Stock material or miscellaneous articles – Sheets or webs edge spliced or joined
Patent
1993-07-09
1995-03-14
Weston, Caleb
Stock material or miscellaneous articles
Sheets or webs edge spliced or joined
156 85, 156 86, 264230, 264342R, 428 77, 428 78, 428913, B32B 3126
Patent
active
053976150
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to heat shrinkable wraparound articles for covering elongate objects such as pipes or cables, or joints therebetween.
2. Introduction to the Invention
Heat shrinkable polymeric or fabric based articles are well known. Typically the articles are in the form of sleeves which possess the property of being able to shrink to smaller diameters when heated. Such a sleeve is constructed with a diameter large enough so that it can conveniently be placed about a substrate, and then it is heated, the heat causing it to shrink to conform to the substrate.
The heat shrinkable sleeves may be closed in cross-section, but, for ease of application inter alia they are preferably wraparound. Examples of such wraparound sleeves are described, for example in U.S. Pat. No. 3,455,336 (Ellis), and in U.S. Pat. No. 4,200,676 (Caponigro, Lopez), U.S. Pat. No. 4,586,971 (Wallace), EP 0163508 (Leest, Peigneur, van Beersel), U.S. Pat. No. 4,359,502 and JP 54-149780 (appno 53-59167).
In the above described wraparound heat shrinkable sleeves, the so-called closures for holding the wraparound closed, i.e., for holding the mating or overlapped ends of the sleeves together, may be mechanical, for example as described in U.S. Pat. No. 3,455,326, or based on direct bonding e.g. by adhesive or fusion, e.g. as described in U.S. Pat. No. 4,200,676 or in JP 54-149780. Where they are based on bonding to, or by, overlapped edges, it is typical to use a laminar panel or patch to bond to the overlapped edges. In these cases it is desirable not only to heat the article to shrink it, and perhaps also to activate an adhesive on the patch, but also to "pat" the patch, i.e. to provide a downward pressure on the patch, typically with a gloved hand, in order to form a good bond. Similarly where direct fusion is used to bond directly overlapped edges, it is typical to leave a section of the sleeve uncoated with adhesive to enable the sleeve (typically polyethylene) to bond to itself. In this case also a downward pressure onto the bonded area is desirable. In these applications it is also necessary to prevent the sleeve ends from slipping relative to each other, causing the wraparound sleeve to open. In certain situations application of a downward pressure and prevention of sleeve end slippage is difficult, if not impossible to achieve.
SUMMARY OF THE INVENTION
We have discovered a method of joining the ends of a wraparound cover which automatically generates a downward or radial pressure on the overlapped ends of the sleeve, and optionally also on a patch. The method also prevents relative slippage of the overlapped sleeve ends.
Thus the first aspect of the present invention provides a method of covering an elongate substrate comprising:
(i) positioning a wraparound heat shrinkable cover around the substrate so that the ends thereof overlap;
(ii) positioning a first laminar panel over the line defined by the overlapped ends of the cover, the first laminar panel being bondable (either directly, or by the action of an adhesive coating on at least part of its surface facing the cover) to the cover, at least when activated by heat;
(iii) positioning a second laminar panel over the first laminar panel, the second laminar panel being wider than the first laminar panel, so that its longitudinal edges project beyond the edges of the first laminar panel, and securing the said projecting longitudinal edges to the underlying cover portions, without the application of heat; and
(iv) applying heat, wnereby the cover begins to shrink generating hoop stresses in the cover which tension the second laminar panel secured thereto, causing it to exert a generally radially directed force onto the underlying first laminar panel.
In one embodiment according to the invention the first laminar panel itself, or an adhesive coating thereon, must be activated by heat to bond it to the cover.
This invention is particularly advantageous for covering joints in weight coated steel pipes. Weight coated steel p
REFERENCES:
patent: 3455336 (1969-07-01), Ellis
patent: 3770556 (1973-11-01), Evans et al.
patent: 4200676 (1980-04-01), Caponigro et al.
patent: 4356222 (1982-10-01), Harakawa et al.
patent: 4359502 (1982-11-01), Caponigro et al.
patent: 4424246 (1984-01-01), Pieslak et al.
patent: 4586971 (1986-05-01), Wallace
patent: 4731273 (1988-03-01), Bonk et al.
patent: 5022941 (1991-06-01), Doheny, Jr. et al.
Translation of Japanese Patent 54-149780, Showa Electric Wire & Cable Co., publication date Nov. 24, 1979.
British Serach Report, British Patent Application No. 9100373.1, Apr. 26, 1991.
International Search Report, International Application No. PCT/GB92/00028, Mar. 20, 1992.
John Robin
Van Beersel Jos
Burkard Herbert G.
Gerstner Marguerite E.
N.V. Raychem S.A.
Weston Caleb
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