FR2775931A1 - Hot transfer printing process, useful for automobile registration, wheel or property marking, etc. - Google Patents

Abstract

A hot transfer printing process in which the substrate (1) to be printed, is flat and rigid, is new. A hot transfer printing process employs a flat rigid printing substrate (1) which cannot be wound about a cylinder of 70 mm diameter by elastic deformation.

Description

The present invention relates to a process for printing materials

  flat and rigid by thermal transfer.

  In the current state of the art, thermal transfer printing, by means of a thermal printing head pressing a ribbon comprising a transferable material on a support to be printed in order to obtain identification signs, is not performed only on flexible print media. The most common print media are adhesive paper media for barcode labels as well as flexible and

  small areas such as credit cards or business cards.

  Current printers press the ribbon on the support to be printed which is itself supported by a back pressure element. This element, which is generally a roll, is sufficiently flexible and deformable to conform the support to be printed on the print head in order to conform to the

geometry of the latter.

  As a result, the known techniques are limited to the printing of

  flexible and deformable print media.

  However, flexible print media only respond to a small part of the

  signaling and identification needs.

  On the other hand, current techniques for printing rigid supports while offering the guarantees of durability over time necessary - such as screen printing, computer-assisted cutting of adhesive film, engraving, etc. - are complex, expensive, slow and / or require qualified personnel. The present invention proposes to extend the current limits of thermal transfer printing of identification signs to printing supports made of rigid and flat materials such as metals, glass, synthetic materials and other materials. provided with rigidity and having little or no ability to be wound or unwound without retaining a permanent or semi-permanent deformation. Thus the method according to the invention provides a new result which has never been obtained by putting

  using known transfer techniques.

  According to the invention, the thermal transfer printing method is characterized in that the support to be printed is flat and of such rigidity that it is impossible to wind it on a cylinder with a diameter of 70 mm by -2-

elastic deformation.

  According to particular modes of the invention - During printing, the print head can have a degree of freedom determined by its possible rotation around an axis parallel to the direction of printing and whose orthogonal projection on support to be printed, of this same axis, is one of the two axes of symmetry of the maximum printing surface. During printing, the counter-pressure element may have a degree of freedom determined by its possible rotation around an axis parallel to the direction of printing and the projection of which is orthogonal to the support to be printed, similarly axis, is one of the two axes of symmetry of the surface

maximum printing.

  - The back pressure element, used to position and support the support to

  print, can be a rigid plate.

  - The support to be printed can consist of several assembled elements

  between them before printing as a sandwich.

  - The element of the support to be printed, one of its faces constituting the face to be printed, may have a surface hardness lower than one of the others

  elements composing the support to be printed.

  - The transferable material can be colored.

  The printing of the signs being obtained by a transfer method

  thermal using a print head controlled by a computer tool.

  The movement of the print medium relative to the print head, or of the print head relative to the print medium, allows the print head to scan the surface simultaneously print media. These movements being controlled and directed by the tool

  IT using known techniques.

  The print head can be connected to the entire print system, either by a pivot link whose only degree of freedom is a rotation along an axis substantially parallel to the direction of relative movement between the print head and the support to be printed during printing, either by a

  low amplitude ball joint (a few degrees).

  It is understood that such an arrangement allows the head to oscillate and makes it possible to compensate, during printing, for slight variations in flatness.

  of thickness and warping of the support to be printed.

  This provision is not limiting and other known means can be used to obtain the requested result or to meet the requested requirements. According to a preferred form of the invention, the back-pressure element,

  supporting the surface to be printed, is made of a rigid and flat material.

  The primary function of this element is to position the support to be printed

  compared to other elements of the printing system.

  In order to compensate for slight differences in flatness, thickness and warping of the support to be printed, the latter may be made up of several elements, permanently assembled together before printing, arranged in such a way that the element, one of which of its faces constitutes the face

  to be printed has a lower surface hardness.

