FR2581097A1 - Method and machine for manufacturing a support, such as coated cardboard or paper - Google Patents

Abstract

Method and machine for manufacturing a coated support from a conventional support. At least one varnish of the offset type 10, either loaded or non-loaded, is applied onto at least one face of the said support F, a powder of plastic heat-fusible material or a blowing agent or a pigment is deposited by spraying 12 onto the said varnish, and a physicochemical conversion of the varnish is effected 13 as well as a physical and/or chemical conversion of the powder or powders deposited in order to obtain a coating. Application: manufacture of coated cardboards and papers.

Description

METHOD AND MACHINE FOR MANUFACTURING A SUPPORT, SUCH AS
COATED PAPER OR CARDBOARD "
The subject of the invention is a method and a machine for manufacturing a coated support, the term support being understood here in the broad sense of a thin surface based on cellulose fibers, such as paper, cardboard or the like but also in the sense of homogeneous or non-homogeneous sheet of natural and / or synthetic fibers with or without the addition of plastic.

 The invention also applies to thin supports of the type known under the name of "non-woven" and which have, in certain embodiments, an appearance similar to that of paper.

 Printing media of the coated paper type currently exist in very many qualities and are manufactured industrially by numerous processes, one common characteristic of which is that of requiring machines and / or installations which are important for their implementation, so that such machines and / or installations are economically profitable only for the production of large series or large tonnages of a given type of coated paper. Indeed, any change in production generally implies the complete cleaning of the installation, - which can include machines several meters high, and several tens of meters long - then the adjustment of said machines to adapt them to the new product envisaged, so that the manufacture of low tonnages or small series is, not only! very difficult to achieve but also of a pro-ibitive cost.

 In addition, known machines or installations do not allow obtaining, in a simple manner, coated or tinted coated paper or cardboard.

 It is, in general, an object of the invention to provide a method and a machine for its implementation which overcome these drawbacks.

 It is also an object of the invention to provide a method and a machine for its implementation which make it possible, in a simple manner, to obtain supports such as coated paper or cardboard differing from one another by their hand, their color or any other aspect characteristic desired by modern printing, decor and / or packaging techniques.

 A method according to the invention, for the manufacture of a coated support, from a usual support, is characterized in that one applies, on at least one face of said support and advantageously by printing techniques offset, at least one varnish or the like of the offset type, loaded or unloaded, in that, where appropriate, a powder or a mixture of powders, such as a plastic powder, is deposited on said varnish or the like hot-melt, a swelling agent, a pigment, etc., in that it causes a physico-chemical transformation, for example, a polymerization of said charged or uncharged varnish or the like as well as a physical and / or chemical transformation of the or powders deposited for obtaining a coating, and in that one carries out, if necessary, a rolling of said deposit either during or after said physico-chemical transformation which can be carried out in one or more stages .

 The thickness of the layer of varnish or the like can be of the order of a few microns to ten microns.

 The fillers are included in a proportion ranging up to 25% by weight of the varnish.

 In an advantageous embodiment, the excess powder particles are removed by suction and / or blowing prior to the processing operations of the worm ni's and / or of the said powders.

 In one embodiment, the physico-chemical transformation of the varnish or the like is a polymerization or crosslinking which is carried out in two stages and the rolling or calendering of the deposit takes place following the two said stages.

 According to a preferred embodiment, the physico-chemical transformation of the varnish or the like, charged or uncharged, is carried out using infrared and / or ultra-violet radiation.

 These are the same means that are used for the physical and / or chemical transformation of the powder (s).

 In an advantageous embodiment, the product of varnish type or the like brought back by the techniques of offset printing on at least one face of the support is an acrylic polyester comprising oligomers, prepolymers and polymers, all of these constituents being crosslinkable UV radiation, with or without absorber or photo-initiator.

 In another embodiment, also advantageous, the product reported by the techniques of offset printing is an organosol, loaded or not loaded, that is to say a PVC solution, loaded or not loaded, more or less plasticized and stabilized in light and heat.

 In an embodiment using products of this type, the application of an organosol of 30 to 50% of dry extract is followed by two passages in ventilated ovens, the first intended to evaporate almost all of the solvents and the following to complete rendering the film-forming deposit.

