US1983352A - Printer's blanket and method of making - Google Patents

Description

06. 4, 1934. T E I 1,983,352

PRINTER'S BLANKET AND METHOD OF MAKING I Filed May 16, 1930 Patented Dec. 4, 1934 PRINTERS BLANKET METHOD OF MAKING Theodore '1. Ellis, Worcester, Mass, assignor to New England Fibre Blanket Company, Worcester, Mass, a corporation of Massachusetts Application May 16, 1930, Serial No. 452,960

32 Claims.

The present invention is concerned with methods of printing newspapers, and materials for facing the impression cylinders of rotary presses for newspaper printing and analogous uses. It is further and more particularly concerned with woollen press blankets adapted to serve as the facing or outer member of composite packings, for impression cylinders of rotary printing presses. My purpose in making the present application is to disclose and protect improvements which I have made in the construction and mode ofrhanufacture of such blankets as the result of long experience and exhaustive investigation and experiment, and to give to the art the benefit of the knowledge which I have gained through my experience and investigation. The following disclosure expresses the results of continuous experience of nearly forty years as a pressman employed in newspaper ofiices, a. manufacturer and dealer in press blankets and other supplies used in press rooms, and as an expert consultant and adviser on problems and questions of practice arising in the operation of newspaper printing presses. In the course of this experience during which I have become familiar with patents and other publications dealing with press blankets of various constructions, as wellas the articles actually used, I have been impressed with the dearth of exact knowledge of the basic funof the rotary printing press unit, and of the principles on which woollen blankets should be con structed to give them the characteristics needed to best meet the requirements of the printing unit. Therefore, before explaining the objects and characteristics of the present invention in detail, and

in order that these objects may be better under-- stood, I will describe briefly at this point the conditions existing in and among the members of the printing unit.

The printing unit of a rotary press consists of a rotary type carrying cylinder and a rotary impression cylinder. In the standard'newspaper press the type cylinder is called the plate cylinder and carries a number of stereotype printing plates clamped to its outer surface. Ordinarily eight such plates are mounted on the same cylinder in two groups, each group subtending approximately half the circumference of the cylinder and containing four plates arranged side by side lengthwise of the cylinder. The impression cylinder is covered with a, facing fabric of a compressible and resilient nature in order'to compensate for irregularities in the stereotype plates. It is always customary to couple two or more of such damentals that govern and control the operation.

units together in a pair in order to print on opposite sides of the paper sheet or web, and to provide a, number of pairs of units in the same press for simultaneously printing thus a number of sheets. At the present day it is frequently necessary thus to couple as many as eight units to print 64 pages at once in the same press, and

to run the press at speeds up to that which will produce 60,000 newspapers per hour. Still larger papers, up to 96 pages, and faster speeds are now 65 advocated.

Each pair of printing units is supplied with a separate sheet of paper, which passes between the cylinders of one unit for printing on one side, called the first impression, and then between the cylinders of the second unit of the pair for printing on the opposite side, called the second impression. The speed of feeding the sheet through two units of one pair must be the same in order to avoid either breaking the sheet by increasing 76 tension on the one hand, or a progressive accumulation of slack on the other hand, and all the sheets passing through the various pairs'of units in the same press must be synchronized in order to bring them to the assembling, cutting and fold- 80 ing instruments of the press in theirproper sequence.

To synchronize 16 sheets, more or less, of brittle news print paper, each traveling at well over 30 feet per second, without a variation in speed between the different sheets of as much as one ten-thousandth of an inch per revolution is a serious problem. This problem is intensified by the fact that the surface of the'plate cylinder (constituted by the lines of type on the printy me Plates) is always uneven and of changeable unevenness, which requires the impression cylinder to be covered with a yielding facing, the surface of which tends to travel at a higher peripheral speed than the plate cylinder. The uneven surface of the printing cylinder adds a further complicating factor to the problem, and so also does the requirement that the compressible facing of the impression cylinder must suffer as little deterioration as possible, but instead must remain substantially the same while sus-' taining pressure application of great force by the printing plates with millions of repetitions.

These problems have long existed, and have been measurably solved by the blankets and pack- 1 5 ings manufactured under the patents of Frank E. Ellis, No. 1,296,782, March 11, 1919, and Cochran and Youngs, No. 1,227,557, dated May 22, 1917; at least sufficiently to meet the requirements of the newspaper printing art up to witha' hitherto undreamed of number of pages at in the course of a run,

in the last few years. But recent developments in newspaper printing have so intensified'the old problems, and introduced new ones, that the pre- Since the year 1925 there have been changes amounting virtually to a revolution in newspaper printing practice caused by the need of printing one time to take care of increased demands for advertisingspace, and a demand for speeds of printing hitherto believed to be impossible. Prior to '1925, 32 pages was about the average size of the editions printed by the larger newspapers,

