SCREEN MATERIAL FOR PRINTING MATERIAL AND A MANUFACTURING METHOD

Abstract: A metal screen material comprising a metal screen, prefer­ ably a cylindrical screen, obtained by electrolytic deposition of a metal upon a screen skeleton and said screen material having a fineness of 250 to 1000 mesh. The screen opening is preferably defined by curved walls extending from the lower side of the screen opening to the up­ per side of the screen opening, the upper side of the screen opening having an area being larger than the lower side of the screen opening. The screen material is advantageously obtained by elec­ trolytic deposition of a metal from an electrolytic bath upon a screen skeleton, the bath solution passing, at least during part of the electrolytic depositing time, through the openings in the screen skeleton connected as the cathode either in one direc­ tion or in the other reverse direction.

Description: Screen material for printing material and a method for printing material using said screen material. This invention relates to a screen material having a fineness of at least 250 mesh and to a method of printing materials by means of this screen material. For printings for which great detail fineness and detail sharpness are desirable, screen material is known to be used in the form of a woven polyester gauze, said polyester gauze meeting the requirements of the fineness desired. Said known screen material presents the drawback that at all times it has to be kept in store under tension mounted on frames. This requires large storage facilities, since a particular screen material which, for instance, is not being used for a long time, must nevertheless be stored in the pretensioned condition on a frame. Another drawback is that, after providing the woven polyester gauze with holes, this gauze loses its dimensional stability, thus precluding the possibility of meeting the requirements applicable to a particular printing. A further drawback is that the known screen material does not very well assume its original condition after having been used, so that when using such screen material the quality of the product being printed greatly decreases after a relatively short period of time. Still another drawback is that cross threads and weft threads of the woven polyester gauze are not anchored with each other, so that, when using a screen having screen openings of 400 mesh, it frequently occurs that a large number of openings have dimensions that differ from those desired. At last, there is an important drawback in that rounded threads are used for said screen materials, as a result of which the permeability to material passing through the screen openings strongly depends upon the thickness of the threads from which the polyester gauze is made. It is now the object of theinvention to provide a screen material which does not have said drawbacks and which is particularly well suited for printings to be performed with great detail sharpness and detail fineness, without the need for said screen material to be stored in a pretensioned condition on frames, thus making it possible to gain considerable savings in terms of storage space requirements. In addition, said screen material retains its dimensional stability and so provides for unlimited useability. This object is attained according to the invention by electrolytic deposition of at least one metal upon a screen skeleton and has a fineness of 250 to 100 mesh. When using such a screen, printed products are obtained which have excellent properties, also when such screens are used over an extended period of time. It is quite surprising that it is possible to form metal screens having such a finesness. With particular advantage, the upper side of the screen opening has a surface which is larger than the lower side of the screen opening. Such type of screen presents excellent properties. Quite effectively, the screen opening is defined by curved walls extending from the lower side of the screen opening to the upper side of the screen opening as this provides excellent printing results. The screen material is very effectively obtained by electrolytic deposition of a metal upon a screen skeleton, the bath solution passing, at least during part of the electrolytic depositing time, through the openings in the screen skeleton connected as the cathode. The forced movement of the bath solution through the openings in the screen skeleton results in screens being formed which have the aforesaid openings and afford the forming of a relatively rigid screen material that has a very great fineness as well. With particular advantage, the screen material consists of a cylindrical screen, which type of screen has not been available so far with the fineness as indicated. It goes without saying that this makes it possible to produce in a very simple manner printings having the detail fineness and great detail sharpness as desired. The invention further relates to a method for printing materials while using a screen material having a fineness of at least 250 mesh, in said method being a screen used which comprises a metal screen obtained by electrolytic deposition of at least one metal upon a screen skeleton and having a fineness of 250 to 1000 mesh. In the method of the invention, printing effectively proceeds by using a screen obtained by electrolytic deposition, in which case at least during part of the electrolytic depositing time the bath solution passes through the openings in the skeleton screen. Other claims and many of the attendant advantages will be more readily appreciated as the same becomes better understood by reference to the following detailed description and considered in connection with the accompanying drawings in which like reference symbols designate like parts without the figures. FIG. 1 is a view of a screen material according to the invention; FIG. 2 is sectional view of a screen material according to the invention; and FIG. 3 is a view of a cylindrical screen material according to the invention. Fig. 1 shows a screen material 1 consisting of a metal screen 1 obtained by electrolytic deposition of at least one metal 2 upon a screen skeleton 3. The screen has a fineness of 400 mesh, so that there are 400 openings 4 per 2,54 cm. The electrolytic bath as used for depositing said metal is a well known electrolytic bath containing an organic compound comprising at least one unsaturated bond which ( I does not belong to a =C-S=O group such as butyne diol. Fig. 2 shows more particularly the shape of a number of openings in the screen. As seen, the free upper side 5 of the screen opening has a larger area than the area of the screen opening on the lower side of the screen 6. The screen opening is defined by the curved walls 8 of the lands bounding the screen opening 4. In addition, it is evident that the metal deposited by electrolytic deposition mainly extends on one side of the screen skeleton. On the other side of the screen skeleton, only a small layer thickness 7 of the electrolytically deposited metal has precipitated. This is more particularly shown in fig. 2. The shape of the screen openings is obtained by connecting a screen skeleton as the cathode and by having the electrolytic solution flow in the direction from the cathode to the anode or in the reverse direction. Preferably the direction of flow is from the cathode to the anode. The screen according to the invention is particularly well adapted for printings for which hitherto woven polyester gauze has been used. The screen material according to the invention distinguishes itself very favorably from the woven polyester gauze by the dimensional stability of the screen material used, which results in the remaining screen material retaining its nondeformable character when forming the openings in the screen material, the screen permeability being no longer dependent upon the thickness of the lands of the screen material by properly selecting the walls of the screen openings, and, finally, the size of the screen openings being ensured at all times, also after an extended period of use, this being in contradistinction to applications using woven polyester gauze. Fig. 3 shows a cylindrical screen material according to the invention in the form of a cylindrical screen 1' said cylindrical screen material being particularly suitable for continuous printing.

