EP0989227B1 - Process for treating flocks of a flocket support and the product obtained - Google Patents

Abstract

Flocks, already attached to the substrate, are lightly impregnated with polymer resin in aqueous emulsion in a bath. The material, thus impregnated, is dried. The resin attaches any loose flock fibers to the substrate. It limits ink penetration into the flock, in any subsequent printing stage. An Independent claim is included for the product of such manufacture. Preferred features: The resin content in the aqueous bath is preferably 2-12 dry wt%, especially 6-7%. Impregnation density is 100-150 g/m<2>. The resin is deposited in a moist environment on the flocked side only. Processes typically involve moistening, coating or atomization. Following impregnation, excess resin solution is wrung out using pressure rollers, which also even-out the deposit.

Description

The present invention relates to a process for treating the flocks of a flocked support, the support being any, for example paper, cardboard, plastic, textile or nonwoven. The invention also relates to the product obtained by this process, whether or not it is subsequently printed.

It is customary to decorate flocked supports, by printing on the flocks multicolored patterns or by marking the flocks by thermal application of a colored or metallized film, the latter method being generally known by the term "hot foil". The flocked supports are thus decorated in many fields, for example packaging and packaging, decoration, clothing, or wall covering.

The flocked supports can be decorated by screen printing, but such an impression does not accurately reproduce finely screened quadrichrome patterns, because the screen-printing frames used are limited by the mesh size.

The flocked supports can also be decorated by gravure printing, but this type of printing is also limited in terms of the quality and fineness of the graphic representation, and also requires the prior implementation of specific printing tools. such as engraved cylinders, which are very expensive.

In addition, screen printing as the heliographic printing require to deposit a large amount of ink on the flocks, and this whatever the nature of the support to print.

• contrairement au procédé d'impression sérigraphique ou héliographique, les machines d'impression offset ou flexographique sont sensibles aux flocks libres qui sont toujours plus ou moins présents sur un support flocké ; en effet, ces flocks libres quittent le support flocké lors de son passage à travers la machine d'impression et viennent se coincer dans des parties de la machine, telles que les cylindres d'entraînement et les plaques, ce qui détériore la qualité d'impression et nécessite des nettoyages fréquents, et donc des temps d'arrêts importants ;
• comme l'impression offset, flexographique ou par jet d'encre ne dépose que de faibles quantités d'encre sur le support à décorer, une quantité substantielle de ce dépôt d'encre peut être absorbée par les flocks du support flocké qui présentent, comme tout textile, un certain pouvoir d'absorption, ce qui réduit d'autant l'intensité des coloris imprimés et limite les possibilités de réalisation de coloris soutenus ou vifs.

There are also known offset or flexographic printing processes, but these can not be implemented in a simple way to decorate a flocked surface, for the following reasons:

• unlike the screen printing or gravure printing process, offset or flexographic printing machines are sensitive to free flocks that are always more or less present on a flocked medium; in fact, these free flocks leave the flocked support during its passage through the printing machine and become jammed in parts of the machine, such as the drive rolls and the plates, which deteriorates the quality of the machine. printing and requires frequent cleaning, and therefore significant downtime;
• since offset, flexographic or inkjet printing deposits only small amounts of ink on the support to be decorated, a substantial amount of this ink deposit can be absorbed by flocked flocked media which have, as any textile, a certain absorption capacity, which reduces the intensity of the printed colors and limits the possibilities of producing sustained or lively colors.

The marking of a flocked support by thermal application of a colored or metallized film is also possible, under certain conditions. In such a method, a colored or metallized layer is applied to a temporary support, usually a transparent polyester film, and then is partially transferred to the flocked support flocks using a heating tool, such as a punch, which briefly briefly presses said layer against flocked flocked media, said layer then being transferred onto the flocked portions of the support which have been crushed by the punch. However, the marking of a flocked support is more delicate than that of a paper or a cardboard, because of the textile and irregular nature of the flocked support, which requires to respect precisely particular conditions of application, to to know the selection of a hot stamping film adapted to the flocked support, and the absolute respect of the marking conditions on a precise machine and very well adjusted. Even if these conditions are fully respected, the marking of very fine drawings or texts of very small dimensions can not be done in good readability or will be resistant to friction.

