Record receiver having plural interactive leaves or a colorless – Having plural interactive leaves
Reexamination Certificate
1999-01-12
2001-04-03
Hess, Bruce H. (Department: 1774)
Record receiver having plural interactive leaves or a colorless
Having plural interactive leaves
C346S076100, C428S036900, C428S131000, C428S195100
Reexamination Certificate
active
06211117
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to printing plastics substrates and in particular to printing plastics substrates, such as markers for identifying electric cables etc., using a thermal transfer printing process.
U.S. Pat. No. 5,676,478 discloses a printer for printing plastics tubular markers for applying to individual cables. These plastics tubular markers may be heatshrinkable or non-heatshrinkable. The printer comprises a thermal print head having an array of pixels, each of which can be thermally activated, in order to melt the surface of the plastics tubular markers and to form a corresponding image thereon. This process is slow because the plastics tubular markers have to be advanced sufficiently slowly for and image to be formed. The process is also unreliable, because the print head is liable to become clogged with melted plastics material.
It is known to print onto plastics by applying pressure and heat to a printing ribbon registering against the plastics material, such that a print composition carried by the ribbon is transferred to the material. Conventionally, thermal transfer ribbons rely upon a wax or resin to transfer the dry ink onto the feedstock substrate.
This method of printing has inherent drawbacks; for example, the ink can be removed by means of heat, chemical action or abrasion. This can result in important printed images becoming unreadable. Furthermore, over time, the action of ultra violet radiation on pigments in the ink can result in the image fading.
SUMMARY OF THE INVENTION
We have now devised arrangements which offer significant advantages relative to the arrangements which have been provided hitherto.
In accordance with this invention as seen from a first aspect, there is provided a method of printing onto a plastics substrate, the method comprising applying heat and pressure to a print carrier registering against the substrate resulting in transfer of a printing composition carried by the print carrier to the substrate, the printing composition comprising a first pigmentation material arranged to penetrate into the plastics substrate to form a substantially permanent mark below the surface of the substrate, and a second pigmentation material arranged to adhere to the surface of the substrate overlaying the substantially permanent mark.
The invention enables a single stage printing process to be used to print a marking of predetermined configuration onto a plastics substrate, the marking comprising a sub-surface marking and corresponding surface printed marking. The dual nature of the marking provides advantages in terms of durability, particularly for use in harsh environments, or situations where the mark is liable to be subject to chemical action, or abrasion in the normal course of events or in cases of unauthorized tampering.
The invention is particularly suitable for use in providing plastics printed markers for identifying articles.
Thus, preferably the method comprises advancing a length of elongate plastics strip or flattened tubing longitudinally of itself past the print carrier and printing indicia at successive longitudinal intervals onto said plastics strip or tubing.
The plastics strip or tubing may be formed with transverse lines of weakness after it has been printed.
Also, in accordance with this invention as seen from a second aspect, there is provided a thermal transfer printer in combination with a plastics substrate, the printer having a thermal transfer print head and a print carrier carrying a releasable printing composition, which print composition comprises a first pigmentation material capable of penetrating into said plastics substrate, and a second pigmentation material capable of adhering to the surface of said plastics substrate.
The printing composition carried by the print carrier comprises the first and second pigmentation materials and also, preferably, a plastics material facilitating penetration into the substrate.
In one embodiment, the plastics material of said printing composition may be the same as the plastics material of the plastics substrate.
In an alternative embodiment, the plastics material of said printing composition may be different from the plastics material of the plastics substrate. In this instance, the plastics material transferred from the print carrier and penetrated into the substrate will be identifiable in the resulting printed marker, at least upon microscopic inspection.
It is preferred that the plastics material of said printing composition comprises a thermoplastic material, such as PVC, a polyolefin or the like, more preferably, a homopolymer material.
It is preferred that the print carrier comprises a plastics film (desirably comprising polyester) preferably of a thickness substantially in the range 4-15 microns, more preferably approximately 6 microns. The print carrier is capable of separating from the print composition it carries during the thermal transfer printing process. Desirably the print carrier is wound from a reel store.
The print composition (or ink) carried by the print carrier is preferably touch dry. The first and second pigmentation materials are preferably relatively dark in color and may for example be blue or black. The pigmentation materials may for example comprise dyes of suitable composition to ensure that one penetrates the substrate and the other adheres to the surface of the substrate during the printing process.
One or other (or both) of the first and second pigmentation materials may comprise a mixture or composition of a plurality of dyes.
It is preferred that the printing composition comprises the pigmentation materials and the plastics material bound in a matrix material. The printing composition is preferably applied to the print carrier as a layer. The matrix material may, for example, comprise a relatively soft, high molecular weight material such as a wax or wax-like material.
The thermal transfer printer may be arranged to print any predetermined indicia mark upon the substrate.
Preferably the plastics substrate comprises an elongate length of plastics strip or tubing, which is preferably preformed with transverse lines of weakness at intervals along its length, to define successive markers. The lines of weakness may be provided by a line of perforations or by a partial cut through the thickness of the plastics material: however, the lines of weakness may be formed at any desired intervals, so forming markers of any desired lengths.
Preferably, the plastics strip is semi-rigid. Preferably, the plastics strip comprises an adhesive backing.
In use, as the plastics strip or tubing advances through the printer, the position of the perforations or lines of weakness between successive markers needs to be determined, so that the printer can determine where to position each successive print on each successive marker.
Thus, preferably datum markings are formed at regular intervals along the plastics strip or tubing, the spacing between each marking being related to the length of each marker, the printer comprising a sensor arranged to sense the position of each marker as the plastics strip or tubing is advanced through the printer and control means arranged to control the position at which successive prints are formed on successive markers of the plastics strip or tubing, in accordance with the output of the sensor.
In use, the sensor detects the position of the datum markings, so that the printer knows when it can start printing each successive marker.
Preferably a datum marking is provided on each of the successive markers. However, it is envisaged that datum markings may not be provided on every marker, in which case the printer is preferably arranged to calculate the position at which each successive marker is to be printed.
Preferably the markings are transparent and thus do not affect the appearance of the markers on which they are provided.
Preferably the markings are formed of a UV reflective material such as ink.
Preferably, the printer comprises a UV light source which irradiates the strip or tubing, the sensor bein
Haggerty John Nicholas
Mathias Timothy
Meech Dominic Roger
Gallagher Thomas A
Gordon David P.
Hess Bruce H.
Jacobson David S.
Spirent PLC
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