 In such an embodiment, moreover, the rolling or timing step can be omitted.

 Using the process according to the invention, supports such as paper and / or cardboard and / or similar products are obtained which have, on at least one of their faces, a coating determined by the nature of the product fed by offset, that is to say by the carry-over process, the thickness of which can be determined at will by the density of the projection of the powders according to the wishes of the practice.

 The surface appearance is advantageously given by rolling or calendering.

 To this surface appearance also contribute the neutral ingredients added to the powders, such as talc, calcium carbonate, kaolin or the like present in a proportion ranging up to 50% by weight of said powders.

 Thus, such coated paper or cardboard can advantageously be used, apart from all the usual applications of printing, for obtaining forgery-proof documents, for example documents of an official nature, and this by micro-embossing or micro -mapping of the sleeping surface, the characteristics of which are then chosen to allow such intaglio printing.

 It is also possible, in this way, to obtain supports with areas of contrasting aspects as regards both color and relief, and / or the surface appearance (mat, eggshell, glazed, etc.).

The invention will be better understood from the description which follows, given by way of example and with reference to the appended drawing which shows
- In Figure 1, a diagram of a machine, according to the invention, for coating on paper, cardboard, or similar material;
- in Figure 2, a diagram, on a larger scale, of a part of the machine shown in Figure 1
- In Figure 3 a diagram similar to that of Figure 1 but for another machine;
- In Figure 4 a diagram similar to that of Figure 3 but for yet another machine.

 For the manufacture of a coated support, for example of paper or cardboard, the invention provides, in a first embodiment, a machine as shown in FIGS. 1 and 2.

 In such a machine, an offset block 10 receives the sheet of paper or cardboard F, glued on one of its two faces - and which comes from a size-press type gluing device 11, itself supplied as shown by arrow P in Figure 1 from a reel of paper, cardboard or the like.

 In the offset block 10, the sheet F is covered on at least one of its faces with a product capable of undergoing a physico-chemical transformation, as will be explained below, and which is advantageously of the offset varnish or organosol type. At the exit of block 10, the sheet of paper, cardboard or the like coated on at least one of its faces of said product, passes through a device 12 in which one or a plurality of powders are deposited on said product, and advantageously by projection .

These are chosen from plastic powders of the type
- Polyvinyl acetate obtained directly by grinding the resin or by dehydration of a polyvinyl acetate latex, that is to say having a particle size between 50 and 3 F,
- Polyvinyl acetochloride modified or not using products such as maleic anhydride
- Polyvinyl butyral
- Polyacrylic resins or acrylic copolymers obtained by dehydration of their latexes
- Polyvinylidene (vinyl-vinylidene) or (acrylonitrile-vinylidene) copolymers, for example of the type obtained directly or by dehydration of their latexes
- Ethylene-vinyl-acetate copolymers (EVA)
- Mixtures of an EVA resin of the above type with rosin derivatives or any aliphatic or aromatic resin comprising more or less significant additions of waxes of different molecular weights, ie mixtures of products known under the name "Hot dishes, the said products then being reduced to powder by grinding carried out under conditions such as, in particular at low temperature, that any effect of sticking or solidification is avoided so that they can then be projected into a machine according to the invention or being able to use them for the implementation of the method according to the invention.

 The powders can also comprise blowing agents, pure or in mixture, pigments, etc., intended to give the support a coating with predetermined characteristics, for example matt, shiny, eggshell, etc.

 Neutral ingredients such as talc, calcium carbonate, kaolin or the like can be added to the powders in an amount of up to 50% by weight thereof.

 The physico-chemical transformation of the loaded or unloaded product with which at least one of the faces of the support is coated as well as the physical and / or chemical transformation of the powder (s) takes place in a device 13 which follows on from the device 12.

 The device 13 is, for example, a tunnel oven provided with infrared and / or UV ramps 14 which, by the radiation they emit, cause the desired physicochemical transformation, for example polymerization or crosslinking in the case a product of the varnish type and / or a fusion in the case of deposits comprising powders of hot-melt plastic.

 At the outlet of the device 13, the support coated with its coating is, in the case of a continuous installation, stored on a coil 15 after possible passage in a cooling device 17, most simply a ventilated air device.

