[0001] This invention is within the field of three- dimensional (" 3D" ) printing on a textile article .

[0002] More speci fically, this invention relates to a method for 3D printing directly onto a fabric substrate , such as a woven textile for clothing, a fabric sample , fabric footwear, or the like .

[0003] Methods for 3D printing of thermoplastic material directly onto textile substrates are known in the art , for example , for 3D printing directly onto footwear or wearable articles .

[0004] However, known printing techniques suf fer from certain issues related to the adhesion of the thermoplastic material to the fabric and the reliability of that adhesion over time .

[0005] In particular, the known techniques of 3D printing directly onto fabric do not allow for obtaining prints that are able to adequately resist any mechanical stress , especially i f repeated over time , as in the case of frequent washing .

[0006] Moreover, inconveniently, known 3D printing techniques often have aesthetic flaws caused by the typical operation of printing machines , resulting in poor applicability in the case of high-quality or high- fashion garments .

[0007] The obj ect of this invention is to create a method of three-dimensional printing of a thermoplastic material directly onto fabric that overcomes the drawbacks mentioned above , but at the same time provides the same advantages as 3D printing systems of the prior art .

[0008] Said obj ect is achieved by a method for three- dimensional printing of a thermoplastic material directly onto and by means of a fabric according to the attached independent claims ; the claims dependent thereon describe preferred variant embodiments .

[0009] The features and advantages of the method for three- dimensional printing of a thermoplastic material directly onto fabric and of the fabric according to this invention will be apparent from the description provided hereinafter, given by way of non-limiting example according to the appended figures , wherein :

[0010] - Fig . 1 is a block diagram of the steps of a method of three-dimensional printing of a thermoplastic material directly onto fabric according to an embodiment of this invention;

[0011] - Fig . 2 is a perspective cross-sectional view of a 3D printing noz zle in a stage of printing a first layer onto a fabric, in accordance with an embodiment according to this invention;

[0012] - Fig . 3 is an enlarged detail of Fig . 2 ;

[0013] - Fig . 4 is a 3D reconstruction of a digital representation of the printing surface according to an embodiment of this invention;

[0014] - Fig . 5 shows a fabric with a printed portion according to an embodiment of this invention;

[0015] - Fig . 6 shows a preliminary printing path for a printing noz zle to obtain a printed portion on a fabric, according to an embodiment of this invention;

[0016] - Fig . 7 shows a printed portion, printed directly onto fabric, according to an embodiment of this invention, from a preliminary printing path in Fig . 6 ;

[0017] - Fig . 8 shows a printed portion, printed directly onto fabric, according to an embodiment of this invention, forming a tubular structure within which a thread is run;

[0018] - Fig . 9 shows a printed portion, printed directly onto fabric, according to an embodiment of this invention, forming a plurality of tubular structures ;

[0019] - Fig . 10 shows a front cross-sectional view of a printed portion with a tubular structure according to an embodiment of this invention;

[0020] - Fig . 11 shows a front cross-sectional view of a printed portion with a tubular structure according to a further embodiment of this invention.

[0021] According to this invention, the method and fabric described below are intended to be made by 3D printing directly onto any surface of a fabric, without the need for a layer of material interposed between the fabric and without the need for a perfectly flat surface on which to print .

[0022] Additionally, the term "fabric" in this discussion may be used to refer generally to a material selected from the group consisting of any natural fabric, synthetic fabric, knit, woven material, non-woven material, mesh, leather, synthetic leather, woven polymers .

[0023] Additionally, the described embodiments are described in the context of a generic fabric but may also be likewise applied to any article of clothing that includes 3D printing.

[0024] For example, the described embodiments may be applied to hats, caps, shirts, sweaters, jackets, socks, shorts, pants, undergarments, athletic support garments, gloves, wrist/arm bands, sleeves, head bands, any knit material, any woven material, any non-woven material, sports equipment, etc.

[0025] Referring to the attached figures, the method of three-dimensional printing of a thermoplastic material M directly onto a fabric T comprises the initial steps of : [0026] a ) preparing 10 the fabric T on a printing plane P ;

[0027] b ) heating 20 the fabric T to a reference temperature ;

[0028] c ) heating 40 a dispensing noz zle 2 with a thermoplastic printing material M to a predefined noz zle temperature .

