Labeling machines are used to apply labels to all types of containers, both cylindrical containers and non-cylindrical containers, such as regular and irregular shaped polygons. One type of conventional label is a self-stick label, also called a pressure-sensitive label, which is carried by a backing strip or carrier web. Self-stick labels are expensive and create a large amount of waste. Self-stick labels typically used with high-density polyethylene (HDPE) containers, such as milk jugs and juice bottles, are commonly a paper/propropylene/adhesive laminate. In applying the conventional self-stick or pressure sensitive labels to containers, the carrier web with spaced apart labels affixed thereto is unwound from a supply roll and pulled over a bar or blade causing each label to separate from the carrier web, which carrier web is then disposed of. Means are then provided to transfer each label to a container.
The above described method has a number of important limitations and disadvantages. First, the carrier web required for this process adds significant cost to the label being applied. Second, the process of die-cutting on a supporting web limits the type of label materials that can be utilized. Third, the label must be peeled off the carrier web at point of application. This creates limitations in line speed potential, further limits the type of label materials which can be used, such as lightweight stock. In addition it greatly reduces the accuracy of application to the container. Another type of commonly used label is cut from continuous label material wound onto a roll. Labels made from continuous label material are more economical than self-stick labels and are often made from thin, stretchable film. To reduce the cost, the film keeps being made thinner. The stretchiness of the film can make it difficult to ensure that the labels are properly cut.
Conventional labeling machines remove the continuous label material from the roll and feed the label material to a cutting system. The continuous label material is then cut into labels which are transferred onto the circumferential surface of a vacuum drum where they are held in place by vacuum. As the drum rotates the labels pass a glue roller which applies adhesive to the back surface of the label, which is facing outwardly as supported on the drum. The label, with the adhesive applied thereto, is released from the drum as it comes into contact with and is applied to a container.
U.S. patent application Ser. No. 09/024,886 filed Feb. 17, 1998 and Ser. No. 09/301,955 filed Apr. 29, 1999 of which I am a co-inventor, disclose an adhesive station and labeling machine for applying a pressure sensitive label to a container wherein adhesive is sprayed on one side of the label material after the label material has been severed from a web of label stock. The method and apparatus disclosed in those previous applications, incorporated herein by reference, eliminate the need for having a backing strip which is customarily used for carrying a pressure-sensitive label.
Under the present invention, a web label material is fed from a roll or other source of label stock to an adhesive applicator station which applies adhesive to the side intended to be adhered to the container, namely, the side opposite the printing. Following the application of adhesive, the web passes through a cutting station where the individual labels are cut while being supported by vacuum on a rotatable vacuum drum. Although it is possible to have the entire surface of the label intended to face the container covered with adhesive, for many applications it is preferred that the adhesive cover only an area of xc2xd to 1xe2x80x3 adjacent each end. By cutting the web of label material after the adhesive has been applied thereto and cutting through the adhesive as well as the web, it is assured that each label will have adhesive completely to each end thereof. This assures bonding of the labels to the containers completely to each end and avoids the problem of xe2x80x9cflaggingxe2x80x9d of label ends having inconsistent adhesive application.
The web of label material can be any one of a variety of materials including but not limited to foam polystyrene, other foam polymers, polypropylene film, other polymer film and paper. Under one embodiment, cutters or knives are mounted on the rotating vacuum drum and a second rotating drum acts as an anvil cooperable with the vacuum drum to cut the web into labels. Following cutting, each newly cut label, supported on the rotating vacuum drum, successively engages a container while its adhesive is in condition for adhering to the container.
A second embodiment, also uses any suitable label material in roll form, including lightweight label stock. The web of label material is fed to an adhesive application station and a rotary die cutter.
As the continuous web of label material with hot melt adhesive applied thereto is fed into the applicating system, it passes a rotary die cutter adjacent and in contact with a rotary backup and transfer drum containing vacuum applicator plates. Each label is supported on one of a series of vacuum applicator plates which are mounted on a rotatable back-up drum. The vacuum applicator plates are mounted for rotation with the drum and are moveable radially from a retracted position when receiving the web from the adhesive application station and when at the cutting station to a radially outwardly extended position, at which extended position each vacuum applicator plate joins the label to a container. Under the second embodiment, the cutters or knives are mounted on a second rotatable drum positioned to cut a label from that portion of the web which is then aligned with the vacuum applicator plate. The newly cut labels are then successively moved to a container while being retained on the vacuum applicator plate. As the vacuum applicator plates successively move from the cutting station to the application station, they are moved radially outwardly to the extended position.