and this number of pages was the full capacity of an octuple press generally operated at a maximum speed of 24.000 papers or less per hour. When the demand required'more than 32 pages at one printing, parts of the edition had to be printed on different presses and assembled together, which seriously slowed down the speed of production. This condition led to the building of larger presses containing more printing units; successively 40 page presses using 5 rolls of paper, 48 page 6 roll, 56 page '7 roll, and 64 page 8 roll presses; and the operating speed was increased from 24,000 to 60,000 and more papers per hour. A change was also made in the method of casting stereotype plates in order to shorten the time needed for transferring the report of happenings to the printed pages This change was the substitution of the so-called dry flong for the previously used wet flong as the matrix for forming type outlines in the face of the stereotype plates. The wet fiong was made up by hand in the newspaper office as needed. by pasting together three or more sheets of soft matrix paper and two or more sheets of tissue paper on one face with a paste containing water; andv while wet was pressed against the hat dried-under a steam heated platen while in contact with the form. The dry flong is a factory product supplied tothe newspaper printers in a hard and dense, but water absorptive, state. For use it is humidified by causing it to absorb about 20% of its weight of water, which makes it become semi-plastic while "remaining tough. It is then molded by being pressed against the type form, and immediately afterward stripped from the form and dried in a machine called a scorcher, where it is subjected. to the direct application of intense heat. The extreme heat causes the fiong to set and dry quickly, but it also warps the flong, and the resulting stereotype plates cast in the matrix provided thereby have an uneven surfacemuch exceeding the unevenness produced by the wet fiong. However, the saving in time and other advantages due to the dry flong make its use desirable. But the unevenness of the plate surface adds to the burden placed on the impression cylinder facing,

Limitations of time in newspaper press rooms, and the constant demand to get out the edition quickly, and the frequent changes of prohibit in such press rooms the use of the hard packing with built up make-readies used in the printing of books and magazines. In these classes of printing time is available for making truer printing plates, underlaying low parts of the plates, and building up the impression cylinder packing to match irregularities in the printing plates, which is not available in newspaper press rooms. Consequently in the latter the packing must be deep or high type form. It was then inch of impression.

plates made enough to hold the paper up to low spots in the plate, compressible enough to yield for accommodation of high spots in the plate, and resilient.

enough to conform to the different irregularities of substituted plates. The changed conditions just described have imposed requirements which the previously used blankets cannot meet, and have presented a new problem, the solution of a part of which constitutes the present invention.

In order to solve this problem it was necessary to learn all the facts and factors involved. A search of the literature of the art revealed that there has never been any textbook written on newspaper printing press operation, nor any public record made of the conditions existing and operating between the plate and impression cylinders of newspaper printing presses, further than certain published writings of my own. I have also found by investigation that, first, the builders of newspaper printing presses have had no exact knowledge of textiles and textile fibers, their densities, resistance to pressure, and resilience; and, second, that no manufacturers'of woolen and composition textiles have exact knowledge of the requirements of newspaper printing presses or their method of operation or the requirements which the woollen blankets must meet. Consequently woollen blankets made for newspaper presses by different manufacturers have varied greatly and different lots made in the same mill have likewise varied; and

none has been able to perform satisfactorily the harder service required by the changed conditions of newspaper printing before mentioned.

In seeking a solution of these problems I have studied minutely the interaction between plate and impression cylinders, determined definitely the requirements of the woollen impression facing, and, by investigation and invention, discovered the means for meeting those requirements. I will first state the conditions existing in the press, and then describe the new means constituting the present invention, which I have embodied in the structure of the facing material for meeting these conditions.

The pressure between plate and impression cylinders which obtains the best printing results is approximately five pounds per inch of'length of the cylinders, for each one-thousandth of an Impression as used here is a technical term of the newpaper printing art and means the distance to which the type faces of the printing plates extend within the normal circumference of the impression cylinder facing. The standard thickness of printing plates is seven sixteenths 'of an inch, but in practice the thickness is greater or less than standard by amounts up to three or four thousandths of an inch, being usually above standard, and the extreme variatiori radially of the plate cylinder between high and low parts of the plates amounts to' about-six thousandths of an inch. About ten thousandths of an inch of impression into the impression cylinder surface is required to compensate for plate variation and insure uniform printing. To allow for this amount of impression, the surface of the blanket must, in its unstressed condition, be at least an equal distance outside of the pitch point of the impression cylinder; the pitch point 5 between the plate 15;

and impression cylinders. These are, first, indentation of the type projections on the plate cylinder into the impression cylinder facing; second and third, a converging motion and then a diverging. motion caused by the angular lines of the type faces as they approach and recede from the zone of contact, in a circular path; and, fourth, a calender or rubbing motion of the surface of the impression cylinder due to the fact that this surface is outside of the pitch point of the impression cylinder. The fifth motion occurs when the cylinder bearings are worn and some- -what loose, and is a vibrational movement which tends to cause variations and imperfections in the printing. These motions have a powerful tendency ,to disintegrate the blanket. Nevertheless the time limitations in newspaper press rooms, and considerations of cost forbid repacking the impression cylinders with each change of printing plates, and demand that the same packing remain on the press during the printing of many millions of papers. The continually repeated indentation of the type faces into the surface has a disintegrating tendency, and the changing angularity of the type faces while indented into the impression facing tends to tear the surface thereof. The impact load delivered by the plates under a normal pressure of about the order of thirty-six hundred pounds on the impression cylinder, three hundred to five'hundred times a minute, is increased many times when, as not infrequently happens, the paper breaks and winds around the cylinder before the press can be stopped.

The excess circumferential travel of the impression cylinder, which under best conditions is about one mile for each one million papers printed, has a rubbing effect on the paper which also tends to destroy the impression surface.

This linear excess may be different in different units of the same press, due to the surface on one impression cylinder being higher than on an-- other, and this disparity tends to prevent perfect synchronization of the paper webs passing through the different units.

The object of my invention then has been to produce a facing structure or material which will i a) Remain intact under unusual strains many times repeated during millions of impres- SlOIlS;

(b) Suffer no substantial elongation despite difference in radius and circumferential speed from the plate cylinder surface;

(0) Be compressed and diminished in thickness normally not more than .001" with each million of newspapers printed;

(d) Absorb the multiplied pressure exerted when the paper breaks and Winds around the cylinder;

(6) Automatically compensate for uneven plate surfaces by yielding, and without being made permanently uneven in its thickness and on its surface;

(I) Prevent surface disintegration due to angular strain;

(g) Prevent such movement within its structure as would cause chafing and cutting of its component fibers;

(h) Provide a predetermined density adequate to meet the different printing variables that exist;

(1') Provide adequate resisting pressure to the printing plate for clear, sharp printing, at a point about .006" below the surface;

(7') Provide a substantially frictionless outer surface permitting slippage in contact with the paper, without appreciable surface wear and with the result of permitting perfect synchronization of the paper web with other webs passing through units similarly equipped.

