US 2730456 A
Description (OCR text may contain errors)
Jan. 10, 1 B. K. GREEN ET AL 2,730,455
MANIFOLD RECORD MATERIAL Filed June so, 1955 PAPER COATING OF MICROSCOPIC HYDROPHILIC COMPLEX COLLOID RUPTURABLE CAPSULES CONTAINING PRINTING FLUID INVENTORS BARRETT K. GREEN 8 LOWELL SCHLEICHER Mm Wmm THEIR ATTORNEYS United States Patent MANIFOLD anconn MATERIAL Application June 30, 1953, Serial No. 365,198
6 Claims. (Cl. 117-36) This invention relates to manifold record material, and
more particularly pertains to such record material which has a transfer coating thereon of microscopic gelled hydrophilic colloid capsules, each of said capsules consisting of a dense oil-impervious shell-like Wall of filmforming complex colloid material deposited around a nucleus of an oily water-immiscible printing fluid by coacervate forces, said capsules being rupturable by printing or writing pressures applied to the record material so as to release said printing fluid for transfer to an under lying sheet.
The encapsulating material which encloses the oil droplets is a complex of gelledfilm-forming hydrophilic colloid materials, as contrasted with capsules made of a single gelled hydrophilic colloid material, which characterizes the encapsulating material of the microscopic oil-containing. capsules with which the record material is coated, as disclosed in applicant Greens co-pending application for United States Letters Patent, Serial No. 365,184, which was filed on the same day as this application.
By a complex of gelled film-forming hydrophilic colloid materials is meant the gelled state of a product formed by the union, in an aqueous medium, of two kinds of hydrophilic colloid materials having opposite ionic charges in said medium, the union being brought about by such difference in charge, the complex having characteristics differing from the colloid components;
The record material of this invention also is distinguished from that disclosed in applicant Greens United States Letters Patent No. 2,374,862, and applicant Greens and Robert W. Sandbergs: United States Letters Patents 2,548,366; 2,550,466; 2,550,467; 2,550,468; and 2,550,469, in that in the patent disclosures, instead of using microscopic oil-containing capsules in the transfer coating, the oily printing fluid was contained in droplet form in a continuous gelled hydrophilic colloid film.
In forming a continuous hydrophilic colloid film, there is a permeable condition set up whereby, even though the surface of the film is hardened by treatment that closesthe surface pores, cracks may form. through handling, or due to environmental conditions, which rupture the film. In such cracks the voids holding the oil are opened up because the cracks run straight through the voids. As the walls separating the voids in the film are somewhat permeable to the oil, oil may leak out, not only from theregion of. the cracks; but from: uncracked portions ofthe film, leaving the: film inadequate to per form its function.-
In the present invention the microscopic capsules, al though adherent toone another and to the paper, main-- tain their individuality so that if cracks are made by bending, of the paper, the cracks in the coating will run between the capsules and not through them. Also, in the present invention the microscopic capsules are made impermeable to'the oil .by a method disclosed and claimed i'n'app'licants co-pending application for UnitedStates Letters Patent, Serial No; 365,105, tiled the someday as this application. That method will be described in this application, insofar as applicable, but will not 'be claimed herein. 3 The manifold sheet of this invention, therefore, is superior to those shown in the patents to which reference has been made, insofar as shelf-life and durability are concerned. I
Therefore, it is an object of this invention'to provide a manifold sheet having a transfer film coating, on' a surface thereof, which is composed of microscopic cap sules of gelled complex film-forming hydrophilic colloid material, each of said capsules consisting of a dense'oilimpervious shell-like wall of the complexcolloid mate rial deposited around a nucleus of an oily printing fluid by coacervate forces, and the capsules being present in such number as to be in substantial contig'uity. I Inasmuch as the invention contemplates the use of colorless color-reactant materials, which constitute the oil, or which form a part of or is carried by the oil, it is another object of the invention to make such a mani fold sheet in which the transfer coating is substantially colorless, but which will render colored marks upon a properly sensitized receiving sheet. With these and incidental objects in view, the invention includes certain novel features of structure and combinations of elements, a preferred form or embodiment of which is hereinafter described with reference to the drawing which accompanies and forms a part of. this specification.
The drawing shows the manifold sheet of this invention in an enlarged and exaggerated form, so that the features may be discernible.