[0029] In particular, according to the invention, the method comprises the steps of :

[0030] d) after step a ) , sampling 30 the fabric directly or indirectly and recording a plurality of surface points 3 of a printing surface 4 of the fabric T to obtain a digital representation 4 ' of the printing surface immediately prior to beginning printing;

[0031] e ) defining a printing path 5 to be traveled by the dispensing noz zle 2 according to processing of the plurality of surface points 3 recorded in step d) ;

[0032] f ) moving 60 the dispensing noz zle 2 according to the printing path 5 defined in step d) in such a way that the dispensing noz zle 2 maintains a substantially constant height Q relative to the printing surface 4 and, simultaneously, dispensing the thermoplastic printing material M from the dispensing noz zle 2 directly onto the fabric T to deposit the first layer 51 of thermoplastic printing material . [0033] Preferably, step e ) comprises the step of calculating a preliminary printing path 5 ' to print on the printing plane P or on a perfectly planar virtual fabric having a predefined thickness , for example a thickness between 0 . 01 and 0 . 3 millimeters . Moreover, preferably, step e ) comprises calculating the height deviation dQ of each point of the plurality of surface points 3 with respect to the printing plane P or the virtual fabric along a vertical direction V perpendicular to the printing plane P or the virtual fabric . Subsequently, the method provides for correcting the preliminary printing path 5 ' by processing this height deviation dQ to obtain the printing path 5 . In accordance with a preferred variant embodiment , the method comprises the step of obtaining a digital representation 4 ' of the printing surface 4 by means of three-dimensional interpolation of the plurality of surface points 3 . In this variant , step e ) comprises the step of calculating a preliminary printing path to print on the printing plane P or on a virtual fabric and subsequently calculating a height deviation dQ for each point of a plurality of digital surface points 3 of the digital representation 4 ' of the printing surface relative to the printing plane P or the virtual fabric along a vertical direction V perpendicular to the printing plane P or to the virtual fabric . Moreover, the method provides for correcting the preliminary printing path by processing said height deviation dQ to obtain the printing path 5 .

[0034] This ensures a suitable and strong adhesion between the first layer of the thermoplastic printing material and the fabric, precisely because of the compensation of the non-planarities of the fabric .

[0035] Preferably, the processing of the height deviation dQ is the algebraic sum of said height to the vertical coordinate that the dispensing noz zle 2 would have to travel as planned in the preliminary path, i . e . , i f the correction were not applied .

[0036] According to an embodiment of the invention, prior to step f ) , the method comprises the steps of :

[0037] el ) extruding 50 a predetermined quantity of thermoplastic printing material M, and subsequently retracting 50 a second predetermined quantity of thermoplastic printing material so as to reduce the ris k of thermoplastic material escaping from the noz zle ;

[0038] e2 ) next , moving the dispensing noz zle 2 from its rest position to a start of printing position on the printing path 5 and extruding a quantity of thermoplastic material M equal to the second predefined quantity of thermoplastic printing material of step el ) , so as to recover the retraction of step el ) and fill the cavity of the dispensing nozzle 2.

[0039] According to a particularly advantageous embodiment, in step e) the thermoplastic printing material M is a thermoplastic polyurethane (TPU) and the predefined nozzle temperature is at least equal to 230°C or higher, preferably higher than 233°C. Surprisingly, this ensures the material adheres adequately to the printing surface, even over time.

[0040] In an even more advantageous variant embodiment, the thermoplastic printing material is a thermoplastic polyurethane, wherein the predefined nozzle temperature is at least equal to 230°C or higher, and the fabric T is heated to a reference temperature at least equal to 70°C or higher. This ensures an even better adhesion between thermoplastic and fabric.

[0041] According to an embodiment, the reference temperature is between 40°C and 100°C, preferably between 70°C and 90°C.

[0042] According to an embodiment, the predefined nozzle temperature is between 190°C and 260°C, preferably between 220°C and 240°C.

[0043] According to an embodiment, the predetermined quantity of thermoplastic printing material M and/or the second predetermined quantity of thermoplastic material is a quantity between 0.1 grams and 5 grams. [0044] Preferably, during the movement of the dispensing noz zle 2 in step f ) , the movement speed of the dispensing noz zle 2 is between 100 mm/min and 130 mm/min, preferably about 120 mm/min .