A further object is to devise methods of producing articles having these characteristics; and to provide a method of adjustment of printing units and determination of the correct thickness of facing member for a given impression cylinder.

The foregoing objects have been accomplished by the new features of body structure and surfacing which are now described in connection with the drawing. The end product of the invention is a printer's blanket of which the body is constructed of wool fibers and the surface is composed of a flexible and elastic composition of nitrocellulose or equivalent cellulosic compound, with an emollient. Generically it is in the same category with the Ellis Patent No. 1,296,782 previously mentioned, but specifically it differs widely therefrom and contains many features of improvement.

In the drawing,--

Fig. 1 is a section of one of the units of a rotary printing press to illustrate the character of machine with which my improved impression facing or blanket is used;

Fig. 2 is a fragmentary enlarged section of the impression cylinder of such unit, showing the manner of securing the impression blankets thereto in accordance with the present invention; I

Fig. 3 is a weavers diagram of'the preferred design and drawing-in draft for the body structure of my improved blanket;

Fig. 4 is a plan view, on an enlarged scale of a fragment of the fabric woven according to the diagram of Fig. 3;

Fig. 5 is a section of the fabric taken on line 5-5 of Fig. 4 parallel to the warp;

Fig. 6 is a sectional view of the blanket body after fulling and shearing;

Fig. 7 is a view similar to Fig. 6 showing the body structure after pressing;

Fig. 8 is a similar section of the completed blanket with its cellulosic coating on one face, this figure indicating also the successive steps in applying such coating;

Fig. 9 is a fragmentary plan view of one end of the blanket as prepared for application to the impression cylinder.

Like reference characters designate the same parts wherever they occur in all the figures.

Body structure.Novel features are provided herein respect of thequality of wool used, the characteristics of warp and filling yarns, and the weave. Prime considerations in the finished structure are tensile strength, uniformity, homogeneity, strong resistance to compression yet with capacity for yielding considerably, and rapid resilience in returning substantially to previous thickness after relief of compressing pressure. These qualities are obtained by the duality of the woolused and the processes followed in spinning and weaving it. For the warp, strength is particularly" important, since the blanket is applied to the cylinder with. the warp running in the direction in which tension is applied to tighten it; and for both warp and filling, and particularly the filling, great capacity for felting and shrinking is required.

I have found that for the warp Delaine wool,

preferably that raised in Ohio, is superior to others, wherefore I preferably spin the warp from the grade of wool known as half blood Ohio staple (60s). For the filling I prefer FallTexas fine clothing (64s to 66s), for this grade of wool is characteristically elastic, sound, and pliable, and has exceedingly good felting qualities, being fine in diameter and short in length. Other wools substantially equivalent to those named may be used however; as :half blood Michigan wool or a mixture of the two for the warp, Australian instead of Texas for the filling, etc. In fineness the grades above named are approximately midway between the coarsest and finest fibers. These wools are separately sorted, scoured, and dried according to the usual standard practice of woollen yarn manufacture. They are carded; and in carding a departure from the regular routine is made. The weight of the roping is made heavier than usual, being from '70 to 71 grains per 25 yards for the warp, and '73 to '74 grains per 25 yards for the filling, as against 60 to 62 grains respectively used 'in ordinary mill practice. The heavier roping results in a more uniform and stronger yarn, with pronounced beardv on the surface, whereby more compact felting is obtained. 1

The carded wool roping is drawn and spun on mules or spinning frames. The warp yarns are given a tighter twist than the filling yarns (from 12 to 13 turns per inch for the warp as against 9 to 10 turns per inch for the filling) and is spun with the regular twist, while the filling yarns are spun with the reverse twist. The use. of opposite twists in warp and filling is important, and results in substantial uniformity in thickness after felting, eliminating the pronounced variation in cross sectional dimension which occurs when the twist of both warp and filling yarns is the same.

These yarns are woven into a plural-ply fabric united by binder warps. In the. specific construction illustrated in Figs. 3, 4 and 5, the fabric is two-ply and every fourth warp yarn is a binder which passes around every fourth pick of the filling alternately in the two plies. a and a reprei to permit greater felting fabric to be built up in sent the binder warps of opposite series, those of the series a passing over the picks b, b of the face ply and around the picks c, c of the back ply, while the intermediate binders pass over the picks b, b of the face ply and around the picks c, c of the back ply. d, d and e, e represent the face warps of the two plies. i

The woven structure was designed as here shown with the object of making an open fabric than is possible with a close weave, and to make the length of warp yarns the minimum in proportion to the length of the fabric. The use of a relatively small number of binder warps passing on a long slant from one ply to the other, instead of weaving with the main warps passing from top to bottom of the fabric, prevents elongation under stress. It will be understood of course that variations may be made in the design of fabric from that here shown and described provided the results last described are obtained in measurable degree. This open weave gives great felting possibility, enabling the thickness by the fulling process to a great excess over its thickness as it comes from the loom. Such great thickness gives bulk, from which any desired degree of density in the finished product can be obtained by pressing. An important factor in this result is the tension of the binder warps during weaving.

