Optics: measuring and testing – By dispersed light spectroscopy
Reexamination Certificate
2001-05-02
2004-06-22
Evans, F. L. (Department: 2877)
Optics: measuring and testing
By dispersed light spectroscopy
C356S319000, C356S326000
Reexamination Certificate
active
06753956
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a textile dyeing method and apparatus. In particular, the invention relates to a modified dyeing method and apparatus comprising an automated analysis system for a dyebath.
2. Description of Prior Art
The textile industry is a major consumer of water. Approximately 160 pounds of water are required to produce one pound of textile product. Most of the 100 billion gallons of water used by the textile industry each year are consumed primarily in the dyeing and finishing processes for the textiles, namely yarn, fabric and carpet. The vast majority of this water is discharged to the sewer. The waste water, or dyebath, includes dissolved and suspended organic and inorganic chemicals, and, thus, the conventional dyeing process places a significant demand on water resources as well as waste treatment facilities, especially in areas such as Dalton, Georgia, where carpet manufacturing plants are highly concentrated.
In a batch dyeing process, one piece (or several pieces) of the textile product is dyed in a vessel containing the dyebath. The bath is agitated or stirred and/or the textile product is tumbled in the bath so that the single dyebath has repeated contact with each portion of the textile product. The vessel may be pressurized, and heat is added to the bath to provide the desired temperature/pressure/time cycle for the dyeing. The piece of textile is then rinsed and removed from the vessel so that another batch may be dyed, and the depleted dyebath is discarded. The textile material is then dried and/or processed further on other production equipment.
In a continuous dyeing process, a piece of textile product is passed lengthwise through one or more pieces of machinery constituting a dye line or dye range. Subsequent pieces of product are sewn together to form a continuous chain of material proceeding through the dye range. The textile material may be exposed to multiple baths (typically of higher concentration than in batch dyebaths), rinses, and drying stages along its path, but it encounters each stage in succession and for a limited time in each.
Typically, continuous dye processes provide economies of scale and are attractive for larger production lot sizes in a particular color, whereas batch dye processes provide manufacturing flexibility and economic benefits in the case of small lot sizes. Certain products are also more amenable to either continuous or batch dyeing processes.
The nature of the batch dyeing process for textiles is especially wasteful. In the conventional batch dyeing processes, the dyebath is used only once per dye cycle, then discharged to the sewer. In addition, the valuable auxiliary chemicals mixed in the dyebath are lost with each discharged batch of water, which themselves place significant loads on the waste treatment system.
Both continuous and batch dyeing processes are common for broadloom carpets. Continuous dyeing offers cost advantages and greater ease in obtaining uniform color over a large production lot size. In contrast, batch dyeing is now used predominately for heavy-weight, high-end carpets which cannot be dyed as well with a continuous processes. Batch processes also offer the advantage of production flexibility due to the small lot size.
The conventional batch dyeing of nylon broadloom carpets is typically performed in an atmospheric vessel, or beck. Water, auxiliary chemicals, dyes and the carpet are loaded in the beck, with the carpet sewn in a loop so that it continuously enters and exits the dyebath, providing agitation and bath-to-carpet contact. The bath is slowly heated and then held at a specified, critical dying temperature for a given amount of time. Both the temperature and hold time are product dependent. As the bath is heated, the dyes penetrate the fiber of the carpet and form chemical bonds. The elevated bath temperature is held for a sufficient period of time to permit the dyes to migrate to a uniform distribution over the carpet, producing a level dyeing. A patch check on the carpet is then performed, and if the carpet is properly shaded, the bath and carpet are then diluted with fresh water to bring the carpet to a temperature acceptable for handling. The carpet is then removed, and the bath including virtually all of the auxiliary chemicals and any residual dyes is drained to the sewer. Several disadvantages of this conventional process are that it consumes excessive water, wastes the stored thermal energy in the dyebath, and releases dyes and auxiliary chemicals to the waste stream.
The dye used in the batch dyeing process is typically a mixture of three components—yellow, red and blue—with a ratio and total quantity selected to give the designed color for the textile product. The auxiliary chemicals used in the batch dyeing process typically include wetting agents, pH control agents, leveling agents, chelating agents, and others which aid the dyeing process, but are not consumed during the dyeing process like the dyes are consumed.
Generally, by the time the finished color of the carpet is achieved in the conventional batch dyeing process, the dyebath has undergone several changes. The dyebath temperature is about 200° F., in contrast to the initial starting, ambient temperature of about 60° F. There has been a small amount of dilution to the dyebath due to condensate of the injected steam, the preferred mode of heating. Most but not all of the dye has been transferred from the bath to the carpet fiber, but the auxiliary chemicals are essentially unchanged, and remain in the bath.
This spent dyebath, destined for the sewer in the conventional process, represents a significant investment of energy and chemicals which are available for reuse. Dyebath reuse offers the opportunity to reduce the consumption of water resources, to reduce energy consumption in the dyehouse, to conserve/reuse expensive auxiliary chemicals, and to reduce environmental pollution. There is also the potential for production rate increases due to reduced heatup times required by the present invention.
Presently, only for certain combinations of dyes and fibers, there is the possibility to reuse spent dyebaths in subsequent dyeings. However, for these combinations the amount of residual dye left in the baths is generally sufficient to result in off-shade dyeings of subsequent batches. Therefore, for these combinations, the concentration of residual dye for each of the component dyes must be accurately determined, and the recipe for the next dyeing be adjusted accordingly.
Dyebath reuse with manual intervention has been demonstrated on a limited scale for a wide variety of textile products. Yet the barrier to industry-wide implementation is the human involvement required to implement dyebath reuse. A trained chemist is necessary to collect test samples at the end of every dye cycle. The samples must then be transported to an equipped laboratory and analyzed for dye concentrations, and the corrected recipe calculated. It simply is not practical to have personnel on hand round-the-clock to perform these analyses since it can be difficult to find trained chemists willing to work on all shifts, and the employment costs are prohibitive. Further, the human involvement may also lead to analysis and/or calculation errors. Therefore, a solution to this problem is to automate the dyebath analysis process, which the present invention provides.
Various methods and apparatus are known in the textile industry that attempt to relieve some of the disadvantages of the conventional batch dyeing process. For example, U.S. Pat. No. 3,807,872 to Pronier, entitled “Process For Regulating The Concentration Of A Bath Of Dye Or Coloring And Equipment For Implementing This Process” discloses a method and apparatus to control concentration of a dye in a dyebath linearly over time. As disclosed, the first step is the preparation of the dyebath using all the additives except the dye substances. Then a certain volume of the dyebath is taken to act as a pure reference sample. S
Carey Richard A.
Clark James Leonard
Holcombe Wiley Don
Tincher Wayne Coleman
White Elizabeth Wise
Deveau Todd
Evans F. L.
Georgia Tech Research Corp.
Thomas Kayden Horstemeyer & Risley LLP
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