US2036471A - Ink transfer media - Google Patents

Description

Patented Apr. 7, 1936 UNITED .STATES PATT OFFlCE INK TRANSFER MEDIA Paul H. Gill, Belmont, Mass, as'signor to 'ihe Gill Corporation, Cambridge, Mass, a corporation of Delaware 4 Claims.

This invention relates to ink-transfer media comprising, broadly speaking, a flexible fibrous base and a pigmented oleaginous and/or waxy vehicle carried by the base, such as typified by typewriter ribbons and carbon papers. Inasmuch as my invention may be applied with especial advantage to such typewriter adjuncts as ribbons and carbon papers, I shall confine the following description thereto, but it should be understood that my invention may be embodied in transfer media serviceable in connections other than with a typewriter.

In accordance with the present invention, I use as part of or as the complete oleaginous vehicle for the ink composition constituting the impregnant of typewriter ribbons or the coating on carbon papers one or more oils of an oxidizable character and I associate with such vehicle a phenolic compound that inhibits the, oxidation of such vehicle. This means that a large number of oils that could heretofore be used only with disadvantage and hence generally used in limited amount, if at all, in making typewriter ribbons and carbon papers are rendered highly valuable for such purpose. Thus, it becomes possible in accordance with my invention to use various animal or vegetable oils of an oxidizable character, which are highly eifective as wetting or wettingout agents for the pigments suspended therein, in lieu of the mineral oils heretofore used without running into the difficulties which would otherwise arise on account of the oxidizable character of such oils. Indeed, the presence of a suitable phenolic compound in such animal or vegetable oils as lard oil, neatsfoot oil, sesame oil, rapeseed oil, or the like, which are by themselves unstable under atmospheric influences, inhibits the oxidation of such oil sufliciently so that the typewriter ribbons are much longer lived and give much better satisfaction than would otherwise be the case, for, in the absence of the phenol, one would run into one or more of such troubles as gum formation or glazing in the ribbons with attendant low recovery or tendency for the ink composition to difiuse into the spot last hit by the type, rancidity or foul odor, and the development of undesirable stiffness or inflexibility in the ribbons, all of which troubles would be accelerated by the exposure of the ribbons to sunlight and heat.

In applying the principles of the present invention in the making of typewriter ribbons, I prepare an ink composition for impregnating the closely woven high grade cotton, silk or other .fabric ordinarily used as the flexible fibrous base or carrier'for the composition. The ink compo- (Wll. 197-172) sition may, as usual, comprise finely ground lampblack or equivalent pigment, but rather than using mostly mineral oil as the oleaginous vehicle for such pigment, I prefer to use as most or all of the oleaginous vehicle normally oxidizable oils 5 or blends of oils of the character hereinbefore mentioned, e. g., lard oil. Such oils are superior to mineral oils in their wetting or wetting-on properties of the pigments suspended therein and hence lead to typewriter ribbons of improved ink- 10 transferring ability. Such oxidizable oils or blends of oil are treated in accordance with my invention with about 0.5% to 2% or more of a suitable phenolic compound which is preferably soluble in the oils. While it is possible to use 15 various phenols or phenolic compounds as the inhibitors of oxidation or anti-oxidants of the oxidizable oils, I prefer to use an anti-oxidant selected from a group consisting of alpha naphthol, catechol, and pyrogallol, as these phenols have 20 been found to be most-eifective as anti-oxidants of a large number of phenols examined as to antioxidative effect. Of the preferred three phenols, I consider alpha naphthol to be best for the reason that it is somewhat more effective as an in- 25 hibitor than catechol and far less expensive than either catechol and pyrogallol in terms of a given inhibiting effect and does not have the color instability or acridity of odor inhering in pyrogallol. Vaseline or equivalent body material may, if de- 30 sired, be added to the pigmented oleaginous vehicle containing the anti-oxidant to impart thereto the desired consistency. If desired, a dye of the desired hue may also be added to the oleaginous vehicle. For instance, a black ink com- 35 position may not only be pigmented with lampblack, but be dyed with nigrosine or other suitable black dye. The resulting ink composition is squeezed into or otherwise introduced as an impregnant into the pores and interstices of the ribbon of fabric constituting the base, the composition being heated, if desired, to facilitate impregnation. The extraordinary effectiveness of alpha naphthol as an inhibitor of the oxidation of oxidizable oils can perhaps best be appreciated from the fact that whereas some lard oils lacking an inhibitor become practically solid when kept for live days in an oven at F., the presence of about 0.5% to 2% of alpha naphthol therein preserves them practically unchanged through the same treatment. The same applies to red oil and to other oxidizable oils such as are used in accordance with my invention.

