Radiant energy – Irradiation of objects or material
Reexamination Certificate
1998-07-11
2001-01-30
Anderson, Bruce C. (Department: 2881)
Radiant energy
Irradiation of objects or material
C442S327000
Reexamination Certificate
active
06180950
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The subject invention relates to a unique apparatus for continuous uniform heating synthetic fibers by resonant absorption of laser energy.
2. Description of the Prior Art
Thermoplastic man-made fibers can be permanently heat-set after drawing and orientation. The fiber will possess structural integrity and will maintain its desired configuration below the prescribed heat set temperature. Thermoplastic fibers or yarns from these fibers can be processed with conventional “long” and “short” direct contact heaters used for a variety of purposes in the textile industry. Yarns made from thermoplastic fiber in the form of a continuous filament are capable of a pronounced degree of stretch and rapid recovery and can be subjected to an appropriate combination of deforming, heat setting and development treatments. These yarns can also be bulked.
Twist yarn is made by a continuous process on the false twist principle, where two or more yarns are fed to a twister which inserts extra twist to double them, heat sets the yarns and then untwists the plural yarns and winds them on plural separate spools.
Conventional microfiber production typically consists of taking a higher denier fiber, placing it in a conventional contact heater and then directing the fiber to a drawing machine where it is stretched to a smaller diameter (smaller denier).
Conventional false twist and heat stretching may be accomplished by use of so-called “short heaters” or “long heaters”.
The main advantages associated with conventional “short heaters” over “long heaters” include: (1) Relatively shorter yarn paths with the ability to have a truly linear yarn path; (2) Greater flexibility of process parameters and end products; (3) Self-cleaning properties of the heater; and (4) Better textile characteristics at today's existing speeds or higher production speeds and resultant identical textile characteristics.
With conventional “short heater” technology, heater temperatures generally are maintained in a substantially constant range regardless of the type of yarn or denier. For example, heavier denier polyester is typically heat treated within a temperature range of between about 205 degrees C. to about 215 degrees C. Higher temperature levels will generally vary with the type of raw material, the total denier, the denier per filament and the linear speed, thereby having a direct positive effect on reduction of power consumption. In addition, the consumed power of the high temperature short heater without yarn is dramatically reduced compared to today's conventional long heater technology on the basis of the much shorter length of 600 mm verses the 2,500 mm of the long heater. Typically, the heater surface in contact with the atmosphere is reduced four to five times, thereby minimizing loss of heat with a resultant decrease in consumed energy.
Conventional processing heaters, however, typically utilized direct-contact heat, for instance, a heated metal plate to heat the fiber. Such heaters are relatively inefficient because they heat not only the fiber being processed, but also the surrounding area. Additionally, conventional heaters are generally two to three meters in length, requiring relatively large processing area to accommodate such equipment.
Laser treatment of fibers is also known to the art. For instance, Japanese Patent No. 59-157,310 relates to a thick and thin synthetic fiber and a method for its manufacture. A method for manufacturing the thick fiber is disclosed having variations in refractive index in the direction of the fiber access and thick and thin sections which is characterized by the fact that the oriented thermoplastic synthetic fiber is subject to intermittent irradiation with laser light under tension. Accordingly, the Japanese patent disclosure is directed to varying the diameter of the fiber over its length by means of an intermittent heating or pulse heating to portions of the fiber.
Bossman, et al. in U.S. Pat. No. 5,017,423 discloses the use of a laser to remove material from the fiber that is to be treated to reduce the denier.
Macken, et al. in U.S. Pat. No. 4,156,124 discloses image transfer laser engraving. The Macken, et al. apparatus and method relies upon indexing of the work piece in relation to the pattern mask.
Kajikawa, in U.S. Pat. No. 4,950,862 discloses laser machining apparatus using a focusing lens array to delivery laser energy to the sample being treated.
Accordingly, there exists a need for an improved method and apparatus which will produce an even heating of the fiber in a uniform manner. Those skilled in the art have recognized a significant need for an improved process and apparatus for even and continuous heating to produce false twist and/or diameter reduction of the fiber such as by stretching, so that it results in a microfiber. Moreover, those skilled in the art recognized a significant need for processing equipment which will reduce the size of conventional “long heaters” and “short heaters” and which will be energy efficient. The present invention fulfills these needs.
SUMMARY OF THE INVENTION
This invention provides an improved apparatus for non-contact quantum mechanical heating of thermoplastic fibers by resonant energy absorption of laser energy by the fiber.
In a presently preferred embodiment, the unique micro heater apparatus comprises a laser furnace furnished with a collimator and back reflector, employed to enhance the efficiency of the invention. In this respect a collimated laser beam with back reflector, i.e., “Laser Heater” is provided. The inventive Laser Heater will have a traversement path of from about 127 mm to 1M in length and will be about 50 mm to 101 mm in diameter. In false twist processing, the Laser Heater can be a source of non-contact heat before, after or during the false twisting process. For this process separate laser beams are utilized for each yarn processed.
For the diameter reduction of the yarn, several yarns are drawn through the Laser Heater at one time. Typically, the non-contact heat zone is from about 127 mm to about 1M in length and from about 50 mm to about 101 mm in diameter with approximately no more than 5% variance in heat from the center to the outer circumference of the furnace. Several yarns can accordingly be drawn through the heat zone at one time.
In the foregoing diameter reduction embodiment, the established heating zone is established between one or more spools of yarn on each side. Accordingly, the diameter reduction of the yarn(s) being drawn through this Laser Heater is a function of three factors (1) the adjusted heat in the Laser Heater, (2) the draw tension on the yarn(s) and, (3) the traversement speed of the yarn(s).
The wavelength of laser energy for the heat treatment will vary depending upon the thermoplastic fiber to be process. Accordingly, the wavelength can range from Infrared (IR) to visible/Ultraviolet of the Electromagnetic spectrum depending upon the absorption spectrum of the particular fiber. The heating of the fiber results from exciting it to a higher energy state by absorption of a resonant wavelength. This energy has to be eventually dissipated so the fiber (a molecular polymer) can relax to a stable ground state. This relaxation process is dependent on the type of laser energy utilized. For visible/Ultraviolet, the energy is released through fluorescence (non heat), and internal conversion to IR energy which eventually becomes classical heat (all wavelengths). For IR absorption, the energy eventually converts on hundred percent to classical heat within the cell, thus, evenly heating fibers for conventional machine processes (i.e., drawing and false twisting).
This invention may be used to heat a wide variety of thermoplastic fibers including but not limited to, *A.C.E., *Compet, *Dacron, *Fortrel, *Kodel, Polyester, *Trevira, *Celion, Nylon 6, Nylon 6,6, *Tencel, *Fibro, Cuprammonium, *Saran, Acetate, *Ryton (PPS), Phillips, *Acrilan, *Cresian, *Mannacryl, *SEF, Polyethylene, *Herculon, *Marvess, *Alpha, *Essera, *A
Anderson Bruce C.
Frisenda Frank
LandOfFree
Micro heating apparatus for synthetic fibers does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Micro heating apparatus for synthetic fibers, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Micro heating apparatus for synthetic fibers will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2478789