US3227073A

US3227073A - Ink repellent inking pad and cover for stencil printing devices

Info

Publication number: US3227073A
Application number: US238669A
Authority: US
Inventors: John J Reich
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-11-19
Filing date: 1962-11-19
Publication date: 1966-01-04
Anticipated expiration: 1983-01-04

Description

Jan. 4, 1966 J. J. REICH 3,

INK REPELLENT INKING PAD AND COVER FOR STENCIL PRINTING DEVICES Filed Nov. 19, 1962 gg M LL;

v- 4 gig/5 United States Patent 3,227,073 INK REPELLENT INKING PAD AND C(WER FtER STENCTL PRENTENG DEVlCES John 3. Reich, 6314 W. Patterson Ave, Chicago, Ill. Filed Nov. 19, 1962, Ser. No. 238,669 9 Claims. (Cl. 191-125) This invention relates to an ink distributing pad and cover therefor and more particularly to an ink distributing cloth and cover for use in duplicating apparatus. This application is a continuation-in-part of Serial No. 817,973, filed June 4, 1959, and now abandoned.

Most conventional duplicating apparatus, whether of the hand stamp type, belt type or rotary drum type employ a cloth member to distribute the printing ink onto the surface of a stencil or similar printing matrix. The ink distributing cloth is generally referred to as an inking pad and will be designated as such herein for purposes of explanation.

In conventional rotary duplicating apparatus, i.e., stencil duplicators, the inking pad, which is generally constructed from commercially available cloth such as cotton flannel, wool, rayon, etc. or laminations of these materials, is physically attached to the surface of a perforated drum or cylinder which serves as an ink reservoir. Ink is supplied to the interior of the perforated drum, and centrifugal force during the operation causes the ink to pass outwardly through the perforations in the drum and into the pores or interstitial passages in the inking pad. The ink is drawn through the pad and forced through the openings in the stencil by a pumping action created by the alternating pressure developed by contact with the roller of the duplicating machine. Thus, the ink passes through the stencil onto the paper to be printed which is pressed against the surface of the stencil by the impression roller. The inking pad acts to hold the ink within the rotating perforated drum and also, under pressure from within the cylinder, to evenly distribute ink over the surface of the stencil. The ink employed can either be in a fluid state or can be paste, whichever is desired. In all instances, however, an inking pad is essential to the efficient performance of the duplicating apparatus.

The presently available inking pads have several inherent limitations which necessitate their frequent removal from the duplicating apparatus and which cause difliculties which have not been heretofore adequately compensated for. Some of the limitations present in conventional inking pads for duplicating apparatus are: (1) the ink vehicle tends to separate from the ink pigments in the inking pad due to capillary action within the inking pad; (2) the ink vehicle which becomes separated from the ink pigment accumulates on the lower surface of the cylinder and drips off the cylinder; (3) the separated ink vehicle evaporates from the inking pad causing the pad to become dried out; (4) the ink vehicle is preferentially absorbed from the ink pigment by the inking pad causing a stiff crust of pigment to be built up within the perforated cylinder; and (S) the separation and evaporation of the ink vehicle causes inks to lose their characteristics upon prolonged storage within the duplicating apparatus.

All of the above enumerated difliculties, and others, stem from the separation of the ink vehicle from the ink pigments due to capillary action within the inking pad. Several modifications have been devised to counteract the effect of the ink vehicle separation by capillary action including; the use of high viscosity oil based inks, the use of water based inks conventionally containing dyes, the use of emulsion inks, frequent changing of the hiking;

pad and regular cleaning of the perforated cylinder to re- 3,227,073 Patented Jan. 4, 1966 move caked ink. The remedies presently available to users of duplicating apparatus do not solve the problems attendant with the use of inking pads, in which the capillary separation of the ink vehicle takes place, and maintenance costs and higher cost inks greatly increase the cost of operation of the duplicating apparatus.