In making carbon papers, ink composition of the same general character as have been herein- 55 before described for use in making typewriter ribbons are brought to the desired waxy consistency by the addition thereto of one or more such wax or waxlike bodies as carnauba wax, montan wax, ceresin, stearic acid, or the like, the consistency being such that at low temperature the composition will not smooch clean paper laid thereover, but at the same time will lend itself to transfer to the paper under sensible pressure. The waxlike composition, whose oleaginous vehicle is stabilized in accordance with my invention, is applied in the usual manner as a coating oi the appropriate thickness upon a suitable tissue paper base, preferably a rag paper base. The anti-oxidant serves to impart the desired permanency to the resulting coated or carbon paper, that is, to prevent the coating from becoming unduly hardened or embrittled and thereby acquiring a poor ink-transferring ability, becoming cracked or otherwise damaged and detracting unduly from the desirable initial flexibility to the paper. I shall use the expression "pigmented oleaginous vehicle" to define generically the ink composition serving as an impregnant in typewriter ribbons and/or the ink composition serving as a coating on carbon papers, even though such latter composition is of a waxy consistency, as it is the oleaginous vehicle that malres transfer of the inir composition possible in both instances. In saying that the oils used for the purposes of my invention are of an oxidizable character, I mean that they contain one or more unsaturated fatty acids or fatty acid giycerides in sufiicient amount to render such oils unstable or oxidizable in the presence or air, thereby becoming malodoroue or acquiring resinous or gummy oxidation prod note, or undergoing other physical and/or cheini- A cal changes.

I clainlz i. an inlr-transfer medium adapted for use with typing instrumentalities comprising fibrous base, pigmented oleagincus vehicle carried by such bare and being oi such highly onidiaabie character as to be normally unsuitable for use in said medium, and an anti-oxidizing phenolic compound associated with said vehicle in amount adequate to inhibit the oxidation of said vehicle sumciently to render it suitable for use in said medium in that said medium is capable of having a long useful life while possessed of appropriate flexibility and diifusibility of said vehicle irom one locality in said base to another.

2. An ink-transfer medium adapted for use with typing instrumentalities comprising a fibrous base, a pigmented oleaginous vehicle carried by such base and being of such highly oxidizable character as to be normally unsuitable for use in said medium, and alpha naphthol associated with said vehicle in amount adequate to inhibit the oxidation of said vehicle suillciently to render it suitable for use in said'medium in that said medium is capable of having a long useful life while pomessed of appropriate flexibility and difiusibility of said vehicle from one locality in said base to another.

3. An ink-transfer medium adapted for use with typing instrumentalities comprising a fibrous base, a pigmented lard oil carried by such base, and an anti-oxidizing phenolic compound associated with said 011 in amount adequate to inhibit its oxidation sufficiently to render it suitable for use in said medium in that said medium is capable oi having a long useful life while possessed of appropriate flexibility and diffusibility of said oil from one locality in said base to another. v

d. An ink-transfer medium adapted for use with typing instrurnentallties comprising a fibrous base, pigmented lard oil carried by such base, and alpha naphthol associated with said oil in amount adequate to inhibit its oxidation sufllciently to render it suitable for use in said medium in that said medium is capable oi having a long useful liie while possessed of appropriate flexibility and dliiusibility 01 said oil from one locality in said base to another.

FAUL H.