INKJET PRINTING ON POLYESTER TEXTILES

Abstract

A method of pre-treating a polyester textile for inkjet printing with a water-based disperse dye ink composition, which method comprises treating at, least a part of, a surface of the polyester textile to increase its hydrophobicity.

Claims

1. A method of pre-treating a polyester textile for inkjet printing with a water-based disperse dye ink composition, which method comprises treating at, least a part of, a surface of the polyester textile to increase its hydrophobicity.

2. A method according to claim 1, comprising forming a hydrophobic polymer coating on the surface providing for optimal inkjet printing of a water-based, disperse dye ink composition having a surface tension between 35 dynes/cm (35 mN/m) and 50 dynes/cm (50 mN/m).

3. A method according to claim 2, wherein the hydrophobic coating imparts a measurable surface free energy from 5 dynes/cm (5 mN/m) to 30 dynes/cm (30 mN/m) lower than the surface tension of the water-based disperse dye ink composition.

4. A method according to claim 3, wherein the measurable surface free energy is between 15 dynes/cm (15 mN/m) and 35 dynes/cm (35 mN/N).

5. A method according to claim 1, wherein the pre-treating comprises an atmospheric plasma process using one or more of a silicon-containing compound in air.

6. A method according to claim 1, wherein the polyester textile is a woven polyester fabric of weight per unit area 10 g/m.sup.2 to 100 g/m.sup.2.

7. A method of digital printing of a polyester textile, which method comprises pre-treating, at least a part of, a surface of a polyester textile so as to increase hydrophobicity; inkjet printing a water-based disperse dye ink composition on the treated surface of the polyester textile; and heating the printed polyester textile so as to fix the printed image on the treated surface of the polyester textile.

8. A method according to claim 7, wherein

1. treating comprises a pre-treatment according to claim 1.

9. A method according to claim 8, wherein the inkjet printing comprises inkjet printing a water-disperse dye composition having a surface tension between 35 dynes/cm (40 mN/m) and 50 dynes/cm (50 mN/m) on the pre-treated surface of the polyester textile.

10. A method according to claim 7, wherein the heating comprises heating the printed polyester textile to a temperature of 100° C. to 130° C. within 60 seconds or less of the completion of the inkjet printing.

11. A method according to claim 7, wherein the heating comprises dry heating without directly contacting a heat source with the printed polyester textile.

12. A method according to claim 7, wherein the polyester textile is a woven polyester fabric of weight per unit area 10 g/m.sup.2 to 100 g/m.sup.2.

13. A method of printing to a polyester textile, the method comprising inkjet printing a water-based disperse dye ink composition on a surface of the textile which has, at least in part, been treated to increase its hydrophobicity; and heating the printed polyester textile so as to fix the printed image on the treated surface of the polyester textile.

14. A method according to claim 13, wherein the treated surface has a measurable surface free energy between 5 dynes/cm (5 mN/m) and 30 dynes/cm (30 mN/N) lower than the surface tension of the water-based, disperse dye composition.

15. A method according to claim 14, wherein the wherein the inkjet printing comprises inkjet printing a water-based, disperse dye composition having a surface tension between 35 dynes/cm (35 mN/m) and 50 dynes/cm (50 mN/m) on the pre-treated surface of the polyester textile.

16. A method according to claim 13, wherein the heating comprises heating the printed polyester textile to a temperature between 100° C. and 130° C. within 60 seconds or less of the completion of the inkjet printing.

17. A method according to claim 13, wherein the polyester textile is a woven polyester fabric of weight per unit area 10 g/m.sup.2 to 100 g/m.sup.2.

18. A blank polyester textile, which is at least in part, surface treated with a hydrophobic coating.

19. A blank polyester textile according to claim 18, wherein the surface has a measurable surface free energy between 15 dynes/cm (15 mN/m) and 35 dynes/cm (35 mN/N).

20. A blank polyester textile according to claim 19, comprising a woven polyester fabric having weight per unit area 10 g/m.sup.2 to 100 g/m.sup.2.

21. A printed polyester textile, comprising, at least in part, a surface treated with a hydrophobic coating wherein the treated surface carries a printed image formed by inkjet printing a water-based disperse dye ink composition on the treated surface of the polyester textile.

