Patent Application
20070084556
Various products such as personal care or cosmetic products (e.g., toothpaste and lotions) are sold to consumers in flexible plastic tubes. Squeezable tube-shaped containers have a tubular body with one end heat-sealed along a straight line seam. For instance, see U.S. Pat. Nos. 5,632,951; 3,197,532; 5,908,124; and 5,213,235, which disclose the use of blow molding techniques for forming tube-shaped containers. In addition, U.S. Pat. No. 5,908,124 discloses the formation of an integral twist-off closure to eliminate the need for providing a separately manufactured closure. Also see U.S. Pat. No. 4,540,542 which discloses a method of making an extrusion blow molded container with an integral, removable closure and U.S. Pat. No. 5,141,136 which discloses a squeeze bottle having dual openings.
Generally, the squeeze tube is formed by cross-sealing the tubular body with a cross-sealing apparatus. There are generally five techniques for sealing including hot jaw sealing, wherein the tube is pressed between a pair of heated sealing jaws; sonic welding; induction sealing where a magnetic field is used to excite foil within the tube wall structure to melt the plastic before pressing together; hot air sealing, wherein heated air is used to melt the plastic before pressing; and laser sealing where a laser is used to heat the plastic before pressing. In most cases, the tube is not labeled or decorated in the seal area because damage to the label, ink, or surface coating can occur during sealing. The label or coating can discolor due to the heat, or the label coating or ink may lose adhesion to the tube and separate due to the heat. In addition the application of label material, coating or ink on the surface of the tube in the seal area may affect the seal integrity or contaminate the inside of the seal area and prevent sealing. For these reasons the tube label and decoration generally does not cover the entire surface area of the tube.
The present invention is a method for applying a label to the sealed area of a squeeze tube. The method involves adhering a label to a tube and sealing the tube so that a squeeze tube is formed wherein the label covers the sealed area of the squeeze tube. In particular embodiments, the method involves the prestep of treating the tube under conditions which achieve a dyne level of at least 38. The present invention also relates to a squeeze tube produced by the method of the invention.
It has now been found that the labeled surface area of a squeeze tube can be extended to encompass the sealed area of the tube by applying the label to a tube prior to sealing. Particular embodiments of the invention embrace the use of an uncoated tube to promote label adhesion, while other embodiments provide that the tube is pretreated under conditions which achieve a dyne level of at least 38.
As used in the context of the instant invention, a squeeze tube is a flexible, cylindrical package made from plastic (e.g., low to high density polyethylene, polypropylene, polyvinyl chloride, and softouch, dual layer, and coextruded plastics) or laminate (ethylene vinyl alcohol resin) with one open end and one closed end. The package is filled through the open end with a machine designed for filling tubes. Subsequently, the filled tube is sealed at one end resulting in a package with a cylindrical, open end and a flattened, closed end.
For the purposes of the instant invention, a tube can be coated or uncoated prior to label adhesion. A coated tube is intended to mean a tube used in the manufacture of a squeeze tube in which an organic surface coating has been applied. Such organic surface coatings include any solvent-based, water-based or radiation-curable coating material designed to provide abrasion resistance, barrier properties and optionally enhanced gloss or matte finish. Such surface coatings include epoxies, urethanes, polyesters, acrylics, and the like. Conversely, an uncoated tube is intended to mean a tube which lacks an organic surface coating.
The method of the instant invention can be carried out with a variety of label materials using a variety of adhesives. As such, solvent-type adhesives, emulsion-type adhesives or hot-melt type adhesives are suitable so long as the adhesive selected can withstand the heat and pressure of end sealing. Such adhesives include, for example, rubbery adhesive agents, vinyl acetate adhesive agents, ethylene-vinyl acetate adhesive agents, polyvinyl alcohol adhesive agents, polyvinyl acetal adhesive agents, vinyl chloride adhesive agents, acrylic adhesive agents, polyamide adhesive agents, polyethylene adhesive agents, cellulose adhesive agents, polysulfide adhesive agents and hot-melt type high-polymer-containing adhesives.
The term label is used herein in the conventional sense to refer to a tag attached with adhesive to a surface so as to identify the object or its contents. Labels of the instant invention are affixed to the surface of a tube (i.e., not a component of the tube itself) to provide product identifiers, product source/manufacturer identifiers, bar codes, nutritional information, decoration, and the like. Labels can be made of single or multiple layers and panels of any suitable paper or plastic material commonly employed in the labeling of consumer products. Advantageously, a label of the instant squeeze tube covers all or a portion (e.g., 20%, 40%, 50%, 60%, 80%, or 100% of the surface area) of the flattened, closed end of the squeeze tube, also referred to herein as the sealed area of the squeeze tube. As such, more surface area of the consumer package is available for providing product information or decoration.
To facilitate adhesion, particular embodiments of the present invention embrace pretreating the unlabeled tube under conditions which achieve a dyne level of at least 38. In other embodiments, a dyne level of 38 to 48, or more is achieved. Such conditions include treating the tube with flame, plasma, or corona to enhance label adhesion. For example, corona treating involves discharging up to about 10,000 volts of electricity from a ceramic electrode to a ground roll over which the tube film is passing. This high voltage field called corona alters the surface of the film, raising the surface energy of the film so that label adhesion is enhanced.
Because the label of the instant squeeze tube covers the seal area of the squeeze tube, particular embodiments of the instant invention embrace the use of a tube filling and sealing machine which seals the tube by heating the internal surface of the tube so that the label is exposed to minimal heat during sealing. Suitable sealing techniques which heat the internal tube sealing surface before applying sealing pressure include hot air sealing, sonic welding, laser, and induction. Machines of this type are routinely used in the art of squeeze tube, bag and pouch manufacturing.
A label affixed to a squeeze tube in accordance with the instant method can achieve label peel strength adhesion values in the range of 1000 to 2500 grams/inch at 12 inches/minute pull speed optionally, label peel strength adhesion values in the range of 600 to 1200 grams/inch or 800 to 1500 grams/inch are also satisfactory under particular conditions.
Moreover, the label as affixed herein withstands testing that would simulate normal use of the squeeze tube including, but not limited to, the moisture resistance testing, filled and unfilled; oven temperature storage at 45° C., filled and unfilled; product resistance; water submersion; soap water testing; eight weeks-long term storage at 45° C.; and flexing.
The instant method finds application in the manufacture of squeeze tubes for a variety of consumable or purchased goods or products including consumable products such as personal care products (e.g., soaps, shampoos, make-up, insect repellents, and the like); first aid products (e.g., ointments, sunscreens, and the like); cleaners (e.g., detergents and cleaning solutions); paints; and foodstuffs (e.g., yogurt, cheese-like products, jelly, and the like). The instant method is a significant improvement in the manufacture of squeeze tubes because the product label can encompass nearly all of the available squeeze tube surface thereby enhancing the package appearance.