The conventional inking pad cover, which is placed on the surface of the inking pad when the duplicating apparatus is not in service, is subject to the same disadvantages as is the inking pad. Two forms of duplicator covers are presently available, the absorbent cover and the barrier cover. The barrier cover, which is generally a heavy wax or plastic coated paper sheet, is constructed in a manner to prevent the evaporation of the ink from the surface of the inking pad. However, the nature of the barrier cover is such that it is completely nonporous and the barrier cover will not absorb any ink. If excess ink or separated ink vehicle is present upon the surface of the inking pad it will run between the inking pad and cover to the lower surface of the cylinder where it will drip onto the floor or supporting means for the duplicating apparatus. The absorbent cover, generally constructed of a kraft or sulphite paper, is made to absorb excess ink on the surface of the inking pad. The absorbent cover is, therefore, also subject to the capillary separation of the ink vehicle from the ink pigments, and does not prevent the drying out of the inking pad and the formation of pigment crusts within the inking pad and perforated cylinder.

It is the principal object of this invention to provide an inking pad and/ or cover which diminishes the capillary separation of the ink vehicle from the ink pigments.

It is another object to provide an inking pad and/0r cover for use in duplicating apparatus which eliminates the necessity for frequent cleaning of the duplicating apparatus and replacement of the inking pad and cover. A further object is to provide an inking pad and/or cover which reduces the evaporation of the ink vehicle and reduces the crusting of the ink upon the surface of the inking pad and perforated cylinder. A still further object of the invention is to provide an inking pad and/or cover for use in duplicating apparatus which diminishes the capillary separation of the inking vehicle from the ink pigments which is economical to construct and which is convenient to use in duplicating apparatus.

These and other objects of the invention will be perceived from the following detailed description and from the drawing in which:

FIGURE 1 is a perspective view of an ink reservoir for a duplicating apparatus showing a specific embodiment of the inking pad and cover.

In general, the inking pad 6 and cover 8 shown in the drawing are of a web material which is constructed from fibers which are ink repellent, or have an ink repellent coating applied thereto. The ink repellent coating is applied to the inking pad 6 and cover 8 in an amount sufficient to reduce or prevent the capillary flow of ink vehicle within the inking pad 6 and cover 8 but less than that which blocks the interstitial passages and prevents ink from pasing therethrough under pressure from an ink reservoir and under printing pressure.

For purposes of explanation the inking pad 6 and cover 8 are described hereinafter as employed with a conventional duplicating apparatus of the rotary drum type. As shown in the drawing, the conventional rotary duplicating apparatus includes a perforated drum 10 which contains a plurality of perforations l2 evenly spaced over its surface. Ink is supplied to the interior of drum it) by conventional means (not shown).

The inking pad 6 is provided with suitable means 14 for attaching the pad to the drum It) and securing the same tightly against the outer surface of the drum 10.

The inking pad 6 is composed of a porous web material or a plurality of layers of porous web material which is constructed from ink repellent fibers. For oil base inks, repellent fibers, such as fluorocarbon resin fibers (e.g., polyfluoroolefin fibers) are employed. For Water base inks, fluorocarbon fibers are employed as well as polyolefin resin fibers such as polypropylene. A sponge material is also contemplated as within the use of the term fiber. The inking pad 6 may also be composed of a nonrepellent material such as cotton flannel, silk, Wool, rayon or nylon, etc., which are treated with an ink repellent coating compound to form an ink repellent coating on the surfaces of the individual fibers that make up the pad. Suitable ink repellent coating compounds are the chromium complexes of perfluoroacids, fluorocarbon resins, silicone resins, waxes, the insoluble salts of fatty acids having at least approximately 12 carbon atoms and chromium complexes of fatty acids having at least approximately 12 carbon atoms. It should be noted that the use of the term coating is intended to encompass both the formation of a coating on the surface of the fiber, such as occurs when using silicone resins or the salts of fatty acids, and the chemical reaction with the inking pad fibers such as occurs when using the chromium complexes of ctatty acids or perfluoroacids.

