REMOVING SURFACE FIBERS AND LINT

BACKGROUND

Substrates like textiles may have a surface morphology including surface features, such as lint or textile fibers on their respective surfaces. These substrate surface features may form an irregular surface structure or topography which may interfere with printing quality in direct to textile applications as these can interfere with and cause a printing fluid to be applied in a non-uniform layer on the irregular surface.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustration, certain examples will now be described with reference to the accompanying drawings, in which:

FIG. 1 shows a schematic illustration of a conditioning device according to an example in a top view;

FIG. 2 shows a schematic illustration of a radiation part of a conditioning device according to an example in a side view;

FIG. 3 shows a schematic illustration of a printer according to an example in a top view;

FIG. 4 shows a schematic illustration of a product according to an example in a top view;

FIG. 5 shows a schematic diagram illustrating a method according to an example;

FIG. 6A shows a schematic diagram illustrating emitted power over wavelength of different radiation parts of various examples; and

FIG. 6B shows a schematic diagram illustrating absorption over wavelength of different absorbers of various examples.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings. The examples in the description and drawings should be considered illustrative and are not to be considered as limiting to the specific example or element described. Multiple examples may be derived from the following description and/or drawings through modification, combination or variation of certain elements. Furthermore, it may be understood that also examples or elements that are not literally disclosed may be derived from the description and drawings by a person skilled in the art. Whereas different examples are described herein, it is understood that features of these examples may be used individually or in combination thereof to derive further variations beyond those explicitly describes herein.

A method and a device for conditioning a textile and a product including a conditioned textile substrate are disclosed herein. Conditioning is provided for selectively removing undesirable surface features which may cause surface obstructions, such as surface fibers and lint, from a textile substrate in an area to be printed on. The undesirable surface features may be removed selectively from the substrate by burning the undesirable surface features. This may be achieved by applying a conditioning fluid to the textile, the conditioning fluid having an absorption spectrum differing from an absorption spectrum of the textile substrate. Then, the textile may be exposed to electromagnetic radiation, such as ultraviolet (UV) or infrared (IR) radiation, having a radiation spectrum in a wavelength band matching the absorption spectrum of the conditioning fluid. The radiation spectrum and the absorption spectrum of the conditioning fluid may match to such an extent that radiation transforms into heat to burn off the undesirable surface features, such as lint and fibers because of their relatively low thermal mass when compared to the bulk of the substrate. Heat is created locally where the conditioning fluid has been applied. The remainder of the textile, outside of the conditioned area, may remain unaffected. The non-conditioned area of the textile may have an absorption spectrum different from that of the conditioning fluid so that the textile will not be heated in the area free of the conditioning fluid, even if irradiated in that area.

After removing undesirable surface features from the conditioned area, a smooth surface, free of fibers and lint, is obtained which provides an optimal substrate for printing an image thereon.

FIG. 1 shows a schematic illustration of a conditioning device 100 in a top view. The conditioning device 100 comprises a printing part 1 and a radiation part 2. The radiation part 2 of the conditioning device 100 according to an example is separately shown in FIG. 2, in a side view. Reference is made to FIG. 2 where applicable. The printing part 1 and the radiation part 2 as shown in FIG. 1 may be part of a single stage or a two stage conditioning device 100.

In the examples of FIG. 1 and FIG. 2, the conditioning device 100 provides a pretreatment of the substrate S to prepare a predetermined area A of the substrate S for printing an image, by selectively removing undesirable surface features L from the predetermined area A of the substrate S onto which printing will take place. The substrate S may be a textile, fabric or garment, for example, comprising natural fibers. Examples for natural fibers are wool, silk, camel hair, angora, cotton, flax, hemp, and jute. Examples of garments are T-shirts, sweaters, jackets, shorts and the like. A textile also may be provided in the form of a sheet or in the form of a continuous web which is fed from a textile supply roll. The pretreatment may be an operation to selectively remove lint and surface fibers from the substrate S to generate a smooth surface area for printing.

