US1974714A - Compound for preparing matrices for printing purposes - Google Patents

Description

Patented Sept. 25, 1934 N D s mrss PATENT QFFECE 'coMPo NnfFon PREPABING MATRICES FOR PRINTING PURPOSES No Drawing.

4 Claims.

' Our invention relates to matrices such as are usedin the manufacture of stereotype and. other printing plates. ,More particularly, our invention relates totheprocess of manufacturing matmi rices which 'is-performed as follows:

The surface of'a'base plate is treated mechanical1y;by grindingor the 'like, so asto renderit smooth and uniform and this mechanically treated surfaceis then treated with an impregnating compound containing a filler for the pores of the base plate and an adhesive. To the surface so treated and impregnated, a coating compound is applied which is'allowed to dry, whereupon the matrix is treated mechanically, i. e.

' ground or polished, etc., to render its surface smooth anduniform. l

.According to our invention, the plate is treated with an impregnating and a coating composition, and the impregnating composition is so prepared as to effect a firm binding of the coating composition to the matrix.

Thematerial of the matrices which serves'as the baseztmay be cardboard, asbestos, vegetable fibre, and a great variety of other suitable materials. This material is molded into thin sheets. or boardsu- L Compounds of various compositions havealready been suggested for coating the sheets. or boards, but all such compounds are more or less unsatisfactory.

As is known, the types, stereotype plates,.or electrotypes from which any number of prints is obtained by means of the matrices, are applied to the surface of the matrix after it has been slightly moistened so that the projecting portions of the original are impressed into the surface of the base. From the matrix thus obtained a stereotype plate is cast, usually in lead.

There are two methods of performing the molding operation, cold molding and hot molding. Cold molding is generally preferred on account of its more rapid performance, which is particularly important for automatic casting inachines but the matrices in order to be suitable for cold molding must possess particular propertiesin order to fulfil the requirements of mode ern practice.

The processes of manufacturing such matrices which have been applied in practice, or have been described in literature, do not come up to all these requirements and therefore produce unsatisfactory matrices the defects of which have never been eliminated. Such defects are partly of a technical character but the principal defect is that it was impossible heretofore to obtain a Application September 2a, 1930, Serial No. 483,966.- In Germany May 19,

clear reproduction of pictures by the stereotype process, particularly for newspapers, in which low quality paper is used.

The causes of such defective reproductions are the more or less coarse texture of the material of the matrix and the unsuitable properties and limited durability of the coating compounds. It has been attempted to obtain better results by hot moldingbut clearly defined prints have-not been obtained inthis manner. In addition, the iunfavorable operating conditions 'of the 'hot molding process, high pressure and elevated temperature, cause rapid wear of the expensive types, -stereotype plates or electrotypes from which the matrices are copied. Since cold molding is preferable in view of rapid production, which is particularly important for illustrated daily papers, a matrix in order to fulfil all requirements of modern practice, must be adapted to be molded by the cold process, and notwithstanding the short time available for performing the process the matrix must be of such a character that it will copy thefinest impressions while at the same time possessing a high covering power and resiliency and being resistive to the heat of the liquid metal. The matrix must not be damaged anywhere, and particularly, in the case of a coated matrix, its material must nowhere be exposed, even at the most delicate points.

A matrix prepared according to our invention will stand the casting of a great number of stereotype plates in a modern automatic casting machine, and fiat plates as Well as arched plates such as are used in rotary printing machines, may be cast from the matrices with equal facility.

A matrix prepared according to our invention is practically free from defects. Autotype plates obtained from such a matrix will yield the finest, and most clearly defined reproductions.

It is further possible to use a matrix prepared according to our invention, for producing therefrom other matrices in the same manner as the original matrix has been manufactured. In other words instead of casting a stereotype from the original matrix, a negative matrix is prepared from a matrix according to our invention by applying to such finished matrix a matrix which has been treated with the impregnating and coating compositions in the manner described. A matrix obtained in this manner is ready for immediate use as a printing plate.

