US2271112A - Fade resistant printed or dyed matter - Google Patents

Description

Patented Jan. 27, 1942 FADE RESISTANT PRINTED. OR DYED MATTER Johan Bjorksten, Chicago, Ill., assignor to Ditto, Incorporated, Chicago, 111., a corporation of West Virginia No Drawing.

Application March 17, 1938,

Serial No. 196,374

4 Claims.

This invention relates to improvements in printed or dyed matter, and is more particularly concerned with the preparation of duplicate copies having high resistance to fading.

Most dyestuifs used in transfer or duplicating processes fade when exposed to light and air over a period of time. This is in general true of the water and alcohol soluble dyes, including such commonly used dyes as methyl violet, crystal violet, fuchsines or magentas, anthraquinones, chrysoidine and the like, 'the water and alcohol soluble anilinedyes, such as I aniline blue, Victoria blue'and orange, Nile blue and the like and the water and alcohol soluble azo dyes such as Congo red, Bismarck brown and the like.

Some of the most important and widely used transfer processes involve the use of water and alcohol soluble dyes. The most commonly used process at the present time is the so-called hectograph process wherein a master sheet containing the printing or other design prepared with water and alcohol soluble dye or ink is applied to a moistened gelatinous copy mass, the dye or ink being largely transferred thereto in reverse; the. copies are then made by applying the copy sheets to the'copy mass, each receiving a proportion of the dyes or ink t form a copy of the design.

In the hectograph process the design or writing is generally made on the original or master copy by typing or writing directly on the master sheet, using a water and alcohol soluble ink or through a ribbon containing the water and alcoholfispiuble ink.

Qther duplicating processes which also use water and alcohol soluble inks generally have the ink applied to a transfer paper, sometimes called carbon paper. In one such process the master moistening the copy sheet with a solvent and I applying the copy sheet to theside of the master sheet which has the design in reverse, that is, to the back of the master sheet.

- In all cases fading of the design takes place to a considerable extent due to exposure of the copies to sunlight and air during ordinary usage.

Various attempts have been made to increase the fade resistance of duplicator copies. Some of these attempts, such as the bentonite process, described in U. S. Letters Patent 2,088,417, have increased the light fastness of copies to an appreciable extent, but none of the methods has been entirely satisfactory.

It is therefore an object of this invention to provide duplicating or transfer copies having improved resistance to fading.

In accordance with this invention fading of copies can be greatly retarded by covering the copy with a coating containing a substance which absorbs chemically active radiation, thus preventing such radiation from reaching the dyestufl particles.

In one aspect of the invention the light absorbtive material is incorporated with the dyestuff of the ink. In such instances the light absorbtive material need-not be a substance capable of transmitting visible solar light, although preferably it should have a selective absorption of light such that it is of the same color as the dyestufi.

The ink containing the light absorbtive may be used directly or may be used in typewriter ribbon or as a coating on transfer or carbon paper.

In another form of the invention the light absorbtive material is coated on paper either before or after the application of the design. When the paper is coated prior to the application of the design, the light absorbtive material should be of sufiicient porosity to permit the penetration of dyes to deeper layers. In either case, however, the light absorbtive material should preferably be substantially colorless, and capable of transmitting a substantial proportion of available solar light.

In general the preferred light absorbtive mate rials are those which absorb the highest amount of active light without deleteriously affecting the clarity and coloration of the copies.

The preferred material will absorb a substantial proportion of the light within the range of 2900 to 4000 A, for example" at least 25% of light within 2900 to 4000 A., and preferably at least of light within the range of 3200 to 4000 A., and t will preferably transmit at least 50% of the a ailable visible solar light. It has been found, h wever, that the range of. wave lengths in whic most of the fading of duplicating copies take place is above 3500 A., andis particularly prevalent between 3500 and 3700 A., orin the socalled near'ultra violet region. This is so largely because ultra violet and near ultra violet are the most chemically active on duplicating dyes and because most duplicating copies are generally exposed to indoor light or window glass filtered sunlight which contains near ultra violet to the exclusion of ultra. violet. However, where the copies may be exposed to the direct rays of the sun the absorption of rays below 3500 A. becomes important. Moreover it appears to be the 'case that in general any substance which will absorb light even in a narrow band, to a substantial degree, particularly within the band of 2900 to 4000 A., will give increased fade resistance to duplicator copies of the type which have a design containing water and alcohol soluble dyes. For example, substances which absorb to 90% throughout a band of 2900 to 3200 A. have been found advantageous, even though their absorption in other ranges was low. Furthermore for specific dyes there are in some instances certain wave bands which are more detrimental than other bands. In such instances a light absorbtive material will be satisfactory if it absorbs solely in the active band region, and not so satisfactory if it absorbs solely in a band range of lesser activity. However, in general, the harmfulrays are in the ultra violet region and at least extend into the wave bands of 3200 to 4000 A., generally with the 3500 to 3700 range. v