They must be taut but not stretched appreciably. If these warps are slack, the surface of the goods after felting will show ridges; while if substantially stretched during weaving theywill prevent proper felting.

FuZling.-The woven go ds are felted by a fulling process, in the performance of which any of the suitable known fulling mills may be used. However, I have devised certain new steps by which superior and more uniform results are obtained, which are here specified for the benefit of the art. The mill rolls are driven at a relatively slow speed, preferably at 125 revolutions per minute for 20" rolls, in order'to avoid chafing the fabric and making it tender. The fulling soap is preferably applied cold; at any rate not heated more than necessary and uniform application to the goods, and a soap mixture of approximately 7.5 ounces of dry flake tallow soap and .75 ounces of 58% pure alkali to the gallon of water is preferred. The temperature of the mill is maintained within a range of approximately 65 F. to 90 F.,'and soap .or water is added from time to time as needed to maintain a proper lather or to prevent the soap from becoming pasty. There must be enough soap to prevent chafing, but not an excess. Excessive or pasty'soap slows down or stops the fulling process. The spring pressure on the mill is equalized and a moderately heavy pressure is maintained. A

After starting the mill, the operation is carried on continuously, at least without any extended stoppages or interruptions, until the fabric has diminished by fulling as much as it will in'length and width. When no further fulling takes place this process is finished. In specific instances of which observations have been made, the time required for complete fulling has been about eight hours, the reduction in length of the fabric in the neighborhood of from 35% to 40%, the reduction in width about 45% to 50%, and the increase in thickness 60% and more.

It is to be remembered that the foregoing specific values are illustrative of the nature a): the invention and not limiting as to its scope. In fact considerable variations in thickness and density of blanket material may be made in accordance with the principles of this invention tomeet particular conditions of different makes of printing press, different individual presses, and the practices of different press rooms. These characteristics of the felted goods are affected both by the thickness and the closeness of weave of the original fabric; which factors in turn are governed by the weight of the warp and filling strands, the number of plies in which the fabric is woven, and the distance between-the warp strands and between the adjacent picks of the filling. Blankets originally made of more than two plies are constructed essentially like the twoply design here shown.

The goods may be scoured after weaving and before fulling, but preferably are not; for the fulling treatment itself thoroughly scours and cleans the fibers. The fabric is not gigged or napped before ful i g, as the raising of a. nap does not increase the bulk of the felted fabric nor improve its surface.

After fulling, the felted fabric is washed and r'insedin warm water, at approximately 110 F. for a long enough time to remove all the soap. The phenol-phthalein test is usedto determine freedom from soap. The goods are then dried-on a tenter, with only sufficient to insure thorough tension to hold them dried, it is sheared or cropped to remove the heavy fibrous surface and is thereafter sanded and again sheared. The first shearing cuts off the heavy surface fibers. The sanding operation is performed with a roll covered with sandpaper in Order to raise the ends of the fibers for the final shearing. A brush may be used instead of a sand roll or together with'the sand roll. Preferably the felt is run a number of times through the shear for shearing each face, and preferably the ends are reversed between runs. In sanding a very light contact is used; just enough to raise-the ends of the fibers without cutting into the body of the felt. The fibers are sheared very close to the body to produce a velour character of finish with a short pile. 4

At this point, and thereafter at different stages in the commercial production of blankets, the fabric is gauged with micrometer calipers to detect imperfections and insure uniformity of the product. In gauging I prefer to use an automatic dial micrometer, the spindle and anvil of which are in diameter and the spindle is spring actuated toward the anvil to exert a pressure of 4 pounds per square inch. This statement of preference, however, is not a factor oflimitation, for other measuring devices and other spring settings of this one may be used, provided care is taken to insure uniformity of pressure in taking all caliper measurements. Records of these measurements are made and preserved for future reference.

Pressing-The goods at this stage are not firm, compact and dense enough to meet the conditions previously outlined. They are brought to the required density by a pressing operation, in the course of which they are reduced in thickness to a gauge which has been determined by trial and test as the correct thickness for the purpose. But first, to insure that the goods will retain the condition to which they are brought by pressing, they are impregnated with a sizing preparation which is adapted to act as a binder, to prevent springing apart of the fibers after being released by the press, brought'to a prescribed condition of dampness, and dried while under pressure.

The sizing preparation should be flexible and moisture resistant after drying, in order to insure substantial permanence in the condition to.

which the fabric is brought by pressing. The best composition for this purpose known to me at present is a product obtained from the endosperm of vegetable seeds. This product in the commercially refined condition consists of approximately 25% galactan and 64% mannan in combination, with small percentages of pentosans, albuminoids, cellular tissue and mineral matter. It is applied in a water mixture or emulsion containing preferably about 2% of the endosperm product, reckoned on the basis of the evaporated dry concentration of this product. While I claim the sizing step of the combined process broadly without limitation to the specific sizing material used, I also claim as a specific aspect of the invention the use of this endosperm preparation in the step of pressing my felt blanket structure to a prescribed thickness. The sizing preparation is provided in a bath which is preferably maintained at a temperature in the neighborhood of 140 F. to 170 F. and the felt is run repeatedly for the best results in rapid and thorough impregnation.

The correct moisture content at the time of pressing is obtained by drying the fabric to substantially complete dryness after sizing, and then dewing the fabric by passing it several times under a spray of water and rolling it up and letting it stand for a long enough time to effect substantially uniform distribution of the moisture throughout the fabric. Standing for an hour and a half is usually enough for this purpose, but the period may be lengthened or shortened at need. The procedure last described is preferred to that of pressing the goods while they are still wet or damp from the sizing step, because it affords a better control of the moisture content at the time of pressing and enables exactly the right amount to be present. But the invention is not limited thereto.

