Compositions: coating or plastic – Coating or plastic compositions – Metal-depositing composition or substrate-sensitizing...
Patent
1984-10-24
1986-07-08
Yarbrough, Amelia B.
Compositions: coating or plastic
Coating or plastic compositions
Metal-depositing composition or substrate-sensitizing...
106 27, 346205, 427150, 427152, 4284231, C09D 1100
Patent
active
045991111
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a desensitizing ink for wet offset printing on an acceptor surface of a chemical duplicating set comprising at least two superposed sheets, one of the facing surfaces of which has an electrophilic acceptor coating and the other a nucleophilic coating capable of producing a chromogenic reaction with said electrophilic acceptor coating.
According to the British Pat. No. 1,433,469, desensitizing inks are already known that contain polypropyleneglycol with a molecular weight between 400 and 5,000, making it possible to print in letterpress, flexography or gravure on the acceptor surface of a duplicating set, and thus to prevent any color formation in the areas thus printed when a subsequent writing or typing is performed on the duplicating set.
As mentioned in the British Pat No. 1,525,269, the holde of British Pat. No. 1,433,469 did not succeed in formulating a desensitizing ink based on polyalkyleneglycol making it possible to print in wet offset the acceptor surface of a chemical duplicating set.
As described in Swiss Pat. No. 628,288, the holder of the present invention has worked out a desensitizing ink based on polyalkylene glycol or other nucleophilic alkoxylated compounds of high molecular weight, making it possible to print the acceptor surface of a chemical duplicating set by wet offset printing, following an alkoxylation to such a degree that their hydrophilic lipophilic balance (HLB) is between 2 and 9 in order to allow on the one hand, a continuous ink transfer from the inking rollers to the hydrophobic areas of the wetted printing plate of an offset press, and on the other hand, to desensitize the corresponding areas of the acceptor surface of the chemical duplicating set.
In order to increase the molecular weight of the desensitizing compound, the ink, according to the invention, is characterized in that the nucleophilic alkoxylated compound is bridged by an aliphatic or aromatic polyisocyanate derivative or again by an aliphatic or aromatic polyacid derivative which further makes it possible to improve the transfer of the ink on the inking rollers of the wet offset press. As a result, an ink flow of constant thickness is produced by the inking rollers. This ink film withstands particularly well the resulting impact on the emulsion of the dampening water in the ink, before being transferred successively to the offset printing plate then to the blanket and finally as a desensitizing ink layer, at a rate of 1.5-5 g/m2, on a paper support.
According to the invention, a desensitizing ink for wet offset printing of the acceptor surface of a chemical duplicating set, can be formulated the following way:
EXAMPLE 1
On a 3 roll mill, 70 parts of a varnish obtained by the reaction of 63 parts of polypropylene glycol (M.W. 2,500) with 5 parts of hexamethylene triisocyanate and the addition of 32 parts of an acid modified phenolic resin are mixed with 13 parts of titanium dioxide, 1 part of silicon oxide and 6 parts of calcium carbonate.
12 parts of the alkoxylated derivative are added to the ground ink. The HLB value of the ink amount to 3 (.+-.1). This ink shows a suitable reheology for wet offset printing.
EXAMPLE 2
On a 3 roll mill, 68 parts of a varnish obtained by the reaction of 66 parts of propoxylated diethylene triamine (M.W. 2,500) with 9 parts of trimethylol propane treated with 3 moles of toluyl diisocyanate and the addition of 25 parts of an acid modified phenolic resin are mixed with 12 parts of titanium dioxide, 2 parts of silicon oxide and 6 parts of calcium carbonate.
12 parts of the alkoxylated derivative are added to the ground ink. The HLB value of the ink amounts to 4 (.+-.1). This ink shows a suitable rheology for wet offset printing.
EXAMPLE 3
On a 3 roll mill, 60 parts of a varnish obtained by the reaction of 58 parts of polypropylene glycol (M.W. 2,500) with 8 parts of ricinoleic acid, 10 parts of trimethylol propane treated with 3 moles of toluyl diisocyanate and the addition of 24 parts of a neutral esterified collophony resin are mixed with 20 p
REFERENCES:
Derwent Abstract, Accession No. 79-36543B/19, U.S.S.R. Patent, Dec. 8, 1978.
Japanese Patent Abstract, vol. 6, No. 89, May 27, 1982, see p. M-132 (967).
Amon Albert
Weil Roger
O'Brien Anthony A.
SICPA Holding S.A.
Yarbrough Amelia B.
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