Pipes and tubular conduits – Flexible – Braided – interlaced – knitted or woven
Reexamination Certificate
2000-05-25
2001-10-23
Hook, James (Department: 3752)
Pipes and tubular conduits
Flexible
Braided, interlaced, knitted or woven
C138S122000, C138S133000, C138SDIG003, C138S127000, C428S036910
Reexamination Certificate
active
06305428
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to hoses excellent in flexibility and useful as electric cleaner hoses.
BACKGROUND OF THE INVENTION
Due to their excellence in thermal moldability and low production cost, hoses mainly formed with polyvinyl chloride resins (PVC) have generally been employed as electric cleaner hoses. For example, hoses composed of a hose wall and a wire reinforcement covered with a resin and united with the hose wall are known. A hose like these can be fabricated by spirally winding a resin-covered wire reinforcement, which is a steel wire covered with a PVC resin, around a mandrel, further covering the resin-covered reinforcement with a tube of a soft PVC resin or spirally winding a tape of a soft PVC resin around the resin-covered reinforcement to form a hose wall, separating the hose thus formed from the mandrel. In the hose thus obtained, the hose wall and the resin-covered reinforcement are bonded together or fused such as to be unitary with each other.
However, for making soft PVC resins flexible, a variety of liquid plasticizers are added thereto . When hoses fabricated with such soft PVC resins are used over long periods of time, the plasticizers contained therein begin to bleed out (seep out) on their surfaces. As a result, the plasticizer content of the PVC is lowered with an increase in hardness (stiffness). Consequently, these hoses become less flexible and their risk of fatigue failure becomes higher as the hoses are bent repeatedly.
In addition, with such recent global environmental problems as poisonous gases generated by burning PVC waste leading to an acid rain as well as the PVC itself being considered carcinogenic, there is a trend toward imposing restrictions on the use of PVC resins. Moreover, hoses made with PVC resins are rather heavy and difficult to handle.
U.S. Pat. No. 6,024,134 discloses a hose which comprises a hose wall formed by spirally winding a laminated tape and bonding the adjacent side edges of the covering layer each other, and a hard spiral reinforcement for reinforcing the hose wall and retaining the hose configuration, wherein the laminated tape is constituted of a main layer of a polyester-series thermoplastic resin polyurethane resin and a covering layer of a soft resin is laminated on at least one surface of the main layer. This literature describes that this hose is excellent in flexibility and durability, the degree of its shrinkage is low, and that it can favorably be used as a duct hose.
SUMMARY OF THE INVENTION
Thus, an object of the present invention is to provide a flexible hose capable of maintaining its excellent flexibility over a long period of time.
Another object of the present invention is to provide a lighter hose with excellent flexibility without using a halogen-series resin (e.g., PVC).
Still another object of the present invention is to provide a hose which is useful as an electric cleaner hose.
The inventors of the present invention made intensive studies to achieve the above objects and finally found that a hose with excellent flexibility can be obtained by: forming a hose wall with a resin composition comprised of a resin component containing a specific rubber component and an olefinic resin, and a lubricant to be added to the resin component; and providing a spiral reinforcement of an olefinic resin whereby the shape of the hose wall is maintained. The present invention was accomplished based on the above findings.
In summary, the flexible hose of the present invention comprises a soft hose wall (A) and a spiral reinforcement (B) for retaining the configuration of the hose. The hose wall (A) is formed with a composition comprised of (A
1
) a resin component containing a diene-series or hydrogenated diene-series rubber component and an olefinic resin, and (A
2
) a lubricant.
The rubber component may be a random or block copolymer of styrene and butadiene. The olefinic resin may be a polypropylene-series resin. The ratio of the rubber component to the olefinic resin may be about 30/70 to 95/5 (weight ratio). The lubricant (A
2
) may be a higher fatty acid or its derivative (e.g., a higher fatty acid amide), a higher alcohol or its derivative, a hydrocarbon-series wax, a polyorganosiloxane (e.g., a silicone oil), or a fluorine-containing resin. The amount of the lubricant (A
2
) may be 0.1 to 10 parts by weight relative to 100 parts by weight of the resin component (A
1
) constituting the hose wall. The spiral reinforcement (B) is formed with an olefinic resin (B
1
) harder than the resin component (A
1
) of the hose wall. The modulus of bending elasticity of the spiral reinforcement (B), determined by a tension test in accordance with Japanese Industrial Standard K 6758, may be 10,000 kgf/cm
2
or higher. The spiral reinforcement may be hollow, and into the hollow may be inserted an electric conductor.
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patent: 6024134 (2000-02-01), Akedo et al.
patent: 6037025 (2000-03-01), Matsunaga et al.
Nakamura Sakuro
Shima Hidenori
Hook James
Pillsbury & Winthrop LLP
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