In the manufacture of matrices according to our invention, the impregnating composition referred to below is either intimately mixed with the material of the matrix, or a sheet of cardboard, asbestos board or the like is prepared from the material, without previous admixture of our composition, ground at one of its faces, or at both faces, so as to remove any irregularities of its surface and any variations of its thickness. In this case the face of the matrix thus prepared is impregnated with a suitable liquid composition, which may for instance consist of 5 litres water, 200 grammes glue, 70 grammes wax, 10 grammes nitric acid and 100 grammes suspended metal powder.

liquid constituents of the coating compound which is subsequently applied to'the impregnat ed surface, for fibrous material of the" kind referred to has strong but unequally distributed absorbing capacities. Apart from this, the impregnating composition owing. to the-adhesives contained therein imparts to thebase material the necessary adhesive capacity while the. mate-1 rial is applied to the type .or type plate under I pressure, forcing the projecting portions of the N ,Parts. Water 500 Metal powder of high melting-point 50 Casein ;....Y 35 Mineral powder i 400 Wax 10.

-:G1ycerine 10 Nitric acid 1,5 Alcohol 20 The coating composition is applied to the matrix base in cold or hot condition by any suitable process. It may be brushed or sprayed onto the impregnated face, or faces, of the matrix.. Obviously the coating layer must be of uniform thickness and of uniform fineness. The finished matrix has a surface which is perfectly smooth and homogeneous and has a metallic lustre. The finished matrix is ground and polished and in this condition is equal to a metal plate, with a perfectly clear and fine reproduction of the original. The same clearness is imparted to the stereotype plates which are cast, or the negative matrices which are molded, from such matrix. The coating composition, particularly on account of the addition of metallic constituents of high melting point, imparts to the matrix almost metallic hardness after the matrix has been dried, but when the matrix is moistened it becomes again ductile and rubberlike so that owing to its plasticity impression is effected in a very short time, about a minute, in cold condition and at a comparatively low pres The impregnating composition fills the pores of the base material and thereby, prevents rapid and unequal absorption of the sure. Notwithstanding this softness of the matrix, it retains a very clear and well defined impression while on the other hand the type or other original for which the matrix has been molded, is not worn by the soft and plastic material.

In order to conserve the valuable matrix and to protect it against damage during impression we may insert a metal foil, for instance, aluminium foil, between the back of the matrix and the usual backing of felt or fabric which prevents impression of the texture of the backing into the moist matrix. v

A matrix which has been prepared in accordance with our invention is very durable and .possesses all properties required for rendering it perfectly resistant to the high temperature of stereotype-plate casting so that it will stand the casting of a practically unlimited number of stereotype plates by automatic rapid casting machines for rotary printing machines.

- The matrices are suitable forautotypesfrom the finest screens which are reproduced in all the clear-ness and fine definition of the original.

We wish it to be understood that we do not desire to be limited to the exact-detailsof construction shown and describedfor obvious modifications will occur toa person skilled in the art.

Weclaim: 1.;

' l.- The processof 'manufacturing matrices for printing purposes, consisting of a base plate and a coating composition,-: comprising treating mechanically the surface ,ofsaid plate so as to render it smooth and uniform, impregnating the mechanically treated surfaceof said plate with a composition containing a filler for thepores of said base plate, and an adhesive, applying a coating. to said treated and impregnated surface, allowing. said coating tobecome dry, and -me-- chanically treating the finished matrix was to render it,smooth and uniform.

2. As a new article of manufacture, a matrix for printing purposes, comprising a base of fibrous material, impregnated witha mixture of an adhesive, .a water-repellent material and a metal powder and coatedwith a mixture of a plasticizer, a water-repellent material, finely divided metal of high melting point and a mineral filler.

3. As a new article of manufacture, a matrix for printing purposes, comprising abase of fibrous material, impregnated with a mixture of an adhensive, a water-repellent material and a metal powder and coated with a mixture of casein, wax, metal bronze and mineral powder in the proportion of 3.5:l:5:40.

4. The process of manufacturing matrices for printing purposes, consisting of a base plate and a coating composition, comprising admixing to the material of the matrix an impregnating composition containing a filler for the pores of the material and an adhesive, molding a base plate from said material, treating mechanically the surface of said plate so as to render it smooth and uniform, applying a coating to said treated and impregnated surface, allowing said coating to become dry, and mechanically treating the finished matrix so as to render it smooth and uniform.

RICHARD JUNGHANEL. HANS GROSS.