The present invention relates to a method for inkjet printing a silicone-based composition onto a textile substrate, and to an inkjet printing system for carrying out such a method.
The field of the invention is that of the manufacture of textile articles comprising one or more zones coated with a material comprising one or more silicone polymers, the material preferably being intended to come into contact with the skin.
By way of non-limiting examples, the invention makes it possible to manufacture textile articles of the compression and/or support device type, medical compression orthosis type, town everyday stocking type, sports pantyhose type (compression or not), comfort compression pantyhose type, etc.
To apply a composition to a textile substrate, a conventional method is coating. Coating consists of covering the textile substrate with a layer of polymer, in particular a layer of polyvinyl chloride (PVC), polyurethane (PU), or in fact silicone, for example.
When silicone is used, the textile substrate is coated with a curable silicone composition in order to form solid silicone coatings. The silicone composition conventionally comprises a silicone polymer, for example polydimethylsiloxane (PDMS), a cross-linking agent, and optionally a catalyst. When the composition is applied to the surface of the textile substrate, cross-linking of the silicone polymer occurs (polyaddition or polycondensation), resulting in the formation of a cross-linked silicone material.
The silicone composition may be of the one-component or two-component type. In the case of a two-component silicone composition, the latter typically comprises a first component comprising a silicone polymer, and a second component comprising a cross-linking agent which makes it possible to initiate cross-linking of the polymer, and optionally a catalyst. The first component may also be termed a resin. Cross-linking is only possible when the two components are mixed together. In the case of a one-component silicone composition, the silicone polymer and the cross-linking agent are contained in a single component, and the cross-linking is initiated when said component is sprayed onto the textile substrate, by contact with air or by heating to a high temperature.
However, the coating method suffers from disadvantages.
One of these disadvantages is that this method is not suitable for producing precise and relatively complex patterns produced on predetermined zones of the textile substrate. In fact, the zones of the textile substrate covered with the silicone composition are generally wide and coarse, and are typically in the form of bands. The production of patterns such as geometric figures of the circular, round or square type, for example, or indeed of more complex patterns or representations is limited with this method, in particular the coating of shapes or dots of the order of a micron.
Another method exists for applying a silicone-based composition to a textile substrate. This is inkjet printing. The expression “inkjet printing” is generic, insofar as the printing is not limited to an ink per se, but can also be used to print other materials such as silicone, for example.
As is the case with inkjet printing, the silicone-based composition is sprayed onto the textile substrate in the form of droplets.
Examples of systems for printing silicone onto a textile substrate are known from documents CH 678867 and KR 20060094607.
The systems described in those documents comprise a print head provided with a single row of nozzles, which limits the printing speed and therefore the productivity. In fact, a single row of nozzles imposes a slower speed of travel of the textile in order to allow optimized coverage of the material. In order to increase productivity, accelerating the spraying speed of the composition would require the print nozzles to be subjected to greater stresses, accelerating their wear.
The objective of the present invention is to overcome the disadvantages of the prior art.
In particular, the aim of the invention is to provide a method for inkjet printing a two-component silicone-based composition.
The invention also aims to provide a printing method of this type, making it possible to increase the rate of production of the printed textiles, in particular in order to obtain a rate of production which is similar to or at least close to that for coating.
To this end, the invention concerns a method for inkjet printing a two-component silicone-based composition onto a textile substrate, said composition comprising a first component comprising at least one silicone polymer and a second component comprising at least one cross-linking agent, the method comprising the following steps:
The method in accordance with the invention makes it possible to print a pattern onto a textile substrate, this pattern comprising a cross-linked silicone polymer derived from a two-component composition.
In accordance with other advantageous characterizing features of the invention, taken individually or in combination:
The invention also pertains to a printing system for inkjet printing a two-component silicone-based composition onto a textile substrate, said composition comprising a first component comprising at least one silicone polymer and a second component comprising at least one cross-linking agent, the printing system comprising at least one print head itself comprising at least one print nozzle, said print nozzle comprising two outlet orifices, including a first outlet orifice which is capable of spraying the first component, and a second outlet orifice which is capable of spraying the second component, and means for relative displacement between the print head and the textile substrate.