In the examples of FIG. 1 and FIG. 2, the substrate S to be treated, comprises a main substrate layer or bulk layer B and a surface layer L. The main substrate layer B includes bound or densely distributed fibers in a woven, non-woven, knitted or similar arrangement. The surface layer L may include loosely arranged or loose fibers or lint described herein as undesirable surface features L or artifacts extending and/or formed from the main substrate layer B of the substrate S. Lint and fibers further may be considered part of the substrate S itself as they originate from the material of the substrate S. In one example, a fiber density of the main substrate layer B is at least to times, or even at least 20 or too times, higher than a fiber density of the surface layer L. Due to the difference in fiber density, the surface layer L has a lower thermal mass than the main substrate layer B. For example, the ratio of thermal mass between the main substrate layer B and the surface layer L is between to and too.

In the example of FIG. 1, the printing part 1 of the conditioning device 100 may comprise a receiving surface 10 for receiving the substrate S and a print head, schematically shown at 12. The print head 12 may be located in a carriage, such as a printer carriage or similar to a printer carriage. The receiving surface 10 may be a printer platen or may be similar to a printer platen. The substrate S is placed on the receiving surface 10 between the print head 12 and the receiving surface 10. The receiving surface 10 has a width in the x direction and a length in the y direction, as shown in FIG. 1, with z designating the vertical direction. In one example, dimensions of the receiving surface 10 may be such that at least a substrate S of a size of a regular T-shirt may be received. For example, at least one of the width and the length of the receiving surface 10 may be between 0.2 meters and 5 meters or between 0.2 meters and 2 meters. In FIG. 1, the length of the substrate S also may be defined in the y direction and the width may be defined in the x direction. The receiving surface 10 may be substantially plane or flat. The substrate S is provided on the receiving surface 10 so as to provide a substantially plane substrate surface on the receiving surface 10.

In the example of FIG. 1, the printing part 1 may be to deposit a conditioning fluid on the substrate S within the predetermined area A. The predetermined area A is shown as a heart shape in FIG. 1. The printing part 1 may have the configuration of or be similar to a drop-on-demand printer, including an inkjet-type print head, such as a thermal inkjet or piezo-electric print head, for example. The printing part 1 may comprise a 2-axis carriage. The 2-axis carriage comprises a carriage part for holding the print head 12, an x-axis guide bar 24 and two y-axis guide bars 26. The 2-axis carriage is to move the carriage including the print head 12 in two dimensions parallel to and above the substrate S and/or the receiving surface 10.

The x-axis guide bar 24 is to guide and move the carriage including the print head 12 along the width direction x of the receiving surface 10. Further, the two y-axis guide bars 26 are to support the x-axis guide bar 24 and are to guide and move the carriage including the print head 12 along the length direction y of the receiving surface 10. Further, the 2-axis carriage may comprise a drive unit and a control unit to carry out and control the movement of the carriage. Thus, the print head 12 may be arranged moveably in the x and y directions over the receiving surface 10 by positioning the carriage. The print head 12 may be further arranged to be fixed in z direction over the receiving surface. Thus, the print head 12 may be to move in a plane parallel to the substrate S.

In one example, the print head 12 may be to scan along the width direction x of the receiving surface 10 by means of the x-axis guide bar 24 across a strip portion of the substrate S between left- and right-hand boundaries (as shown in FIG. 1) of the predetermined area A. A strip portion may be defined as a row or swath printed along the width direction x of the receiving surface 10. During scanning, the print head 12 may eject a conditioning fluid, as described further below. The conditioning fluid thus is printed in a row or swath along the width direction x within the predetermined area A.

After scanning one strip portion and printing one swath of the conditioning fluid, the carriage including the print head 12 may be moved along the length direction y of the receiving surface 10 in order to arrange the print head 12 for printing a next strip portion between left and right-hand boundaries of the predetermined area A. The next strip portion may be immediately adjacent to or overlapping with the preceding strip portion. The offset between two subsequent strip portions may be in the range of 0.5 cm to 10 cm, e.g. in the order of about 0.5 cm, 1 cm or 2 cm, depending on the length of a nozzle array of the print head 12, for example. The scanning speed may be in the order of 50-200 cm/s, for example. This procedure may be repeated until the predetermined area A has been fully scanned by the print head 12, with a number of swaths of conditioning fluid printed adjacent to each other or in an overlapping print mode. Printing in the x direction may be performed both from left to right and from right to left (as seen in FIG. 1).

The printing of one strip portion may be performed in continuous swaths. During continuous printing, the print head 12 may continuously eject the conditioning fluid and scan across the substrate S to deposit the conditioning fluid within the predetermined area A.