In the preferred embodiment of the invention there will be described a manifold sheet having a coating con taining as a primary printing substance the compound 3-,3 bis(p-dimethylaminophenyl) 6-dimethylamino phthalide dissolved in oil, which produces dark blue marks immediately when coming into adsorption contact with a record material sensitized with acid clay-like material such as attapulgite, or zeolite material such as sodium aluminum silicate material, or such in which the sodium has been exchanged for hydrogen or some other metal ion such as disclosed in applicant Greens United States Letters Patent Nos. 2,58l,l86 and 2,641,557. As a secondary color-reactant in the oily printing fluidof the preferred embodiment there is provided a type of color reac tant which oxidizes from a normally colorless form to a colored form when in contact with the clay material's just described, after the passage of some hours or days. The phthalide compound, like all dyes, tends to fade in time, but the secondary color reactant of the oxidizing type forms a color which is lasting. The preferred secondany color reactant is benzoyl leuco methylene blue.
As the oily vehicle in which the color-reactants named above are carried, applicants have chosen for the" pro f'erred embodiment trichlorodiphenyl', the colorre actant's being used therein in amounts equal to several percent, by weight, of the total amount of the printing fluid.
As the encapsulating colloid material for the preferred embodiment, applicants have selected a gelatin-gum arabic' complex, which is formed. during. a: process of CO7 ace'rvation in which the capsules are-formed, although other pairs of film-formingcolloid materials willdo,
In forming. the oil-containing; capsules of. the preferred embodiment of. the invention, 20 grams ofgum arabic are dissolved in 160 gramsof water and into is emulsified grams of trichlorodiphenyl'containing 310,6 percent, by weight, of the two colorreactant material-1s 3,3 bis(p-dimethylaminophenyl) 6-dimethylam-ino1phthab ide and the benzoyl leuco methylene-glue,.-preferably -itr equal amounts.- The emulsion is carried-on untildlie; drop size of the 'oil is from 2. to 5 microns. "Next m i 3 grams of gelatin is dissolved in 160 grams of water and mixed with the emulsion. This mixture of colloid sols is then diluted by adding water uniformly and slowly, with agitation, until coacervation occurs, the complex gum arabic-gelatin colloid material forming around the droplets of the oil. These colloid surrounded droplets make aggregates of from several microns in diameter up to 70 microns in diameter depending on the rate and extent of dilution. The added water should amount to about 500550 grams. Up to this time all the ingredients are kept at approximately 50 C., which is above the gel point of the ingredients. Now that the colloid material has deposited around the oil droplets forming particles, the colloid material is caused to gel by pouring it into a quantity of cold water; for instance, water at zero degreescentigrade. The mass is agitated and then let standfor one hour at not over 25 centigrade. At this point thetotal weight of all ingredients should be about 3960 grams. At this point the pH is adjusted to between 9and 7, such adjustment being made with sodium hydroxide, and the material is left for 30 minutes or more in this state. The capsules are then hardened by pouring in about 20 grams of a solution of formaldehyde in water, of about 37% formaldehyde content, and the materials are agitated for ten minutes or more at 3 centigrade or lower. This material is adjusted to the right water content to form a coating composition, that is to say, Water may be added or taken away by filtering or centrifuging until the right coating viscosity is obtained. At this stage the coating composition is a creamy white fluid. If a portion of this fluid is sparsely dispersed in water and placed under a microscope, it will be seen to consist of microscopic capsules of the hydrophilic complex colloid material, the individual capsules being several microns in diameter and containing one or more droplets of oil. As the water content is decreased, the capsules tend to form aggregations like bunches of grapes.
When the material is of the right consistency it is coated on paper by rollers, spray, brushes, or any other of the commonly used methods of coating paper, and allowed to dry. The material is of such a nature that the capsules are adherent to each other in the coating, and will adhere to the paper, without the addition of any other binder material.
For more details concerning the process of making the microscopic capsular material, reference is made to our co -pending application Serial No. 365,105 regarding the process to which attention has been drawn. In that application, methods are disclosed for determining the ratio of one colloid to the other that can be used to make a complexcolloid. The colloids do not necessarily have to be used in a one-to-one ratio, but such ratio is preferred.
