US 2285763 A
Description (OCR text may contain errors)
June 9, 1942. G. A. VASEL 2,285,763
- PRINTERS BLANKET Filed Dec. 16, 1939 Ka/eosE/M INVENTOR.
Patented June 9, 1942 Application December 16, 1939, Serial No. 309,555
.My invention relates to tympans or printers blankets and has for an object the provision of articles of this type which are characterized by a resilient backing and a hard smooth working surface. v
The plates and type employed upon ordinary printing presses although intended to lie uniformly in a plane, do vary to some extent in height therefrom. .It is, therefore, desirable that the blanket or tympan be sufliciently resilient to.
compensate for irregularities in the plates or type. In the past. this backing material or blanket has been formed ofmanila paper of various grades, sometimes treated with mineral oil and sometimes in'combination with rubber, or with the solids of latex rubber deposited thereon. It has also been proposed to utilize woven fabrics with oil and ink resistant coatings, .and in some of these prior suggestions the blanket consists of eleven or more individual plys or layers of selected materials, which make for high, if not prohibitive cost.
In carrying out my invention in one form thereof, I provide a tympan or printers blanket comprising a backing of a resilient, polymerized vinyl chloride with a super-coat of Cellophane. More specifically the resilient layer comprises an acetylene derivative known to chemists as a polymer of one of the vinyl halides (the latter including chlorides, bromides and iodides and excluding fluorides), and a plasticizer or solvent in suflicient quantity to impart a substantial degree of resilience'to the synthetic product. The solvent may consist of nitro derivatives or aromatic hydrocarbons, such as o-nitro-diphenylether in proportions of from one-half to four parts to one ,of normally insoluble polymerized vinyl chloride, and the solvent may include dinitrobenzene and dinitrotoluene. A further suitable composition for the backing may consist of eight parts of insoluble polymerized vinyl chloride, three parts of tricresyl phosphate, and three parts of dibutyl phthalate. This product is now available on the market under the trade name of Koroseal. The super-coat or outer layer of the tympan or blanket consists of a thin sheet of water resistant cellulose of the type marketed under the names of Cellophane. "Sylraph and Kodapak, and in the claims defined as a smooth, hardfaced, waterproof, cellulosic sheet or material.
My invention is further characterized by the fact that a strong bond is secured between the layer of Koroseal and the outer layer of Celloa temperature of about 175 F. is suflicient to secure an adequate bonding of the two materials. The single figure of the drawing is an enlarged fragmentary view of an embodiment of my invention.
In the drawing, the backing, or lamination I0 is formed of Koroseal of the type heretofore specified, and which comprises a synthetic rubber-like material having the property of being practically constant in volume. It has high impact strength,
. high resistance to attack by vegetable and mineral phane by the application of heat at temperatures below those which will dry out or cause the embrittlement of the Cellophane. I have found that oils, printers inks, solvents and acids, and it is water resistant to an extraordinary degree. In consequence, its volume remains constant and there is no tendency for it to swell or increase in volume, a result which would be highly detrimental to its use in printers blankets or tympans.
The super-coat or outer lamination I l as I have stated, comprises Cellophane whose thickness, by way of illustration, may range from 0.003" to 0.005 with the Koroseal backing having a thickness ranging from between 0.004" to 0.007, or the thickness of the blanket or tympan as a whole may range from 0.007" to 0.012", or it may be materially greater or less in thickness depending upon the requirements, the foregoing figures being by way of illustration and not by way of limitation. However, the resiliency should not be so great as to cause squashing as will occur if Koroseal is used in thicknesses materially in excess of 0.010". I
The layers or laminations l0 and II are adhesively secured or autogenously bonded together by passing the two materials in sheet or strip form between heated rollers so that the layer, I 0 is heated to a temperature at which it tends to become liquid or highly tacky, for example to about to 175 F. The roller or presser plate applied to the Cellophane need not be heated so that the Cellophane is only momentarily subjected to a temperature of about F., and only long enough for the strong autogenous bond between the two sheet materials to be effected by the adhesive quality exhibited by the thermoplastic layer 10 of Koroseal atthis temperature. At such a temperature and for such a short'time interval there is no drying out or embrittlement of the Cellophane.