By virtue of the presence of two distinct outlet orifices for spraying the first component and the second component respectively onto the textile substrate, the silicone polymer is prevented from cross-linking in the print nozzle, or at least in the printing system, i.e. before being sprayed onto the textile substrate in the form of droplets. This makes it possible to avoid degradation of the printing system, or even of rendering the printing system inoperative and making printing impossible.
It should be noted that when the printing system comprises several print nozzles, one or more of them may comprise two outlet orifices as described above, and one or more of them may comprise a single outlet orifice.
Advantageously, the printing system may be used for inkjet printing a two-component composition, but also for inkjet printing a one-component composition, and in fact using the same print nozzles.
In accordance with other advantageous characterizing features of the invention, taken individually or in combination:
The invention also pertains to the use of a printing system as described above for inkjet printing a one-component silicone-based composition and/or a two-component silicone-based composition.
The invention will be better understood from the following description which is given solely by way of non-limiting example and is made with reference to the accompanying drawings, in which:
The subject matter of the invention is a method for inkjet printing a silicone-based composition onto a textile substrate. The silicone composition is two-component, i.e. it comprises two components intended to be mixed with each other when printing a pattern onto the textile substrate.
The method employs a printing system. For the purposes of simplification, the printing method and the printing system will be described at the same time in the remainder of the present text.
With reference to
The method comprises a step for spraying the first component and the second component onto the textile substrate 3 via the print nozzles 12 of the printing system 1.
The term “silicone-based composition” is used to mean a composition comprising one or more silicone polymers. A silicone polymer, also known as a silicone elastomer, is composed of silicon-oxygen Si—O chains comprising chemical functions bonded to silicon atoms.
When the silicone polymer is sprayed from the print nozzle toward the textile substrate, said polymer cross-links to form a printed pattern on said textile substrate. Cross-linking corresponds to the formation of one or more three-dimensional networks, by chemical or physical means. During cross-linking, chemical bonds, known as bridges, are created between the macromolecular chains of silicone polymer. Cross-linking may occur at the outlet from the print nozzle, before the composition comes into contact with the textile substrate, or when the composition comes into contact with the textile substrate. Cross-linking may occur by polyaddition or by polycondensation.
As indicated above, the silicone-based composition is a two-component composition. A first component comprises at least one silicone polymer, and a second component comprises a cross-linking agent.
The cross-linking agent is capable of initiating cross-linking of the silicone polymer when it comes into contact therewith, i.e. when the first component and the second component are mixed. Mixing of the two components may occur before the components come into contact with the textile substrate, or when the components contact the textile substrate. Preferably, the silicone-based composition comprises at least 50% by weight of silicone polymer with respect to the total weight of the composition, and more preferably at least 70%. The weight of the composition corresponds to the sum of the weight of the first component and the weight of the second component.
The silicone polymer is advantageously compatible with skin, i.e. it is suitable for contact. This means that the silicone polymer does not present any biological or toxicological risk when in contact with the skin and does not cause a skin reaction.
In practice, the thickness of the silicone layer is preferably in the range 0.1 mm to 2 mm.
The textile substrate is preferably a device or a compression and/or support article for the lower limbs or the upper limbs of the human body. The method of the invention thus makes it possible to print patterns or representations, optionally of complex shape, onto devices or articles intended to treat a patient, in particular for lymphoedema.
The textile substrate may, for example, comprise footwear (socks, hold-up stockings, for example) and non-footwear of the adjustable compression or support article type (elastic and inelastic), as well as armsleeve, or gloves.
The textile substrate may in particular be of the knitted, woven, lace or non-woven type.
The system 1 comprises one or more print heads 10 and means 20 for relative displacement between the print head(s) 10 and the textile substrate 3. A plurality of print heads 10 may be designated as a print head array.
