Conventional screen printing on garments such as T-shirts was traditionally limited to printing over only a small portion of the middle of the shirt. Accordingly, pallets were designed which supplied the requisite support to the center portion of the shirts during printing and maintained the center portion of the shirts in a stationary position as the shirts and pallets were advanced into successive registration with each of a number of printing stations whereby the composite of the colors printed at each of the stations resulted in production of a multi-colored image on the center portion of the shirt.
Recently, there has been a demand for T-shirts having printing over substantially the entire surface of the shirt, particularly including the sleeves. To accomplish this, belt presses are employed wherein the shirts are laid flat on a conveyor belt which transports the shirts to one or more printing units. Since there is nothing inside the shirts, as there is when utilizing conventional pallets, the shirts lay completely flat, so that prints can be made to extend across the entire side of a shirt front or back with little or no gap at the lateral edges of the shirt, which gaps are unavoidable when utilizing conventional pallets. Thus, the images printed on one side of the shirt can meet the images printed on the other side of the shirt to allow for a continual image extending across the front and back of the shirt. To assure that the print extends completely to the lateral edges of the shirt and particularly to allow print to cover the sleeves, prints are actually made larger than the shirt so that the print extends beyond the outer edges of the shirt. Thus, the print extends not only over the entire side of the shirt including the sleeves, but also extends beyond the edges of the shirt, with the portion of the print extending beyond the shirt edge being applied directly onto the belt upon which the shirt rests.
Belt presses have been found to suffer numerous shortcomings. A principle shortcoming is the high initial purchase cost of belt presses. Another shortcoming is that the belt must be cleaned following each printing before another shirt can be loaded onto the belt. This results not only in additional expense associated with the washing mechanism and/or personnel to carry out the washing, but also imposes a limitation as to the types of inks which can be applied since many types of inks, such as plastisol, are not easily removable from the belt. Additionally, since the print extends beyond the edges of the shirt, there is considerable waste of ink which is printed on the belt only to be later scrubbed off.
A still further shortcoming of belt presses is inaccurate alignment. Since the shirts are not secured upon a pallet, as is the practice with more conventional rotary screen presses, but, rather, merely lay upon the belt, detailed prints are not achievable. That is, even where adhesive spray is applied to the belt, the adhesive will only secure the back side of the shirt in a stationary position on the belt, while the front side of the shirt which is to be printed upon remains free to move around. Thus, even during printing of one color at a single station, design detail is limited due to the freedom of movement of the top side of the shirt, wherein the shirt moves slightly during printing resulting in a blurred image if too much detail is attempted. Furthermore, printing of multi-colored images requires very accurate registration from one print to the next which accuracy is not achievable with belt printers due to the aforementioned freedom of movement of the shirt resting on the belt. Thus, belt press prints are usually limited to at most only two or three colors, with limited design detail.
Also, flash curing of inks is limited due to the effect of the heat on the belt. While flash curing is attainable with some belts, this is generally only employed to print on dark material in which a base of white ink is applied and flash cured prior to printing another color directly on top of the white ink. Due to the aforementioned inaccurate registration between successive prints, such accurate multi-layer printing techniques are not realizable with belt presses.
In light of the above discussed shortcomings associated with belt presses, it is desirable to provide a pallet for supporting a shirt which allows for printing over the entire surface of the shirt, particularly including the sleeves, which pallet maintains the shirt in a stationary position thereupon as the pallet is brought into successive registration with each of a plurality of printing units to provide the requisite registration accuracy necessary to make detailed multi-colored prints.
Moreover, it is desirable to provide a pallet which allows for printing over the entire surface of a shirt which lends itself to employment on conventional rotary screen presses, particularly allowing for retrofit onto pre-existing rotary screen presses. This would preclude manufacturers wishing to print images over the entire shirt surface from having to purchase a completely new press to achieve this, as is currently required.
Such pallet should lend itself to commercial production, allowing for rapid loading and unloading of shirts therefrom for good productivity and decreased turnaround time. The pallet should preferably allow for shirt loading and shirt unloading to be performed generally equally rapidly. More particularly, it should not take longer to load a shirt onto a pallet and extend the sleeve panels in preparation for printing than to unload the shirts from the pallet following printing. A slower rate of shirt loading in comparison with the rate of shirt unloading imposes a limitation on the production rate attainable with the pallet. It is an object of the present invention to provide a shirt pallet which allows shirts to be loaded as quickly as they are unloaded, thereby providing significantly increased production rates.