Plastic and nonmetallic article shaping or treating: processes – With incorporating dye susceptible material or dyeing workpiece
Reexamination Certificate
2000-09-21
2003-06-03
Tentoni, Leo B. (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
With incorporating dye susceptible material or dyeing workpiece
C264S211000
Reexamination Certificate
active
06572803
ABSTRACT:
TECHNICAL FIELD AND BACKGROUND OF THE INVENTION
This invention relates to an apparatus and process for infusing liquid dyestuff into synthetic yarn at the point of fiber production. The apparatus and process has application with any synthetic filament fiber, including but not limited to nylon, polyester and polypropylene. The process can be carried out on partially-oriented yarn (“POY”) which is subsequently texturized by one of several known processes, on fully-oriented yarn, or on yarn which is left in its flat state.
Current technology for providing color to synthetic yarn is based on the principle of combining natural, white polymer feedstock together with dye to produce a colored material called “master batch.” Master batch is initially produced in chip form, and is then melted and extruded into filaments. This process is described in the Haggard, et al., U.S. Pat. No. 5,516,476, (“'476 Patent”), which is incorporated herein by reference. Melting and extruding master batch chips has several significant disadvantages, including higher cost due to higher waste, increased time and costs associated with master batch production, and various adverse effects on downstream processes. Since the chip material is produced in batches, it is often difficult to achieve precise color matches from batch to batch. A color dryer is required, further adding to costs. Static electricity during the run can cause the master batch chips to stick together and not feed properly. Chip size is also very important, and any significant variation can cause streaks and other defects in the filament fibers ultimately produced. Furthermore, variations in the quality of the process control employed as a master batch undergoes color drying and extrusion often adversely affect the final product. For example, heat variations within the extruder can cause color streaks or shifts in a master batch. Unfortunately, the ability to make adjustments to the color during processing is very limited, because such adjustments can only be made from light to dark or from dark to light on the shade. Complete color changes require complete clearing of the entire extrusion line, which results in wasted material and may create 8 to 12 hours of downtime, which significantly delays the extrusion process.
The apparatus and process according to the present invention eliminates altogether the need to produce master batches of colored polymer. Because master batches are not used, the need for a master batch production line is completely eliminated. A side-arm extruder, master batch feed system and master batch dryer are no longer required, and the costs, inconveniences and inefficient use of time associated with master batch production are completely eliminated. Color repeatability is improved at reduced production and capital investment costs. Moreover, change from one color to another is very rapid, permitting quicker response to market demands for particular colors.
The novel apparatus and process of the present invention achieves these improvements by injecting non-molten liquid dye directly into the spin pack after the screens and immediately before the point at which extrusion of the molten polymer occurs through the spinnerette. Introducing the liquid dye into the spin pack assembly upstream from the spinneret further permits color to be added to the polymer without passing the dye through an extruder. Bypassing the extruder saves additional time and eliminates costs typically associated with the cleaning and maintenance involved in changing colors during conventional master batch production processes.
The liquid dye used in the present invention is less expensive than master batch chips. The color may be quickly adjusted during production runs, which reduces overall waste. Furthermore, the exact color may be repeated from one batch to another and within the same batch. Color may also be changed on each thread line, or on multiple thread lines by position, which further enhances production flexibility. Since the liquid dye is not passed through an extruder prior to entering the spinneret, streaks in the final product are eliminated that would have otherwise been created due not only to chip size variation, but also to exposure of the dye to heat and oxidation within the extruder. Polymer strength is also improved, as are light fastness and weathering characteristics.
Using the apparatus and process of the present invention results in increased customer satisfaction. Eliminating the use of master batches reduces the time required for shade match approval by two to six weeks, reduces production lead times, permits small lot production quantities to be offered, and allows specific shades to be reproduced on re-orders. Such competitive advantages, along with the improvements in the coloring process described above, are unique to the present invention, and have thus far not been achieved using conventional master batch techniques.
SUMMARY OF THE INVENTION
Therefore, it is an object of the invention to provide an apparatus and process for dyeing polymer material during the filament extrusion process.
It is another object of the invention to provide an apparatus and process for dyeing polymer material during the filament extrusion process using a liquid dye.
It is another object of the invention to provide an apparatus and process for dyeing polymer material during the filament extrusion process using a liquid dye that does not have to be mixed with a molten carrier prior to being introduced to the molten polymer material from which the fiber filaments are formed.
It is another object of the invention to provide an apparatus and process for dyeing polymer material which does not require the use of a master batch, and eliminates all of the materials, equipment and costs associated with such use.
It is another object of the invention to provide an apparatus and process for dyeing polymer material which results in fiber filaments having one or more colors that can be accurately duplicated from one batch to another.
It is another object of the invention to provide an apparatus and process for dyeing polymer material which improves the strength, lightfastness, and weathering characteristics of the synthetic fiber filaments ultimately produced.
These and other objects of the present invention are achieved in the preferred embodiments disclosed below by providing a method for infusing liquid dyestuff into synthetic yarns at the point of fiber production, which includes the step of providing a molten polymer, at least one non-molten liquid dye, and a spin pack assembly adapted for receiving and mixing the molten polymer and the non-molten liquid dye therein to form a colored molten polymer composition. The spin pack assembly includes a screen for filtering the molten polymer therethrough, and a spinneret adapted for receiving and extruding the colored molten polymer composition therethrough to form a plurality of colored fibers adapted for being formed into the synthetic yarns. The liquid dye and the molten polymer are metered into the spin pack assembly and mixed together between the screen and the spinneret to form the colored molten polymer composition. The polymer composition is then extruded through the spinneret, thereby forming the colored fibers.
According to one preferred embodiment of the invention, a method of infusing liquid dyestuff into synthetic yarns at the point of fiber production is disclosed in which a molten polymer, a plurality of non-molten liquid dyes, and a spin pack assembly are provided. The spin pack assembly is adapted for receiving and mixing the molten polymer and the non-molten liquid dyes therein to form a colored molten polymer composition, and includes a screen for filtering the colored molten polymer composition therethrough and a spinneret adapted for receiving and extruding the molten polymer composition therethrough to form a plurality of colored fibers adapted for being formed into the synthetic yarns. The liquid dyes and the molten polymer are metered into the spin pack assembly; and mixed tog
Coe Michael Scott
McCamy Charles P.
Shaikh Humayun N.
Adams, Schwartz & Evans P.A.
Burke Mills, Inc.
Tentoni Leo B.
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