Each print head 10 comprises at least one print nozzle 12, making it possible to spray the silicone-based composition onto a specific zone 4 of the textile substrate 3.
Preferably, the printing system 1 is suitable for printing both a two-component composition and a one-component composition.
In the case of inkjet printing a one-component silicone-based composition, the polymer and the cross-linking agent are contained in the same component. The polymer may be cold-cross-linkable or hot-cross-linkable.
For a cold-cross-linkable single-component silicone polymer, cross-linking is initiated by the moisture in the air, i.e. when the composition is expelled from the print nozzle and comes into contact with the ambient air. For a single-component silicone polymer which can be cross-linked when hot, the composition is first sprayed onto the textile substrate 3, then the temperature is increased until cross-linking is initiated, preferably to a temperature in the range 90° C. to 200° C. at atmospheric pressure. The cross-linking temperature obviously depends on the nature of the silicone polymer.
Preferably, each print head 10 comprises a plurality of print nozzles 12. The print nozzles are preferably disposed in a plurality of rows of nozzles 12. A row of print nozzles 12 comprises a minimum of two print nozzles.
Preferably, the rows 11 of print nozzles 12 form a rectangular matrix 13, 14, consisting of mutually parallel rows 13 and mutually parallel columns 14 which are perpendicular to the rows 13.
In accordance with an optional variation, the print head 10 may comprise several rows 11 of print nozzles 12 which are parallel to one another but offset with respect to one another, such that the nozzles 12 are disposed in a honeycomb arrangement.
In accordance with one embodiment, the printing system 1 comprises at least one first print nozzle 12a which is capable of spraying the first component, and at least one second print nozzle 12b which is capable of spraying the second component of the two-component silicone-based composition onto the textile substrate 3.
Preferably, the first print nozzle 12a and the second print nozzle 12b belong to the same print head 10, as illustrated in
This is advantageous when the printing system is used for printing a one-component silicone composition, since the rate of production is improved. When the two-component silicone composition is used, in addition to an improvement in production, the silicone polymer is prevented from cross-linking in the print nozzles, or at least in the printing system, i.e. before arriving on the textile substrate. This makes it possible to prevent degradation of the printing system, or even of rendering the printing system inoperative and making printing impossible.
In accordance with an embodiment shown in
The first outlet orifice 15a and the second outlet orifice 15b may be concentric, as shown in
As regards the displacement means 20, these may include a mechanism 30 for translation of the print head 10.
In accordance with a preferred embodiment, the translation mechanism 30 is configured to carry out transverse and/or longitudinal translation of the print head 10 allowing, for example, flexible material 2 to be sprayed in the form of oblique bands.
In accordance with an optional variation, the displacement means 20 may comprise a mechanism for rotating or tilting the print head 10.
In accordance with another variation, the print head 10 may be fixed within the system 1.
Furthermore, the displacement means 20 comprise a mechanism 40 for moving the textile substrate 3 beneath the print head 10, in a translational and/or rotational movement.
The running mechanism 40 comprises two rotating rollers 41 and a support 42 driven by the rollers 41 and designed to receive the textile substrate 3.
In the example of
Other running mechanisms 40 may of course be envisaged without departing from the scope of the invention, as illustrated in
Advantageously, the system 1 may comprise a device 60 for controlling the quantity of flexible material 2 sprayed at each jet. The piloting device 60 may be configured to control the quantity of silicone-based composition 2 individually sprayed from each nozzle.
Moreover, in operation, all of the print nozzles 12 can spray the silicone composition simultaneously, or in fact only certain nozzles 12 can spray the silicone composition simultaneously.
The use of this control device 60 therefore allows for uniform coverage of an extensive zone 4 of the textile substrate 3 produced from flexible material 2 if the device 60 is configured so that all of the nozzles 12 spray flexible material 2 simultaneously.