In another example, the print head 12 may comprise a page wide print bar having a nozzle array width spanning the width of the receiving surface 10, also designated as page wide array, or a designated treatment area thereof. The page wide print head (not shown) can be provided on a y-axis carriage for movement in the y direction, for example, wherein the y-axis carriage could be implemented using the two y-axis guide bars 26 as shown in FIG. 1. Printing a swath of conditioning fluid in the x direction could be performed by sequentially or simultaneously printing the conditioning fluid by the page-wide nozzle array between left- and right-boundaries of the predetermined area A of the substrate S. Printing subsequent swaths in the y direction can be performed by moving the y-axis carriage in the y direction.

In a further example, the conditioning device 100 may comprise a feed mechanism to feed the substrate S in the form of a sheet or continuous web through a printing zone, e.g. in the lengthwise direction y, with the print head 12 located above the printing zone. The print head 12 may comprise the page wide array or may be located on the x-axis guide bar 24 supporting a carriage for printing in the x direction.

In the example, the conditioning fluid has an absorption band matching with a radiation band of the radiation source 30. In some examples, the radiation source 30 may be a commercially available emitter. The conditioning fluid may be compatible with available printing technology, such as inkjet printing technology. In this case, a standard print head can be used to eject the conditioning fluid and print the conditioning fluid in the predetermined area, following digital or analog printing methodology in the same way as an image is printed.

In different examples, the conditioning fluid may be an ink including an electromagnetic radiation-absorbing active material and an aqueous or non-aqueous vehicle. The electromagnetic radiation-absorbing active material may be an IR light absorber, a near-infrared (NIR) light absorber, a plasmonic resonance absorber, a UV light absorber and combinations thereof. These electromagnetic radiation-absorbing active materials may be provided in the form of or may include a dye or pigments. In one example, the conditioning fluid includes pigmented carbon black ink and a transparent Tint Fluid agent to promote absorption in the IR band. In another example, the conditioning fluid may include an additive to absorb energy at the radiation wavelength ranging from about 360 nm to about 410 nm to promote absorption in the UV band.

In one example, an IR light absorber includes a dispersion comprising a metal oxide nanoparticle having the formula MmM′On wherein M is an alkali metal, m is greater than 0 and less than 1, M′ is any metal, and n is greater than 0 and less than or equal to 4; a zwitterionic stabilizer; and a balance of water. The metal oxide nanoparticles may be present in the dispersion in an amount ranging from about 1 wt % to about 20 wt % based on the total weight of the dispersion. In some other example, the zwitterionic stabilizer may be present in the dispersion in an amount ranging from about 2 wt % to about 35 wt % (based on the total weight of the dispersion). In yet some other examples, the weight ratio of the metal oxide nanoparticles to the zwitterionic stabilizer ranges from 1:10 to 10:1. In another example, the weight ratio of the metal oxide nanoparticles to the zwitterionic stabilizer is 1:1. For example, M can be an alkali metal like lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), or mixtures thereof.

In one example, NIR absorbing dyes or pigments may include anthroquinone dyes or pigments, metal dithiolene dyes or pigments, cyanine dyes or pigments, perylenediimide dyes or pigments, croconium dyes or pigments, pyrilium or thiopyrilium dyes or pigments, boron-dypyromethene dyes or pigments, or aza-boron-dipyrromethene dyes or pigments.

In one example, a plasmonic resonance absorber may comprise an inorganic pigment. The inorganic pigment may comprise lanthanum hexaboride (LaB₆), tungsten bronzes (A_xWO₃), indium tin oxide (In₂O₃:SnO₂, ITO), antimony tin oxide (Sb₂O₃:SnO₂, ATO), titanium nitride (TiN), aluminum zinc oxide (AZO), ruthenium oxide (RuO₂), silver (Ag), gold (Au), platinum (Pt), iron pyroxenes (A_xFe_ySi₂O₆), modified iron phosphates (A_xFe_yPO₄), modified copper phosphates (A_xCu_yPO₂), modified copper pyrophosphates (A_xCu_yP₂O₇), and combinations thereof.

In one example, a UV light absorber may be an inkjet fluid having an additive to absorb energy at the radiation wavelength ranging from about 360 nm to about 410 nm. The additive may be selected from the group consisting of a compound containing from 3 to 5 fused benzene rings and a coumarin derivative. The ink further my include a co-solvent and water, for example.

