Compositions: coating or plastic – Coating or plastic compositions – Marking
Reexamination Certificate
1999-07-26
2001-08-28
Klemanski, Helene (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
Marking
C106S031610
Reexamination Certificate
active
06280510
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an ink composition for a meltable ink usable in a printing apparatus in which ink droplets are ejected from ink ducts. The present invention also relates to an ink composition for a meltable ink usable in a printing apparatus, said composition containing a meltable base material. The present invention also relates to a number of esters derived from 2,2′-biphenol.
Ink compositions are well known, for example, from U.S. Pat. No. 5,122,187. However, such ink compositions generally result in printed ink layers which are either too brittle or too soft on the receiving materials, so that the gum, scratch and fold resistance (GKV), particularly of the different ink layers of different colors disposed on one another is inferior.
In order to toughen ink formulations which are too brittle or to stiffen crystalline materials which are too soft, it is necessary to use an amorphous binder. After the cooling of the melting ink composition the printed images are then less vulnerable. The amorphous state also ensures good light transmission, this being favorable for color fastness and use on overhead sheets.
It is known from U.S. Pat. No. 5,421,868 that these amorphous binders can considerably increase the viscosity of the ink in the melted state, this being a disadvantage with respect to the operation of the printing apparatus. For this reason it is preferred to use binders which contain monomer compounds.
It is well known that monomer compounds, e.g. waxes, are generally crystallizable. The purer the compound and the lower the molecular weight, the easier it is to form a crystal lattice. However, binders are known which contain monomer compounds, which, when used in an ink composition for a printing apparatus, solidify amorphously on the receiving material. If an ink provided with such binders is printed on a receiving material, said binders admittedly form an amorphously solidified phase, but in the course of time they will exhibit partial after-crystallization. The result is that the properties of the printed layer change so that the gum, scratch and fold resistance decreases, the color impression changes and the transparency is reduced.
SUMMARY OF THE INVENTION
It has been surprisingly been found that if binders are used which contain esters of 2,2′-biphenol and acids with an aromatic character, no after-crystallization occurs in the printed ink layer under normal ambient conditions, despite the low molecular weight of these esters. As a result of avoiding after-crystallization, the binder according to the present invention is particularly suitable for use as a carrier material for an ink composition, in which the binder is the main constituent of the ink composition. These inks yield printed layers which retain their good properties for very long periods when they are stored under normal conditions. A good ink composition can also be obtained with a binder according to the present invention in which the ink also contains a meltable base material in the form of a crystalline-solidifying monomer compound and an amorphous polymer or oligomer binder. By a careful choice of the constituents, these inks can be adjusted very well with respect to melting behavior in the printing apparatus and penetration behavior in the receiving material.
It has been found that good stability of a printed layer is combined with the absence of “cold crystallization” (a phenomenon in which crystallizable substances present in a solid amorphous state crystallize under the influence of the supply of heat) of a monomer compound according to the present invention, under the following conditions: cooling of the melted compound at the very low rate of 5° C./min to past the solidification point and then heating the solidified compound at a rate of 20° C./min to past the melting temperature. More suitable are those compounds which themselves remain completely amorphous when the melt is cooled at 5° C./min to past its solidification point and then heated from the solidified state at the even lower rate of 5° C./min to past the melting temperature. Particularly suitable compounds are those which also remain amorphous when blended with the oligomer binder Crystalbond 509 of Printlas™ (compound: Crystalbond=2:1 weight/weight), and stored for 48 hours at 50° C. Ink compositions provided with such compounds yield printed layers which ever after some months' storage under normal conditions show no deterioration in GKV and transparency.
The binders known heretofore always have partial crystallization under these conditions. However, esters of 2,2′-biphenol and methoxybenzoic acid or methylbenzoic acid do not exhibit crystallization under any of the conditions described above, and are also new compounds.
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patent: 4931095 (1990-06-01), Nowak et al.
patent: 5122187 (1992-06-01), Schwarz et al.
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patent: 9110711 (1991-07-01), None
Ricoh Co Ltd., 06 200202, Jul. 19, 1994 (Abstract).
Dorogov, M.V., vol. 126, No. 14, 1997, Chemical Abstracts, no month available.
Everhardus Roelof Hendrik
Kelderman Erik
Kortenhoeven Nicolina M.
Faison Veronica F.
Klemanski Helene
Oce-Technologeis B.V.
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