Recoverable articles
AssigneeRaychem Corporation
InventorsJohn A. Midgley, David D. Nyberg
Life of this patent
Estimating the term…
Abstract
Flexible hollow articles comprise an expanded elastomeric inner member and an outer restraining means. The restraining means is made of a notch-sensitive material so that when score lines are made in the restraining means, they can be propagated through the material by distorting the article. The stiffness and elongation of the restraining means, and the peel strength of the bond between the inner member and the restraining means, are so chosen that when suitable score line are made in the restraining means, at least part of the restraining means can be pulled away from the inner member, thus permitting the inner member to recover. The articles are useful for covering substrates, especially splices and terminations in electrical cables.
Claims48
A flexible, shrinkable, hollow article which comprises
- (1) a hollow inner member which is composed of an elastomeric material and which is in a radially extended condition;
- and
- (2) a hollow outer restraining means
- (a) whose inner surface is secured to the outer surface of said inner member and which maintains said inner member in said radially extended condition, said inner and outer surfaces being secured to each other by a bond whose peel strength is less than 50 lb. per linear inch width at 21.degree. C.;
- (b) whose outer surface forms the outer surface of said article and is free of score lines whose depth is 5 to 90% of the thickness of the restraining means;
- and
- (c) is composed of a material which
- (i) has a 2% secant modulus at 21.degree. C. of 4,000 to 120,000 psi;
- (ii) has an ultimate elongation at 21.degree. C. of at least 20% at a separation speed of 200% per minute and at most 150% at a separation speed of 2,000% per minute;
- and
- (iii) has a notch sensitivity such that when there is formed in the outer surface of the restraining means a score line whose depth is 5 to 90% of the thickness of the restraining means, then by distorting the article so as to exert a bending moment about the axis of the score line, the depth of said score line can be substantially increased.
A flexible, shrinkable, hollow article which comprises
- (1) a hollow inner member which is composed of an elastomeric material and which is in a radially extended condition;
- and
- (2) a hollow outer restraining means
- (a) whose inner surface is secured to the outer surface of said inner member through a layer of a hot melt adhesive and which maintains said inner member in said radially extended condition, said inner and outer surfaces being secured to each other by a bond whose peel strength is 4 to 30 pli at 21.degree. C. and at least 4 pli at 49.degree. C.;
- (b) whose outer surface forms the outer surface of said article and is free of score lines whose depth is 5 to 90% of the thickness of the restraining means;
- and
- (c) is composed of a material which
- (i) comprises an organic polymer;
- (ii) has a 2% secant modulus of 15,000 to 100,000 psi at 21.degree. C. and at least 4,000 psi at 49.degree. C.;
- (iii) has an ultimate elongation at 21.degree. C. of 35 to 120% at a separation speed of 200% per minute;
- and
- (iv) has a % Torn Depth of at least 40%.
A flexible, shrinkable, hollow article which comprises
- (1) a flexible hollow inner member which is composed of an elastomeric material and which is in a radially extended condition;
- and
- (a) whose inner surface is bonded to the outer surface of the inner member and which maintains the inner member in the radially extended condition, the inner and outer surfaces being bonded to each other by a bond whose peel strength is 7 to 15 lbs. per linear inch width at 21.degree. C.;
- (b) whose outer surface forms the outer surface of said article and is free of linear indentations whose depth is 5 to 90% of the thickness of the restraining means;
- and
- (c) is composed of a material which
- (i) has a notch sensitivity such that, when there is formed in the outer surface of the restraining means at least one linear indentation whose depth is 50 to 90% of the thickness of the restraining means, they by distorting the article so as to exert a bending moment about the axis of such a linear indentation, the depth of such linear indentation can be substantially increased to provide at least one section of the restraining means which can be pulled away from the inner member;
- and
- (ii) has a 2% secant modulus at 21.degree. C. of 15,000 to 40,000 psi and has an ultimate elongation at 21.degree. C. of 50 to 100% at a separation speed of 20% per minute, wherein the material has sufficient flexibility that (a) the cross-section of the restraining means can be deformed without breaking the bond between the inner member and the restraining means and (b) such a pulled away section can bend through at least a 90.degree. angle without cracking.
Dependencies are inferred from the claim text.