Pressing is performed in any way and by any means which will enter into solution with the cellulose compound. and will accomplish the desired result, as between heated rolls, between a platen and a bed, or between a roll or cylinder and a bed. A progressive and continthrough the bath, under pressure by rolls therein,

uous operation, as between rolls, or a roll and a curved bed, is preferred. The best results are obtained by pressing in two stages; effecting about 75% of the desired reduction in thickness in the first stage, and the balance in the second stage. While a wide variation in the finished thickness and density of the felt is obtainable by suitable pressure application, I find that the best results as to density, compressibility and resilience of the pressed felt are obtained if the reduction in thickness is about 20% from the thickness to which the felt is brought by shearing, before it has been sized, dried and dewed. The pressure and heat application in the press are maintained for a long enough time to dry the felt substantially by the end of the second pressing and to set the sizing agent and develop the moisture-resisting qualities of the latter. In other words, when a rotary press is used, the speed of traverse of the felt is regulated to the temperature of the roll and the thickness of the felt in such manner that the latter will be relatively completely dry after the second run.

When thus pressed, the blanket is finished except for the application of a'surface coating or layer, and has its final characteristics of density, thickness, compressibility and resilience. In order that these qualities may be provided in the desired-values and desired uniformity, the felt is gauged after pressing and the measurements compared with those made after fulling. If any departure from standard is noted as to any of these characteristics the cause is ascertained at once and correction made.

. i Coating.-The blanket body thus constructed Details of -one specific coattion so that its presence on the felt will be more 6 readily apparent; but there is no oil or other emollient, and no opaque pigment in the solution. Forall practical purposes then the first this solution are made and quickly dried. The

total content of this solution constitutes the first coat, whether applied in one layer or more than one. The blanket with this coat is calendered under heat, suitably after each application, to insure the maximum perfection of continuity in the coating material, whereby this material is made to serve as a seal for the subsequently applied coatings to prevent the softening agent used in the later coatings penetrating into the blanket body when affected by frictional heat generated under the conditions of use of the blanket.

Calendering at this time, and also after application of the subsequent coats isan important step. Previous to each calendering the thickness of the goods is gauged, with the use preferably of the automatic dial micrometer previously. mentioned, and the calender is set with its rolls absolutely parallel and near enough together-to compress the goods .010", or thereabout, below the micrometer reading. Excessive or uneven pressure by the calender will distort the felt and cause subsequent coatings of the nitrocellulose to flow unevenly. Hence great care is taken to insure exact evenness in each calendering operation. After being calendered the goodsare again gauged with a micrometer gauge to detect any unevenness which may have developed and inform the operator if any correction is needed in the setting of the calender or the composition or mode of application of the coating solution. The first coating is indicated in the left-hand part of Fig. 8 of the drawing as e.

A second coating 6 is applied on the first coating, preferably in a number of applications, and is calendered hot in the same way and with the same care and precautions as the coating e'.'

This second coating is composed in part of nitrocellulose, but contains a large content of a softening agent or emollient in solution, and pigment. Preferably castor oil is used as the softening agent, since this is a non-drying oil and is well known to be mutually soluble with nitrocellulose and is otherwise suitable for the pur- The preferred proportions of ingredients 'inj'this solution are,--25% nitrocellulose, 53%

castor oil, and 22% pigment, mixed with sufilcient volatile'solvent to make it fluid or plastic enough to be spread over the fabric. Other oils which are sufficiently non-drying to serve my purpose may be used, and are substantially equivalent to castor oil within the scope of this invention. a

A third coating e of preferably. the same composition as the coating e or approximately the same, is spread over the latter and calendered hot, in the same manner as the coating e Finally a fourth or top coating e is applied, likewise preferably in a number of successive applications. -This final coating is of a different composition than the preceding ones, containing less emollient and pigment and more nitrocellulose. Its preferred composition is 53% nitrocellulose, 34% castor oil and 13% pigment, with suflicient volatile solvent to make it plastic. It is calenderedcold.

The composite coating thus constituted is built up to a substantial thickness, .012" more or less in the preferred forms of the invention. Its various compositions in different parts have an:

important effect. The large component of castor oil in its major part modifies the harshness and brittleness of pure nitrocellulose, making the coating pliant and yielding when the blanket is secured to the press cylinder, and prevents the coating from parting or cracking, even though the bottom layer thereof is substantially pure nitrocellulose. Such bottom layer is so thin that it possesses the flexibility characteristic of thin films of even rigid substances, and it is besides united homogeneously at all points to the superposed layers containing a large proportion of castor oil. Thus it does not appreciably detract from the flexibility of the whole coating. Otherwise the bottom layer has an important function, not merely in sealing in the oil content of the next outer coating, but also in effecting a secure bond with the fibrous blanket body.