1 Other colorless adsorption color reactants which form color immediately on contact with acid clay-like material, such as the mentioned attapulgite, are malachite green-lactone, which is 3,3 bis(p-dimethylaminophenyl) phthalide, and the ethyl or propyl homologues thereof, which form bluish green marks on the acid-like clay sensitized receiving sheet. Other comparable and equivalent materials are found in United States Patent No. 2,548,366, to which attention has been dinected.
The material in the oil which produces the mark on the receiving sheet need not be a reactive material but may have an intrinsic color of itself, such as dissolved dyes,'like Sudan III or nigrosine.
There may be substituted for the gum arabic or the gelatin, or both, hydrophilic colloid materials selected so that they have different ionic charges when dispersed in water, or can be made to have such different ionic charges by adjustment of the pH of the water, so that coacervation may be brought about by dilution with water as dis closed'in more detail in said co-pending process application. It is necessary that one or both of the colloid materials be gellable in order that the encapsulation may be completed. The encapsulating film material contains portions of both the gum arabic and the gelatin molecules, and for that reason is called a complex colloid material.
The oils which may be substituted for trichlorodiphenyl are any of the water immiscible oils, which are inert as to the other materials used in forming the capsules, such as petroleum fractions like parafiin oil, vegetable oil such as castor oil and cottonseed oil, animal oils such as sperm oil and lard oil, and any other various synthetic oils such as methyl salicylate.
The coating material should be used in such quantity on the paper that when dried the coated area will be profusely supplied with the microscopic capsules so that they are in contiguity, but such thickness need be no more than a fraction of a thousandth of an inch, because the size of the capsules is in terms of several microns. A four pound coating on a ream of paper 25 inches by 38 inches is satisfactory.
A sheet of ordinary writing paper, coated on one surface with the described coating composition laid with that coated surface on the attapulgite-sensitized surface of a receiving sheet forms a manifold system which is responsive to very light printing or writing pressures, such as are ordinarily used in every-day printing and writing, so as to make clear and distinct marks on the receiving sheet, yet the coating is so durable that it will undergo rough handling without premature rupture of the capsules and is proof against the deleterious influences of the environment, either atmospheric or artificial.
The method of manufacture of these capsules is such that the capsules are impermeable to the oil, although the capsules may be made porous by very fast dilution of the mixture of the sol and emulsion.
While the form of the invention herein shown and described is admirably adapted to fulfill the objects primarily stated, it is to be understood that it is not intended to confine the invention to the one form or embodiment herein disclosed, for it is susceptible of embodiment in various other forms.
What is claimed is:
1. A record material base sheet having on a surface thereof a coating consisting of a profusion of microscopic oil-containing, pressure-rupturable capsules, each of the capsules consisting of an oily water-immiscible printing fluid as a central nucleus and a dense oil-impermeable shell-like coating therefor of gelled, film-forming complex hydrophilic colloid material evenly deposited therearound by coacervation forces, said colloid material being the gelled product of the union, in an aqueous medium, of substantially equal parts, by Weight of two different colloid materials having opposite ionic charges in said medium, said union being caused by such opposite charges, and said capsules being in substantial contiguity on the base sheet and being mpturable by printing or marking pressures.
2. The record material of claim 1 in which the base sheet is paper.
3. The record material of claim 1 in which the oily printing fluid consists of an oil vehicle in which is carried a colorless color-reactant which turns to a colored form on contact with paper sensitized by having thereon acid clay-like material.
4. A record material base sheet having on a surface thereof a coating consisting of a profusion of microscopic oil-containing, pressure-rupturable capsules, each of the capsules consisting of an oily water-immiscible printing fluid as a central nucleus and a dense oil-impermeable shell-like coating therefor of gelled, film-forming complex hydrophilic colloid material evenly deposited therearound by coacervation forces, said colloid material being the gelled product of. the union, in an aqueous medium, of substantially equal parts, by Weight, of gelatin and gum arabic by reason of their opposite ionic charge, and said capsules being rupturable by printing or marking pressures applied to the coated sheet, the capsules being in substantial contiguity.
5. The record material of claim 4 in which the base sheetis paper.
6. The record material of claim 4 in which the oily printing fluid consists of an oil vehicle in which is carried a colorless color-reactant which turns to a colored form on contact with paper sensitized by having thereon acid clay-like material.
References Cited in the file of this patent UNITED STATES PATENTS Green Apr. 10, 1951