Printing – Stenciling
Reexamination Certificate
1999-01-12
2001-03-06
Hilten, John S. (Department: 2854)
Printing
Stenciling
C101S424000
Reexamination Certificate
active
06196126
ABSTRACT:
1. Field of the Invention
The present invention relates to rotary screen textile printing, and, more particularly to preventing the accumulation of printing pigment on undesired portions of the exterior surface of rotary printing screens.
2. Background of the Invention
Textile printing involves the application of color in the form of pigment to fabric in a design or pattern using a form of localized pigmenting. Modern textile printing processes include flat-bed screen printing, rotary screen printing, engraved roller printing and heat transfer printing. Rotary screen printing involves generally a technique for printing fabric that uses perforated metal screens shaped into the form of hollow cylinders. A fabric piece or web is fed past one or more screen arranged in succession with each of screens corresponding to the patterns for each color in a design. A color paste (or pigment) is fed into the interior of the cylinder along its longitudinal axis. A small metal roller or metal or rubber squeegee forces the paste from the interior of the cylinder through the holes and onto the fabric. The paste is squeezed through the cylinder in those areas where the holes in the screen are uncovered. Generally, the steps in this process include the preparation of a print paste, the printing of the fabric and fabric drying. Alternatively, the process may include fixation or curing of the pigment and a final washing off of the printed fabric. Through the use of laser engraving and CAD design techniques, very complex patterns may be created using rotary screen printing machines.
Rotary screen printing is widely used and offers numerous advantages over other types of textile printing. This process is faster than flat screen printing, having the capability to handle printing speeds up to 120 meters/minute. It permits the quick change over of patterns and also provides for continuous, repeating patterns. Moreover, changing colors is more economical than in roller printing processes such as intaglio printing.
In practice, because the width of the fabric being printed may vary slightly, the engraved pattern on the rotary screens is wider than the fabric to be sure the entire fabric is printed. It has been observed that, during the rotary screen printing process, pigment tends to accumulate or buildup on the exterior surface of the screens at a point just outside the fabric edge. This buildup may result in a so-called “dirty edge” on the printed fabric. This effect is not acceptable, particularly when printing knitted tubular fabric for body-sized garments.
Thus there is a need to prevent and/or remove excess pigment buildup on the rotary screens during printing. The present invention addresses these and other needs in the field.
SUMMARY OF THE INVENTION
The present invention addresses the problem that has been encountered during the printing of textile fabrics using a rotary screen printing process. The invention controls the described buildup of excessive printing pigment on the exterior surface of the rotary screens. The present invention utilizes a flexible wiper member which is biased against the exterior surface of the rotary printing screens in the marginal areas along either side to move the excess pigment away from the fabric being printed. The flexible wiper member prevents any appreciable amount of excess pigment to accumulate on the rotary screen exterior surface. A lubricating stream is provided upstream from and adjacent to the wiper member to maintain the pigment buildup in a pliable condition and to ensure that the flexible member does not attack the fragile rotary screen.
The present invention includes an apparatus for preventing excessive pigment buildup on at least one prescribed portion of the exterior surface of a rotary printing screen in a region adjacent the edge of the fabric being printed. The apparatus includes a flexible wiper member biased against the at least one portion of the exterior surface of the rotary printing screen and positioned in the excessive pigment region. The apparatus further includes a mounting bracket for holding the wiper member in a predetermined orientation with respect to the exterior surface of the rotary printing screen. A lubricant mist or stream may be applied to the outer surface of the rotary printing screen adjacent to and upstream of the flexible wiper member. The apparatus may further include a tensioning system attached to the mounting bracket for biasing the flexible wiper member against the exterior surface of the rotary printing screen.
In an alternative embodiment the present invention further relates to an apparatus for preventing excessive pigment buildup on at least one prescribed portion of on the exterior surface of a rotary printing screen in a region adjacent the edge of fabric being printed. The apparatus includes an preliminary flexible wiper member biased against the at least one portion of the exterior surface of the rotary printing screen and positioned in the excessive pigment region. The preliminary flexible wiper member is angled to the axis of rotation of the rotary printing screen so as to push a major portion of the excessive pigment buildup away from the fabric being printed. The apparatus further includes a primary flexible wiper member positioned downstream of the preliminary flexible wiper and biased against the exterior surface of the rotary printing screen. The primary flexible wiper is positioned in the excessive pigment region and is angled to the axis of rotation of the rotary printing screen so as to push a remaining portion of the excessive pigment buildup away from the fabric being printed. The apparatus may further include first and second lubricant streams applied to the rotary screen exterior surface adjacent to and upstream of the preliminary and primary flexible wiper members respectively.
The invention may further include a lubricant stream delivery system including at least one air supply line, a lubricant supply line, at least one lubricant metering valve in fluid communication with the lubricant supply line where the metering valve discharges to the air supply line to form at least one lubricant delivery line. The system further includes at least one rigid bendable conduit in fluid communication with the lubricant delivery line and a nozzle mounted on the rigid bendable conduit such that the nozzle is adapted to apply a lubricant stream to the exterior surface of the rotary printing screen.
The system may further include a plurality of lubricant metering valves connected to the lubricant supply line, each of the lubricant metering valves discharging to a plurality of air supply lines to form a plurality of lubricant lines. A plurality of rigid bendable conduits is in fluid communication with the plurality of lubricant lines, each of the conduits including a nozzle mounted thereon.
Thus it is an object of the present invention to improve the quality of printed textiles printed using a rotary screen process.
Still another object of the present invention is to create high quality printed goods using a rotary screen textile printing process with fabric that varies in width during the printing process.
A further object of the present invention is prevent the buildup of pigment/pigment on the exterior surface of a rotary printing screen during fabric printing process without causing damage to the rotary printing screens.
These and other objects and aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiments when considered in conjunction with the drawings. It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one embodiment of the invention and, together with the description, serve to explain the principles of the invention.
REFERENCES:
patent: 2070667 (1937-0
Bruce James E.
Hiatt Jerry D.
Smith Garnett H.
Hilten John S.
Intex Corporation
Nguyen Anthony H.
Rhodes & Mason P.L.L.C.
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