US2137256A - Manufacture of inked ribbons - Google Patents

Description

Nov. 22, 1938. r. A. WALDIQGN MANUFACTURE OF INKED RIBBONS Original Filed July 19, 1932" l4 ATTORNEY Patented Nov. 22, 1938 UNITED-STATES PATENT OFFICE 2,131,250 MANUFACTURE or man masons Frederick A. Waldron, wesrnela, N. J.

wed June 22, 1937 Application July 19, 1932, Serial No. 623,368

, Rene 11 Claims. (01. 91-10) 6 These ribbons are made out of finely woven fabric, such as muslin, cotton, or silk, and accord- 7 ing to the methods commonly employed, a strip of this material is, without .any preliminary treatment, passed through an ink bath (composed of 10 suitable pigment in an oil base) so that capillary attraction will cause an absorption of ink. It is then subjected to pressure rolls'to regulate the inking of the. ribbon. A light roll .prmsure produces a heavily inked, more juicy ribbon II which gives wet and darkly shaded, dense printing, and more or less splash, while with. heavier roll pressure the ribbon retains less ink so that the ribbon is less juicy and the printing is of a lighter shade. with the same ink bath, the B shade variation is obtained by variation :of roll pressure. The rolling or squeezing of the ribbon wet with inkis not a selective operation, for coloring matter and oil are pressed out in sub-' s'tantially the same proportion in which they 26 were present in the ink bath. There is, there- .fore, less actual pigment in the ribbon subjected to the greater pressure and hence its useful life is much impaired.

Inthemanufacture of ribbons, no attention 30 seems to have been given to the hygroscopic property of the fabricfwhereby more or less moisture is absorbed from the atmosphere. This moisture variation varies the condition of the fibres (as is ten known in the textile art) 35 and its presence resists the absorption of the oil and pigment. This brings about a. lack of uniformity of the finished product.

The fabric used for ribbon'manufacture ap-.

pears to the naked eye to be closely woven, but 40 when held up to the light, or when observed under a low power microscope, it has the appearance of a fairly open screen. Wh'en,this fabric is immersed into the ink bath, the ink penetrates the fibres and fills the interstices between the 46 threads. The pressure applied by the rolls not only squeezes out the pigment and oil but also acts to flatten out the threads and reduce the interstitial areas. Release of the pressure allows the threads to resume their original form 50 so as to absorb more'or less of the ink film extending across the interstices. There is, however, considerable free ink in this film causing juiciness. When the ribbon is struck by the type, the threads are flattened out, the interstitial spaces reduced, 55 and this free ink splashes out onto the paperand type. On release of the pressure, the threads resume their original form with a thinner film of ink between them. This juicy condition continues until the free ink has been removed by-splashing it out of the ribbon.

, The present invention contemplates improvements in the manufacture of typewriter ribbons and the like whereby the pigment oil ratio inthe finished ribbon is predetermined and materially greater than in the original ink bath, so that the ribbon may have a longer life and beef more uniform shade during use. At the same time excessive juiciness of the new ribbon is avoided and initial outward flow of ink to paper retarded and held back for more eflicient future use. 5 Furthermore the recovery of the ribbon after a rest is improved.

Accordingly, the ribbon is, during the process of manufacture, subjected to a process wherein the impregnation is accomplished in a vacuum 2 treated strip offabric without mechanically squeezing the strip or flatteningout the fibres. This impregnated strip will absorb more pigment and vehicle than where the former squeezing process iswelied'upon. To retain the'added pigment, the invention contemplates'expanding or exploding the threads of fabric and reducing air -space and the removal by evaporation under reduced pressure and at low heat of the excess vehicle (or oil) only, in order that the finished product-shall contain a maximum amountof ink of a predetermined controllable content of oil. and pigment whereby the pigment is not injured.