When the ink repellent coating is applied to the fibers of the nonrepellent material, care must be taken to avoid applying the coating compounds in an amount which blocks interstitial passages of the material. If too much coating compound is applied, the centrifugal force and the pumping action will be insufficient to cause the ink to pass through the pores in the ink pad material. It has been found that in most instances a coating which is from about 0.1 to percent by weight of the ink pad material is sufiicient to provide the material with an ink repellent coating which resists and diminishes the ca pillary separation of the ink vehicle and ink pigment. When more than 25 percent by weight of ink repellent coating is employed, the inking pad normally has a portion of its interstitial passages blocked and the fiow of printing ink therethrough is hindered to such an extent that poor copies are obtained from the duplicating apparatus. By employing a pad constructed as described above, the ink employed with the pad may be of an improved composition. In this connection, the ink need not be made to withstand capillary separation. Therefore, the ink more readily dries on the paper than the ink employed with previously available inking pads.

In the illustrated embodiment, the cover 8, which is shown disposed about the surface of the inking pad 6 is composed of a porous web material constructed from ink repellent fibers. For oil base inks, repellent fibers such as fluorocarbon resin fibers (e.g. polyfluoroolefin fibers) are employed. For water base inks, fluorocarbon fibers are employed as well as polyolefin resin fibers, such as polypropylene fibers. The porous web material may also be constructed from nonrepellent fibers such as sulphite paper, kraft paper, cotton flannel, silk, wool, rayon, nylon cloth, etc. which are coated with an ink repellent coating compound, such as that described above in connection with the inking pad that renders the cover repellent to the ink and reduces the capillary separation of the ink vehicle and ink pigment. The amount of coating compound applied to the material is limited to a value such that the cover remains porous, thereby allowing any excess ink present on the surface of the inking pad to be absorbed into the pores of the cover, and thus prevent the dripping of the ink from the duplicating apparatus. The absorbed ink vehicle does not become separated from the ink pigment within the cover and does not evaporate from the ink.

Various features of the above described inking pad and cover will be perceived from the following examples.

4. Example 1 A one percent solution of a chromium complex of a perfluoroacid, commercially available as Minnesota Mining Scotch Guard 803, in methyl alcohol is prepared and an inking cover constructed from sulphite paper and an inking pad of a cotton flannel having a nap on one side is immersed in the perfiuoroacid solution for three minutes, a time found sufiicient for the cover and inking pad to become thoroughly wetted by the solution. The cover and inking pad are removed from the solution, the excess solution is removed from the cover and pad by wringing, and the cover and pad are air dried.

A cover and inking pad are produced which greatly diminish the capillary separation of the ink vehicle from the ink pigment in both water base and oil base inks and repeated use of the cover and inking pad produced shows that the ink Within the perforated drum does not evaporate through the surface of the inking pad or become crusted upon the inking pad or the interior of the perforated drum.

Example 2 An inking pad and cover were made according to the method of Example 1 employing a five percent solution of a silicone resin, one such resin commercially available being Dow Corning Antifoam A. The coated inking pad and cover were found to resist the capillary separation of water based inks and likewise allowed the opera tion of of a duplicating apparatus for extended periods of time with long off cycles with a significant reduction in the evaporation of the vehicle or caking of the ink pigments either on the inking pad or within the perforated cylinder.

Example 3 An inking pad and cover are made from a cotton flannel cloth and sulphite paper respectively by immersing the inking pad and cover in a five percent water solution of sodium stearate until thoroughly Wetted. The inking pad and cover are then treated with a five percent solution of calcium chloride which reacts with the sodium stearate to produce insoluble calcium stearate and the inking pad and cover are dried. After drying the inking pad and cover are subjected to a heat treatment to melt and fuse the calcium stearate onto the surface of the individual fibers of the inking pad and cover. The inking pad and cover produced are ink repellent to water base inks and diminish the capillary separation of the ink vehicle from the ink pigment.

Example 4 An inking pad and cover were made according to the method of Example 1 employing a five percent solution of chromium complex of stearic acid, commercially available as Du Pont Quilon. The ink pad and cover produced are of a nature which reduced the capillary separation of water base ink vehicle and likewise allowed the repeated operation of the duplicating apparatus Without the degradation of the ink.

Example 5 An inking pad and cover are constructed from tetrafiuoroethylene ink repellent fibers. The inking pad and cover exhibits similar ink repellent properties as the ink repellent coated inking pad and cover of Example 1 and resists the capillary separation of the ink vehicle of both water base and oil base inks.