 According to the invention, one also proceeds to an operation of calendering, or laminating of the coating. As shown in FIG. 2, this rolling is advantageously carried out by a roller device 16, which is housed in the tunnel oven 13, or at the outlet thereof, the ramps 14 being divided into a first bundle of ramps 14a, for example UV lamps ensuring the polymerization or crosslinking of the offset varnish layer, while the ramps 14b, for example infrared radiation lamps arranged upstream of the device 16 in the direction of movement of the sheet, ensure the transformation physical or gelation of plastic powders before rolling by rollers 16.

 In a variant, not shown, the radiation devices 14a and 14b are constituted as separate assemblies, advantageously provided with means allowing their movement, for example in the form of oven-tunnels mounted on wheels so that the spatial arrangement of the two devices relative to each other and relative to device 12 can be changed at will.

 The manufacture of a coated support using the machine as described above is thus extremely simple, so that one can envisage the manufacture of small or medium series, for example such low tonnages. only 2 tonnes, by modifying only the products brought by transfer in the block 10, and / or those deposited by projection in the device 12, and / or the irradiation in the device 13 or the scheduling conditions through the device 16 .

 The method according to the invention makes it possible to obtain paper, cardboard or the like coated in full width had this by xeprise the base support, itself manufactured at very high speed on conventional machines with very wide width.

 By an appropriate choice of the deposited product (s), and of the processing characteristics, as explained above, the coating can be glossy or matt, lightly or very loaded, hard or flexible, and this for obtaining the desired hand.

 The offset block 10 can be arranged for the transfer, on the front of a support, of a multiplicity of varnishes intended to supply. a "shaped" coating and, for the transfer onto the back of said support, of a single varnish intended to form a single-color background.

 The paper used, in the case of coated paper, can be of very low grammage, of the order of 60 g per m2, and the coatings deposited of the order of 10 to 30 g / m2.

 It is also possible, according to the invention, to choose the characteristics of the calendaring operation in such a way that the regularity of the desired surface condition is obtained by modifying, for example, the temperature and pressure characteristics of the rollers. calendar.

 It is also possible, in an alternative embodiment, to simultaneously conduct the coating, as described above, and an impression on the uncoated face of the support, by the addition, in block 10, of the usual blankets of offset printer.

 An appropriate choice of the add-on product, the physico-chemical transformation technique and the timing even makes it possible to obtain supports such as coated papers or cardboards having the appearance of "luxury" coated sheets without having to use the machines. complex and high pressure usually required to obtain this type of surfacing.

 In the machine illustrated in FIG. 3, provision is made to organize the offset block 10 in such a way as to bring to the glued paper obtained from size-press11 at least two varnishes of different families, the first of which is capable of being quickly crosslinked by ultraviolet radiation, and which acts like a sealer.

In such an installation, the offset block 10 is then followed by a tunnel with ultraviolet radiation 20 and then optionally by a first tunnel with infrared radiation 22 in which a pre-po-polymerization or pre-crosslinking of the second deposited varnish is carried out. on the sheet F in the block 10, when the temperature reached at the station 20 is insufficient, the device 22 being followed, in the direction of travel of the sheet, by the device 12 for depositing powder (s), the device 13 to infrared radiation which contains the timing means 16 and, finally, a cooling device 25 intended to bring the treated support to room temperature.

 In the installation illustrated in FIG. 4, the offset block 10 is followed by an ultraviolet radiation tunnel 20 where the physicochemical transformation is carried out of a first varnish acting as an anchor sealer, this device 20 being followed by the powder deposition device (s) 12, followed by an infrared device 22 ′ similar to device 22 of the previous embodiment, then device 13, then calendaring means 16.

 Although the method and the coating machine according to the invention have been described above with reference to paper, it is understood that the invention is in no way limited to such a support.

 On the contrary, it is permissible, by the method and the machine of the invention, to treat supports such as cardboard or thin supports of "non-woven", or the like.

EXAMPLE
Excellent quality coated papers were obtained using as starting material a paper as produced from a usual uncoated paper machine, weighing 300 g / m 2 and produced by the Aussedat Rey Company for its graphic layers.

 In a first embodiment, the offset varnish used is that sold by the SICPA Company under the name Vernis 949.