According to the present invention, the material is passed rapidly from the atmosphere through a liquid seal (preferably mercury) and communicating with a high vacuum chamber, so that moisture, air, and gases (principally water vapor) may be removed from-the strip. The escape of the air and gases is so sudden that the fibres are loosened and eikpanded, and hence the thread size is increased. The vacuum chamber is associated with one side of .a liquid seal having coating and impregnating bath of ink, preferably floated on mercury. The surface of the below the exposed surface of the coating or impregnating liquid or' mercury. The liquid pressure acts to force the ink into the evacuated strip and does not mechanically squeeze it out, as do the pressure rollers.

The strip material then passes upwardly through the liquid seal and into the same or a second vacuum chamber where it is heat treated under vacuum. For typewriter ribbon manufacture, this operation is carried out so that the temperature of the ribbon is kept below that in- 'jurious to ink or pigment, but above the vaporization point of the oil vehicle. This temperature will vary in range depending on the characteristics of materials used and final oil content required, but will in no event impair or injure the pigment of the ink, but will be suificient to vaporize and promote rapid evaporation of the oil to the required amount. The strip now contains all the pigment which it had absorbed, but less oil. It is then preferably subjected to a squeezing operation while still under the vacuum, so that the pigment is compacted, and kneaded into the fabric, and a suitable, smooth finish provided. The material is then passed through another mercury seal to compensate for the pressure difference between this second chamber and the atmosphere.

The accompanying drawing shows, for purposes of illustrating the present invention, one of the many embodiments in which the invention may take form, it being understood that the drawing is illustrative of the invention rather than limiting the same. In this drawing:

Fig. 1 is a diagrammatic sectional view through an apparatus suitable for the manufacture of typewriter ribbons;

Figs. 2 and 3 are fragmentary sectional views on the lines 2-2 and 3-3 of Fig. 1;

Figs. 4 and 5 are diagrammatic views illustrating the normal thread size and the enlarged thread size caused by sudden evacuation of moisture and gases from the fabric; and

Figs. 6 and 7 illustrate the condition in former ribbons overcome in ribbon made as described herein.

The apparatus comprises two stationary 'vacuum compartments A and B carrying downwardly extending suction tubes as indicated at III, II, I2, and I3, and guides in the form of rollers I4 and I6, or glass rods I5, I5, l5".

to facilitate threading the strip through the apparatus. Each of these containers is adapted to contain an inert liquid, such as mercury, into which the lower ends of the tubes III, II, I2, and "I3 extend. The chambers A and .B are connected to a suitable exhaust pump, indicated at 22, so as to evacuate the air and gases from the chambers, and when the air is evacuated from these chambers, the mercury is sucked up into the tubes III, II, I2, and I3 as indicated-. The two-compartment arrangement is preferred over a larger single vacuum chamber, as it permits a. more flexible control.

Asupply of ribbon fabric R. isindicatedat 25. It fed down underneath the roller I4 up through the suction tube I0, and into vacuum chamber A where it passes between-two electric heaters 26, 26 pressed toward one another by springs 21 so as to heat the fabric, preferably without ironing it.

The compartment A contains two guide rollers 28 and 29, one'above the suction tube I0, the other above the suction tube I I.

An ink reservoir is indicated at 30. Itis connected by float valve 3| and pipe 32 so as to discharge ink into the lower part 33 of the chamber A where it floats on top of the mercury in column II.

The ribbon R passes down through the ink bath between scrapers indicated at and into the mercury tube II. It then passes underneath between the glass guides I5, I5, and I 5" which exert some scraping action, and continues up through the mercury column I2. It then passes by scrapers indicated at 35 and 36 and between electric or other heaters 31, 31. These heaters may be suspended from the point 38, if desired. The ribbon then passes about a roller 39 (which may, if desired, be heated) and between this roller and a second or pressureroller 40.

The meeting line of these rollers is directly above suction tube I3. If desired, the ribbon may be passed between heaters 4|, 4| before entering the mercury in the tube I3. It then passes down underneath the roller I6 and up into a winding reel 42. The rollers 39 and 40 are power driven and are pressed toward one another by an adjustable weight 43 carried on a bell crank arm 44 which pushes the roller 40 against the roller 39. The reel 42 is driven by a suitable reeling mechanism.