22. A printed polyester textile according to claim 21, which has a measurable surface free energy between 15 dynes/cm (15 mN/m) and 35 dynes/cm (35 mN/N).

23. A printed polyester textile according to claim 22, comprising a woven polyester fabric having weight per unit area 10 g/m.sup.2 to 100 g/m.sup.2.

Description

[0134] The present disclosure will now be described in more detail with reference to the following Examples and the accompanying drawings in which:

[0135] FIG. 1 is a graph showing plots of height of capillary rise in the warp direction against time of untreated and surface treated thin woven polyester fabrics during a standard capillary rise test (DIN 53924);

[0136] FIG. 2 is a graph showing plots of height of capillary rise in the welt direction against time of untreated and surface treated thin woven polyester fabrics during a standard capillary rise test (DIN 53924);

[0137] FIG. 3 is a graph obtained by optical reflectance studies showing plots of absorption/scattering (K/S) of light against percentage of an ink composition comprising a disperse dye and an aqueous carrier comprising a polyol having at least 5 carbon atoms inkjet printed on an untreated and a surface treated thin woven polyester fabric before and after washing;

[0138] FIG. 4 is a graph obtained by optical reflectance studies showing 2 dimensional plots of a CIELAB colour space (a* against b*) of the ink composition inkjet printed on an untreated and a surface treated thin woven polyester fabric before and after washing;

[0139] FIG. 5 is a graph obtained by optical reflectance studies showing plots of the ratio of front and back absorption/scattering (K/S)) against percentage of the ink composition inkjet printed on an untreated and a surface treated thin woven polyester fabric before and after washing;

[0140] FIG. 6 shows graphs plotting percentage ink (abscissa) against optical density (ordinate; OD=log.sub.10(1/R) where R is reflectance) of a linearization test pattern comprising 10 patches (10% to 100%) on a touch satin polyester fabric formed by inkjet printing ink compositions comprising a disperse dye and an aqueous carrier comprising a polyol having at least 5 carbon atoms following heating with near infra-red lamps as compared to heating with a calendar; and; and

[0141] FIG. 7 shows graphs plotting percentage ink (abscissa) against the ratio (ordinate) of optical densities front and back (OD.sub.back/OD.sub.front) of a linearization test pattern comprising 10 patches (10% to 100%) on a touch satin polyester fabric formed by inkjet printing ink compositions comprising a disperse dye and an aqueous carrier comprising a polyol having at least 5 carbon atoms following heating with near infra-red lamps as compared to heating with a calendar.

EXAMPLE 1

[0142] An atmospheric pressure plasma treatment was carried out on two commercially available thin woven polyester textiles herein designated PES Penang 60 g and PES Satin 80 g.

[0143] PES Satin 80 g is a woven fashion 100% polyester satin fabric of weight per unit area 80 g/m.sup.2 which can be purchased from many suppliers in China.

[0144] PES Penang 60 g is a woven fashion 100% polyester fabric of weight per unit area 60 g/m.sup.2 which can be purchased from suppliers in China and Indonesia. Technical data for these polyester (PES) textiles are shown in Table 1.

[0145] The treatment used a PLATER® atmospheric plasma technology apparatus (from GRINP® s.r.l., Italy) providing for roll-to-roll processing of the textiles through a plasma source providing a dielectric barrier discharge between electrodes of surface area 50 cm.sup.2 .

[0146] Samples of each textile were exposed to a plasma generated at a temperature of 140° C. by a continuous dielectric barrier discharge (at 690 W) in air containing hexamethyldisiloxane (HMDS). The flow rate of the air mixture to the plasma source was held at 1.2 ml per minute. The feed of each textile between the electrodes was held at 8 metres per minute and repeated through sixteen roll-to-roll cycles.

TABLE-US-00001 TABLE 1 Weight Yarn count (DEN) Yarns/cm PES Textile (g/m2) Weft Warp Weft Warp PES Penang 60 g 60 80 80 32 44 PES Satin 80 g 80 50 30 46 110

[0147] The treatment was determined to lower the surface energy of the thin woven polyester textile by a drop test using mixtures of distilled water and isopropanol (IPA).

[0148] In this test, the contact angles of the mixtures on the treated polyester textiles were roughly determined using an optical microscope and compared with the contact angles of the mixtures on the untreated polyester textiles. Table 2 tabulates the results of the test.

