US2014043A - Printing plate - Google Patents

Description

Sept. 10, 1935. 1.. HARBISON ET AL 2,014,043

PRINTING PLATE Filed 001;. 8, 1931 FIG. 2

WWWI' l4 FIG. 3

l NVE NTO RS LY/V/V m/ea/so/v sum/5y c. W/LSO/V BY THEI TTORNEYQ Mm Patented Sept. 10, 1935v UNITED STATES! PATENT OFFICE PRINTING PLATE York Application October 8, 1931, Serial No. 567,556

3 Claims.

This invention relates to the art of printing, and more particularly to apparatus for utilizing resilient non-metallic material in place of the usual form of metal plates heretofore employed in printing.

In accordance with this invention we utilize a soft and resilient non-metallic material, preferably rubber or a rubber compound, to form the plates from which the printing is done.

In accordance with our invention we start with the original type, cuts or half-tones which are to be reproduced and we make from this original type or the like, a matrix or mat. After the matrix or mat is completed, as will be hereinafter described more in detail, the plate is made from it; in the present instance preferably by placing unvulcanized rubber or like material in the form of a sheet on the matrix and then vulcanizing by applying heat and pressure.

After the completion of the vulcanizing process the plate is removed from the matrix and may then be secured to a metal plate to provide a rigid backing. Alternatively, however, a metal backing plate may be secured to the rubber plate during the process of vulcanizing.

The composite plate may then be mounted in a press and used for printing by inking the plate and bringing the plate into engagement with the material to be printed. Because of the fact that the plate is flexible, soft and resilient, considerably less pressure is used in printing than is the case with metal plates. We have found that many other advantages may be obtained by our invention.

In accordance with our invention it is possible to print upon any stock from tinfoil to corrugated paper, calicoes, cotton cloth and other material with a rough or uneven surface. Damage to the plates in handling and transportation is practically negligible and because of the considerably smaller weight, the cost of transportation and storage of the plates is greatly reduced.

Moreover, because of the fact that the plates are soft, flexible and resilient and because of the fact that considerably less pressure is used in printing, the paper is not embossed and can be handled with greater dispatch in automatic feeders and in folding machines. Better register is obtained because less shrinkage is apt to occur in the paper, also softer effects may be obtained.

The use of less pressures in printing results in less wear on the printing presses and rollers. The use of expensive press packing and tympans is eliminated and make-ready is. reduced to a minimum.

The features of novelty which we believe to be characteristic of our invention are set forth with particularity in the appended claims. Our invention itself, however, both as to its fundamental principles and as to its particular embodi- 5 ments, will best be understood by reference to the specification and accompanying drawing, in which Fig. 1 is a cross-sectional exploded view of the matrix before pressure is applied. 10

Fig. 2 is a cross-sectional view of a completed matrix with the unvulcanized rubber in position for the application of pressure and heat, and

Fig. 3 is across-sectional view of the com-' pleted printing plate or type. 16

In producing the plates from which the printing is to be made we first start with type, cuts, or half-tones, a section 5 being shown in the exploded view of Fig. 1. This type body is preferably treated with an organic or inorganic dusting. powder 6 such as mica, graphite, a soap or starch, or is given a coating of light oil. Next we place over the face of the type or cut one or more layers of paper I impregnated with material which may be caused to flow by the application of heat and pressure, such for instance as bakelite,and on top of this is placed one or more layers of fabric 8 such as cloth likewise impregnated with a similar material, and on top of this there is placed one or more layers of paper 9 similar to the first layers. The paper used is preferably moistened before being applied which usually gives a better impression with less pressure. The fabric may be omitted if desired but better results will generally be obtained when it is used.

Upon the built-up matrix we next place a compacting material l0 such as felt and subject the whole mass to heat and pressure. A pressure of substantially 100 lbs. per sq. in., will be found 40 satisfactory along with suflicient heat to cause the bakelite to flow. The hardened bakelite reinforces and strengthens the matrix produced to a point where it is able to stand the above mentioned pressure and heat necessary to vulcanize rubber. The fabric layers 8 interposed between the paper layers 1 and 9 serves the purpose of bleeding from the matrix, gases and moisture evolved, during the process, thereby preventing the formation of bubbles or blisters, and also serves to stiffen the matrix. The compacting material Ill forms no part of the matrix, as will be understood, being merely used during the hardening of the matrix to obtain an even distribution of pressure over the matrix. The

thickness of the matrix below the printing face may be regulated by the amount of compacting material used and the pressure applied during the formation of the matrix.

After the completion of the matrix, as shown in Fig. 2, the matrix l2 or an unvulcanized rubber plate I3 which is preferably an especially comounded oil resistant compound, is dusted with a suitable dusting powder [4 shown applied to the matrix. The plate 13 is then placed over the face of the matrix and is vulcanized by applying heat and pressure. In general, the rubber used should have a volume loading suflicient to produce, after vulcanization an initial durometer hardness lying between 70 and 90, and it is noted that vary satisfactory results have been obtained using rubber having a volume loading sufllcient to produce after vulcanization, an initia1 durometer hardness of approximately 80.

After vulcanization the rubber plate I3 is removed from the matrix and may be secured to a metallic sheet ii to produce a rigid backing or, if desired, the rubber may be vulcanized directly to the metal backing plate. In Fig. 3, the

vulcanized printing plate I 5 is attached to the backing plate 18. In the case of direct vulcanizing, the unvulcanized rubber I3 is first placed on the face of the matrix, and then a layer of fabric is placed over the unvulcanized sheet and the metal plate is placed over the fabric which' may either be bare or frictioned or cemented with rubber compound. This fabric has the effect of preventing blisters between rubber and the metal.

After the vulcanization the completed plate is ready to be set into the press. In setting up the press the pressure is reduced to what is known as kiss contact by decreasing the thickness of the packing on the platen. This is preferably 5 done by using fewer sheets of paper or backing material. The press packing is a rubber blanket which is covered with a tympan of ordinary cheap paper instead of the tough manila stock used in connection with metal plates. Ordinary inks may be utilized or if colors are desired water color inks or aniline dyes may be used.

While we have described certain preferred embodiments of our invention, it will be understood that modification and changes may be made without departing from the spirit and scope thereof as will be understood by those skilled in the art. Particularly, while we have described our process with reference to the formation of printing plates, it will be understood that other articles may be formed by the process herein disclosed.

We claim:

1. A printing plate of the class described comprising a layer of vulcanized rubber having an initial durometer hardness between 70 and 90.

2. A printing plate of vulcanized oil resistant, loaded rubber having an initial durometer hardness exceeding 70.

3. A printing plate having a printing face of vulcanized oil resistant rubber having an initial durometer hardness of substantially 80.

LYNN HARBISON. SIDNEY C. WILSON.

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