Patent Application
20060029797
Statement as to rights to inventions made under federally sponsored research and development: Not Applicable
1. Field of the Invention
The invention relates generally to the field of tapes used in a sealing function when protecting or sealing pipes, pipe joints, pipe connectors, electrical wires, cables, connectors, and the like, and more particularly to a linerless, self-shrinking, cross-linking, self-fusing elastomeric tape that includes a mesh layer that serves as a liner in storage, and yet is a part of the tape in application.
2. Brief Description of Prior Art
Many articles are coated for protection from the environment in a variety of ways including the application of a thin sheet or tape in a wrapping operation. The technology for the application of such coatings generally includes a highly tacky separate adhesive layer used to achieve adhesion to the substrate and overlapping layers to each other. These tapes are usually tacky in the relaxed state rendering them difficult to handle and, when formed into a roll or liner adhere together rendering them difficult if not impossible to unwind after a short time. To avoid this problem, self-adhering tapes of the prior art have been provided with a removable liner between overlapping layers. Removal of the liner is time consuming and may be difficult when it becomes tightly adhere to the tape.
As will be seen from the subsequent description, the preferred embodiments of the present invention overcome shortcomings of the prior art.
The present invention in the preferred embodiment is a rubber composition intended for, but not restricted to, use as a sealing tape that includes a first component that is a halogenated rubber, or combination thereof, and a second component that is a non-halogenated rubber. By inciting cross-linking between layers of the rubber composition, the one layer is substantially non-tacky in the relaxed state while the adjacent layer is tacky. Both layers are composed of a semi-cross-linked elastomer that when forced into intimate contact, will further fuse with increase of time and temperature providing improved stability and strength. This results in a continued presence of an inward pressure on the wrapped area for the life of the splice.
The tape of the present invention further includes a mesh that when in its relaxed state, acts as a release liner between the layers of the rubber composition. When the tape is wrapped in an application, the mesh is likewise stretched and wrapped allowing cross-linking between the layers of the composition through a plurality of openings in the stretched mesh. Particularly, allowing the layers to extrude through the openings of the mesh for purposes of bonding.
In accordance with the present invention, a linerless, self-fusing, cross-linking elastomeric tape is disclosed. The present invention discloses a rubber composition that is substantially non- tacky in the relaxed state but whose overlapping layers cross-link layer to layer when stretched and wrapped on a substrate. In the broadest context, the composition blend of the present invention consists of components configured and correlated with respect to each other so as to attain the desired objective.
Referring to
Any cross-linkable polymer may be employed in the practice of this invention. The halogenated rubber component may include, but is not in any way limited to, the following polymers: butyl rubber, halogenated butyl rubber, isobutylene, homopolymer, ethylene/propylene/diene terpolymers, ethylene/propylene copolymers, polybutadiene, polyisoprene, halogenated isoolefin/paralkylstyrene copolymer, natural rubber and combination mixtures thereof.
The blend composition 12 further includes a cure system to allow the resultant product to have cross-linkable properties at room temperature. The cure system as will be described is preferably blended with the halogenated rubber component.
The cure system is a combination of phenolic resins. The amount of the curing agent will generally vary depending upon the types utilized and especially the desired degree of cure, as is well recognized in the art. However, in general, the preferred embodiment of the cure system is about 0.5% to about 1.5% of the total mixture blend.
It has now been found that the incorporation in the halogenated rubber component of the described cure system, in the amounts described, produces a marked improvement in the resultant product's cross-linking properties and further causes the blend to be room temperature cross-linkable.
Various additives can be further used in suitable amounts. For example, various reinforcing agents or fillers known in the art may be combined with the blend 12 at any point during production. Further, various colorants may be added such as carbon black and the like, and various resins known in the art can be utilized in the present blend. Moreover, the inclusion of a separate tackifier known in the art and known for its intended purposes preferred.
The described mixture 12 further incorporates a petroleum product, preferably polybutene. The preferred proportion of polybutene in the mixture is from about 20% to about 30% of the total mixture.
The first halogenated rubber component which includes the cure system, and the non-halogenated component are combined in amounts effective to produce the desired improvement in strength and stability. The relative amounts are as follows:
The relative proportions of the halogenated rubber component used in the practice of the present invention fall within a rather narrow range. The proportion of the halogenated rubber component is from about 10% to about 25% of the total blend. A wetting agent known in the art is further included with the halogenated rubber component. The wetting agent as is known, causes the mixture to blend easier. The preferred proportion of the wetting agent is from about 0.5% to about 1.5% of the total blend;
It is preferred to use from about 1% to about 1.5% of colorant in the total blend. To achieve the desired effect it is preferred to use carbon black in the composition;
As stated, the preferred proportion of petroleum product in the mixture is from about 20% to about 30% of the total mixture;
The amount of a particular filler or pigment which can be used without adversely effecting the fusion properties for example of the resultant product can be readily determined by those skilled in the art. However, such filler can be included in an amount equal to about 48% to about 55% of the blend;
The amount of the tackifier in the mixture is from about 0.5% to 1.5% of the total mixture;
Provided that the proportion of the halogenated rubber component (including the wetting agent and the cure system) in the mixture does not exceed about 30% of the total blend; and
The proportion of the cure system in the mixture does not exceed about 1.5% of the total mixture.
The mesh 14 is a bendable, deformable, and stretchable netting constructed of, but not limited to, cloth, metal, or rubber material. As best shown in
As stated, while the tape lo is in storage, the mesh layer 12, unstretched, serves as a release liner between layers of the tape 10. In its stretched state, the mesh 14 allows cross-linking between layers of the composition 12. As a result, a removable liner as disclosed in the prior art is unnecessary.
The resulting tape product is strong but can be readily stretched without breaking and is readily handleable over a wide temperature range.
In practicing the present invention, there is formed a blend which is capable of cross-linking, and when stretched, tries to exert continuous force to the application which thereby affects the seal. The blend further demonstrates the presence of a strong cross-link network that upon time and temperature will cross-link the mastic to the elastomer.
The composition blend is prepared by mixing procedures well known in the art, using conventional techniques. This may include for example, initially blending the ingredients in solid form using standard blending equipment at elevated temperatures to improve blending. The resultant blend is then usually cooled, and preformed. Sheets may be prepared such as by passing the blend through a calendar or an extruder equipped with a sheet die. Tapes are produced by cutting the sheet to form tapes having the desired width. Post cross-linking of both layers is affected during the above process.
Further, the mixing order is not critical. For convenience, the components may be blended at one time. Alternatively, the halogenated rubber component (and components of the described cure system) may be blended first, followed by addition of the non-halogenated components and additives.
Layers of the rubber composition 12 are post cured after forming into the final product. The application forms a stretchable tape with “built-in” memory to reform back to its shape before stretching.
Attachment means of the mesh 14 to the formed blend 12 is known in the art.
Referring to
It has been found that the blended composition demonstrates substantially improved thermal and aging stabilization. Thus, not only is the strength improved, the over characteristics of the resultant product are improved.
The resulting tape of the present invention may be used in a wide variety of applications such as splicing, encapsulation, and connection.
Although the description above contains many specificities, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of the invention. It will be obvious that embodiments described may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the present invention.
Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given.
U.S. Provisional Application for Patent No. 60/573,065, filed Aug. 9, 2004, with title “Linerless, Self-Fusing Elastomeric Tape” which is hereby incorporated by reference. Applicant claims priority pursuant to 35 U.S.C. Par. 119(e)(i).
| Number | Date | Country | |
|---|---|---|---|
| 60573065 | Aug 2004 | US |