TABLE-US-00002 TABLE 2 PES Penang 60 g PES Satin 80 g % Composition Contact Angle/° Contact Angle/° Water IPA untreated treated untreated treated 100 0 0 >90 <45 >90 98 2 0 >90 <45 >90 95 5 0 >90 0 >90 90 10 0 <45 0 <45 80 20 0 0 0 0 70 30 0 0 0 0 60 40 0 0 0 0

[0149] As may be seen, the contact angle of all the mixtures on untreated PES Penang 60 g were zero. The contact angle of distilled water on untreated PES Satin 80 g was less than 45° with penetration occurring within 30 seconds. The contact angle of the water and isopropanol mixture 98:2 on untreated PES Satin 80 g was also less than 45° but penetration occurred within 5 seconds.

[0150] Mixtures of water and isopropanol in which the percentage isopropanol is below 10% showed contact angles greater than 90° on treated PES Satin 80 g and treated PES Penang 60 g—these results indicating that the treated polyester textiles showed little or no wettability as compared with the untreated polyester textiles.

[0151] Capillary rise tests on treated and untreated samples of PES Satin 80 g and PES Penang 60 g were carried out according to DIN 53924. The samples were conditioned at 35% relative humidity at a temperature of 25° C. for 12 hours prior to the test. Triplicate strips of the treated samples were suspended vertically in a mixture of deionised water and isopropanol (or 1,5-pentadiol) containing a blue dye (CI RB49) and having a surface tension of 40 dynes/cm (40 mN/m). The rise in capillary height in warp and weft directions of the samples was examined over a period of 5 minutes in time intervals of 30 seconds.

[0152] FIGS. 1 and 2 show plots of the results of these test—it being clear that the wicking height of the treated samples in each direction is near zero throughout the whole period whereas the wicking height of the untreated samples quickly rises.

EXAMPLE 2

[0153] Treated and untreated samples of PES Satin 80g was subjected to inkjet printing using a Reggiani ReNOIR Compact 180 (600 dpi×600 dpi) inkjet printer and a black water-based disperse dye ink composition comprising a polyol having more than 5 carbon atoms.

[0154] The black water-based disperse dye ink composition and other suitable disperse dye ink compositions are described in Tables 3 and 4. The inkjet printing provided a (calendar) contact time of 1 minute before fixing by dry heating at a temperature of 210° C. for 30 seconds.

[0155] Some of the printed samples were subjected to washing immediately following the printing. The washing was carried out by immersion in water with stirring at a temperature of 40° C. for 30 minutes. The colour strength and colour hue on the printed surface and the extent of penetration of colour was examined after the washing and compared with printed samples which were not washed.

[0156] FIG. 3 is a graph obtained by optical reflectance studies (on a GretagMacbeth Spectrolino® spectrometer D19C, D196, D118, RD-19, SPM 50/55/60/100) with KeyWizard V2.5 software from X-Rite Europe GmbH, Switzerland) showing plots of absorption/scattering (K/S) on the printed surface of ten treated and untreated samples of PES Satin 80 g wherein the percentage dye in the ink composition varies before and after the washing.

[0157] As may be seen, the colour strength is significantly greater (up to 25%) on the printed surface of the treated sample as compared to the printed surface of the untreated sample—both before and after the washing.

TABLE-US-00003 TABLE 3 % by weight C Component (C) Yellow Red Dye Disperse Yellow 54 2.70 Dye Disperse Red 60 5.50 Propoxylated Glycerol 23.00 19.00 Glycerol 0.97 Xylitol 4.00 4.00 Sorbitol 8.00 8.00 Urea 0.50 1.00 Napthalenesulfonic acid, Na+ salt 2.00 Block Copolymer Non-ionic Surfactant 3.97 PE Block Copolymer Non-ionic Surfactant 1.82 Alkylbenzene Sulfonate Anionic Surfactant 0.20 Alkylnaphthalene Sulfonate Anionic Surfactant 0.10 0.10 Lignosulfate 1.00 Acrylic Based Anionic Surfactant 1.50 Defoamer 0.05 0.02 Biocide 0.80 0.40 Water Balance Balance

[0158] FIG. 4 is a graph obtained by optical reflectance studies showing 2 dimensional plots of a CIELAB colour space (a* against b*; ink compositions of Tables 2 and 3) on the printed surface of treated and untreated samples of PES Satin 80 g before and after the washing.