When applied it is in thin enough solution to surround and embed the surface fibers of the body, but it is so limited in quantity and so quickly dried that it does not penetrate to any appreciable depth beyond the outer fibers, and therefore does not stifiEen and harden the body, but leaves the latter with substantially the same elastic compressibility and resilience as it possessed before being coated. But theinnercoating layer, by surrounding and solidifying on the surface fibers of the body, creates such a firm bond that the entire tensile strength of the outer fibers is available to retain the coating on the body. a

The outermost layer of the coating is considerably harder than the intermediate layers because it contains a larger proportion of nitrocellulose. The proportions between nitrocellulose and oil here are such as to make this layer flexible and at the same time tough and semihard so that the type faces and their sharp edges.

do not make permanent indentations or cuts when pressed into it. Its content of nitrocellulose is sufilcient to prevent undue leakage or exudation of oil from the interior layers or oil reservoir, drawing therefrom only sufficient oil to replace the loss due to frictional heat. Its

outer surface is smooth, resistant to abrasion, and capable of slipping readily on the surface of the paper. -Its flexibility, toughness and resistance to abrasion enable it to bear the repeated impact of printing plates and passage of the paper web without sensible deterioration during the printing of many millions of papers over periods of many weeks. tion permits the slippage incident to its greater linear travel and enables paper webs passing over different impression cylinders in the same press to be perfectly synchronized. In short, the composition of said outer layer is practically ideal to serve the requirements of the outer blanket. I-Iowevenas the frictional heat generated in'the operation 'of -the press causes the oil to be gradually drawn out to the surface of thislayer and dissipated, said layer would eventually become dry and brittle except forthe excess of oil content in the intermediatelayers. More oil is contained inthe latter than is needed for flexibility alone of the intermediate part of the Its low coefficient of fric- 4 coating; the excess being provided as a reserve supply to replace losses of oil from the outer surface. Transfer of oil between parts of this composition takes place under the influence. of heat, and when a deficiency of oil o'ccurs in the outer layer, a demand for oil to supply the loss is caused, which draws sufficient oil from the intermediate layers to satisfy it. Thereby the outer surface is maintained in proper, condition substantially as long as the blanket remains serviceable otherwise.

In thus describing the total coating-as consisting of four definite layers, I have not intended to state narrow limitations as to the number and compositions of the intermediate layers. Each of the layers, so-called, of the foregoing description consists preferably of several subsidiary applications or coatings, and these latter may vary from one another more or less as to their content of nitrocellulose and oil. Thus, for instance, after the first coat or application, which contains no oil, has been applied, the following coats may contain first a little oil, and then relatively more and more oil until the coating has been built up to the region of greatest richness in oil, after which the oil content of successive applications may be progressively diminished until the outermost coating of substantially the composition best suitedfor the outer surface has been applied. That is, thegeneric invention with regard to the coating, of a variation in its composition between innermost and outermost layers, with the correct amount of oil in the outermost layer, an excess'of oil in the middle layers, and no oil or virtually none in the innermost layer, may be obtained in various ways, all within the scope of protection which I claim.

The sanding and close shearing of the blanket body, previously described, severs the surface fibers and leaves a multitude of free ends which stand up more or less and are in better condition to be surrounded and embedded by the coating material than would be the case if they were not thus out. They eifect a much firmer attachment of the facing than can be made with an unsheared felt. Such surface fibers project through the innermost layer of the coating and to some extent into the second, and possibly the third, layer, but they all terminate well within the outer surface of the coating.

The innumerable fibers projecting above the main structure of the felt also provide a thin intermediate cushion between the body structure and the facing coat. This intermediate cushion is a leveling factor for absorbing plate variation, and it takes up the greater part of these variations without transmitting much compression to the body of the felt. But the compressibility and resilience of the entire body is available in reserve for accommodating excessive inequalities in the plate surface.

These factors of the composite blanket cooperate to preventdisintegration' and permanent compression, at least to any objectionable extent. Tests of material constructed as herein described have shown no more than .010" decrease in thickness after printing twelve million newspapers, the surface coating being then still intact and the surface fibers of the body erect.

Tests of the blanket material for compression and recovery or comeback show 98% recovery to original thickness (which is practically complete recovery) five minutes after release of pressure which has compressed the blanket 10% from its manufactured thickness. This quality of resilience is greater than necessary to meet ordinary printing conditions and enables the blanket to recover from the impression of one plate or set of plates and absorb the impressions of different plates.

Felt blankets may be used singly and alone on iron impression cylinders, or in conjunction with other blankets of the same or different construc tion. A desirable combination is to place one over an under blanket composed largely of cork, the latter having additional compressibility and cident occurs such as the breaking of the paper web and wrapping ofthe paper several times around the impression cylinder before the press blanket.

Attachment of blanket to impression cylinder.-Impression cylinders of newspaper printing machines are made smaller in diameter than the pitch diameter. This is necessary to provide space for the resilient blanket or packing. Printing press manufacturers have their own individual.

standards. Some cut the cylinder surface only .125" below the pitch line, others .156" below, and others more or less than the above named values. To meet these conditions my blankets are manufactured in various thicknesses or gauges, but all according to the principles hereinbefore described and following substantially the same steps.

The standard impression cylinders are provided with a longitudinal slot at one side from its outer surface into an interior cavity. In this cavity are mounted one or more reels to which one end of the blanket is secured and by rotation of which it is put under tension. .The practice heretofore has been to secure pins within one edge of the slot, such pins being about in diameter and spaced about 2" apart, and to impale one end of the blanket on these pins while the other end is secured to one of the reels after wrapping the blanket around the cylinder. This method of attachment' is unsuitable to secure blankets under the tension required to meet the changed conditions of modern printing. My blanket has a tensile strength of 9,000 pounds in a width of 36", which is the width generally used. But pins of the type and arrangement heretofore used provide means of carrying a stress of only about 280 pounds, and tensions greater than this will cause the blanket to tear away from the pins. Toovercome this condition I sew a heavy strip of canvas, shown at f in Fig. Q "0 each end of the blanket, and secure both Q ps to the reelsg, tightening the blanket by reel in both ends. By this means substantially the tensile strength of thebianket is made availa. i eded.