The strip of fabric R is drawn through the I apparatus at a comparatively high speed in the direction indicated by the arrows. The fabric on the'roller 25 is the ordinary fabric employed for typewriter ribbons. It contains air, moisture, and gases, and is drawn underneath the mercury in container I1 and up through the tube II. It suddenly emerges into the vacuum'chamber and immediately passes through the heating zone caused by the heaters 26, 26. This operation brings about a sudden release of the air and gases, particularly moisture vapor, from the fibres, and causes the fibres to swell, expand'materially as indicated diagrammatically in the differences between Figs. 4 and 5. The rapid escape of the air and gases from the inside of the fibres looses and expands the fibres and closes up the interstices between the threads.

While. the fabric is in this condition, it is highly absorbent. It is plunged underneath the ink in the ink bath and carried directly down into the mercury tube II under and underneath the guides.

Owing to the great difference in the specific gravity of: the ink and mercury, the mercury acts as a frictionless distributor of ink throughout the fabric. This method. of ink distribution in the fabric is also useful in processes wherein there is no preliminary evacuation of air and gases. As the coated fabric becomes more submerged in the mercury column, the ink absorbed by the evacuated fibres is pressed into the fibres by liquid pressure above atmospheric. This efiects a true impregnation of the fabric for the fabric with freshink is subjected to the pressure above atmospheric while the ink is still in the liquid state without any drying or evaporating of the vehicle. True impregnation cannot be accom- 75- plished in a vacuum alone. In the present case the mercury column acts as "a hydrostatic impregnator producing a continuous eifect normally obtained by pressure pumps on the intermittent impregnating processes. It also acts as a seal. A pressure difference, somewhat more than fifteen pounds per square inch, is available for," pressing the ink into the fibres without any roll-" ing or squeezing action which would tend to distort the fibres or remove the ink from the fibres. The mercury itself effects a fixed and uniformly distributed quantity of ink in the fabric. The

ribbon then passesbetween the scrapers 35 and 36, which are adjustable by means-of the linkage indicated, so as to remove mechanically carriedof the ink, principally oil, is evaporated at the reduced pressure, thereby decreasing the amount of oil carried in the ribbon without decreasing the amount of pigment carried by the ribbon;

This temperature is so low as not to affect the tween the pressure rollers 39, 40 carries thefull quota of pigment but much less oil or vehicle than would be the case were the ribbon subjected to theusual. pressure rolling. The pressure rolling operation acts to further press the pigment into the fibres and to give a smooth finish to the ribbon. The ribbon is then passed through the inert mercury column in tube l3 and under roller l6 to the winding mechanism.

Owing more speed at. which the ribbon is passed through the apparatus, there is some tendency of the mercury to be bodily displaced by the ribbon, or to surge on account of its movement. To cut-down the movement of the mercury, one may insertan open coiled spring in each tube, as indicated at. Drain cocks 46 and may be provided for draining off the ink or scrapings, and additional scrapers 41, 48 may be provided for the rollers 39 and 40.

Figs. 6 and 7 illustrate the conditions present in ribbons of the prior art. The fibres F- are partially filled with ink and the free ink fills the interstices as shown at I, Fig, 6. When a type character 0 strikes the ribbon, it flattens out the threads and closes the interstices somewhat as shown in Fig. 7. The free ink splashes out onto the type and paper making a ragged impression. On release of the pressure, the threads resume their former shape but less ink ,is in the interstices, as indicated by the dotted lines in Fig. 6.

Ribbons'made according to this process are characterized by a marked increase in opacity when held up to the light. They have a much greater pigment-vehicle ratio than is possible in the usual process of rolling which merely removes oil and pigment in thesame proportions as in the ink bath. This effects a materialand controlled increase in the viscosity and flowing P wer of the ink in the finished ribbon. There is no free ink to splash out and the juiciness of storage reservoir in the margins of the ribbon and in the center of the ribbon (not struck by the 3 type) so that the recoveryof the ribbon after a rest period is far greater than that normally experienced with ordinary ribbons; Uniform,

, clear, sharp impressions are produced until the fabric is destroyed. 1

The shade of the written matter may be controlled by changing the ink used rather than by changing the pressure. Shade of writing is, therefore, not solely dependent on the amount of pigment carried by the ribbon but depends rather upon the color of the pigment used.