TABLE-US-00004 TABLE 4 % by weight C Component (C) Blue Black Dye Disperse Yellow 54 0.50 Dye Disperse Blue 359 5.00 Dye Disperse Blue 360 3.80 Dye Disperse Orange 25 2.70 Propoxylated Glycerol 17.00 16.00 Xylitol 5.30 4.00 Sorbitol 8.00 7.00 Urea 1.00 Napthalenesulfonic acid, Na+ salt Block Copolymer Non-ionic Surfactant 4.70 PE Block Copolymer Non-ionic Surfactant 2.60 0.30 Alkylbenzene Sulfonate Anionic Surfactant 0.50 Lignosulfate 3.07 Acrylic Based Anionic Surfactant 1.50 1.50 Defoamer 0.05 0.06 Biocide 0.20 0.30 Water Balance Balance

[0159] As may be seen, the colour hue is significantly better on the printed surface of the treated sample as compared to the printed surface of the untreated sample—both before and after washing.

[0160] FIG. 5 is a graph obtained by optical reflectance studies showing plots of the ratio of front and back absorption/scattering (K/S)) against percentage of the ink composition inkjet printed on an untreated and a surface treated thin woven polyester fabric before and after washing.

[0161] As may be seen, the ratio is significantly higher (up to 25% higher) for the treated sample as compared to the untreated sample—indicating that unwanted penetration of the ink composition is significantly less on the treated sample as compared to the untreated sample.

EXAMPLE 3

[0162] The inkjet printing of three water-based, disperse dye ink compositions of different surface tensions (A to C) on a surface treated (touch satin) polyester textile (100%) having weight per unit area of 180 g/m.sup.2 was studied.

[0163] Ink composition B corresponds to black of Table 4 and ink composition A and B differed only in an added amount of an ethoxylated non-ionic surfactant (0.20% for ink composition A and 0.50% for ink composition C) lowering surface tension.

[0164] The (static) surface tensions of the ink compositions A to C were determined (using the ring method of Du Noüy) as 38 to 39 dynes/cm (38 to 39 mN/m) for B; 31 to 32 dynes/cm (31 to 32 mN/m) for A and 27 to 28 dynes/cm (27 to 28 mN/m) for C (that is B>A>C).

[0165] In a first experiment, the polyester textile was treated by exposure to a plasma (Plasma 1) containing hexamethyldisiloxane (HMDS) in helium in atmospheric plasma technology apparatus (PLATER® 1000 LAB from GRINP® s.r.l., Italy) providing for roll-to-roll processing of the textile through a plasma source providing a dielectric barrier discharge between electrodes of surface area 50 cm.sup.2 .

TABLE-US-00005 TABLE 5 Plasma 1 Plasma 2 Monomer HMDS HMDS Gas He He Flow rate Gas l/min 10 10 % chemistry 80 80 Distance [mm] 1 1 Evaporator [° C.] 140 140 Thermo [° C.] 72 72 Speed [m/min] 2 4 Power [W] 3500 2500

[0166] In a second experiment, the polyester textile was treated by exposure to a plasma (Plasma 2) containing hexamethyldisiloxane (HMDS) in the same apparatus but under different conditions as compared to the first experiment. The particular conditions for the first and second experiments are set out in Table 5.

[0167] The printing to each of the treated polyester textiles was carried out by inkjet printing the water-based, disperse dye ink compositions at using a Reggiani ReNOIR Compact 180 inkjet printer (600×600 dpi; IL 300%) and immediately heating on a calendar (Monti Antonio S.p.A, Italy; Model 72-2600) at 210° C. and 1.9 bar for 30 seconds.

[0168] The resultant samples (one for each water-based disperse dye ink composition) were examined for rub fastness according to BS EN ISO 105-X12:2016 and the optical density (OD) and penetration (P) of the ink composition for each sample in the best case (the first experiment) determined.

[0169] Table 6 tabulates the relative percentage changes in optical density and penetration in each sample as compared to the untreated polyester textile.

[0170] As may be seen, the ink composition having the highest surface tension (B) shows the highest optical density and the lowest penetration in the printed image as compared to inkjet printing on the untreated polyester textile.