In the example of FIG. 2, the radiation part 2 of the conditioning device 100 may be to expose the substrate S to electromagnetic radiation R, in particular the predetermined area A imprinted with the conditioning fluid. In particular, the radiation part 2 is to illuminate the substrate S after the predetermined area A has been imprinted with the conditioning fluid. The radiation part 2 may include a radiation source 30, such as a lamp, which is stationary above the conditioning surface 10 or which can be moved in the y direction or in the x and y directions, similar to the movement of the printhead 12, to align the radiation source 30 with the treated predetermined area.

The radiation source 30 may comprise a single emitter such as an LED, for example, or it may comprise an array of emitters, such as LED or other light sources. The LED may be an UV-LED or an IR-LED, for example. The radiation source 30 is provided at a distance G from the substrate S. The radiation part 2 may be to radiate light in a predefined or preset wavelength band, for example UV-A, UV-B, UV-C, IR or NIR band. The arrows below the lamp 30 illustrate a possible direction of light for illuminating the substrate S.

For example, when using a conditioning fluid having an IR light absorber, the wavelength of the radiation source 30 can be in the range of 780 nm to 1 mm. When using a conditioning fluid having an NIR light absorber, the wavelength of the radiation source 30 can be in the range of 780 nm to 3 μm. When using a conditioning fluid having a plasmonic resonance absorber, the wavelength of the radiation source 30 can be in the range of 100 nm to 410 nm. When using a conditioning fluid having a UV light absorber, in particular UV-A, UV-B and UV-C, the wavelength of the radiation source 30 can be in the range of 315 nm to 410 nm, 280 nm to 315 nm and 100 nm to 280 nm, respectively.

The radiation source 30, in general, emits light at a spectral band aligned with a maximum absorption band of the conditioning fluid. Exposure time and radiation energy are selected so as to sufficiently heat the undesirable surface features L, such as fibers and lint, to burn the undesirable surface features L but not the bulk layer B of substrate S. The conditioning fluid and the radiation band are selected such that radiation does not impact the non-conditioned portion of the substrate S. For example, the absorption band of the substrate S and any dyes used for pre-coloring the substrate S may be lower than are outside of the radiation band of the radiation source 30.

In one example, an exposing time may be ranging from about 0.1 seconds to about 20 seconds, or from about 0.1 seconds to about 5 seconds. To achieve a desired amount of heating at the predetermined area A, power settings of the radiation part 2 may be adapted. A power setting may range from about 3.5 W/cm²to about 10 W/cm². The power setting may depend on the type of substrate, type of radiation source 30, the conditioning fluid and/or the distance G. In consequence, an energy exposure may range from about 0.5 J/cm²to about 20 J/cm², for example.

In one example, the substrate S has a radiation absorption pattern. Further, the conditioning fluid has another different radiation absorption pattern. For example, the radiation absorption pattern of the substrate S and the radiation absorption pattern of the conditioning fluid may have maxima in respectively different wavelength bands. In one example, the radiation absorption pattern of the substrate S has a minimum in a wavelength band where the radiation absorption pattern of the conditioning fluid has a maximum. Similarly, the radiation absorption pattern of the substrate S may have a maximum in a wavelength band where the radiation absorption pattern of the conditioning fluid has a minimum. When depositing the conditioning fluid on the substrate S, the radiation absorption pattern of the part of the substrate S treated with the conditioning fluid will be modified and may become the same as or close to the radiation absorption pattern of the conditioning fluid.

In general, in the examples of FIG. 1 and FIG. 2, the pretreatment operation may comprise providing the predetermined area A of the substrate S with the conditioning fluid and exposing the substrate S to radiation. The radiation has a wavelength band which matches with a maximum of a radiation absorption pattern of the conditioning fluid but not with a radiation absorption pattern of the substrate S.

Accordingly, the radiation source 30 can be selected such that an emission power pattern of the radiation source matches with the radiation absorption pattern of the conditioning fluid. For example, the radiation source 30 can be further selected such that its emission power pattern does not match with the radiation absorption pattern of the substrate S itself. Consequently, the radiation source 30 may be to expose the substrate S to electromagnetic radiation having a wavelength band which matches with a maximum of the radiation absorption pattern of the conditioning fluid to selectively remove the undesirable surface features L from the substrate S in the predetermined area A.