Claims: CLAIMS 1. A screen material having a fineness of at least 250 mesh, characterized in that, the screen material consists of a metal screen obtained by electrolytic deposition of a metal upon a screen skeleton and has fineness comprised between 250 and 1000 mesh. 2. A screen material according to claim 1, characterized in that the upper side of the screen opening has an area which is larger than the lower side of the screen opening. 3. A screen material according to claim 1 or 2, characterized in that the screen opening is defined by curved walls (8) extending from the lower side of the screen opening to the upper side of the screen opening. 4. A screen material according to one or several of the preceding claims, characterized in that the screen material is obtained by electrolytic deposition of a metal upon a screen skeleton, the bath solution passing, at least during part of the electrolytic depositing time, through the openings in the screen skeleton connected as the cathode. 5. A screen material according to claims 1-4, characterized in that the screen material comprises a cylindrical screen. 6. A method for printing materials using a screen material having a fineness of at least 250 mesh, characterized in that a screen material is used consisting of a metal screen obtained by electrolytic deposition of at least one metal upon a screen skeleton and having a fineness of 250 to 1000 mesh. 7. A method according to claim 6, characterized in that the printing proceeds by using a screen obtained by electrolytic deposition, the bath solution passing through the openings in a screen skeleton during at least part of the electrolytic depositing time. 8. A method according to claim 6, characterized in that in the screen material the upper side of the screen opening has an area which is larger than the lower side ot the screen opening. 9. A method according to claim 6, characterized in that the screen opening is defined by curved walls extending from the lower side of the screen opening to the upper side of the screen opening. 10. A method according to claim 6, characterized in that the screen material is a cylindrical screen.

Inventors: MEUZELAAR, BOB, THUIS, HENRICUS HERMANUS W.
Applicants: STORK SCREENS B.V.
Application year: 1985
Main classification: B41C1
IPC codes: C25D1, B41N1, G03F7, B41C1