Etching a substrate: processes – Nongaseous phase etching of substrate – Relative movement between the substrate and a confined pool...
Patent
1996-10-22
2000-02-29
Loney, Donald
Etching a substrate: processes
Nongaseous phase etching of substrate
Relative movement between the substrate and a confined pool...
216 83, 216 91, 216 92, 156155, B44C 122
Patent
active
060305428
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a polyester film for the leader tapes used to connect a practically used magnetic tape with a take-up shaft, hub or reel to have the magnetic tape wound around it, and also relates to a production process thereof.
PRIOR ART
For connecting a magnetic tape with a take-up shaft, hub or reel to have the magnetic tape wound around it, a leader tape more excellent in mechanical strength than the magnetic tape is used for preventing that the magnetic tape is damaged by the severe tension acting when the tape starts and stops running. At present, the base used for most magnetic tapes is a biaxially oriented polyester film, and the base used for the leader tape is also a simply thicker polyester film. As a result, in an extreme case, it can happen that a 188 .mu.m thick leader tape is connected with a 12 .mu.m thick magnetic tape. The difference between the magnetic tape and the leader tape in thickness makes the tape winding form irregular, to abnormally deform the magnetic tape, causing recording and reproduction errors.
Methods studied to solve the problem include the use of another material higher in strength as the leader tape, to raise the mechanical strength of the leader tape, for allowing the leader tape to be thinned, the mechanical grinding of the polyester film to thin it only at the joint with the magnetic tape, the sand blasting of the polyester film, to thin it only at the joint with the magnetic tape, etc. However, the use of another material has a problem of cost. The mechanical grinding method has problems of processing accuracy, degree of freedom in thickness pattern, and surface roughness. The sand blasting method has problems of processing accuracy, degree of freedom in thickness pattern, and surface soil. So, these methods are unsatisfactory.
DISCLOSURE OF THE INVENTION
The object of the present invention is to provide a method for highly accurately processing a leader tape made from a polyester film used for connecting said magnetic tape with a take-up shaft, hub or reel to have the magnetic tape wound around it, in order to let the thickness pattern of the leader tape have a desired form such as a taper, thereby providing a polyester film for the leader tape to allow the magnetic tape to remain without being abnormally deformed, and also to provide a production process thereof.
According to a study by the inventors, the object of the present invention can be achieved by a polyester film for leader tapes, comprising a polyester film having been brought into contact with an alkaline liquid, to be etched at least on one side, to have a thickness pattern, and a process for producing a polyester film for leader tapes, comprising the step of bringing a polyester film into contact with an alkaline liquid, to etch the polyester film at least on one side, with the etched depth controlled differently from position to position, for processing to have a desired thickness pattern.
In the polyester film for leader tapes of the present invention, it is preferable that the thickness at the tip is 10 .mu.m or more and 80% or less of the original thickness. If the thickness at the tip is less than 10 .mu.m, the mechanical strength is too low to withstand the use for a long time, and the rigidity is too low to allow easy work of bonding to the magnetic tape. If the thickness at the tip is more than 80% of the original thickness, the effect attributable to thinning cannot be obtained. It is most preferable that the thickness at the tip is 10 .mu.m to 150 .mu.m. Furthermore, in the process for producing a polyester film for leader tapes of the present invention, it is preferable that etching is effected by immersion into an alkaline liquid, and in this case, it is preferable to control the etched depth by controlling the immersion time. Moreover, in the process of the present invention, the polyester film can also be covered with an alkali resistant protective coat on one side of the polyester film, to allow the etching to occur only on the other side.
BR
REFERENCES:
patent: 3706423 (1972-12-01), Neff
patent: 3809218 (1974-05-01), Furst
patent: 4090680 (1978-05-01), Farsh
Koide Kazuyoshi
Okabe Kazuo
Sato Ken-iti
Loney Donald
Miller Austin R.
Toyo Metallizing Co., Ltd.
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