Once, the predetermined area A of substrate S is printed with the conditioning fluid and exposed to radiation, the radiation R is transformed into heat and constituents of the surface layer L, in particular lint and fibers, within the predetermined area A of the substrate S are burnt due to their lower thermal mass compared to the fibers in the main substrate layer B. The radiation power of the radiation part 2 and/or the exposure time to radiation by the radiation part 2 may be controlled in order to control the amount of heat locally generated for burning of the undesirable surface features L and to not affect the main substrate layer B. The main substrate layer B hence remains substantially unaffected.

The conditioning device 100 as described with respect to FIG. 1 may be a stand-alone device to which the substrate S is supplied and from which the substrate S is taken after processing. In another example, the conditioning device 100 may be part of a processing line wherein it may be located upstream of a printer 3, which is described below with reference to FIG. 3, for example. An advance direction of the substrate through the processing line is shown by arrow P in FIG. 1 and arrow P′ in FIG. 3. In still a further example, the conditioning device 100 can be integrated in a printer. If the conditioning device 100 is integrated into a printer, a printer carriage and carriage drive mechanism can be used to support and scan a print head to eject conditioning fluid. The radiation source 30 can also be supported by the printer carriage or can be installed at a fixed position in the printer above a print zone. The substrate S to be processed can be located on a printer platen. If the substrate S is a continuous material web, a printer feed mechanism can be used to transport the substrate through a print zone.

In FIG. 1, the radiation part 2 of the conditioning device 100 and the printing part 1 of the conditioning device 100 are shown as separate units by way of example. Nevertheless, the radiation part 2 and the printing part 1 may be integrated in a single unit.

In one example, the radiation part 2 may be arranged downstream of the printing part 1. In this example, the substrate S may be provided in the form of a sheet or continuous web that is fed in the lengthwise direction y through a printing zone and an illumination zone, with the printing part 1 located above the printing zone and the radiation part 2 located above the illumination zone. In another example, the radiation part 2 may comprise a 2-axis carriage similar to or the same as the 2-axis carriage of the printing part 1. Thus, in different examples, the radiation source 30 may be static or movably arranged in x and/or y direction of the receiving surface 10 so as to scan across the illumination zone in x- and/or y-direction of the receiving surface 10.

In one example, the radiation source 30 may comprise a page wide lamp or a page wide array of lamps. The page wide lamp or the page wide array of lamps may be to simultaneously or successively radiate light at the substrate S.

A radiation power of the radiation source 30 may be set depending on a distance G between substrate S and the radiation source 30 and/or a size of the substrate area to be exposed to radiation. The radiation power may range from about 3.5 W/cm²to about 10 W/cm². Further, an exposure time may be set from about 0.1 seconds to about 20 seconds, for example.

An exposure time may be set by controlling the speed of the feeding mechanism for the sheet or the continuous web in lengthwise direction y through the illumination zone. The speed may be set such that the time for running the substrate S through the illumination zone ranges from about 1 seconds to 20 seconds. In another example, the sheet or the continuous web may be stationary such that the radiation source 30 of the radiation part 2 may be to scan across the substrate S for an exposure time of about 1 seconds to 20 seconds.

In the example where the radiation part 2 is implemented with the printing part 1 in a single unit, the printing zone and illumination zone may at least overlap or coincide. In one example, the carriage part for supporting the print head 12 may also support the radiation part 2. In another example, the radiation part 2 may be statically arranged in the conditioning device. The radiation part 2 may be to radiate light during printing of the conditioning fluid. Further, the radiation part 2 may be arranged upstream of the printing part 1 in the same unit. Thus, the radiation part 2 can follow a scanning movement of the printing part 1, thereby illuminating parts of the substrate S which have been conditioned.

FIG. 3 shows a schematic illustration of a printing device 3 according to an example in a top view. Reference is made to FIGS. 1 and 2, where applicable. The printing device 3 may comprise a printer platen 50, a print head 42, an x-axis guide bar 44 and two y-axis guide bars 46. The printing device 3 may be equal or similar to the printing part 1 of the conditioning device 100 as described with respect to FIG. 1. Thus, for details regarding the printing device 3, reference is made to FIG. 1. Further, the carriage can support a print head 42 to print a colored printing fluid on the predetermined area A′ of the substrate S. The predetermined area A′ may correspond to the predetermined area A of the substrate S according to FIGS. 1 and 2 after conditioning the predetermined area A of the substrate S and exposing the substrate S to electromagnetic radiation to selectively remove undesirable surface features L, such as lint and fibers.

