Record receiver having plural interactive leaves or a colorless – Having a colorless color-former – developer therefor – or... – Having nonchromogenic liquid spread-control or...
Patent
1991-12-03
1994-02-08
Schwartz, Pamela R.
Record receiver having plural interactive leaves or a colorless
Having a colorless color-former, developer therefor, or...
Having nonchromogenic liquid spread-control or...
503215, 503226, B41M 5124
Patent
active
052848132
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a first sheet for copysets of pressure-sensitive copying papers in accordance with the introductory part of claim 1.
BACKGROUND OF THE INVENTION
Such first sheets, which are also sold under the name "CB forms," are known. The trend toward making such first sheets of constantly lower weight per unit area has brought the result that the opacity of such papers leaves something to be desired. Particularly when the microsphere coated back of the first sheet is also imprinted, the printing is visible through the thin paper and spoils the appearance of the front side.
Attempts have been made to improve the opacity of such papers by increasing the filler content in the first sheet and also by putting a nonreactive coating on the front. But it has been found that conventional coatings can improve the opacity and printability of the front side, but the easy divisibility required in copysets is lost.
By "easy divisibility" the following is meant. A copyset consists as a rule of a first sheet (CB), one or more middle sheets (CFB) and a back sheet (CF). For use, several of these sets are assembled into a block and cemented together at one narrow side. The adhesion of the glue for proper separation of one set at a time from the block, between the CF back and the CB top, must be less than it is between the CB bottom and CFB top and the CFB bottom and CF top. In the case of uncoated-surface first sheets the problem was solved by adjustment by means of surface preparation or by controlling the absorptiveness of the backs. Such measures failed, however, in the case of first sheets whose front surface was coated with pigments.
EP-A-0 274 886 proposed to provide the coated front additionally with a synthetic, reactive size or with a coating-texturing agent or with both agents, in order to assure easy divisibility.
A disadvantage of this proposal is that synthetic reactive sizes require, for complete curing, a certain time of exposure to a temperature range above 100.degree. C. If this is not provided, e.g., when the coating unit runs too fast, or if the drying capacity of the coating unit constitutes a bottleneck, the synthetic size does not cure, with the result that the moisture repellency or adhesive repellency necessary for the easy-division adhesive on the CB sheet provided with an imprintable front surface coating is not achieved.
OBJECT OF THE INVENTION
The present invention therefore has set for itself the object of making available a first sheet for copysets of pressure-sensitive copy papers which will not have the disadvantages listed above, and will have a constant degree of moisture repellency independent of the drying conditions and will therefore permit a reliable easy-division sizing.
DESCRIPTION OF THE INVENTION
This object is achieved in a first sheet according to the generic part of claim 1 in that the front coating contains nonreactive moisture-repellent agent in a proportion of 5 to 15 wt % with respect to the dry content of the coating.
Nonreactive moisture-repellent agents, such as wax sizes, wax emulsions, metal salts of fatty acids, such as stearic acid, ester waxes, oxidized polyethylenes, copolymer dispersions and dispersions of organic prepolymers, are known in themselves and have heretofore been used in paper technology mainly in combination with glutinized starch in sizing liquids for application in the sizing press within the paper machine; see "Handbuch der Papier- und Pappefabrikation," 1971, pages 1282 ff. under the heading, "Oberflachenleimung," giving additional literature references.
Wax sizes as well as metal salts and ammonium salts of fatty acids, especially stearic acid, are used individually also in coating inks for printing papers in order to improve the inherent slipperiness of the sizing pigments in calendering, the condition of the printing ink in the printing process, and the so-called "dusting." The amount used in the coating ink was limited to 0.3 to 1.2 wt % absolutely dry, with respect to the dry content of the coating
REFERENCES:
patent: 4448445 (1984-05-01), Chang et al.
Feldmuhle Aktiengesellschaft
Schwartz Pamela R.
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