One of the features of my invention resides in the fact that no special cements or adhesive materials must be externally applied to the laminations l0 and I I, and in the fact that the bonding of the two materials may be readily and economically effected. Neither the Cellophane nor the Koroseal is exposed to high damaging temperatures such as printing press operation, a characteristic of my.
tympan or blanket is that it decreases what is known in the printing'art as batters; that is, the passage of a folded or wrinkled sheet, or foreign matter through the press does not result in the permanent deformation of the tympan; on the contrary the tympan surface is disturbed but momentarily and immediately regains its smooth uniform character upon discharge of the foreign matter. from the press; wherefore uniformity of printing is secured after abnormal operation or passage of foreign matter through the press. Variations in the thickness of paper do not affect the quality of printing since the tympan of my invention will compensate therefor. I can also print uneven surfaces, such as mottled or imitation leather materials; the foregoing being exceedingly diiiicult and costly operations prior to my invention.
In connection with heavy solid printing forms,
or plates, a substantial decrease in shock to and wear of the press results due to reduction in the impact blows effected by the resilience of my aforesaid tympan or blanket.
The layer of Cellophane not only presents a hard, uniform working surface, but solvents may be readily used thereon quickly and completely to clean the surface thereof from inks and other marks thereon. The Cellophane, or equivalent coating, is water repellent and possesses longwearing qualities far greater than any surface known by me to have been used as I propose.
My invention is further characterized not only by the foregoing features, of great value to the printing art, but also by the fact that the cost of materials comprising my improved blanket is materially less than for those used in blankets of the type now available to the trade, such for example as complicated multiple laminated blankets. Besides a lower first cost, in accord with my invention, my blanket has a longer life and achieves better and more satisfactory results in the printing itself.
While I prefer the use of Koroseal as the under lamination, any resilient material to which may be bonded the outer lamination of Cellophane comes within the purview of my invention. For example, a synthetic rubber, of which there are a number now available on the market, such as the one sold under the trade name of Neoprene," may be used as the under lamination, the outer lamination or coat being bonded or secured thereto at temperatures below those producing the embrittlement of Cellophane, or like materials. "Neoprene is obtained by the polymerization of chloroprene, the latter being the result of the reaction between monovinyl acetylene and hydrochloric acid.
Further in accord with my invention, the outer thin lamination, being relatively hard and unyielding and bonded to the adjacent resilient lamination the stresses which arise from entry of foreign materials between the printing plates and the tympan, and thus prevents stress of the resilient layer beyond its elastic limit. This better procures recovery, and prevents the occurrence of a squash or permanent set in the tympan. Moreover slight unevenness of the type or plate is automatically taken care of. Greater pressures may be used in the printing operation without increasing the size of some of the dots since the hard surface beingrelatively unyielding moves only an amount to compensate for surface irregularities which would without a tympan made in accordance with my invention increase the size of some of the dots and produce unsatisfactory printing.
Therefore, in a narrower aspect of my invention, my tympan or printers blanket is characterized by its thinness, its double laminated construction, the outer one presenting a hard, smooth, uniform, true surface, and the second being resilient without undue softness and cooperating with the first to maintain over the entire printing surface equalized printing pressures regardless of non-uniformity in the surface of the printing plate. The foregoing is in contrast with the thick multi-layer articles previously suggested which are both costly and not nearly equal in performance with my tympan or blanket.
While I have shown particular embodiments of my invention, it will be understood that I do not limit myself thereto since many modifications may be made, some of which I have indicated in the foregoing, and I therefore contemplate by the appended claims to cover any such modifications as fall within the spirit and scope of my invention. In the claims the term printers blanket is used as generic to the various overlays used in the printing art and generally referred to in that art as printers blankets or tympans.
What I claim is:
1. A printers blanket comprising an underlayer consisting of a resilient material selected from the group consisting of polymerized vinyl halides and chloroprene, and a thin super-coat in autogenous relationship thereto consisting of a smooth. fiberless, hard-surfaced, waterproof 0 thicknex of said under lamination lying between cellulosic sheet.
2. A printers blanket consisting of a thin lamination of synthetic rubber and a thin lamination in autogenous relationship thereto consisting .of a smooth, hard-surfaced, water-proof cellulosic material, said synthetic rubber consisting of a resilient material selected from the group consisting of chloroprene and polymerized vinyl halides.
3. A printers blanket comprising an outer lamination of a smooth, hard-surfaced, flberless, water-proof cellulosic sheet whose thickness lies between about three and five thousandths of an inch, and an under lamination in autogenous relationship thereto and comprising a resilient material selected from the group consisting of chloroprene and polymerized vinyl halides, the
about four and seven thousandths of an inch, and
the blanket thickness not exceeding the sum of the lamination thicknesses.
GUSTAV A. VASEL.