To make the flocked support easily printable by the aforementioned methods, it is also possible to modify the flocked surface by crushing the flocks by calendering or graining with a heating cylinder, smooth or embossed pattern, pressurized, but in this case, the appearance and the touch of the flocked medium thus crushed are altered.

Document FR-A-2 718 673 describes a composite material that can be used as a dielectric having improved protection characteristics, in particular moisture-proofing characteristics, or as a metal-layer support for forming flexible printed electrical circuits, as well as a method of manufacturing this composite material. The composite material comprises an electrically and / or thermally insulating substrate, on at least one face of which is formed a protective layer composed of flocked heat-resistant fibers (bonded) on the face of the substrate. The flocked fibers are then impregnated with a heat-resistant resin in solution in an organic solvent so as to obtain a layer of resin reinforced by the fibers. In the case where it is desired to produce flexible printed circuits, a resin loaded with CuO ₂ grains is used and the substrate coated with the protective layer of fibers impregnated with the resin thus charged is then subjected to an immersion metallization process in a aqueous CuO ₂ reduction bath and dipping in a copper copper bath. The "printing" of the electrical circuits on the composite material thus metallized is carried out by the usual known methods (generally by photogravure). This document does not describe how to solve the problems related to the printing of colored patterns on a flocked print medium, by means of an offset or flexographic printing machine.

The object of the present invention is to propose a process for treating the flocks of a flocked support, which makes it possible to maintain a soft and pleasant feel of the flocked support thus treated, which makes it possible to print the latter by conventional offset printing processes. flexographic, ink-jet or thermal marking using a colored film or metallized, under the usual conditions of implementation of these methods, without special adjustment or use of special raw materials, while allowing a precise reproduction of multicolored motifs, especially in four-color process, with the quality of a photograph.

This object is achieved by a flock processing method as defined in appended claim 1.

Embodiments of the method according to the invention are defined in the dependent claims.

According to another characteristic of the invention, the method consists of depositing the resin in a humid medium on the flocks, on the one side of the flocked surface of the support, by any method such as wetting, impregnation, coating or coating. spray. Advantageously, the process consists, after impregnation of flocks with the resin in aqueous dispersion, to spin said flocked support thus impregnated between two pressure rollers to evacuate the excess resin and to uniformize the resin deposit.

Advantageously, the resin is a synthetic polymer resin chosen from acrylic esters, synthetic latices and polyesters-polyurethanes, so that the flocked support thus impregnated retains a soft, dry and non-sticky feel.

Preferably, the support is selected from the supports of paper, cardboard, plastic, textile or nonwoven.

The invention also relates to the product obtained by the process as previously described, characterized in that it comprises a flocked support whose flocks are impregnated with dry resin whose density is between 2 and 12 g / m ² , preferably between 6 and 7g / m ² .

Advantageously, the resin-impregnated flocks of the aforementioned product are printed with multicolored patterns, for example in four-color process, by an offset, flexographic, ink-jet printing or thermal application process of a colored or metallized film.

We will now briefly describe the implementation of the method according to the invention.

The flocked carrier is made by a method known per se, using conventional textile fibers and an adhesive polymer resin to bond the flocks to the selected carrier. Preferably, according to the invention, flocks of small dimensions, for example between 0.3 and 2 mm, are used, and the fibers are chosen from natural fibers, rayon fibers based on viscose, or fibers made of cotton, so that the support thus flocked has a soft and pleasant touch.

The flocked carrier is then impregnated with another emulsion polymer resin in an aqueous bath, rather than an organic solution, to protect the environment.