A method employed to determine the precise amount and level of treatment of the inking pad and cover fibers in order to provide an inking pad or cover which will not support the capillary separation of the ink vehicle from the ink pigment is one which employs the measurement of the angle of contact of the ink vehicle on the surface of the inking pad or cover which has been treated in a manner as set forth in the preceding examples. The angle of contact is the internal angle (i.e. within the droplet) formed by a plane tangent to the droplet at the point where it contacts the surface of the inking pad or cover. An angle of more than 90 degrees occurs when the droplet of ink vehicle forms more than a hemisphere on the surface of the inking pad or cover. A drop of the ink vehicle is placed on the surface of the inking pad or cover and the angle that the droplet of ink vehicle forms with the inking pad or cover is measured after equilibrium has been reached. It has been found that an angle of contact of more than 90 degrees is necessary to prevent the capillary separation of the ink vehicle from the ink pigment within the inking pad or cover. If the droplet of ink vehicle assumes an angle of contact of 90 degrees or less the inking pad or cover will be susceptible to the capillary separation of the ink vehicle from the ink pigment and will not be suitable to overcome the disadvantages attendant therewith.

Although the inking pad and cover have been particularly described with respect to their use in a duplicating apparatus of the rotatable drum type it is apparent that the ink repellent inking pad and cover can also be utilized in other forms of duplicating apparatus, such as the belt type stencil duplicating machines or conventional inking duplicating devices, (eg stamp pads and the like) where evaporation and the capillary separation of the ink vehicle from the ink pigment is undesirable.

It can be seen that an inking pad and cover have been provided which greatly diminishes or prevents the capillary separation of the ink vehicle from the ink pigment. By preventing the separation of the ink vehicle from the ink pigment, conventionally available duplicating apparatus can be operated with repeated on and oif cycles without the necessity of a rigorous maintenance of the machine or the frequent cleaning or replacement of the inking pad and cover and/ or printing ink.

Various of the features of the invention are set forth in the following claims.

What is claimed is:

1. An inking pad for use with a duplicating apparatus comprising, a porous fiberous web material having interstices formed between adjacent fibers for passage of ink therethrough, means for attaching said inking pad to a duplicating apparatus, said fibers being ink repellent to a degree sufficient to substantially restrict the flow of ink through said interstices by capillary action, said interstices being of a size such that said inking pad has a sufiicient porosity to allow the flow of ink therethrough under printing pressure.

2. An inking pad for use with a duplicating apparatus comprising, a porous fiberous web material having interstices formed between adjacent fibers for passage of ink therethrough, means for attaching said inking pad to a duplicating apparatus, said fibers being ink repellent to a degree sufiicient to form an angle of contact of more than 90 with a droplet of ink vehicle whereby the flow of ink through said interstices by capillary action is substantially restricted, said interstices being of a size such that said inking pad has a sufiicient porosity to allow the flow of ink therethrough under printing pressure.

3. An inking pad for use with a duplicating apparatus comprising, a porous fiberous web formed from an ink repellent material, said inking pad having interstices formed between adjacent fibers for passage of ink there through, means for attaching said inking pad to a duplicating apparatus, said fibers being ink repellent to a degree sufficient to substantially restrict the flow of ink through said interstices by capillary action, said interstices being of a size such that said inking pad has a sufiicient porosity to allow the flow of ink therethrough under printing pressure.

4. An inking pad for use with a duplicating apparatus comprising, a porous fiberous web formed from an in repellent material selected from the group consisting of fluorocarbon resins and polyolefin resins, said inking pad having interstices formed between adjacent fibers for passage =of ink the-rethrough, means for attaching said inking pad to a duplicating apparatus, said fibers being ink repellent to a degree suflioi-ent to substantially restrict the flow of ink through said interstice by capillary action, said interstices being of a size such that said inking pad has a sufficient porosity to allow the flow of ink therethrough under printing pressure.

5. An inking pad for use with a duplicating apparatus comprising, a porous fiberous web material having interstices formed between adjacent fibers for passage of ink therethrough, means for attaching said inking pad to a duplicating apparatus, said fibers having an amount of an ink repellent coating material thereon sufiicient to substantially restrict the flow of ink through said interstices by capillary action, said interstices being of a size such that said inking pad has a sufiicient porosity to allow the flow of ink therethrough under printing pressure.

