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(11) | EP 1 650 052 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Press for flat sublimation heat transfer printing |
| (57) The finding relates to a press for flat sublimation heat transfer printing to be
employed in the printing of sportswear, pullovers, mats/carpets, banners, knitwear
and other clothing accessories, as well as in other sectors such as the printing on
tiles, glass, metallic items, of the type where it is foreseen that the material to
be printed (1) and the print paper (2), on which the drawing to be transferred is
printed, are compressed between two plates (3,4), one of which is heated to a temperature
such that the ink of the drawings of the print paper undergoes the effect of sublimation,
whereby the steam deposits itself on the surface of the material to be printed and
where the action of the sublimation heat transfer printing takes place in an environment
in a state of reduced pressure. Such press is characterised in that it presents a
reduced pressure or "vacuum" chamber (10), containing a plurality of mutually overlapping
laminar bodies (12,13), which form a pack (11) which engages the entire surface of
one of the two plates, preferably that which acts as a work surface, on which the
print paper and article to be printed are extended.
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[0001] The present finding relates to a press for flat sublimation heat transfer printing, according to the general part of claim 1.
[0002] Among the diverse printing systems employed in the textile sector, in particular in the printing of sportswear, pullovers, mats/carpets, banners, knitwear and other clothing accessories, as well as in other industrial sectors where the print is realised on tiles, glass, metallic items, such as doors, profiles, blackboards, trays and others, the so-called "sublimation heat transfer printing" system is quite widespread.
[0003] Such method foresees first of all that the surface of the material to be printed is placed in mutual contact with the surface of the print paper on which the print motif, composed of a drawing, a text or other logo types, is stamped.
[0004] Afterwards, the two elements are compressed between, two plates, one of which is heated to a temperature such that the ink of the drawings of the print paper undergoes the effect of sublimation, whereby the steam deposits itself on the surface of the material to be printed, realising therefore the desired print.
[0005] At the current state of the art, sublimation heat transfer printing is realised with presses composed, substantially, by one plate called the "heated plate", against which a printing surface is compressed, on which the article to be printed and the printed paper are arranged.
[0006] With such operation technique a uniformity of colours on the surface of the printed article is obtained, but a satisfying penetration of the inks inside the fibres of the same article may not be obtained.
[0007] This implies that, with the colour set only on the surface of the article to be printed, non-coloured fibres are visible when the weft of the fabric results expanded, which involves, disadvantageously, a not always acceptable aesthetic effect, in particular on quality clothing articles.
[0008] To obtain a penetration of the inks inside the fibres of the fabric to be printed, presses have been realised in which the process of sublimation heat transfer printing takes place in an environment in a state of reduced pressure.
[0009] At the present state of the art, such process, known by the generic term "vacuum", is not very widespread due to the difficulty to realise reduced pressure chambers equipped with a perfect vacuum seal and where the pressure is of uniform value over the entire surface area of the same.
[0010] The object of the present finding is to realise a press for sublimation heat transfer printing of "vacuum" type, which lacks the inconveniences manifested in similar machines of known type.
[0011] Specifically, the object of the finding is to realise a press for sublimation heat transfer printing which, through the regulation of the "vacuum", permits the realisation of a penetration of the inks inside the fibres, for a depth which may range from few m up to the entire thickness of the same, such that the print forms on both sides of the printed fabric.
[0012] A further object of the finding is to realise a press for sublimation heat transfer printing which realises a homogenous pressure on the entire surface area of contact between the print paper and the body to be printed, even in the presence of thickness variations of the body itself.
[0013] Such objects are obtained by a particular constructed form of the reduced pressure chamber, containing a plurality of mutually overlapping laminar bodies, which form a pack which engages the entire surface of one of the two plates, preferably that which acts as work surface, on which the print paper and the article to be printed are extended.
[0014] Structurally, the laminar bodies comprise a hermetic membrane and a porous layer between which at least one metallic grid may be possibly inserted and where the entire pack is laterally enclosed by a metallic frame, anchored on the plate and which slides along the entire external profile of the plate itself.
[0015] On the lateral frame, a seal is applied which ensures the hermetic seal when the two plates are mutually fitted, and suction holes are made to realise the reduced pressure state inside the chamber defined with the closing of the plates themselves and the value of the "vacuum" is regulated through an external solenoid valve, inserted in series with the suction pump.