Zn thus particularly describing the principles and details of construction. of my new felt press blanket, I have intended to give all particu- .ais necessary for enabling those skilled i he art to practice the invention. These particul contain the best means, so far as now known to me, for meeting and, satisfying the exacting requirements of the modern newspaper printing presses. At the same time I desire it to be understood that-I claim protection for all variations from the exact particulars herein set forth which come within the scope of novelty of the new steps contained therein. It is to be understood furthermore that I do not limit my protection in all its phases to the combination of a blanket body with .a facing coat of nitrocellulose or its equivalent,

but claim independently the novel characteristics of the blanket body alone. Such body is not inoperative in the absence of the attached facing 'resiliency to absorb excess pressure when an acars fulled to felted condition to a definite thickness substantially greater than its woven thickness.

2. A felt printers blanket consisting of felted loosely woven superposed plies made of woollen warp and filling yarns, some of the warps being binders passing about picks of the filling, first in one ply and then in the adjacent ply, the felt being held under resilient compression by binder material therein, which is flexible, moisture resistant and substantially permanent after drying.

3. A printers blanket comprising a fabric loosely woven from woollen yarns, said fabric being fulled and felted and held permanently compressed by a binder material which is flexible and moisture resistant; but havingcapacity for further compression and rebound in use.

4. A woven woollen printers blanket held in a state of permanent compression by a binder material containing galactan, said binder material being flexible and moisture resistant.

5. A woven woollen printers blanket held in a state of permanent compression by a binder material containing mannan, said binder material being flexible and moisture resistant.

6. A woollen felt blanket for use on the im-' pression cylinder of a newspaper printing press, comprising the product of 'a loosely woven construction of loosely twisted woollen yarns after being fulled to substantially increased thickness and compressed to a thickness intermediate the woven and fulled thicknesses, and containing binding material which is flexible, moisture resistant .and substantially permanent after drying and -maintains the blanket-in its compressed condition with capacity for further compression and elastic rebound therefrom.

ric loosely woven from'high felting woollen yarns,

'7'. A printers blanket made of a woven woollen fabric, fulled, felted and held in resilient corn.-

-pressionby a quantity of size substantially equal to that remaining after the felt has been saturated in water containing in the order of 2% of galactan-mannan size and dried.

8. A felt printers blanket made of a woven, woollen fabric fulled, felted and held in resilient.

compression by galactan and. mannan binder 'material.

9. A felt printers blanket made of awoven woollen fabric, fulled, felted and held in resilient compression by vegetable seed gelactan-mannan binder material.

10. A printers blanket comprising a felted fabsaid fabric being highly felted, the felt being held compressed in a state of high density and resilience by. a binder material which is flexible, mois- 1 ture resistant and substantially permanent in dry condition.

11. A coated printers blanket comprising a woven, fulled and compressed blanket body composed of wool fibers, in whichthe fibers are held in a normal state of compression by binder material; and a composite coating of wear-resisting flexible cellulosic matter in intimate union with the surface fibers on one side of said body,

said coating containing an oily s'oftener'except in its innermost or bottom zone which is substantially oil free.

12. A printers blanket comprising a compressed felted body of woollen fibers containing dried galactan-mannan binder material which is flexible, moisture resistant and substantially permanent, binding together the compressed fibers in a condition permitting further. compression and rebound therefrom: and a substantially solid surface coating of flexible wear-resistant and ink-repellent matter bonded to the outer fibers of said body.

13. A printers blanket comprising a woollen felt body and a coating of wear-resisting, flexible cellulosic substance in a plurality of layers having respectively different compositions; the innermost of said cellulosic layers surrounding and embedding the surface fibers of the felt body and being of a solid composition which firmly grips such fibers, the intermediate layer being a mixture of the cellulosic substance with an oily softening agent, and the outermost layer being also a mixture of the cellulosic substance with the softening agent but having a substan- 1 felt body and a coating comprising in its inner- 1 most part hard and elastic substance surrounding and gripping the surface fibers of the body, its outermost partbeing composed of the substance mixed with a sufficient content of oily softening agent to render it flexible while still being tough 1 and firm, and its intermediate portion being a mixture of the substance and oily softening agent, but containing a larger relative content of the softening agent than the outermost: portion serving in effect as a reservoir containing a surplus supply of the softening agent to replenish losses of the softening agent from the outer surface of the coating.

15. A printers blanket comprising a woollen felt body having exposed fibers on its surface and j a coating comprising a cellulose compound with an admixture of oily softening agent applied to the surface of the said felt body, the innermost portion of said coating being composed of cellulose compound substantially free of said oil? 1 softening agent and surrounding and gripping the outermost fibers of said body.

16. A printers blanket comprising a woollen felt blanket body and a coating on'one surface thereof comprising an inner layer of substantially oil-free nitrooellulosesurrounding and gripping the'surface fibers of the body, an intermediate layer bonded to the inner layer containing nitrocellulose and a relatively largev amount of oily softening agent, and an outer layer bonded to the intermediate layer containing a greater proportion of nitrocellulose and a less proportion of the oily softening agent than the intermediate layer.

1'1. The method of making a highly'dense and resilient printers blanket which comprises loosely weaving high felting woollen yarns, fulling said fabric thoroughly to produce substantially maxiing it with heat while compressed in a highly dense and resilient state.

18. The method of making a highly dense and ness, sizing the so felted material, compressing resilient printers blanket which comprises loosely weaving a plurality of plies of woollen fillingyarns, with woollen warp yarns 'to produce a loosely woven thick fabric, fulling said fabric thoroughly to produce substantially maximum felted thickness,'impregnating the felt with vegetable seed galactan-mann'an size, strongly compressing the sized felt while damp and drying it while under such compression with heat whereby a dense resilient substantially moisture-proof printers blanket is obtained.

