JPS6364813B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for curing coatings on moving tape material, and more particularly to a method and apparatus for curing resin coatings on magnetic tape by electron bombardment.

The magnetic tape media uses a tape based on a polymer such as Mylar, polyethylene terephthalate, available from DuPont and a resin coating with embedded magnetic particles. The manufacturing process for such tapes requires that the coating be cured by heating or electronic bombardment. The present invention relates to the curing of tape coatings of the latter type.

The problem in the past has been absorbing enough energy from the electron beam to cure without overheating. It has been recognized that a single exposure of a magnetic binder tape to a high energy electron beam is an inadequate means of curing the binder. It was known that if the energy in the electron beam was insufficient to cure the binder, or the energy was high enough to cure, the tape could be overheated, exceeding the glass transition temperature of Mylar, which is approximately 80°C. This difficulty could probably be eliminated by passing the tape through a low-energy electron beam several times, but the time required to cure the tape would have a negative impact on production efficiency, making it difficult to control the temperature of the tape. I can't.

These and other shortcomings of conventional methods and apparatus for curing magnetic tape coatings include the use of a means for generating an electron beam, a rotatable tape manipulation means made of high atomic number material placed within the electron beam; is eliminated by the present invention, which has the ability to internally control the temperature of the tape with sufficient precision to prevent overheating without interfering with the curing process.

Two preferred embodiments of the invention will be described. 1st
In embodiments, hollow and relatively large diameter
A roller with a coolant inside is provided within the electron beam. The magnetic tape to be cured is rotatably supported on rollers within the electron beam. Preferably, the rollers are made of materials such as copper or steel. Then, the electrons that penetrate the tape and are projected onto the roller bounce back and pass through the tape again, increasing the amount of electron beam hitting the tape.

In two embodiments of the invention, a plurality of cooled rollers are rotatably mounted parallel to each other within the electron beam, and the tape snakes around the rollers within the electron beam. The rollers are preferably made of high atomic number materials such as copper or steel and are internally cooled. In the second embodiment, electrons also bounce.

It is therefore an object of the present invention to provide an improved method and apparatus for curing magnetic tape coatings with electronic bombardment while cooling the tape.

Another object of the invention is to obtain a magnetic tape coating that is cured by electron bombardment in which the electrons bounce back through the tape.

Yet another object of the present invention is to control the temperature of the tape to prevent overheating while proceeding with curing.

The novel features and advantages of the apparatus and method of the present invention include:
It will become clear from the embodiments of the invention which are explained below by way of example with the aid of the figures.

In FIG. 1, a coated polymeric tape 10 approximately 66 cm wide and approximately 0.005 cm thick is passed through the apparatus of the present invention for curing. Tape 10 can be made of any of a variety of polymeric materials, such as polyethylene terephthalate (Mylar) and others. The coating of magnetic material is well known in the industry and can be any of the various types of materials that can be cured by heat or electronic bombardment. See, for example, US Pat. No. 4,004,997.

The tape 10 advances horizontally from a coating station (not shown) into a shielded housing 24, past a first roller 12, and around a large diameter roller 14, preferably copper or steel, to generate an electron beam. The electron beam passes through the electron beam 16 generated by the device 18 and proceeds vertically downward. During its passage through beam 16, the coating on the tape is cured. The tape then leaves contact with the surface of roller 14 and wraps around another roller 20 before moving horizontally again. Roller 14 rotates tape 10 at a predetermined speed, for example about 254 cm/sec, by a motor drive (not shown). Ideally in most cases about 133 Mrad/cm/min (about 4000 Mrad/cm/min)
ft/min).

The electron beam 16 penetrates the tape 10 and bounces off the roller 14 to some extent (approximately 20%) and penetrates the tape 10 again, increasing the total radiation (electron) dose through the tape. Since the electronic bombardment causes the roller 14 to heat up, a means of controlling the cooling of the roller and thus the tape in contact with it is required.

As mentioned above, the present invention is primarily concerned with controlling the temperature of the tape during curing. Some energy is stored in the tape before it is heated to the point of deformation. Conversely, if the temperature of the tape is too low, curing will not proceed. The actual operating temperature will depend on the chemistry of the binder and base substrate used. Curing temperature and deformation temperature are parameters well known to those skilled in the art. The present invention deals with providing the technician with an apparatus to control and select the temperature range in which a particular binder/base substrate will be cured without deformation.

To further the above objective, the ring-shaped space 57
A coolant, water or any other liquid capable of removing heat energy, is placed therein. This ring-shaped space 57 can be fixedly attached to the roller 14 and rotated therewith, or can be freely floating or fixedly attached to the housing 24. In the latter embodiment, the ring-shaped space and the roller are in sliding engagement.
In each case, means are provided for measuring the temperature of the liquid, shown schematically at 56. By way of example, a liquid crosses a sensor 50 and the sensor 50 measures the temperature of the liquid. The sensor sends a signal to controller 51, which compares the signal to a value preset by the operator for the particular tape. The controller then sends a signal to actuator 52 which supplies either heated liquid from valve 54 or cooled liquid from valve 53 depending on the signal sent. Alternatively, if the temperature of the liquid is too low, the liquid and roller 14 are heated by the heating action of the electron beam without supplying the liquid.

When heated or cooled liquid is supplied to the annular space 57 at 55, the liquid overflows as shown schematically at 58. In FIG. 1, the liquid inlet and outlet are shown loosely, since all that is important is that the overall temperature of the liquid in space 57, and therefore the temperature of roller 14, can be controlled. be. The annular space 57 can, for example, be provided with a buffle to increase the velocity of the liquid and facilitate the transfer of energy between the roller 14 and the cooling liquid.