[0016] Still structurally, the finding foresees that on the support plate of the abovesaid laminar pack through holes are made which permit the formation of an air chamber, at atmospheric pressure, under the hermetic membrane such to render homogenous the pressure distribution over the entire pack itself.
[0017] The characteristics of the finding are made clearer through the description of a possible embodiment, provided by way of a non-limiting example, with the help of the appended drawing tables wherein:
- Figure 1 (Table 1) represents a prospective view of a press for sublimation heat transfer printing with two work surfaces;
- Figure 2 (Table II) represents a section view, along the line II-II of Figure 1, of the press in open (or inactive) condition;
- Figure 3 (Table III) represents a section view, along the line II-II of Figure 1, of the press in closed (or operative) condition;
- Figure 4 (Table IV) represents a detailed prospective view of the suction chamber according to the finding.
[0018] As is visible in figure 1, in the press for the sublimation heat transfer printing, the article to be printed 1 and the print paper 2 are arranged mutually fitted and placed extended on a work surface 3.1 and 3.2, on which an upper plate 4 operates.
[0019] The press represented in figure 1 is composed by a double work surface 3 with the upper plate 4, which moves alternately such to avoid down work times.
[0020] As is visible in figures 2 and 3, the work surface 3 is mounted on two pistons 5, which realise the closing of the machine and therefore the mutual compression between the body to be printed 1 and the print paper 2, while the upper plate 4 is equipped with a heated plate 6 which causes the phenomenon of the sublimation of the inks present on the print paper 2 and their fixing on the fibres on the body to be printed 1, all according to a per se known technique.
[0021] The principal characteristic of the finding is constituted by the presence of a chamber 10, comprised between the two plates 3 and 4, which operates in a state of reduced pressure or "vacuum" and is composed of a pack 11 of laminar bodies which, in operative conditions (see figure 2) constitute the support base of the body to be printed 1.
[0022] In detail, as may be seen in fig. 4, the lower laminar body, which rests on work plate 2, is composed of a hermetic membrane 12, while the upper laminar body, which rests against the body to be printed 1, comprises a layer of porous material 13.
[0023] Between the two laminar bodies 12 and 13, two metallic grids 14 and 15 are inserted with different grid dimensions.
[0024] The whole pack 11 anchors laterally on a perimeter frame 16 on which there are holes 17 for the suction of the air from the chamber 10 and the insertion seat of the seal 18 which ensures the hermetic seal of the chamber itself.
[0025] The perimeter frame 16 is locked on the lower plate 3 through screws 19 and everything is enclosed by a transpiring sheet 20, which is placed in contact with the body to be printed 1.
[0026] Operatively, as inferred by comparing figures 2 and 3, with the closing of the two opposing plates 2 and 3 the sublimation printing, i.e. the penetration of the vaporised inks on the fibres of the body to be printed, is facilitated by the force of compression of the two plates 3 and 4 as well as the presence of the reduced pressure chamber 10, whose seal is ensured by the hermetic membrane 12 and by the perimeter seal 18, while the grids 14 and 15 make it possible to obtain the "vacuum" over the entire work surface.
[0027] Finally, to guarantee the high quality of the final printing, in addition to foreseeing a regulation of the values of "vacuum" in the reduced pressure chamber 10 through a solenoid valve 21 mounted in series with the suction pump 22, it is foreseen that on the support plate 3 of the laminar pack 11 at least one through hole 23 is made such that, in operative phase, when the two plates are closed and the reduced pressure chamber 10 is active, there forms, under the hermetic membrane 12, an air chamber 24 at atmospheric pressure, which exerts a uniform thrusting action on the entire surface of the membrane itself (see figure 3).
1. PRESS FOR FLAT SUBLIMATION HEAT TRANSFER PRINTING, to be employed in the printing
of sportswear, pullovers, mats/carpets, banners, knitwear and other clothing accessories,
as well as in other sectors such as the printing on tiles, glass, metallic items,
of the type where it is foreseen that the material to be printed and the print paper,
on which the drawing to be transferred is printed, are compressed between two plates,
one of which is heated to a temperature such that the ink of the drawings of the print
paper undergoes the effect of sublimation, whereby the steam deposits itself on the
surface of the material to be printed and where the action of the sublimation heat
transfer printing takes place in an environment in a state of reduced pressure,
said press being characterised in that it presents a reduced pressure or "vacuum" chamber, containing a plurality of mutually overlapping laminar bodies, which form a pack which engages the entire surface area of one of the two plates, preferably that which acts as a work surface, on which the print paper and article to be printed are extended.
said press being characterised in that it presents a reduced pressure or "vacuum" chamber, containing a plurality of mutually overlapping laminar bodies, which form a pack which engages the entire surface area of one of the two plates, preferably that which acts as a work surface, on which the print paper and article to be printed are extended.
