Pipes and tubular conduits – Flexible – Corrugated
Reexamination Certificate
1999-11-12
2001-02-27
Hook, James (Department: 3752)
Pipes and tubular conduits
Flexible
Corrugated
C138S126000, C138S127000, C138S133000, C138S144000, C138S153000
Reexamination Certificate
active
06192940
ABSTRACT:
BACKGROUND OF THE INVENTION
Hoses mainly formed with a polyvinyl chloride resin (PVC) have been usually used because of their excellence in thermal moldability and low production cost. For example, there are known hoses comprising a hose wall and a hard wire reinforcement which is covered with a resin and united with the hose wall. The hose is produced by spirally winding a hard wire reinforcement covered with a PVC resin on a mandrel, covering the covered reinforcement with a tube of a soft PVC resin or spirally winding a tape of a soft PVC resin on the covered reinforcement to form a hose wall, and separating from the mandrel.
However, there have arisen global environmental problems in recent years, such as poisonous gases generated by burning PVC waste, an acid rain caused thereby and the fact that the PVC itself is considered as a carcinogen. Thus, there is a trend toward a restriction on the use of the PVC resin. Moreover, there have been problems in hoses made of PVC resins in that they are rather heavy and difficult to handle.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a hose for an electric cleaner which is lighter and free from PVC with maintaining the same flexibility as that of the conventional PVC hoses.
It is another object of the present invention to provide a hose which ensures the inhibition of the tearing or damage of the covering layer for the hard wire even when the hose is produced by spirally winding a hard wire reinforcement on a mandrel.
It is still another object of the present invention to provide a hose having a improved adhesion strength between a hose wall and a spiral reinforcement.
The present invention provides the following hose or tube structures to accomplish the above objects.
(1) A hose for an electric cleaner which comprises a hose wall comprising a soft or flexible synthetic resin, and a hard spiral reinforcement fused with or bonded to the hose wall, wherein the hose wall comprises at least one layer of a chlorine-free thermoplastic elastomer (e.g., polystyrenic thermoplastic elastomers, polyolefinic thermoplastic elastomers and polyurethane-series thermoplastic elastomers (TPUs)), the hard spiral reinforcement comprises a hard wire (e.g., a hard steel wire) and at least one covering resin layer formed thereon, and the innermost layer of the hose wall and an outer layer of the covering resin layer are formed with a polymer of the same series. According to the present invention, a light and PVC-free hose can be realized by using, as the soft synthetic resin for the hose wall, the thermoplastic elastomer which is lighter than the PVC resin and has similar flexibility to that of the PVC resin.
(2) The hose wall may have a laminated structure (or a multi-layered structure) comprising an inner layer of a polystyrenic thermoplastic elastomer and an outer layer of a polyolefinic resin. Even if an oil as a softening agent being liable to bleed out to the surface in an environment of high temperatures and humidity and to cause troubles such as tackiness is added to the polystyrenic thermoplastic elastomer, no problem arises in the handling or operation of the hose. Because the outer layer constituting the surface of the hose is formed with the polyolefinic resin (such as a polyolefinic thermoplastic elastomer and an ethylene-vinyl acetate copolymer (EVA)) which can be produced without addition of the oil. In this case, it is preferable to form the outer layer thinner than the inner layer to improve or maintain high flexibility.
(3) The hose wall may have another laminated structure (or a multi-layered structure) comprising a layer formed with a polyester-series polyurethane thermoplastic elastomer (TPU) and a layer formed with a polyether-series polyurethane thermoplastic elastomer (TPU). Since the hose wall is formed with TPUs and comprises the polyether-series TPU layer which is excellent in physical properties such as water resistance and weather resistance, and the polyester-series TPU layer which is inexpensive, expression of various excellent characteristics of the TPU can be ensured at low cost.
(4) The covering resin layer may comprise at least one layer formed with at least one member selected from a polystyrenic thermoplastic elastomer, a polyolefinic thermoplastic elastomer, a polyolefinic resin, and a polyurethane-series thermoplastic elastomer. The hard spiral reinforcement may comprise a hard wire and a polyolefinic resin layer covering the hard wire. These hoses being light and substantially free from PVC resins can be realized, because the reinforcement wire is also covered with the polyolefinic resin or the chlorine-free thermoplastic elastomer.
(5) The hardness of the covering resin layer may be higher than the hardness of the hose wall (the wall is formed with, for example, the chlorine-free thermoplastic elastomer). Since the hard wire (e.g., hard steel wire) is covered with the covering layer having high hardness, for example, even if the reinforcement wire is wound tight around a molding shaft such as a mandrel, the tearing or damage of the covering resin layer can be inhibited effectively.
(6) The hard spiral reinforcement may comprise a hard wire (e.g., hard steel wire), a multi-layer formed on the hard wire (e.g., a covering inner layer formed on the hard wire and a covering outer layer on the covering inner layer). The hardness of the innermost covering layer of the multi-layer (e.g., the covering inner layer) may be higher than the hardness of the outer covering layer of the multi-layer (e.g., the covering outer layer). According to the above embodiment (6), the prevention of deformation or breakage of the covering layer is further ensured by forming the covering layer of the reinforcement into a multi-layered (e.g., double-layered) structure, and employing, as the resin for the innermost layer, the resin having a hardness higher than that of the resin for the outer layer, thereby to increase the hardness of the resin covering layer as a whole.
(7) The hose wall and the covering resin layer for the reinforcement may be formed with the same series chlorine-free thermoplastic elastomer. For example, the hose wall may be formed with a polyurethane-series thermoplastic elastomer (TPU), and the covering resin layer may be formed with a polyurethane-series thermoplastic elastomer (TPU). Since the hose wall (specifically, the innermost layer thereof) and the covering resin layer (specifically, the outer layer thereof) for the hard spiral reinforcement are formed with chlorine-free thermoplastic elastomers (e.g., TPU) of the same series, the covering resin layer can be firmly bonded or fused with the hose wall with easy manner.
(8) The hard spiral reinforcement may comprise an electrical wire covered or coated with a resin (e.g., a polyolefinic resin), a hard wire disposed adjacent to the electrical wire, and a covering resin layer (comprising, e.g., a polyurethane-series thermoplastic elastomer) which covers or closely wraps the resin covered electrical wire and the hard wire. According to the embodiment (8), the hard spiral reinforcement comprise the electrical wire such as a twisted copper wire having an insulating cover of the resin (e.g., a polyolefinic resin), the hard wire disposed adjacent to the electrical wire, and the covering resin layer (e.g., TPU) which covers or is firmly adhered to the resin covered electrical wire and the hard wire. Therefore, a lighter hose substantially free from PVC can be realized for an electric cleaner which provided with an electric circuit utilizing the hard wire (e.g., a hard steel wire), an electric circuit utilizing the covered electric wire, independently.
REFERENCES:
patent: 2898942 (1959-08-01), Rothermel
patent: 2949133 (1960-08-01), Rothermel et al.
patent: 2986169 (1961-05-01), McCormick
patent: 2998474 (1961-08-01), Pavlic
patent: 3080891 (1963-03-01), Duff
patent: 4490575 (1984-12-01), Kutnyak
patent: 5555915 (1996-09-01), Kanao
patent: 5647400 (1997-07-01), Jani et al.
patent: 5778941 (1998-07-01), Inada
patent: 5918642 (1999-07-01
Koma Tadashi
Shima Hidenori
Yamaguchi Norihisa
Hook James
Pillsbury Madison & Sutro LLP
Tigers Polymer Corporation
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