Uniform coverage is also possible thanks to this control device 60, by controlling the quantity of silicone-based composition 2 sprayed by the print nozzles 12 even if only certain nozzles 12 spray said composition 2.
On the other hand, if the device 60 allows only certain nozzles 12 to spray silicone-based composition, partial coverage of the textile substrate 3 by said composition is possible, in particular in the form of patterns.
Optionally, the system 1 may include a device 70 for controlling the spacing between the print nozzles 12. This control device 70 makes it possible, inter alia, to increase the coated zone of the textile substrate 3 or alternatively to print the textile substrate 3 by spraying a matrix of dots of silicone-based composition.
In practice, a matrix of dots of silicone-based composition 2, as illustrated in
Other embodiments of a printing system 1 in accordance with the invention are shown in
The running mechanism 40 comprises two rotating rollers 43 provided respectively for unwinding and winding the textile substrate 3, two longitudinal guide rods 44 and a lateral guide plate 45.
More precisely, the two rollers 43 comprise an upstream roller 43 for unwinding and a downstream roller 43 for winding the textile substrate 3 in the form of a wide textile web.
This textile web runs in a flat manner under the print head 10, between the guide rods 44.
Thus, the guide rods 44 and the lateral guide plate 45 make it possible to guide the textile web longitudinally and laterally, from the upstream roller 43 to the downstream roller 43, while receiving a coating of flexible material 2 when the textile web travels between the rods 44.
The running mechanism 40 comprises a rotating base 46 and at least two rollers 47 rotatably mounted on the base 46 and each designed to receive a textile substrate 3.
The base 46 is movable in rotation about its central axis. The base 46 comprises three branches 48 and three rods 49 fixed to the ends of the branches 48. The branches 48 extend radially with respect to the central axis, while the rods 49 extend parallel to the central axis. The rollers 47 are hollow and rotatably mounted on the rods 49.
Alternatively, the base 46 may have any shape which is suitable for supporting a plurality of rollers 47, for example two or four rollers 47 rotatably mounted on the rods 49 of the base 46.
The textile articles 5 are of the support stocking type 6, comprising an upper edge 7 provided with an opening for insertion of the leg.
Each upper edge is provided with a textile substrate 3 on which a pattern is printed, the material of which being based on a cross-linked silicone polymer. For the purposes of simplification, the pattern produced from a material based on a cross-linked silicone polymer bears the same legend “2” as the silicone-based composition from which it is derived.
In accordance with a first embodiment, the textile substrate 3 is in the form of a strip attached to the stocking 6. In a second embodiment, the textile substrate 3 is constituted directly by the top edge 7 of the stocking 6, covered with the pattern 2 by virtue of the printing system 1.
In
In
In
In
In accordance with a preferred embodiment illustrated in
Preferably, an array 100 of print heads 10 forms a rectangular matrix comprising approximately twenty print heads in length and approximately ten print heads in width. The print heads 10 each preferably have a height of 10 cm, a width of 5 cm and a length of 5 cm, thus forming an array of 200 print heads having a length of 1 metre and a width of 50 cm.
In practice, the print heads 10 have a height which is preferably in the range 1 cm to 20 cm, a length which is preferably in the range 1 cm to 5 cm, and a width which is preferably in the range 1 cm to 5 cm. Each print head 10 comprises at least one print nozzle 12 which is preferably cylindrical in shape and provided with an outlet orifice 15. The print nozzle preferably has a diameter in the range 0.5 cm to 3 cm, and the outlet orifice 15 preferably has a diameter in the range 0.1 mm to 0.9 mm.
The printing system 1 may also comprise a device for controlling the quantity of silicone-based composition sprayed by the print heads 10 of each array 100, or in fact a device for controlling the spacing between the print heads 10 of an array 100.
Moreover, the printing system 1 and articles 5 may be configured differently from
Number | Date | Country | Kind |
---|---|---|---|
FR1906202 | Jun 2019 | FR | national |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/EP2020/066237 | 6/11/2020 | WO |