GB2193467A

GB2193467A - Printing on plastics film

Info

Publication number: GB2193467A
Application number: GB08617231A
Authority: GB
Inventors: Albert Dass
Original assignee: SPRINGFIELD PROOFING SERVICES
Current assignee: SPRINGFIELD PROOFING SERVICES
Priority date: 1986-07-15
Filing date: 1986-07-15
Publication date: 1988-02-10
Also published as: GB8617231D0

Abstract

A material for use in a high definition reproduction system, wherein the material comprises a plastics film and a "clear draft" coating applied to the back of the plastics film, the "clear draft" coating allowing inks to key thereto. The plastics film is preferably polyester, e.g. an acetate with an air-dried liquid coating also of polyester acetate. The material is used particularly for printed labels, e.g. for application to metal containers.

Description

SPECIFICATION A high definition reproduction system The present invention relates to a high definition reproduction system which is particularly, although not exclusively, suited to printing labels for containers and the like. The present invention relates especially to a material which can be printed upon using a high definition reproduction printing system.

Metal containers and the like are usually labelled to indicate their contents, and often the lapel is used to carry decorative pictures and images. The decoration serves the dull purpose of identifying the container to the public and making the container, which would otherwise be plain and unattractive, appealing. As such, the label is a very important component of a products commercial success, and the quality of the label, especially the decoration printed on it, is of some importance. The container may contain any one of a wide range of products from cosmetics, through household products, to foodstuffs, and therefore the range of decorations that may be used is extremely broad.

It has long been known to use wrap around paper labels which can be glued to a container. Paper labels are easily printed upon and are cheap to produce, both important factors where very large quantities of labels are required to be produced. However, paper labels are easily abused, insofar as they can be easily torn or defaced, and in the event of the container contents being spilled, it is not always possible to wipe the label clean. Moreover, paper labels do not easily lend themselves to- being printed upon in such a way as to give a high quality reflective surface finish.

The term "reflective", is understood in the lithographic printing industry to mean glossy and giving the impression of depth. Consequently, paper labels are not considered suitable for many applications.

In an attempt to overcome the problems associated with paper labels, plastics labels have been used, but to date these have been of very poor quality. Initially, attempts were made to print directly onto the front of the plastics material, but it was found that the printed decorations were still prone to abuse as a result of scratching and spillages. The conclusion reached after this was that if the required features of abuse resistance and high quality reproduction were to be achieved, the printed decorations would have to be reverse printed upon the back of the plastics label.

Various plastics materials and printing inks have been used in this way to achieve labels of the required quality. For example, U.V. sensitive inks have been used to print on the plastics material, which are cured upon exposure to U.V. light. In addition, thin film plastics materials which can be heat shrunk onto the containers have been used. None of these have proved entirely satisfactory, the main problem being that the inks used will not adhere properly to the surface of the plastics material which gives rise to a low quality print with poor definition, and are dull and non reflective.

It is an object of the present invention to provide a high definition reproduction system which allows plastics labels to be produced having high quality decoration and a reflective finish, and more especially to produce a material which it can be printed upon using the aforementioned high definition reproduction system.

According to a first aspect of the present invention there is provided a material for use in a high definition reproduction system, wherein the material comprises a plastics film and a "clear draft" coating applied to the back of the plastics film, the "clear draft" coating allowing inks to key thereto.

The plastics film is preferably comprised of a polyester acetate which has dimensional stability at a wide range of temperatures and is sufficiently rigid to allow it to pass through printing presses at very high speeds without wrinkling or twisting. Such a material is a mellinex based material. This material is particularly resistant to abuse in the form of scratching and spillages.

The "clear draft" coating is also based upon a polyester acetate, such as mellinex, but is applied to the plastics film as a liquid coating. This dries on exposure to air to give a matt finish to the rear face of the plastics film which is receptive to inks whilst maintaining high optical clarity. The "clear draft" coating also has good anti-static qualities which prevent it from sticking as it is fed at high speed through conventional printing presses.

The material of the present invention is ide telly suited to use in high speed lithographic printing presses, and produces a printed label having very much improved image definition and reflective properties, as compared with existing print material, insofar as the "clear draft" coating allows the inks to key to it and the plastics film protects the "clear draft" coating and the inks thereon from abuse, whilst retaining its reflective qualities.

The inks used in the high definition reproduction technique of the present invention are formulated to be suitable for printing by the lithographic process - "wet on wet" through a multicoloured machine to give the classical four colour illustration. However, it will be appreciated that variations on this are possible within the understood field of lithographic printing. The inks used must be able to dry and key to the clear draft coating provided on the back of the plastics film. Preferably, the inks used are comprised of organic and inorganic pigments with a minimum percentage of 10% to a maximum of 50%. These were dis persed in a vehicle system comprising rosin modified hard resins, vegetable drying oils and alkyd resins.Up to 10% hydrocarbon distil lates may be included in the ink, and additives in the form of metallic soaps commonly used in lithographic printing inks to accelerate the oxidative drying process may also be added.

In addition, other additives, based on waxes, were included to assist rub resistance and keying. It has been found that these inks have the necessary drying and keying factors insofar as their use on the "clear draft' coating is concerned, and as such, in combination with the material of the present invention, they give- rise to a very high definition printed image and enhanced reflective finish.

As an alternative to the above described inks, opaque white inks have been formulated to print lithographically and dry by the oxidation process and also a further type which would dry and cure on exposure to ultra violet light. Where the application of the opaque white ink by means of a roller coating machine is required, an emulsion system which will air dry and key to the "clear draft" coating, with or without the use of heated air.

Successful gluing is- dependent on the adhesion of "clear draft" coating and inks to the plastics film. This is achieved using the material of the present invention. In order to ensure the glue is hidden on all designs that may be printed a white coating which gives a totally opaque finish when cured is used.

Claims

-CLAIMS

1. A material for use in a high definition reproduction system, wherein the material comprises a plastics film and a "clear draft" coating applied to the back of the plastics film, the "clear draft" coating allowing inks to key thereto.

2. A material according to claim 1, wherein the plastics film is comprised of a polyester acetate.

3. A material according to claim 2, wherein the polyester acetate is a meilinex based material.

4. A material according to any preceding claim, wherein "clear draft" coating is based upon a polyester acetate applied to plastics~ film as a liquid coating.

5. A material according to claim 4, wherein the polyester acetate is a mellinex based material.