Stock material or miscellaneous articles – Layer or component removable to expose adhesive – Release layer
Reexamination Certificate
1995-06-07
2001-03-20
Copenheaver, Blaine (Department: 1771)
Stock material or miscellaneous articles
Layer or component removable to expose adhesive
Release layer
C428S145000, C428S159000, C428S317100, C428S319300, C428S339000, C428S343000
Reexamination Certificate
active
06203874
ABSTRACT:
TECHNICAL FIELD
This invention relates to a copying sheet having a front surface on which powders of toner are to be fixed after having been fused by heating.
PRIOR ART
Formerly, copying sheets were made of a synthetic resin film or a composite film comprising a printing film and a base film releasably affixed to the back surface of the printing film. However, electrophotographic copiers, page printers, laser printers etc., wherein powders of toner were fused by heating and fixed on the front surface of the printing film, were recently miniaturized and became to be operated at high temperature and at high speed. Besides, in color electrophotographic copiers the powers of toner were heated for a comparatively long time. As a result, conventional copying sheets often curled or wrinkled. Especially, copying sheets made of the composite film had a notable tendency to curl or wrinkle.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a copying sheet which does not curl nor wrinkle, when it is heated at a high temperature or for a comparatively long time so that powders of the toner may be fixed on its front surface.
Another object of the invention is to provide a copying sheet which is capable of saving the quantity of pigments such as titanium white to be added to whiten the sheet, and which is capable of reducing the cost of raw materials per square meter of the copying sheet.
In accordance with the foregoing objects, the present invention provides a copying sheet comprising a printing film made preferably of polyester film and a base film made of a foamed polyester film which is preferably a foamed polyethylene terephthalate film.
Referring to polyester films, there are “Viedene”-film (registered trademark), “Scotchpack”-film (registered trademark), “Kodar”-film (registered trademark) etc. other than polyethylene terephthalate film. And their foamed films are pliable and resilient, and have high tensile strength and high tearing strength.
For the purpose of measuring the break strength, break elongation and Young's Modurus of the foamed polyethylene terephthalate film having the specific gravity of 1.0, four specimens were made from respective foamed polyethylene terephthalate films having the thickness of 50, 75, 100 or 125 microns. Then, with respect to each specimen, the break strength, break elongation and Young's modulus were measured. Results of the measurement were shown in the following table.
TABLE
Testing
Measuring
Thickness (microns)
Measuring
Items
Direction
50
75
100
125
Method
Break Strength
Longitudinal
11
11
11
11
JISC2318
(kg/mm
2
)
Transveral
11
10
10
10
JISC2318
Break Elonga-
Longitudinal
100
100
100
100
JISC2318
tion (%)
Transversal
60
70
70
70
JISC2318
Young's
Longitudinal
250
270
270
270
ASTMD882
Modulus
Transversal
260
280
280
280
ASTMD882
(kg/mm
2
)
In the present invention, it is preferable that the foamed polyester film has the thickness of 50 to 200 microns. If the thickness is less than 50 microns, it is feared that the tensile strength and the tearing strength of the copying sheet become weak, though the pliability of the copying sheet is sufficient. While, if the thickness is more than 200 microns, it is feared that the pliability of the copying sheet becomes insufficient.
As to the matting material, for the purpose of asisting the powders of toner to be fixed, it is preferable that silica having the particle size of less than 5 microns is used, while for the purpose of preventing copying sheets from being sent out of a copier as being superposed, it is preferable that silica having the particle size of 3 to 10 microns is used. If silica having the particle size of more than 10 microns, it is feared that silica easily falls away.
As to the thickness of the matting material layer, it is preferable that the thickness of the layer is within a range of 0.5 to 10 microns for the purpose of fixing the powders of toner, while it is preferable that the thickness of the layer is within the range of 7 to 15 microns for the purpose of preventing copying sheets from being sent out of a copier as being superposed.
The matting material may be coated with a solution of coating resins, or may be scattered after a solution of coating resins has been coated, on the front and back surfaces or the back surface of the copying sheet. When the matting material is coated with the solution of coating resins, the matting material may be mixed within the range of 10 to 500 grams per 1 kilogram of the solution.
As to the antistatic agents, conventional antistatic agents can be used in the invention.
As to the adhesives, adhesives having high heat resistance, for example, acrylic resin adhesive etc. are used in the invention.
As to the releasing agents, it is preferable that silicon resin is used in the invention.
REFERENCES:
patent: 5047383 (1991-09-01), Hayashi et al.
patent: 5437917 (1995-08-01), Ohe et al.
patent: 5747174 (1998-05-01), Kimura et al.
Copenheaver Blaine
Earley John F. A.
Earley III John F. A.
Harding Earley Follmer & Frailey
Kisokaseisangyou Co., LTD
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