FIG. 4 shows a schematic illustration of a product 4 according to an example in a top view. The product 4 includes a textile substrate S and an image printed on the textile substrate S in a predetermined area A″. The predetermined area A″ may correspond to the predetermined areas A and A′ after printing the colored printing fluid on the predetermined area A′. In particular, surface fibers and lint are removed from the textile substrate S in the predetermined area A″ by burning. Since, the surface fibers and lint have been burnt, a surface of the substrate S in the predetermined area A′ is flat and smooth. Thus, an image printed in the corresponding predetermined area A″ may have a uniform constitution. The product 4 may be an organic or inorganic textile fabric in the form of a finished article, such as clothing, blankets, tablecloths, napkins, towels, bedding materials, curtains, handbags, shoes, banners, signs, flags or similar articles.

FIG. 5 shows a schematic diagram illustrating a method according to an example. Reference is made to FIGS. 1 to 4, where applicable. The method comprises providing a substrate S which has a maximum of radiation absorption at a first wavelength band, at 110.

Further, the method comprises depositing, on a predetermined area A of the substrate S, a conditioning fluid which has a maximum of radiation absorption at a second wavelength band, at 120. In one example, depositing 120 the conditioning fluid includes printing the conditioning fluid. Accordingly, the radiation absorption of the substrate S in the predetermined area A is adjusted to the radiation absorption of the conditioning fluid by printing the conditioning fluid in the predetermined area A of the substrate S.

Further, the method comprises exposing the substrate S to electromagnetic radiation at the second wavelength band to remove undesirable surface features L from the predetermined area A of the substrate S, at 130. The undesirable surface features may be removed by burning. The first wavelength band differs from the second wavelength band. For example, the second wavelength band may be a near infrared, NIR, band, or an ultraviolet, UV, band. Further, the second wavelength band may be in an ultraviolet, UV, band. For example, the UV band may be the UV-A band.

In one example of FIG. 5, the depositing 110 the conditioning fluid on the predetermined area A and exposing 130 the substrate to electromagnetic radiation are performed successively.

In one example of FIG. 5, the method further comprises printing on the predetermined area A of the substrate S with a colored printing fluid after printing 110 the conditioning fluid on the predetermined area A of the substrate S, at 140. Further, the printing 140 may be performed after selectively removing undesirable surface features L from the predetermined area A of the substrate S, at 130.

In one example of FIG. 5, the electromagnetic radiation has more than 80% of its power in the second wavelength band and less than 20% of its power in the first wavelength band. In the same or another example, an absorption of a part of the substrate S free from conditioning fluid is lower than 40% in the second wavelength band and higher than 40% in the first wavelength band. In the same or yet another example, an absorption of a part of the substrate S treated with the conditioning fluid is higher than 40% in the second wavelength band and lower than 40% in the first wavelength band.

FIG. 6A shows a schematic diagram illustrating emitted power over wavelength of different radiation sources 30. Reference is made to FIGS. 1 to 4, where applicable. In particular, FIG. 6A shows two different graphs F1 and F2 respectively representing emitted power over wavelength for different lamps used as radiation source 30. On the axis of ordinates, an electrical power is shown in kW. On the axis of abscissa, a wavelength is shown in nm.

In the example of FIG. 6A, the graph F1 represents the emitted power over wavelength of a halogen IR lamp. The graph F1 shows that the radiated power of the halogen IR lamp has a maximum in the NIR band, i.e at about 1200 nm. In particular, more than 90% of the power radiated by the halogen IR lamp may be radiated within the NIR band. The rest of the power may be radiated in neighboring bands, for example in bands having larger wavelengths and lower frequencies. In this example, the maximum power is at about 90 kW.

In the example of FIG. 6A, the graph F2 represents the emitted power over wavelength of a ceramic IR lamp. The graph F2 shows that the radiated power of the ceramic IR lamp has a maximum outside the NIR band. In particular, more than 90% of the power radiated by the ceramic IR lamp may be radiated outside the NIR band, for example in bands having larger wavelengths—lower frequencies. Less than 10% of the power may be radiated in the NIR band.

