Patent Application
20060091158
The invention relates to caulk cartridges, and particularly relates to caulk cartridges formed principally of polymer materials.
Traditionally, caulk cartridges have been formed from wound paperboard tubes having an impervious liner and an outer label. The liner for high-barrier applications requiring a very low oxygen transmission rate (OTR) as well as low water vapor transmission rate (WVTR) typically comprises an aluminum foil laminate.
More recently, plastic caulk cartridges have been developed. While plastic cartridges have very low WVTR, many tend to have a high OTR and hence cannot be used in applications requiring a high oxygen barrier. Heretofore, to improve the oxygen barrier performance of plastic cartridges, one approach has been to coextrude a cartridge body as a two-layer structure including an inner layer of material such as EVOH that provides a high oxygen barrier but is relatively expensive, and an outer layer of material (such as polyethylene) that is a poorer oxygen barrier but is considerably less expensive. Because of the high cost of the high-barrier material and the complexity and high cost of the coextrusion equipment and process, cartridges made in this manner tend to be quite expensive such that they cannot effectively compete with paperboard caulk tubes.
The invention addresses the above needs and achieves other advantages, by providing a caulk cartridge and method of making same, employing a relatively inexpensive barrier label in conjunction with a relatively inexpensive cartridge body. More specifically, the barrier label has a non-foil barrier layer such as polymer film (e.g., PET or polypropylene) that is metallized, SiOx-coated, or AlOx-coated, and at least one heat seal layer forming at least one of the opposite surfaces of the label. The label is wrapped convolutely about the cartridge body and its opposite edges are overlapped and heat sealed together via the at least one heat seal layer.
In one embodiment, the label has only one heat seal layer; the opposite surface of the label from the heat seal layer can be formed by the barrier layer or by another layer such as a paper backing layer laminated to the barrier layer. To heat seal the label edges together, one edge is folded inwardly to place the heat seal layer on the folded edge in contact with the heat seal layer on the opposite (non-folded) edge.
In a preferred embodiment, the label has two heat seal layers forming both opposite surfaces of the label. In this embodiment, the label edges form a simple lap seam (i.e., with no fold). One preferred label structure comprises a barrier layer of metallized polymer film sandwiched between two heat seal layers.
The invention also encompasses a method for making a cartridge body. The method entails extruding a continuous tubular cartridge body of polymer composition (e.g., polyethylene), and as the cartridge body advances downstream of the extruder, a continuous web of barrier label is advanced alongside the cartridge body and is wrapped convolutely about the body, and the opposite edges of the label are overlapped in suitable lap or fold seam fashion depending on the label structure. A continuous heat seal process then heat seals the overlapped edges together. The cartridge body with applied label can then be advanced to a cutting station where the body is cut into discrete lengths for formation into caulk cartridges. The method can also include the step of printing the outer surface of the label with graphics and indicia. The printing can be accomplished prior to the step of advancing the label to the cartridge body and wrapping the label about the body; alternatively, the printing can be accomplished after the body with applied label has been cut into discrete lengths.
A caulk cartridge in accordance with the invention can include a nozzle affixed to one end of the cartridge body in suitable fashion, such as by spin-welding. The opposite end of the body is closed by an axially slidable plunger that engages the inner surface of the cartridge body.
Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
The present inventions now will be described more fully hereinafter with reference to the accompanying drawings, in which some but not all embodiments of the invention 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.
With reference to
The caulk tube 10 also includes a high-barrier label 18 wrapped tightly about the outer surface of the tubular body 12 in a convolute fashion. Alternatively, the label 18 could be spirally wrapped about the body. The opposite longitudinal edges of the label form an overlap joint 20 and are sealed together. The label comprises a multi-layer structure including at least one barrier layer providing a barrier against transmission of oxygen, and at least one sealant layer for sealing the edges of the label together, as further described below with reference to particular embodiments of the label.
Thus,
With a label having heat seal layers on its opposite surfaces, such as the illustrated label 18, the overlap joint of the label can be a simple lap joint as depicted in
An advantageous process for forming caulk tubes in accordance with certain embodiments of the invention is illustrated in
The discrete lengths of the tubular body 12 with applied label 18 can be subjected to a further downstream printing operation (not shown) for printing graphics and indicia on the exterior of the label, if desired. The tubular bodies can then be assembled with nozzles 14, filled with product, and closed by applying plungers 16.
As noted, various label structures can be used in accordance with the invention. An alternative label 118 in accordance with another embodiment of the invention is shown in
The tubular body 12 of a caulk tube in accordance with the invention advantageously need not provide oxygen barrier performance because the label 18 provides adequate oxygen barrier performance. The tubular body can, and preferably does, provide moisture barrier performance. Accordingly, the tubular body can be formed of relatively inexpensive materials such as polyethylene (e.g., high-density polyethylene), polypropylene, or the like, and can be a simple one-layer extrusion rather than a more complex and expensive multi-layer coextrusion.
The illustrated embodiments in
Finally, it must be noted that the process of
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. 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.