[0045] Particularly advantageously, in step f ) , the dispensing noz zle 2 preferably maintains a constant or substantially constant height Q relative to the printing surface 4 and less than 0 . 1 millimeters . This ensures an adequate spreading of the thermoplastic printing material on the fabric and, consequently, an improved adhesion, even more so due to the synergic correction of the noz zle height with respect to the fabric .

[0046] Preferably, a substantially constant height Q means a height Q with a variability from an average height value of at most about 0 . 05 millimeters .

[0047] According to a variant embodiment of the invention, after depositing the first layer 51 of thermoplastic printing material directly in contact with the fabric, the dispensing noz zle 2 is moved to deposit 70 the additional layers 52 on top of the first layer 51 , and the temperature of the dispensing noz zle 2 is adj usted to follow a decreasing temperature gradient as the dispensing noz zle moves away from the printing surface 4 , i . e . , as a function of the progressive number of layers added, until a predetermined working temperature is reached . Preferably, the predetermined working temperature is lower than the predetermined noz zle temperature .

[0048] Furthermore , preferably, in step f ) , the method provides for dispensing a first layer 51 of thermoplastic printing material by depositing material along a single line , i . e . , a single extrusion and a single noz zle pass . Additionally, the method provides for the step of dispensing successive layers 52 of thermoplastic material M exclusively over the first layer 51 and exclusively on a single line , so as to form a single-line , ribbon-like structure that is developed in its vertical dimension H in a direction perpendicular to the printing surface 4 , as for example shown in Fig . 6 and 7 .

[0049] In this variant , due to an adequate adhesion of the first layer by means of the method described above , the correct adhesion of the ribbon-like structure as a whole is also ensured .

[0050] According to a further aspect , it is apparent that this invention is also aimed at a fabric T comprising a printed portion 6 made of thermoplastic material directly printed onto the fabric T , preferably according to the method described in the preceding paragraphs .

[0051] Preferably, the printed portion 6 comprises a plurality of layers 51 , 52 overlaid in a single line . In other words, preferably each layer 51, 52 provides for only one passage of the dispensing nozzle 2 for a given height along the vertical direction V.

[0052] Furthermore, preferably, the fabric T is totally free of a region comprising rafts, skirts, or brims.

[0053] Preferably, the single-line, ribbon-like structure runs along the printing path 5 parallel to the printing plane P from an initial end 510 to a final end 520. Furthermore, in its vertical dimension H in the vertical direction V perpendicular to the printing surface, i.e., in height, the ribbon-like structure has an increasing height H from the initial end 510 to the final end 520.

[0054] According to a preferred variant embodiment, the printing path 5 is a spiral path, as for example shown in Fig . 6 and 7.

[0055] According to a further variant embodiment, the printing path 5 has an auxetic shape, as for example shown in Fig. 5.

[0056] According to a variant embodiment of this invention, the printed portion 6 comprises a plurality of layers 51, 52 overlaid in single lines and forming a tubular structure 61, for example as shown in Fig. 8 through 11.

[0057] According to this invention, the tubular structure 61, comprises an internal tubular cavity 610 that is hollow, i.e., free of additional support elements. In particular, the tubular structure 61 is exclusively and directly formed by the plurality of layers 51, 52 overlaid in a single line, without any further support either when the printing is completed or when the printing is in progress. In other words, the arch 611 of the tubular structure 61 is self-supporting and consists solely of a plurality of single-line, overlapping layers, i.e., a single passage of the dispensing nozzle for each height Q.

[0058] Preferably, the tubular structure 61 is suitable for accomodating, in its inner tubular cavity 610, a thread or lace 7 in a slidable manner.

[0059] According to an embodiment, the arch 611 has a substantially inverted "U" shape, as for example shown in Fig. 11.

