GB2081470A

GB2081470A - Preparing original for silk screen printing

Info

Publication number: GB2081470A
Application number: GB8123528A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-08-04
Filing date: 1981-07-31
Publication date: 1982-02-17

Abstract

A method of preparing a positive for silk screen printing comprises applying one or more transparent films 3, each having one or more indicia thereon 5, to a transparent sheet 9 in a desired position or arrangement, the transparent sheet 9 and the or each of said transparent films 3 being adapted for repeatably removable adhesion therebetween. Said adhesion may be by means of, for example, suction, electrostatic attraction, or by the use of an adhesive layer applied to one or both of the contacting surfaces. <IMAGE>

Description

SPECIFICATION Silk screen printing The present invention relates to silk screen printing.

One of the most popular methods of printing currently in use is the silk screen method of printing. This method is widely used in a variety of applications because of its relative cheapness and speed and because of its adaptability for use with different inks for printing on many different materials such as wood, glass, plastics materials and fabrics as well as paper and card.

The main steps in silk screen printing are as follows. Firstly the desired sign or lettering or artwork is painted or photographically located onto a suitable transparent sheet, commonly clear acetate. This forms the so-called 'positive'. Then a 'silk screen', which is now usually made of man-made fibre, is coated with a photosensitive impermeable emulsion.

The artwork is laid face down on the back of the silk screen and an ultra-violet light is then shone through the artwork sheet into the screen. Where the emulsion on the screen is exposed to the ultra-violet light, it is "fixed", but the region of the screen covered by the artwork of the top sheet is not fixed, and the emulsion in these regions can be washed off with water. It will be readily appreciated that the regions of the screen not now covered by the emulsion will correspond to the lettering or designs painted onto the artwork positive.

The final stage of silk screen printing is the actual printing of the design onto a desired material. This is done by laying the silk screen face up on the receiving material and then forcing ink through the mesh of the screen at the unfixed areas of the slik screen corresponding to the desired lettering or design.

Each time a new design is required a new positive, incorporating the desired artwork, must be prepared. This is the lengthiest and most expensive step in the silk screen printing process, and even though each completed silk screen can be used to print a very large number of articles the cost of producing the original artwork for each screen is a considerable proportion of the cost of each completed printed article.

According to the present invention there is provided a method of preparing a positive for silk screen printing, the method comprising applying one or more transparent films, the or each film having located thereon one or more indicia, to a transparent sheet, in a desired position or arrangement, the transparent sheet and the or each said transparent film being adapted for repeatably removable adhesion therebetween.

The indicia located on said film or films may be, for instance, letters, figures, numerals or designs, and may be of any suitable size or configuration.

The transparent sheet and film on which the indicia are located need only be transparent to the type of radiation, such as ultra-"iolet, used in the silk screen process, so that, the radiation is transmitted therethrough to an extent sufficient to fix the photosensitive layer on the silk screen.

The adhesion between the sheet and the or each film should be such that there is no relative movement between the sheet and the or each film during the processing. For instance, adhesion may be obtained by using materials for the films and sheets which have a mutual attraction, by suction adhesion, by using self-clinging material which adheres by electrostatic attraction, or by supplying either or both the sheets and films with an adhesive layer, said layer being protected when not in use by removable backing sheets.

Preferably the adhesion is such as to allow repeated separation and adhesion between the film and the sheet.

Preferably the or each said film is initially located on a backing sheet, and removed therefrom before application to the transparent sheet, the or each said film and said backing sheet being adapted for repeatable, removable adhesion therebetween. The invention also provides a precursor for preparing a positive for silk screen printing, said precursor comprising a backing sheet and mounted thereon a plurality of transparent films, each said film having located thereon one or more indicia, said backing sheet and each said film being adapted or repeatable. removable adhesion thereto.

The invention also provides a method for preparing a silk screen for silk screen printing, the method comprising locating on the silk screen, having applied thereto a photosensitive layer, a positive according to the invention, irradiating said silk screen through said positive to fix said photosensitive layer except where overlaid by indicia on said positive, removing said positive, and removing unfixed portions of said photosensitive layer.

The invention also provides a silk screen process in which the positive is prepared by a method of the invention. Furthermore the invention provides a print when made by such a silk screen process.

The present invention allows silk screen printing to be made more cheaply and quickly than is possible in known systems, by largely eliminating the requirement for a skilled artist or signwriter to produce each individual set of artwork for different signs. In use the desired letters, words, numerals, figures or designs are simply attached to the transparent sheet used as the positive, and then, after the normal production of the silk screen, the letters, designs and so forth may be removed from the sheet and kept until required again.

Preferably the film of transparent material is of clear vinyl.

Preferably the letters, figures, numerals or designs are painted or printed onto the film of transparent material is black vinyl ink.

Preferably a plurality of films are provided, each having a plurality of indicia thereon. For instance, a set of films may be mounted, each having thereon, several identical indicia, for instance, a letter of the alphabet. For use, the individual indicia may be, for example, cut from the film and arranged on the positive as required.

An embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings in which Figs. 1 to 3 show stages in a method in accordance with the present invention for preparing a silk screen positive.

Referring to Fig. 1 of the drawings, a strip 1 has a plurality of identical letters 5 printed in black vinyl ink by a silk screen process on a transparent vinyl film 3. Transparent vinyl film 3 is of a kind readily available; it has an adhesive layer film on the reverse and is protected by a removable paper backing sheet 7.