The following table gives the wave length bands which are most active in accelerating .fading of various dyes used in duplicating processes:

Table I Dye Active Methyl violet 3,5003,700. Crystal violet 3,5003,800. Fuchsine 3,7004,200. Rhodamines... 700-4300. Chrysoidine Shorter than 4,200. Anramme" Shorter than 4,200.

The light absorbtive material may be a single substance or a mixture of substances. It may also be present with a material which itself has little or no absorbtive.power.' For example, the light absorbtive material may include a substance which absorbs almost entirely in the range of 2900 to 3200 mixed with a substance which absorbs almost entirely within the range of 3500 to 3700. The light absorbtive substance may also be mixed with a lacquer which may further contain resins, plasticizer, filler and the like. These additional ingredients will further modify the light absorbtion range.

Representative and useful light absorbtion materials which have been found suitable for im-- proving the fade resistance of duplicating copies are given in the following table:

Table II ttt tfi ihi an an swam a] radiation of y wavelength Angstrom units 2% phen anthrene 3,900-4,100 6 chloro naphthalene- 3,2J-4,000.

., am: no About 3,900. diphenyl benzene v Xanthydrol 3,2004,000.

halanil 0.1% Michler's keton 3,000-4,100. 2% benzyl salicylate. 3,200-3,800.

These substances may be used as such, preferably dissolved in a suitable solvent, or they may be incorporated in any varnish or lacquer. The character of the solvent, or the varnish or lacquer employed does not appreciably change the absorption characteristics essential for this invention.

By referring to Table II and Table I it will be apparent which light absorbtive material should be used with a specific duplicating dye to give maximum fade resistance.

For example benzyl s'alicylateis substantially opaque to'all rays within 3200A. to 3800 A. The most active range for Crystal violet dye is 3500- 3800 A. This material is therefore particularly suitable for retarding the fading of Crystal violet.

The following examples are given to illustrate the invention:

Example I Cholesterol was melted and tri-cresyl phosphate added in such quantity that the resulting mixture remained somewhat plastic at room temperature.

copy made from several hectograph inks containing the following dye-stuffs: Crystal violet, Fuchsin S, Bismarck brown, Methyl violet, Victoria green. This copy was exposed to the radia- Example II A cellulose acetate lacquer containing 10% benzyl salicylate was coated over a hectograph copy prepared by means known to the art, using a Crystal violet containing hectograph ink.

Example III A hectograph ink was made having the following compositions:

Parts by weight Crystal violet 3 Anthranilic acid 3 Hydrochloric acid (conc) 3 Water 15 Example IV Carbon paper was made by applying the following composition to a sheet of tissue paper by means known to the art:

Parts Anthranilic acid 10 Dimethoxy tetra glycol 10. Carnauba w I 5 Crystal violet 6 Example V Paperwas coated and/or impregnated with a 5% solution of benzyl salicylate in alcohol by any of the methods known to the art, such as incorporation in the paper pulp, allowing the material to sink into the paper, or simply coating a solution of the material on the surface of the duplicating copies. It was found that the dyes of the designs would penetrate into the paper and be protected by the light absorbtive material against chemically active radiation.

Inasmuch as the description and examples are largely illustrative in character, any variation A thin coat of this mixture was applied to a part of an evenly colored spot, color- The paper so treated was used to make or modification thereof which conform with the spirit of the invention is intended to be included within the scope of the claims.

I claim:

1. A copy sheet having a design thereon rormed of alcohol and water soluble dye subject to fading on exposure to light within the range of 3200 to 4000 A., said copy sheet having anthranilic acid on its surface in intimate contact with the dye of said characters. v

2. A copy sheet having a design thereon formed of crystal violet, said design being protected against detrimental light rays by a film of anthranilie acid.

3. A hectograph dye composition comprising an alcohol and water soluble dye subject to fading -on exposure to light within the range of 3200 to