Stock material or miscellaneous articles – Hollow or container type article – Polymer or resin containing
Patent
1997-07-03
1999-03-23
Raimund, Christopher
Stock material or miscellaneous articles
Hollow or container type article
Polymer or resin containing
428 369, 428103, 2642091, B29D 2200, D01D 524
Patent
active
058856749
DESCRIPTION:
BRIEF SUMMARY
INDUSTRIAL FIELD OF THE INVENTION
The present invention relates to a lining material, for repairing or reinforcing, for the inner surface of pipelines mainly buried under the ground such as gas conduits, city water pipelines, sewer pipelines, power line, communication line or other laid pipelines.
PRIOR ART
The lining material for such pipeline is required to have airtight coating layer for preventing inner fluid from leaking through damaged section of a pipeline or for preventing ground water from infiltrating into the pipeline.
When a pipeline is partially missing, the lining material is required to have considerably strength for ensuring the inner channel by filling such missing section.
As the construction of such lining material, a tubular unwoven fabric wherein an airtight coating layer is formed on a surface corresponding to the inner surface in its lined state is known.
As it is difficult to manufacture unwoven fabric in tubular form, sheet form unwoven fabric has usually been rolled to form a tube and to form coating layer on it.
For example, in the Specification of the U.S. Pat. No. 4,446,181, it is described a lining material for lining wherein an airtight coating layer is formed in tubular form on one surface of a sheet unwoven fabric, which is rolled with the coating layer outside and of which both side edges are stitched up, an airtight narrow ribbon is applied to the surface of the stitched part, then inserted into a pipeline while turning the lining material inside out.
On the other hand, the JP, A, H1-221223 describes a sheet form unwoven fabric which is rolled in a tube form of which both side edges are stitched up and a tubular coating layer is extruded on the outer surface thereof to be integrated therewith. This material is also inserted into a pipeline while turning it inside out to line the inner surface of the pipeline.
PROBLEMS TO BE RESOLVED BY THE INVENTION
In the lining material described in said Specification of U.S. Pat. No. 4,446,181, as the airtightness of the stitched part is ensured by the ribbon pasted to said stitched part, if the adhesion of the ribbon to the coating layer is insufficient, the inner fluid may leak out.
Especially in the lined state, as the ribbon is pasted to the inside of the stitched part, the ribbon may peel off under the pressure of ground water or others infiltrated through a damaged section of the pipeline and the airtightness may be lost.
When the lining material is applied to the inner surface of a pipeline, the lining material slightly expands in diameter of the pipeline to open the stitched part and, as the result, to exert a tensile strength breadthwise to the ribbon attached over said stitched part. Consequently, it is highly probable that the ribbon may peel off when an external force such as said ground water is applied.
In the lining material described in the JP, A, H1-221223, a tubular unwoven fabric stitched in tubular form in order to manufacture this lining material is passed through an extruder and a tube of synthetic resin is extruded onto the surface of the tubular unwoven fabric to form the coating layer. At this time, in order to improve the adhesion of this tube to the tubular unwoven fabric, the pressure is reduced from the inside of the tubular unwoven fabric; however, the air permeability of the stitched part is higher than the other parts in the tubular unwoven fabric as a sheet unwoven fabric is abutted in the stitched part and, moreover, stitched holes of suture are also air-permeable.
As the consequence, when decompressed from inside of the tubular unwoven fabric, the tube is sucked inside at the stitched part of the abutted part of the sheet unwoven fabric or stitched holes so that pinholes may occur. Even if pinholes are not produced, it is inevitable that the stitched part becomes thinner than the other parts.
In these lining materials, when stitched parts or needle holes open in lining as mentioned before, the thinner section may produce pinholes, through which not only the fluid may leak out, but also the tube
REFERENCES:
patent: 4446181 (1984-05-01), Wood
Maemoto Yukikazu
Saito Hitoshi
Ashimori Industry Co. Ltd.
Raimund Christopher
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