6. An inking pad for use with a duplicating apparatus comprising, a porous fiberous web material having interstices formed between adjacent fibers for passage of ink therethrough, means for attaching said inking pad to a duplicating apparatus, said fibers having an. amount of an ink repellent coating material thereon sutli-cient to substantially restrict the flow of ink through said interstices by capillary action, said coating material being selected from the group consisting of chromium complexes of periiuoroacids, fluorocarbon resins, silicone resins, waxes, insoluble salts of fatty acids having at least about 12 carbon atoms, and chromium complexes of fatty acids having at least about 12 carbon atoms, said interstices being of a size such that said inking pad has a sufficient porosity to allow the flow of ink therethrough under printing pressure.

7. An inking pad for use with a duplicating apparatus comprising, a porous fiberous web material having interstices formed between adjacent fibers for passage of ink therethrough, means for attaching said inking pad to a duplicating apparatus, said fibers having a coating of between about 0.1 percent and about 25 percent by weight of an ink re ellent coating material selected from the group consisting of chromium complexes of perfiuoroacids, fluorocarbon resins, silicone resins, waxes, insoluble salts of fatty acids having at least about 12 carbon atoms, and chromium complexes of fatty acids having at least about 12 carbon atoms, said coating restricting the flow of ink through said interstices by capillary action, said interstices being of a size such that said inking pad has a sufii oient porosity to allow the flow of ink therethrough under printing pressure.

8. For use in a duplicating apparatus, a cover for covering an inking pad comprising, a porous fiberous web material having interstices formed between adjacent fibers for passage of ink therethrough, means for attaching said cover to a duplicating apparatus, said fibers being ink repellent to a degree sufficient to substantially restrict the fiow of ink through said interstices by capillary action, said interstices being of a size such that said cover has a suilicient porosity to allow the flow of ink therein under pressure.

9. For use in a duplicating apparatus, a cover for covering an inking pad comprising, a porous fiberous web material having interstices formed between adjacent fibers for passage of ink there'through, means for attaching said cover to a duplicating apparatus, said fibers having an amount of an ink repellent coating material thereon suf ficient to substantially restrict the flow of ink through said interstices by capillary action, said coating material being selected from the group consisting of chromium complexes of perfluoroacids, fluorocarbon resins, silicone resins, waxes, insoluble salts of fatty acids having at least about 12 carbon atoms, and chromium complexes of fatty 7 8 acids having at least about 12 carbon atoms, said inter- 2,651,255 9/ 1953 Wallich 101125 stices being of a size such that said cover has .a suflicient 2,662,835 12/ 1953 Reid 117-135.5 porosity to allow the flow of ink therein under pressure. 12,303,615 8/1957 Ahlbrecht t a1. 117135.5 2,323,144 2/1958 Dalton 117-1355 X References Cited by the Examiner 5 2,895,853 7/1959 Snyder et a1. 117-4355 X a 3,002,449 10/1961 Sherman 101-1 19 2096 753 ii f f I 117 135 5 3,089,806 5/1963 Mizell 117135.5 X

urp ye a. 2 173 243 9 1939 Young 7 135 EUGENE CAPOZIO, Exammer- 2,510,838 6/1950 Sherman 101--125 X 10 ROBERT E. PULFREY, Examiner.

Claims

1. AN INKING PAD FOR USE WITH A DUPLICATING APPARATUS COMPRISING, A POROUS FIBEROUS WEB MATERIAL HAVING INTERSTICES FORMED BETWEEN ADJACENT FIBERS FOR PASSAGE OF INK THERETHROUGH, MEANS FOR ATTACHING SAID INKING PAD TO A DUPLICATING APPARATUS, SAID FIBERS BEING INK REPELLENT TO A DEGREE SUFFICIENT TO SUBSTANTIALLY RESTRICT THE FLOW OF INK THROUGH SAID INTERSTICES BY CAPILLARY ACTION, SAID INTERSTICES BEING OF A SIZE SUCH THAT SAID INKING PAD HAS A SUFFICIENT POROSITY TO ALLOW THE FLOW OF INK THERETHROUGH UNDER PRINTING PRESSURE.