[0060] According to another embodiment, for example shown in Fig. 9 and 10, the arch 611, is composed of a pair of vertical walls 612, 613 spaced apart from each other and a pair of inclined walls 614, 615, each departing from one of the pair of vertical walls 612, 613 and joining at a vertex 616, so as to form a house-like shape. Such a shape is particularly effective for obtaining a single- line, tubular structure without providing any kind of internal support for the internal tubular cavity 610. Preferably, the tubular structure 61 comprises a base layer 617 , directly adhered to the fabric, which also delimits the inner tubular cavity 610 , from the side toward the fabric, and j oined to the pair of vertical walls 612 , 613 . This allows any thread or lace to slide into the cavity with a friction that depends solely on the type of material that is used to make the print and not on the type of fabric, as well as ensures better adhesion of the tubular structure to the fabric .

[0061] According to an embodiment , shown for example in Fig . 9 , the printed portion 6 comprises a plurality of tubular structures 61 spaced apart from each other along an alignment direction K . This provides a printed portion comprising a discontinuous tubular structure , which is particularly suitable for making fabric gathers when the thread running in the inner tubular cavity is pulled in order to shorten the distance between a first end 62 of a first tubular structure 61 and a second end 63 of a second tubular structure .

[0062] According to an advantageous embodiment , the printed portion 6 comprises at least one j oining structure 65 between a tubular structure 61 and an adj acent tubular structure 61 ' spaced apart . Preferably, the j oining structure 65 is j oined between a final end 620 of a tubular structure 61 and an initial end 621 of the adj acent tubular structure 61 ' . Preferably, in this variation, the j oining structure 65 has a length L greater than the distance S between the final end 620 of a tubular structure 61 and the initial end 621 of the adj acent tubular structure 61 ' , calculated along the alignment direction K . Preferably, the j oining structure is an arc or broken line j oining the final end 620 and the initial end 621 .

[0063] The j oining structure 65 is preferably fully adhered to the fabric . In another variant , the j oining structure 65 is only partially adhered to the fabric .

[0064] The presence of the j oining structure 65 allows to improve the gathering effect of the fabric and deterministic control of the pitch of the gathers , as well as helps to define the final elasticity of the region comprising the fabric and printed portion 6 .

[0065] Innovatively, the method according to this invention overcomes the drawbacks discussed above in reference to the prior art . In particular, due to the possibility of mapping the surface of the fabric j ust before starting the printing phase , it is possible to correct in real time the vertical positioning of the dispensing noz zle in order to keep the distance of the noz zle from the printing surface constant . This ensures a homogeneous deposition of the material , the simultaneous respect of the dimensional values of the manufactured article , and an optimal adhesion of the thermoplastic material to the fabric .

[0066] Advantageously, moreover, the possibility of providing an interpolation of acquired points on the printing surface , in order to obtain a digital representation of the surface , allows to further increase the correct adhesion to the fabric .

[0067] Advantageously, the phase of retracting the thermoplastic printing material , before moving the dispensing noz zle , allows for the preparation of the priming operation ( i . e . , the release of material from the dispensing noz zle outside the printing area onto the fabric ) and the avoidance of the unsightly skirts typically present on the manufactured articles of the prior art .

[0068] Moreover, still advantageously, the particular combination of thermoplastic polyurethane material and high heating temperatures , higher than 230 ° , allows a strong adhesion with the substrate to be obtained and the reliability of durability also for ribbon-like printed portions to be ensured .

[0069] Advantageously, the high degree of adhesion and the precision of deposition obtainable with the proposed technique allow for the construction of tubular structures ( or tunnels ) of desired length and shape directly on the substrate, which are able to adapt to the deformations of the textile allowing, for example, for fibers, cords, electrical cables, and fluids to slide within it, as well as the joints between textile components or quick-lace systems (e.g., choke systems) to be created, and for the application to the textile of shockproof systems, cushioning or thermal insulation, especially in the case of horizontal and/or vertical coupling of multiple tubular structures.

[0070] Said tubular structures are obtained by the design and use of the geometries described, which prevent, during the printing phase, the use of supports, which are typically necessary for traditional tubular shapes, and would become difficult or impossible to remove at the end of the printing, affecting the functionality of the tunnels, as well as allowing manufactured articles with a high area/material ratio to be obtained, given the low thickness achievable for the walls of tubular structures, even less than a millimeter and down to 0.3 mm.

[0071] It is clear that a person skilled in the art, in order to satisfy contingent and specific needs, could make modifications to the invention described above, said modifications being all contained within the scope of protection as defined in the following claims.