The present-application is'a-continuation in part of my copending application Serial No. 429,350, filed February 18,1930. 1

It is obvious that the invention maybe embodied in many forms and constructions, and I .wish it to be understood that the particular form shown is, but one of the many forms. Various modifications and changes beingpossible, I do not otherwise limit myself in any way with respect thereto. I

What is claimed is: h h 1. In the manufacture of typewriter ribbons,

' the step which includes passing an evacuated strip. of fabric downwardly through an ink bath and an inert liquid under progressively increasing pressure from a vacumn to a pressure substantially above atmospheric, whereby the pigment and vehicle of the ink are pressed into the fabric, a

' 2. In the manufacture of typewriter ribbons, the step which includes passing an evacuated strip of fabric downwardly through an ink bath and an inert liquid under progressively increasing pressure from a" vacuum to a pressure substantially above atmospheric, whereby the pigment and vehicle of the ink are pressed into the fabric, and then passing the strip through an inert liquid column and into a vacuum forevaporation of vehicle andin'crease of the pigment vehicle ratio. a V

3. The method of making typewriter ribbons which consists in .vacuum treating a fabric strip to remove air, moisture, and gases, then passing the strip from the vacuum into an ink bath containing pigment and vehicle, continuing said strip through a liquid sealop'en to the atmosphere so that the inked strip is subjected to pressure substantially above atmospheric, then taining pigment and vehicle, continuing said strip through a liquid seal open to-the atmosphere so that the inked strip is subjected to pressure substantially above atmospheric, then continuing the strip from the liquid seal into a vacuum,

heat. treating the strip to cause the removal of a predetermined portion of the vehicle without injury to the pigment, and mechanically applying roll pressure to the ribbon while in the vacuum. 1

5. The method of making typewriter ribbons which consists in subjecting a-moving strip of fabric to a high vacuum and temperature to remove air, moisture, and gases, then passing the strip from thevacuum into an ink bath containing pigment and vehicle and floated on top or a mercury seal open to the atmosphere, continuing saidstrip through said seal open so that the inked strip is subjected to pressure substanstrip from the liquid seal into a vacuum, and heat treating the strip to cause the removal of a predetermined portion of the vehicle without injury to the pigment.

6. The method of making a typewriter ribbon or the like which comprises passing the ribbon fabric downwardly through a bath of liquid ink into an inert liquid column for the purpose of applying a predetermined pressure due to the height of said column and at the same time remove free and surface ink.

7. The method of inking a typewriter ribbon which comprises passing it from a vacuum chamber downwardly into a liquid ink bath, and then into a mercury seal in which the ink bath floats.

8. The process of making a typewriter ribbon which comprises first conditioning the fabric as to air and moisture contact. then inking the fabric without impairing the conditioning, then passing it through an inert liquid pressure column having a pressure above atmospheric, then vacuum and heat treating it to remove volatile material from the ink, then passing it through an inert liquid seal to the atmosphere.

9. The method of inking a. typewriter ribbon which comprises passing the ribbon downwardly into a liquid column containing mercury and liquid ink floating thereon of sufllcient height to providea substantial difference in hydrostatic pressure and press the ink into the fibres.

10. The method of inking a typewriter ribbon which comprises passing the ribbon downwardly into a. liquid column containing mercury and liquid ink floating thereonof suflicient height to provide a substantial difference in hydrostatic pressure and press the ink into the fibres, and mechanically scraping the inked ribbon as it enters the mercury.

11. The method of making a typewriter ribbon or the like which comprises continuously applying ink to continuously moving ribbon fabric and then passing the freshly inked fabric without drying the ink through a hydrostatic impregnator comprising an inert liquid column of greater specific gravity than the ink and of sumcient height to produce a substantial difference in hydrostatic pressure, distribute the ink under pressure throughout the ribbon fabric and remove excess ink while the ink is in the fluid state, and evaporating the excess vehicle of the ink.

} FREDERICK A. WAIDRON.

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