The aqueous bath containing the resin in dispersion is uniformly deposited on the flock of the flocked support, by any method, for example by wetting, impregnation, coating or spraying. Advantageously, the flocked support passes between two rolls, the applicator roll of which comprises a layer of foam impregnated with said emulsion for depositing it on the flocks of the flocked support. Then, the flocked support thus impregnated passes between two pressing rolls, for example one of steel and the other of rubber, to remove the excess resin and to uniformize the resin deposit. It is a sort of spinning step of the impregnated flocked support. The concentration of the impregnation bath is adjusted so as to deposit a very small amount of resin on the flocked supports, so as to maintain a soft and pleasant feel, but the amount of resin must be sufficient to allow subsequent printing, as explained below.

After the impregnation step, the impregnated flocked support is dried by passing through a heat treatment oven to evaporate the water contained in the treatment bath. Then, the product thus treated is rolled up and conditioned under conditions adequate to the nature of the support. In the case of paper or cardboard substrates, the moisture content of the packaging should be close to the media recovery rate. Finally, the product thus treated is cut into formats adapted to the desired types of printing, or in the form of small rolls of dimensions adapted to the different printing machines.

Alternatively, the treatment bath can be applied by coating by passing the flocked carrier between a cylinder and an applicator squeegee.

It is important to note that thanks to the presence of the resin in the flocks, the surface of the flocks is more regular substantially like paper or cardboard, which allows printing in the usual conditions of implementation, without particular adjustment. In particular, offset or flexographic or inkjet printing can be implemented because the presence of the resin in the flocks limits the absorption of the ink by the flocks. In addition, there is no longer a risk of free flocks becoming jammed in the parts of the printing machine because they are held on the support by the resin.

It should also be noted that it is preferable not to carry out a brushing or a cleaning of the flocked support after its treatment by the method of the invention.

Although the invention has been described in connection with particular embodiments, it is quite obvious that it is in no way limited and that it includes all the technical equivalents of the described means as well as their combinations which these enter into the scope of the invention.

Claims (9)

1. Process for treating the flocks of a flocked support, consisting in impregnating the flocks of the flocked support with a polymer resin and in drying the flocked support so impregnated, characterised in that impregnation is effected with a minimal quantity of polymer resin in the form of an emulsion in an aqueous bath, the said minimal quantity of resin being capable of fixing to the support any flocks which are loose and of restricting the penetration of inks into the flocks in the case of a possible subsequent printing stage.
2. Process according to claim 1, characterised in that the content of resin in the aqueous bath is advantageously between 2 and 12% by weight of dry matter, preferably between 6 and 7%.
3. Process according to claim 2, characterised in that it consists in impregnating the flocks with the said emulsion with a density of between 100 g/m² and 150 g/m².
4. Process according to one of claims 1 to 3, characterised in that it consists in depositing the resin in a wet medium on the flocks solely on the side of the support having the flocked surface, by any method such as wetting, impregnation, coating or pulverisation.
5. Process according to claim 4, characterised in that it consists, after impregnation of flocks with the resin in aqueous dispersion, in drying the flocked support so impregnated between two pressing cylinders in order to remove excess resin and to make the deposit of resin uniform.
6. Process according to one of claims 1 to 5, characterised in that the resin is a synthetic polymer resin selected from acrylic esters, synthetic rubbers and polyurethane polyesters, such that the flocked support so impregnated retains a soft, dry, non-adhesive feel.
7. Process according to one of claims 1 to 6, characterised in that the support is selected from paper, card, plastics, textile or non-woven supports.
8. Produce obtained by the process according to one of claims 1 to 7, characterised in that it comprises a flocked support whose flocks are impregnated with dry resin whose density is between 2 and 12g/m², preferably between 6 and 7 g/m².
9. Product according to claim 8, characterised in that the flocks impregnated with resin of the above-mentioned product are imprinted with multicoloured patterns, e.g. in four colours, by an offset, flexographic, or inkjet printing process or by the thermal application of a coloured or metallic film.