  This can be the case for example, without being limiting, if the element located

  on the printable side is a film attached by adhesive bonding.

  In another form of application of the method, it is possible to use as a support for printing a plate made of rigid and transparent synthetic materials, for example a methacrylate plate, on the back of which colored signs are printed. An opaque film, also colored, is then applied to the printed surface so that the signs appear by transparency through the printed plate while being detached in a different background color. This application can be used, without this being a limitation, for producing a plate for

vehicle registration.

  It is thus possible, according to the invention, to print in a durable manner

  flat and rigid supports quickly, simply and inexpensively.

  The accompanying drawings illustrate, without limitation, the present invention

  - Figure n 1 shows a section of the printing process.

  - Figures n 2 and n 3 represent a section of Figure n 1.

  With reference to these drawings, the printing process comprises a support to be printed (1), positioned on a back-pressure element (3), during its - 4- thermal transfer printing of a transferable material (5) by the action of the print head (2) on the ribbon (4) containing the transferable material

  (5); The action of these operations being controlled by the computer tool (9).

  Figure 1 shows the printing process in operation when part of the transferable material (5) has been transferred to the print medium (1) during the relative movement of the print head (2) relative to the support to be printed (1) in a printing direction (6). In this figure n 1, the section plane of the process

  is perpendicular to the printing direction (6).

  FIG. 2, which is a section through the printing process along the plane A-A of FIG. 1 itself perpendicular to the printing direction (6), represents more particularly the possible axes of rotation. The axis (7) of rotation of the print head (2) is substantially parallel to the axis of the print direction (6) and located in the plane of symmetry of the print head (2). The axis (8) of rotation of the back pressure element (3), which meets the same constraints as those of the axis (7), is placed close

  of the back pressure element (3).

  FIG. 3, which is a section through the printing process along the plane A-A of FIG. 1 itself perpendicular to the printing direction (6),

  more particularly represents the axis (8) of rotation of the counter element

  pressure (3). The pivot link thus obtained allows a slight rotation of

the back pressure element (3).

  By way of nonlimiting example, the support to be printed will be a transparent methacrylate plate with a thickness of 5 mm and an area of 600 cm 2, the back pressure element will be an aluminum plate of a

  15 mm thick and the transferable material a black ink.

  According to this same example, the back-pressure element will be fixed and the print head, being fixed by a pivot connection to the mechanical part,

  will move along the media to be printed during printing.

  The method according to the invention is intended for printing plates intended for signage or identification in general and, more particularly for car registration, street marking, or numbering

  of buildings, without these applications being limiting.

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Claims (6)

  1) Thermal transfer printing process characterized in that the support to be printed (1) is flat and of such rigidity that it is impossible to   wind it on a cylinder with a diameter of 70 mm by elastic deformation.   2) A printing method according to the preceding claim characterized in that, during printing, the print head (2) has a degree of freedom determined by its possible rotation about an axis (7) parallel to the direction of printing (6) and of which the orthogonal projection on the support to be printed (1), of this same axis (7), is one of the two axes of symmetry of the maximum printing area.   3) A printing method according to the preceding claim characterized in that, during printing, the counter-pressure element (3) has a degree of freedom determined by its possible rotation around a parallel axis (8) to the direction of printing (6) and whose projection orthogonal to the support to be printed (1), of this same axis (8), is one of the two axes of   symmetry of the maximum printing surface.   4) Printing process according to one of the preceding claims   characterized in that the counter-pressure element (3), serving to position   and to support the support to be printed (1), is a rigid plate.   ) Printing process according to one of the preceding claims   characterized in that the printing medium (1) consists of several   elements assembled together before printing in the form of a sandwich.   6) A printing method according to the preceding claim characterized in that the element of the printing medium (1), one of its faces constituting the face to be printed, has a surface hardness less than one of other   elements making up the support to be printed (1).   7) A printing method according to one of the preceding claims   characterized in that the transferable material (5) is colored.