19. The method of making a felt printers blanket which consists in interweaving woollen warp yarns, having a twist in one direction, with woollenfilling yarns, having a twist in the opposite direction, into a loose fabric, fulling saidfabric, and compressing the fabric, the opposite twists in the warp and filling yarns giving substantial uniformity of thickness after fulling.

20. The method of making a felt printers blanket which consists in interweaving woollen warp yarns having a twist in one direction, with woollen filling yarns, having a twist in the opposite direction, into a loose fabric, fulling said fabric, the opposite twists in the warp and filling yarnsgiving substantial uniformity of thickness after fulling, sizing the fabric with a binder material which is -flexible, moisture resistant and. substantially permanent after the application of heat and pressure, and compressing the fabric with heat, whereby the blanket is held in its compressed condition with capacity when in use for further compression and elastic rebound.

21. In a method of making woollen felt printers blankets, the steps which include spinning yarns with-a loose twist and interweaving such yarns with a loose weave to form a fabric designed to be substantially and definitely increased in thickness by fulling, fulling said fabric for a suificient length of time and with such control of the fulling operation as to accomplish a substantial and definite increase in thickness of said fabric, sizing the fabric with a binder r'fiaterial which is flexible and substantially permanent after drying, and compressing said sized fabric 'under heat and, pressure to a definite thickness.

22. The method of producing a printers blanket which consists in carding wool of medium fineness to make roping of a weight in the order vof 70 to '75 grains per each 25 yards of length,

spinning such roping into yarns with a loose twist, interweaving such yarns loosely as a fabric with a pluralityjof plies of filling yarns and interlocked warp yarns, fulling the fabric to closes;

ly felted condition and greatly increased thickthe sized felt .in damp condition, and under pressure; I

23. The method of making a woollen felt printers blanket which comprises fulling a loosely woven woollen structure to, substantially increased thickness and felted condition, distributing through the felted structure in a liquid vehicle a. galactan-mannan sizing material which is moisture resistant and has substantially permanent binding properties when dry, compressing the sized felt while damp to less than its full capacity for compression, and drying the felt'while under pressure, to produce a woollen body with its fibers held by said sizing material ina normal state of compression and having capacity for further compression and resilient rebound 24. In the production of a felted and compressed woollen printers blanket, the method of maintaining a substantially constant state of comdrying it pression in such blanket, which consists in impregnating the felted blanket body, before compression, with sizing which is flexible, moistureresistant and substantially permanent after drying, compressing the sized felted body while damp and simultaneously drying it by heat.'

25. The method of giving a. predetermined and substantially permanent'density to a felt printers blanket which consists in impregnating the uncompressed blanket with water containing in the order of 2% of a dried concentrated galactanmannan sizing, compressing the sized blanket while damp and at the same time drying it under pressure with heat.

26. The method of giving a predetermined and 90 substantially permanent density to a felt printers blanket, which consists in impregnating the uncompressed blanket with water containing sizing material which is flexible, moisture-resistant and substantially permanent after drying, drying the blanket, then moistening it. with water to a predetermined condition of dampness, compressing the damp blanket and simultaneously drying it with heat application.

2'7. The method of compressing a felt printers blanket to a predetermined and substantially constant condition of density, which consists in distributing throughout'the structure of the blanket a binder consisting essentially of vegetable seed galactan-ma'nnan sizing, drying the blanket, then moistening it with'water to a predetermined condition of dampness, compressing thedamp blanket and simultaneously drying it'with heat application.

28. The method of manufacturing a compressed 110 woollen felt printers blanket with maintenance of given conditions of compression and density, which consists in fulling a loosely woven body composed of woollen yarns, with control of the fulling operation to bring the material to a predetermined thickness, sizing thefulled goods with. a moisture-resistant sizing material, and pressing the sized goods to a predetermined percentage of its original fulled thickness, with adjustment of the compressing pressure and proce- 120 dure to maintain the prescribed thickness.

29. The method of manufacturing compressed woollen felt printers blanket with maintenance of fixed conditions of thickness, density, and compressibility, which consists in interweaving loosely twisted warp and filling yarns into a loosely woven body, fulling the woven body with control and adjustment of the fulling step to produce a felted body of substantially greater thickness than the woven structure, sizing the felted 13w body with a moisture-resistant. sizing material, compressing the felt to a predetermined thickness,

' and setting the sizing material by heat while the felt is under pressure.

30. The method of making compressed woollen 13 5- felt printersblankets with maintenance of given conditions of thickness, density and resilience, which consists in interweaving woollen warp and filling yarns of given weights into a structure having a given thickness and'spacing of component yarns, fulling such body to a felted condition and substantially increased thickness with control and adjustment of the fulling step to maintain such compound dissolved in a volatile solvent and substantially free from oil and evaporating the solvent so quickly that the cellulose compound surrounds the fibers of the blanket which are at and ,near the surface thereof, only, and hardens with a firm grip and bond upon such fibers; applying a further coat of the cellulose compound mixed with a large proportion of emollient oil, and a to the surface of the felt and calendering such surface with heat, so that the cellulose compound is quickly dried and set in embedding and gripping engagement with the outer fibers of the felt, and

is prevented from penetrating substantially into the interior of the felt; then spreading on the first-named coating an intermediate coating of a solution of cellulose compound in a volatile solvent mixed with an excess of emollient oil; calendering the said intermediate layer with heat; and finally spreading an outer'layer of cellulose compound in a volatile solvent containing a smaller proportion of emollient oil, the content of oil in the last-named layer being sufllcient to prevent the cellulosic content thereof from becoming brittle when freed of solvent, but small enoughv to permit it to be tough and solid when dried, and cold-calendering the last named layer.

s THEODORE T. ELLIS.

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