In use, the required letter is cut from the strip 1. It should be noted that it is not necessary to cut completely round the outline of the required letter, but merely to separate the letter from the others in the strip. The vinyl film 3, having the letter 5 located thereon, is then peeled from the paper backing sheet 7 as shown in Fig. 2. The film 3 is then positioned as desired on a clear acetate sheet 9 (Fig. 3). Several such letters or designs of various sizes and configurations may be used to give the lay-out of the completed sign.

To aid with spacings a sheet of graph paper may be laid beneath the acetate sheet to give guide lines for the horizontal and vertical spacings.

In an alternative embodiment the acetate sheet 9 has on its upper surface an adhesive layer to which letters 5 on the vinyl film 3 may be removably attached. This allows the film 7 to dispense with the adhesive layer on its rear surface.

Following the production of the positive as described above, the process continues as in normal silk screening. A silk screen is coated with photosensitive impermeable emulsion, the positive is laid face downwards on the -back of the screen and exposed to ultra-violet light. Excess emulsion from the regions of the screen which were not exposed to the ultraviolet light, being shielded by the indicia on the positive are washed off. The screen can then be used to produce prints by placing it on the material e.g. paper, card, wood, plastics, glass, which is to receive the print. Ink is applied to the screen and squeezed through the parts corresponding to the indicia positive by, for instance, a roller or blade.

After use the positive is then disassembled by removing the films 3 from the clear acetate sheet 9 and replacing them on the backing paper 7 for future use. Thus both films 3 and acetate sheet 9 may be used many times until the relevant adhesive layer fails.

If desired the letters 5 may be painted rather than printed onto transparent film 3 and the film 3 and letters 5 may be of any suitable materials. In this embodiment a vinyl film with vinyl ink printed on top was chosen so as to reduce the possibility of letters being scratched off from the surface of film 3.

In alternative embodiments of the present invention, the indicia may be located on the positive by means other than by adhesive.

Suitable means may be, for instance, the use of self-clinging plastics materials, which adhere to similar material by electrostatic attraction.

Claims

1. A method of preparing a positive for silk screen printing, the method comprising applying one or more transparent films to a transparent sheet in a desired position or arrangement, the or each film having located thereon one or more indicia, and the transparent sheet and the or each of said transparent films being adapted for repeatable removable adhesion therebetween.

2. A method according to claim 1 wherein said adhesion between the film and the transparent sheet is by means of suction, electro- static traction, or the application of adhesive to one or both contacting surfaces.

3. A method according to claim 1 or claim 2 wherein the or each of said films are initially located on a backing sheet, and removed therefrom before application to a transparent sheet, the film and the backing sheet being adapted for repeatable removable adhesion therebetween.

4. A method according to any of the preceding claims wherein the indicia on said film or films are letters or numerals.

5. A method according to any of the preceding claims in which said film is of a transparent plastics material.

6. A method according to claim 5 wherein the said plastics material is vinyl.

7. A method according to any of the preceding claims in which the indicia are painted or printed onto the film.

8. A method according to claim 7 wherein the indicia are painted ot printed in black vinyl ink.

9. A precursor for preparing a positive for silk screen printing, said precursor comprising: a backing sheet, and mounted thereon a plu-.

rality of transparent films, each of said films having located thereon one or more indicia, and said backing sheet and each of said films being adapted for repeatable removable adhe sion therebetween.

10. A method of preparing a silk screen for silk screen printing, the method comprising applying a photo-sensitive layer to a silk screen, locating on the silk screen a positive formed by attaching by repeatable removable adhesion transparent films to a transparent sheet, the or each of said films having one or more indicia thereon, irradiating said silk screen through said positive to fix said photosensitive layer except where overlaid by indicia on said positive, removing said positive, and removing unfixed portions of said photosensitive layer.

11. A method of silk screen printing, the method comprising preparing a silk screen by applying a photo-sensitive layer to said screen, locating on the silk screen a positive formed by attaching by repeatably removable adhesion transparent films to a transparent sheet, the or each of said films having one or more indicia thereon, irradiating said silk screen through said positive to fix said photosensitive layer except where overlaid by indicia on said positive, removing said positive, removing unfixed portions of said photo-sensitive layer, locating said silk screen over an article to be printed upon, and applying ink, paint, or any other suitable material to the silk screen so that said material passes through the silk screen in the regions from which the photo-sensitive layer has been removed, and on to the article to be printed upon.

12. A print produced by a method of silk screen printing according to claim 11.

13. A method according to claim 1 and substantially as herein described.

14. A method of preparing a positive silk screen printing substantially as herein described with reference to the accompanying drawings.

15. A precursor for preparing a positive for silk screen printing, according to claim 9 and substantially as herein described.

16. A precursor for preparing a positive for silk screen printing substantially as herein described with reference to the accompanying drawings.

17. A method of preparing a silk screen for silk screen printing according to claim 10 and substantially as herein described.

18. A method of preparing a silk screen for silk screen printing substantially as herein described with reference to the accompanying drawings.

19. A method of silk screen printing according to claim 11 and substantially as herein described.

20. A method of silk screen printing substantially as herein described with reference to the accompanying drawings.

21. A print produced by a method of silk screen printing as claimed in any of claims 11, 17 and 18.