2. PRESS according to claim 1 characterised in that the laminar bodies comprise a mutually opposed hermetic membrane and a porous layer.
3. PRESS according to claim 2 characterised in that between the hermetic membrane and porous body at least one metallic grid is inserted.
4. PRESS according to claim 1 characterised in that the entire pack is laterally enclosed by a frame, anchored on one of the plates and
which slides over the entire external profile of the plate itself.
5. PRESS according to claim 4 characterised in that a seal is applied on the perimeter frame, which ensures the hermetic sealing when
the two plates are mutually fitted.
6. PRESS according to claim 4 characterised in that suction holes are made on the perimeter frame, to realise the "vacuum" inside the
reduced pressure chamber.
7. PRESS according to one or more of the preceding claims
characterised in that on the support plate of the laminar pack at least one through hole is made which, in the operative phase of the machine, determines the formation of an air chamber of atmospheric pressure on the outer surface of the hermetic membrane.
characterised in that on the support plate of the laminar pack at least one through hole is made which, in the operative phase of the machine, determines the formation of an air chamber of atmospheric pressure on the outer surface of the hermetic membrane.
8. PRESS according to claim 1, where the article to be printed (1) and the print paper
(2) are arranged mutually fitting and placed extended on a work surface (3) on which
an upper plate (4) operates, which moves alternately, where the work surface (3) is
mounted on pistons (5), which realise the closing of the machine and therefore the
mutual compression between the body to be printed (1) and the print paper (2), while
the upper plate (4) is equipped with a heated plate (6) which causes the phenomenon
of the sublimation of the inks present on the print paper itself and their fixing
on the fibres of the abovesaid body to be printed, said press being
characterised in that it is equipped with a chamber (10), comprised between the two plates (3,4), which operates in a state of reduced pressure and containing a pack (11) of laminar bodies which, in operative conditions, constitute the support base for the body to be printed (1).
characterised in that it is equipped with a chamber (10), comprised between the two plates (3,4), which operates in a state of reduced pressure and containing a pack (11) of laminar bodies which, in operative conditions, constitute the support base for the body to be printed (1).
9. PRESS according to claim 8 characterised in that it comprises a first laminar body, placed in the lower position and which places
itself in support of the work surface (3), composed of a hermetic membrane (12).
10. PRESS according to claim 9 characterised in that it comprises a second laminar body, placed above and which places itself in support
of the body to be printed (1), composed of a layer of porous material (13).
11. PRESS according to claims 9 and 10 characterised in- that between the two laminar bodies (12, 13) two metallic grids (14, 15) are inserted.
12. PRESS according to claim 11 characterised in that the two grids (14, 15) are of different dimensions.
13. PRESS according to claim 8 and to one or more of the subsequent claims, characterised in that the entire pack (11) is laterally anchored on a perimeter frame (16).
14. PRESS according to claim 13, characterised in that on the frame (16) holes (17) are made for the suction of air from the chamber (10).
15. PRESS according to claim 14 characterised in that the value of the "vacuum" in the reduced pressure chamber (10) is regulated through
a solenoid valve (21) mounted in series with the suction pump (22).
16. PRESS according to claim 13 characterised in that on the frame (16) the insertion seat is made for the perimeter seal (18).
17. PRESS according to one or more of the preceding claims, characterised in that the hermetic sealing of the chamber (10) is ensured, in operative conditions, by
the hermetic membrane (12) and by the perimeter seal (18).
18. PRESS according to claim 13 and one or more of the subsequent claims characterised in that the perimeter frame (16) is locked on the lower plate (3) through screws (19).
19. PRESS according to claim 13 and one or more of the subsequent claims characterised in that on the support plate (3) through holes (23) are made which permit the realisation
of an air chamber (24) below the hermetic membrane (12).
20. PRESS according to claim 5 and one or more of the subsequent claims characterised in that the entire chamber (10) is enclosed by a transpiring sheet (20) placed in contact
with the body to be printed (1).