Patent Application
20090291241
The present application relates to a helically wound paperboard tape core for a pavement marking tape or other highly aggressive pressure-sensitive adhesive tape.
Pavement marking tape is used to provide markings for guiding or warning drivers. The tape is highly reflective to make it visible at night. In order to adhere firmly to pavement, the tape has an extremely aggressive pressure-sensitive adhesive. As a consequence, the tape sticks tenaciously to the core about which the roll of tape is wound. The first turn of tape about the core contacts the paper surface of the core and thus this turn of the tape is not usable because it becomes fouled by paper fibers. Because pavement marking tape is relatively expensive, the cumulative cost of wasting the first turn of tape on each roll of tape produced can be significant.
Furthermore, unwinding the last turn of the highly aggressive tape from the core can also cause the outermost ply of the core to be lifted with the tape, thus delaminating the core.
The present disclosure is directed to a wound paperboard tape core designed to eliminate this waste of tape by providing a core with a clean-release surface that does not foul the first turn of tape.
A tape core in accordance with one embodiment of the invention has an outermost ply of a semi-transparent or translucent paper. On the outwardly facing surface of the outermost ply is a coating of release material such as silicone. The outwardly facing surface of the penultimate ply of the core (i.e., the ply directly underlying the translucent release-coated ply) is printed with directional indicators (e.g., arrows) showing which direction the tape should be wound about the core. The outermost ply is sufficiently translucent that the directional indicators are visible through the ply. It is important that the highly aggressive tape be wound in the correct direction in order to avoid delaminating the outermost ply from the penultimate ply upon unwinding of the tape.
In another embodiment, the directional indicators are provided on the inwardly facing surface of the outermost ply.
Directional indicators could also be provided (e.g., printed) on the inside surface of the core.
The outermost ply in one embodiment can be a super-calendered bleached kraft paper having a silicone release coating on one side.
Having thus described the disclosure in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The present invention now will be described more fully hereinafter with reference to the accompanying drawings in which some but not all embodiments of the inventions are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like numbers refer to like elements throughout.
Conventionally, tape cores formed as helically wound paperboard tubes have an outermost paperboard ply that presents a bare paperboard surface on which the adhesive tape is wound. As noted, this leads to the problem of the last turn of tape lifting paper fibers from the paperboard surface so that it loses the desired tackiness and cannot be used. Additionally, the tape can also delaminate the outermost ply from the tube. This occurs mainly when the tape is not wound in the “proper” direction about the tape core. More particularly, with reference to
To address these problems existing in prior tape cores, the tape core 10 in accordance with the present invention includes directional indicators 20 that indicate the proper direction to wind the adhesive tape about the core. The directional indicators can be, for example, arrows as shown. Preferably, there are a plurality of the directional indicators 20 spaced about the circumference of the core with a small enough circumferential spacing that in any rotational orientation of the core at least one of the directional indicators 20 is visible. It will be appreciated from
In accordance with one embodiment of the invention as illustrated in
The outermost ply 12n is shown in dashed lines in
The outermost paperboard ply 12n, as noted, is translucent. Typical paperboard plies for use in tape cores or the like have very small visible light transmissivity and would not be suitable for use in the present tape cores. Additionally, as noted, the outermost ply advantageously should be coated on its radially outer side with a release material such as silicone or the like. In accordance with the invention, a special paperboard material is employed for the outermost ply. As one example, the outermost ply can be a super-calendered bleached kraft paper that is silicone-coated on one side, and having a basis weight of about 42 lb/ream and a caliper of about 0.003 inch (0.076 mm). A suitable commercially available bleached silicone-coated kraft paper of this type is Grade 40703 available from Loparex. However, any suitable paper having sufficient visible light transmissivity to allow viewing of the directional indicators through the paper can be used. Advantageously, the outermost ply should have an opacity of about 60 to about 64 as measured by standard test procedure TAPPI T425 or ISO/DIS 2471. It will be understood that opacity is the converse of light transmissivity, such that a high opacity corresponds to a low transmissivity and a low opacity corresponds to a high transmissivity.
Alternatively, tape cores in accordance with the invention can employ an outermost ply 12n of non-paper material such as polymer film.
The tape core 10 can have various dimensions depending on the needs of a particular application. Typical tape cores have an inside diameter ranging from about 1 inches to about 6-inches, with approximately 3 inches being a commonly used size. The length of the core corresponds to the width of the adhesive tape. Typically pavement marking tape is 4 inches wide. The wall thickness of the core can range from about 0.045 inch to about 0.350 inch. As one example, a tape core in accordance with the invention can have an inside diameter of 3.015 inches, a length of 4 inches, and a wall thickness of 0.110 inch.
Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these inventions pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. For example, the directional indicators 20 can be printed on the radially outwardly facing surface of the outermost ply 12n before the release coating is applied. In this case, the release coating has a sufficiently high transmissivity to visible light that the directional indicators are visible through the release coating. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.