FIG. 6B shows a schematic diagram illustrating absorption over wavelength of different absorbers which may be used in a conditioning fluid. Reference is made to FIGS. 1 to 4, where applicable. In particular, FIG. 6B shows two different graphs F3 and F4 respectively representing absorption of power over wavelength for the conditioning fluid and the substrate S. On the axis of ordinates, an absorption is shown in percent. On the axis of abscissa, a wavelength is shown in nm.

In the example of FIG. 6B, the graph F3 represents the absorption over wavelength of a substrate S or a predetermined area A of the substrate S being treated with an electromagnetic radiation-absorbing active material in a conditioning fluid to shift the absorption of the substrate S towards the NIR band. In particular, the electromagnetic radiation-absorbing active material may be an NIR light absorber in the form of or may include a dye or pigments. For example, the NIR light absorber may include anthroquinone dyes or pigments, metal dithiolene dyes or pigments, cyanine dyes or pigments, perylenediimide dyes or pigments, croconium dyes or pigments, pyrilium or thiopyrilium dyes or pigments, boron-dypyromethene dyes or pigments, or aza-boron-dipyrromethene dyes or pigments.

In particular, it may be assumed that the absorption of the conditioning fluid and the absorption of the treated substrate S are the same or approximately the same. In the example of FIG. 6B, the conditioning fluid may be pigmented carbon black ink or low tint fluid agent which is transparent. The graph F3 shows that the absorption of the carbon black ink has a maximum in the NIR band and a minimum in neighboring bands of the NIR band, for example in bands having larger wavelengths and lower frequencies. For example, the absorption in the NIR band may be higher than 35%, wherein an absorption in neighboring bands may be lower than 35%.

Generally, the conditioning fluid may be selected to match a wavelength radiation pattern of a radiation source 30 shown in FIG. 6A as graph F1. Alternatively, the radiation source 30 shown in FIG. 6A as graph F1 may be selected to match a radiation absorption pattern over wavelength of the conditioning fluid shown in FIG. 6B as graph F3.

In the example of FIG. 6B, the graph F4 represents the absorption over wavelength of the substrate S free of any conditioning fluid. The graph F4 shows that the absorption of the substrate S has a maximum outside the NIR band. In particular, an absorption of the substrate S in the NIR band may be lower than about 35%.

Substrate portions free of any conditioning fluid may have a radiation absorption which may increase with wavelength, as shown in the graph F4 of FIG. 6B. Correspondingly, the conditioning fluid may be selected so that the radiation absorption of the conditioning fluid may substantially decrease with wavelength. Thus, the conditioning fluid may be selected so as to have a radiation absorption with a maximum in an NIR band or other defined wavelength bands, such as the UV band, depending on the radiation source to be used.

Experiments have shown that the method and device described herein can safely remove lint and surface fibers from a textile substrate without damaging the bulk of the substrate. In the treated area the texture of the substrate can be perceived more clearly. The method and device can be selective in that portions of the substrate not to be treated remain unaffected. For example, a soft and “hairy” textile will preserve its soft touch and feel outside of treated areas. Further, the method is compatible with most features and protrusions of the substrate, such as knitting patterns, decorative stitching, ornamental or functional seams, buttons, appliqués and the like.

The result of the treatment is very uniform and provides a smooth and flat surface suitable for printing an image thereon. The processing time is relatively low, such as less than two minutes, depending on the size of the area to be treated. Treatment consumes little energy and only little resources, such as a limited amount of conditioning fluid print in the predetermined area. Costs and complexity are low.

Further, the conditioning device 100 can be integrated in a printer and make use of printer equipment, such as a substrate holding mechanism, substrate feed mechanism, printing mechanism and a carriage mechanism. The conditioning fluid may be handled like ink.

The statements set forth herein under use of hardware circuits, software or a combination thereof may be implemented. The software means can be related to programmed microprocessors or a general computer, an ASIC (Application Specific Integrated Circuit) and/or DSPs (Digital Signal Processors). Whereas some details have been described in terms of a computer-implemented method, these details may also be implemented or realized in a suitable device, a computer processor or a memory connected to a processor, wherein the memory can be provided with one or more programs that perform the method, when executed by the processor.

REMOVING SURFACE FIBERS AND LINT

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