[0171] Note that although optical density is not an absolute measure of the sharpness of a printed image, it does generally indicate sharpness because (as can be inferred from FIGS. 1 and 2) an ink composition showing less penetration of the polyester textile will also show less dot gain.

TABLE-US-00006 TABLE 6 Experiment 1 Experiment 2 OD/% P/% OD/% P/% Ink Composition A +20% −15% +6% −8% Ink Composition B 3% higher 10% lower — — than A than A Ink Composition C 3% lower 5% lower — — than A than B

EXAMPLE 4

[0172] The influence of heating with one or two near infra-red lamps (of diameter 50 mm or 75 mm) on the penetration of different water-based disperse dye compositions (cyan, magenta, yellow and black) of similar surface tension on the treated polyester textile (first experiment) of Example 3 was examined.

[0173] The near infra-red lamps were of the fast medium wave emitter type having a radiation peak of 1.4 μm to 1.6 μm, 50 W/cm maximum density of nominal power and 130 kW/m.sup.2 maximum surface power density.

[0174] The inkjet printing (according to Example 3) printed an image (across 100% of the selected area) in which the ink composition density was 7 to 8 g/m.sup.2.

[0175] The heating was carried out under various conditions in which the polyester was held still (in a 1 m oven) beside the near infra-red lamp or lamps or passed by at a pass rate of the polyester textile of 6 metres per minute.

[0176] The optical densities of the samples so obtained were compared with that obtained from heating on a calendar as described in Example 3.

[0177] FIGS. 6 and 7 show respectively graphs plotting percentage ink against optical density (OD=log.sub.10(1/R) where R is reflectance) and percentage ink against the ratio of optical densities front and back (OD.sub.back/OD.sub.front) of a linearization test pattern comprising 10 patches (10% to 100%) for each ink composition and each of the heating conditions on a touch satin polyester fabric.

[0178] As may be seen, although the optical densities of the printed images do not appear to differ significantly, the penetration of the ink compositions on the treated polyester textile is reduced by an amount between 20% and 50% by heating with near infra-red lamp or lamps as compared to heating with a calendar.

EXAMPLE 5

[0179] The colour fastnesses of the samples of Example 4 obtained by heating the polyester textile under two near infra-red lamps (of diameter 75 mm and 50 mm) at a pass rate of polyester textile of 6 metres per minute were compared with the colour fastness of the sample obtained by calendar heating in a rubbing test in accordance with BS EN IS) 105-X12: 2016 Rubbing.

[0180] The dry and wet colour fastnesses (face and length) of the near infra-red heated samples was largely comparable with the dry and wet colour fastness of the calendar heated sample (4 to 5).

[0181] Further, the colour fastnesses of near infra-red heated samples obtained from binary and quaternary mixtures of the water-based, disperse dye ink compositions of Example 4 on the polyester textile of Example 3 were also largely comparable to the dry and wet colour fastness of the corresponding calendar heated sample (4 to 5).

[0182] The present disclosure provides an improved method for digital printing of water-based disperse dyes onto polyester textiles.

[0183] The method is particularly useful for digital printing of water-based disperse dyes having relatively high surface tension to low commercial grade polyester textiles—allowing precise XYZ axis positioning control of the water-based disperse dye ink compositions on these polyester textiles.

[0184] The present disclosure may provide a printed polyester textile having colour fastness to water, colour fastness to wet and dry rubbing and colour fastness to light on polyester textiles which are similar to the printed polyester textiles described in WO 2014/127050 A1.

[0185] The present disclosure offers substantially water-free printing to polyester textiles. This water-free printing is particularly suitable for the decoration of low grade commercial polyester textiles which are to be used as fashion wear and sportswear.

[0186] The presently disclosed methods and polyester textiles have been described in detail having regard to a limited number of embodiments and Examples. It will be appreciated, however, that other embodiments and examples, which are not described in detail herein, are possible provided that they fall within the scope of the accompanying claims.

[0187] Note that references to values of surface tension herein are references to static surface tension values which are known in the literature or can be measured in accordance with a known standard method (or DIN) such as the ring method of Du Noüy.

[0188] Note further that ranges defined herein include the beginning and end values—references to “about” being references to values including the exact value as well as values which achieve the same result. Such values may, for example, be within one decimal place of the exact value.