Instead of providing a ring-shaped space, in the device according to the invention a device for spraying water into the hollow roller 14 can be provided. Similar to the embodiments described above, the temperature of the spray can be controlled by sampling the liquid collected in the roller with a sensor. Information from the sensor is sent to a controller and actuator to either raise or lower the temperature of the spray, or to spray only when cooling is needed. In any case, it is within the scope of the present invention to control the temperature of the roller 14 by bringing the liquid into contact with the inner surface of the roller 14.

In the embodiment of FIG. 2, instead of contacting the tape 10 around a single water-cooled large diameter roller 14, a series of parallel rollers are placed within the electron beam 16 generated by the electron beam generator 18. 26, 28, 30, 32, 34, 36, and 38. In other words, the tape first passes through roller 2.
6 and then a second point parallel to roller 26 but slightly below it in FIG.
It revolves around roller 28. This pattern is repeated for rollers 30, 32, 34, 36, and 38. After exiting rollers 38, tape 10 passes around rollers 20 outside housing 24 to a finishing station (not shown). Rollers 26, 30, 3
4 and 38 are arranged in the first row, and rollers 28, 32, and 36 are arranged in the second row. The first row is closer to the electron beam generator 18. Since the vertical spacing between the first row of rollers is less than the diameter of the second row of rollers, substantially all of the electron beam is incident on the tape.

The tape movement speed and electron bombardment rate are approximately the same as in the embodiment of FIG. Although smaller in diameter than roller 14, rollers 26-38 are also water cooled and made of copper or a suitably high atomic number material. Again, the electron beam that penetrates the tape 10 bounces off the rollers 26-38 and penetrates the tape again, increasing the effective electron dose for curing the tape coating.

As with the embodiment of FIG. 1, means are provided to control the temperature of the rollers 26-38 which control the temperature of the liquid and thus the temperature of the magnetic tape during curing.
A cooling liquid, such as water, is drawn from the interior of the roller 38, as shown schematically at 60, and the sensor 6
1 and measure the temperature. This temperature information is sent to controller 62 to determine whether the temperature is above or below the optimum temperature. This information is sent to actuator 63 which directs hot or cold liquid from taps 64 and 65 to lines 66 and 67, respectively.
is supplied to the system 68 via the .

The terms and expressions used herein are for purposes of explanation and not limitation, and are not intended to exclude other equivalent terms or expressions. It should also be appreciated that various modifications may be made within the scope of the invention.

[Brief explanation of drawings]

FIG. 1 is a partially sectional elevational view of a first embodiment of the present invention. FIG. 2 is a diagram similar to FIG. 1 of a second embodiment of the present invention. 10... Tape, 14... Roller, 16... Electron beam, 24... Housing, 26, 28, 3
0, 32, 34, 36, 38...Hollow roller, 5
0...Sensor, 51...Controller, 53, 54...
Actuator, 57...ring-shaped coolant space,
61...sensor, 62...controller, 63...actuator, 64, 65...tap, 52...actuator.

Claims (1)

[Scope of Claims] 1. A device for generating an electron beam, and at least one device having a peripheral surface for supporting a tape within the electron beam.
a tape transport device for passing the tape through the electron beam, the tape transport device including two rollers and means for controlling the temperature of the roller; and a housing surrounding the electron beam generator and the tape transport device. Equipment for curing resin components. 2. The tape transport device includes a plurality of rollers whose circumferential surfaces support the tape within the electron beam and onto which the electron beam is projected, the rollers being rotatably mounted parallel to each other, and the tape being supported within the electron beam around the rollers. 2. The device of claim 1, wherein the device is serpentine. 3. Apparatus according to claim 2, in which a plurality of rollers are arranged in two rows with respect to the electron beam, the spacing of the rollers in the row closer to the electron beam generator being smaller than the diameter of the rollers in the other row. 4. The apparatus according to claim 1 or 2, wherein the tape enters the tape transport device in a horizontal direction and exits in a horizontal direction. 5. The apparatus of claim 1 or 2, wherein the tape transport device comprises a material having an atomic number at least the same as that of copper. 6. The apparatus of claim 1, wherein an electron beam is projected onto the roller through the tape, and a substantial portion of the projected electron beam is reflected through the tape. 7. Apparatus according to claim 1 or 2, wherein the rollers are made of copper or steel. 8. Apparatus according to claim 1 or 2, wherein the means for controlling the temperature of the roller is to bring a liquid into contact with the inner surface of the roller. 9. The apparatus of claim 8, wherein the liquid is contained within a ring-shaped space defined by the inner surface of the roller. 10 A liquid is placed adjacent to the inner surface of the roller, this liquid is sampled by a sensor, the controller determines whether the temperature of the liquid is higher or lower than a preset value, and the signal is sent to the actuator to control the roller. 3. Apparatus according to claim 1 or 2, wherein the temperature of the roller is controlled by adding heated or cooled liquid to the remaining liquid adjacent to the roller. 11 passing through an electron beam a tape with an uncured coating on its surface that is in contact with a support roller whose inner surface is in contact with a liquid; measuring the temperature of said liquid with a sensor; transmitting information to a controller to compare this temperature with a preset temperature and from the controller to an actuator to increase or decrease the temperature of the liquid. How to harden.