Stock material or miscellaneous articles – Composite – Of carbohydrate
Patent
1995-05-25
1997-03-25
Krynski, William A.
Stock material or miscellaneous articles
Composite
Of carbohydrate
428195, 428211, 4283044, 4283077, 42831111, 428340, 4285377, B32B 2900
Patent
active
056143257
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a coated printing paper for use in machines with sheet or friction feeds, and which paper contains a conductive substance.
More particularly, the invention can be used in the field of indirect electrophotography, which operates on the following principle: a latent electromagnetic image of the original to be reproduced is formed on a suitable surface (e.g., a copier cylinder); this image is developed by electrostatically attracting a toner to it, and the toner image (which is no longer electrically charged) is then transferred and fixed by applying pressure and/or heat to ordinary paper.
Thus, indirect electrophotography does not require the use of a special paper, while direct electrophotography and the other forms of electrographic printing use special papers on which an electrically charged latent image is formed and then developed by direct electrostatic attraction of a toner to the paper. These papers comprise an electroconductive base sheet whose purpose is to dissipate the electrostatic charges produced during these processes, and they have a dielectric coating which, in the case of direct electrophotography, is photoconductive. Such papers are called dielectric and are described, for example, by R. H. Windhager in his article "Characteristics of commercial electrographic sheets," TAPPI Printing Reprography/Testing Conf. (Atlanta) Papers, pp. 105-120 (Nov. 14-16, 1977). The invention does not concern these special dielectric papers.
There are basically two feed systems for machines that handle (e.g., print, read, or sort) paper in sheet form.
1. Suction or vacuum systems, in which the sheet is lifted from the stack of sheets by means of air suction.
2. Friction systems, in which the sheet is pulled from the stack of paper, generally by rollers in its plane. In this case, friction is produced between this sheet and the one below or above it.
The machines that use the second type of feed system are the indirect electrophotographic printing systems, e.g., photocopiers, printers such as laser-beam printers, some labellers, and check reader-sorters.
With these machines, the utilization of coated sheets results in jamming and/or poor-quality or off-center reproductions due in particular to poor separation of the sheets stacked in the feed trays of the machines. Thus, the problem occurs during paper feed.
This separation problem becomes worse as the sheet feed rate increases.
The separation problem also becomes worse when the coated paper is glossy.
To date, only noncoated papers have been used for photocopiers or laser printers because machine-makers in the field of indirect electrophotographic reproduction advise their customers against the use of coated paper, which separates poorly, especially in machines with high-speed feeds averaging at least 50 sheets per minute (currently, some photocopiers can produce on the order of 135 copies per minute).
U.S. Pat. No. 4,778,711, filed on a priority basis in 1986, already contemplates providing coated paper for indirect electrophotographic printing machines and proposes, in particular, to solve the separation problem by recommending that the standard deviation of the coefficients of static friction of the sheets be less than or equal to 0.05.
It also states that the surface resistivity of the coated sheet must be at least 8.times.10.sup.8 ohms for a relative humidity of 85 percent at 20.degree. C. and that, consequently, it is necessary to use coating pigments with high surface resistivity.
Thus, this document will not lead the specialist to decrease the surface resistivity of the sheet; quite to the contrary.
Furthermore, in this patent, separation is considered acceptable if jamming problems occur with not more than 5 sheets in a stack of 1,000, even though in practice the minimum acceptable jamming rate is 1 sheet per 5,000 and the preferred rate, 1 sheet per 20,000.
Secondly, for noncoated papers, attention has already been given to machinability problems, and it has been recommended that conductive substances be used to solv
REFERENCES:
patent: 4778711 (1988-10-01), Hosomura et al.
Abstract Bulletin of the Institute of Paper Chemistry, vol. 48, No. 10, Apr. 1978, p. 1067.
Patent Abstracts of Japan, vol. 6, No. 252 (P-161), 1981.
Patent Abstracts of Japan, vol. 5, No. 188 (P-073), 1981.
Database WPI, Section Ch, Week 9249, Oct. 22, 1992.
Barthez Alain
Chartier Christophe
Arjo Wiggins Papiers Couches S.A.
Krynski William A.
LandOfFree
Coated paper for machines having sheet and friction feed systems does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Coated paper for machines having sheet and friction feed systems, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Coated paper for machines having sheet and friction feed systems will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2201902