with other resins (preferably a polyolefin resin).
The polymers of type (a) mentioned above will be explained in detail.
The polymers which are modified so as to have a carboxyl group and/or its derivative group have no
Ijima Toshiro
Uchida Kensuke
Asahi Kasei Kabushiki Kaisha
Nolan Sandra M.
LandOfFree
Hose for automobile cooling system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hose for automobile cooling system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hose for automobile cooling system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3046333