In another embodiment, the offset varnish is that sold by the same SICPA Company under the names of
Varnish 965 or Varnish 971.

 The thickness of the varnish layer is of the order of 8 to 10.

 The fillers are in a proportion of the order of 20% -25% by weight of the offset varnish and the powders advantageously comprise up to 50% by weight of neutral ingredients such as talc, calcium carbonate, kaolin or the like .

Claims (16)

Claims  1. Method for the production of a coated support, from a usual support, characterized in that at least one varnish is applied to at least one face of said support and advantageously by offset printing techniques or the like of the offset type, loaded or unloaded, in that, if necessary, a powder or a mixture of powders, such as a hot melt plastic powder, a blowing agent, is deposited on said varnish or the like, a pigment or the like, in that it causes a physicochemical transformation, such as the polymerization of said varnish or similar, loaded or uncharged, as well as a physical and / or chemical transformation of the powder or powders deposited for obtaining a coating, in that one carries out, where appropriate, rolling said deposit either during or after said physico-chemical transformation which can be carried out in one or more stages.  2. Method according to claim 1, characterized in that the excess powder particles are removed by blowing and / or suction prior to the processing operations of the varnish and / or of the powders.  3. Method according to claim 1, characterized in that the physicochemical transformation of the varnish or the like is a polymerization or crosslinking which is carried out in two stages and in that the rolling or calendering of the deposit takes place following the two say steps.  4. Method according to claim 1, characterized in that a plurality of varnishes or the like are applied to at least one face of the support, one of which is intended to form a product of the sealer type.  5. Method according to any one of the preceding claims, characterized in that, simultaneously with the coating of one side, a color offset printing is transferred to the other side.  6. Method according to any one of the preceding claims, characterized in that the varnish is of the acrylated polyester type comprising oligomers, prepolymers and polymers crosslinkable to ultraviolet radiation, with or without absorber or photo-initiator.  7. Method according to claim 6, characterized in that the irradiation further comprises the use of infrared radiation.  8. Method according to any one of the preceding claims, characterized in that the powders are chosen from blowing agents, pure or mixed, pigments, or powders of plastic materials of the type  - Polyvinyl acetate obtained directly by grinding the resin or by dehydration of a polyvinyl acetate latex, that is to say having a particle size between 50 and 3  - Polyvinyl acetochloride modified or not using products such as maleic anhydride  - Polyvinyl butyral;  - Polyacrylic resins or acrylic copolymers obtained  naked by dehydration of their latex  - Polyvinylidene (vinyl-vinylidene) copolymers or  (acrylonitrile-vinylidene) obtained directly or by  dehydration of their latex  - Ethylene-vinyl-acetate copolymers (EVA); and  - "hot melt" type mixtures reduced to powder by  grinding.  9. Method according to any one of the preceding claims, characterized in that the fillers represent at most of the order of 25% by weight of the varnish or the like.  10. Method according to claim 9, characterized in that said powders comprise up to 50% by weight of inert products such as talc, calcium carbonate, kaolin or the like.  11. Method according to any one of the preceding claims, characterized in that the product similar to a varnish and reported by offset is an organosol, loaded or uncharged.  12. Method according to claim 11, characterized in that the organosol is 30-50% of dry extract.  13. Machine for implementing the method according to any one of the preceding claims, characterized in that it comprises an offset block (10) supplied with a product such as a varnish, an organosol or the like intended to be applied by the offset printing techniques on at least one face of said support (F), a device (12) for depositing, advantageously by spraying, a powder or a mixture of powders on said varnish, a device (13) suitable for cause a physico-chemical transformation of the varnish or the like as well as a physical and / or chemical transformation of the powder (s), such as a tunnel with ultraviolet and / or infrared radiation as well as means (16) of rolling or filing schedule.  14. Machine according to claim 13, characterized in that it further comprises a cooling device (17,25) at its outlet end from the coated support.  15. Machine according to claim 13, characterized in that the means which cause the physico-chemical, physical or chemical transformations are in two parts, one (20) disposed before the means (12) for depositing the powders and the other (13,22) after said means, in the direction of travel of the support.  16. Machine according to claim 15, characterized in that said means are organized in a modular manner and so that they can be easily moved.