METHOD FOR PRINTING ON A DÉCOR PAPER AND/OR ON A DÉCOR FOIL

Abstract

A method is provided for printing onto a décor paper and/or foil that may be suitable for being used in decorative panels. The method may involve providing a printable substrate. A pattern may be printed on the printable substrate by ejecting droplets of ink by means of at least one inkjet printing head that may include one or more nozzles. After a first predetermined time period, the printing operation may be interrupted for a second predetermined time period and/or a controlling frequency of the printhead may be changed for a second predetermined time period.

Claims

1. A method for printing onto a décor paper and/or a décor foil, the décor paper or the décor foil being suitable for being used in decorative panels, the method comprising: providing a printable substrate; and printing a pattern on the printable substrate; wherein the pattern is printed by ejecting droplets of ink using at least one inkjet print head; wherein the inkjet print head includes one or more nozzles; wherein after a first predetermined time period the ejecting of the ink form the nozzles is interrupted for a second predetermined time period and/or a controlling frequency of the inkjet print head is changed for a second predetermined time period.

2. The method according to claim 1, wherein the second predetermined period of time is shorter than the first predetermined time period.

3. The method according to claim 1, wherein the method is of a roll-to-roll type.

4. The method according to claim 1, wherein a relative movement between the printable substrate and the inkjet print head is performed during the printing.

5. The method according to claim 4, wherein the relative movement is performed during the first predetermined time period and during the second predetermined time period.

6. The method according to claim 1, wherein the change of the control frequency involves a reduction of the control frequency.

7. The method according to claim 1, further comprising providing an ink receiver layer onto the printable substrate before the printing is performed.

8. The method according to claim 7, wherein the ink receiver layer is not provided during the second predetermined time period.

9. The method according to claim 7, wherein the ink receiver layer is provided during the second predetermined time period.

10. The method according to claim 1, wherein the printing is performed using a set of inks; and wherein the set of inks is of the type CMYK or CRYK.

11. The method according to claim 1, wherein the printing is performed using a set of inks; and wherein the set of inks comprises more than four inks.

12. The method according to claim 11, wherein the set of ink comprises a light red and/or a light black ink.

13. The method according to claim 10, wherein the inks are printed onto the printable substrate according to a predetermined sequence that is configured to reduce the amount of ink to be printed on the printable substrate.

14. The method according to claim 13, wherein said the predetermined sequence is CRYK or CMYK.

15. The method according to claim 1, wherein during the second predetermined time period a technical area is formed on the printable substrate.

16. The method according to claim 15, wherein the technical area has a length along a printing direction, that is less than 10 mm.

17. The method according to claim 15, wherein in the technical area is an unprinted area.

18. The method according to claim 15, wherein in the technical area a technical pattern is printed; and wherein the technical pattern is configured to highlight printing defects.

19. The method according to claim 1, wherein the second predetermined time period starts only after completion of printing of a discrete number of printed patterns.

20. A method for printing onto a décor paper and/or a décor foil, the décor paper or the décor foil being suitable for being used in decorative panels, the method comprising: providing a printable substrate; and printing a pattern on the printable substrate; wherein the pattern is printed by ejecting droplets of ink using at least one inkjet print head; wherein the inkjet print head includes one or more nozzles; wherein during printing a print quality control operation is performed; wherein the print quality control operation is configured to identify at least one predetermined printing defect and to send a signal to a printer control unit on the basis of the identification; and wherein the printer control unit is configured to interrupt the ejecting of the ink for a predetermined time period and/or change a control frequency of the inkjet print head for a predetermined time period.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0055] With the intention of better showing the characteristics of the invention, in the following, as an example without any limitative character, several preferred forms of embodiments are described with reference to the accompanying drawings, wherein:

[0056] FIG. 1 shows a transversal section of a printable décor paper;

[0057] FIG. 2 shows an enlarged view of area F2 of FIG. 1;

[0058] FIG. 3 shows some steps of a method for manufacturing a decorative paper according to the first independent aspect of the invention;

[0059] FIG. 4 shows a enlargement of a coating station of FIG. 3;

[0060] FIG. 5 shows a enlargement of a printer of FIG. 3:

[0061] FIG. 6 shows a top view of a portion of a decorative paper obtained in the method of FIG. 3;

[0062] FIG. 7 shows some steps of a method for manufacturing a laminate panel comprising the decorative paper of FIG. 6;

[0063] FIG. 8 shows a perspective view of a laminate panel obtainable through the method of FIG. 7.

DESCRIPTION OF NON-LIMITING EMBODIMENTS

[0064] FIG. 1 schematically illustrates a printable substrate 1 that is printable with an inkjet printer. The printable paper layer 1 comprises a paper sheet 2 provided with an inkjet receiver coating 3. The paper sheet 2 is, in this case, a base printing paper having a weight of about 70 grams per square meter and with a mean air resistance as expressed by Gurley value of between 10 and 30 seconds. The paper sheet is suitable for being impregnated with a thermosetting resin so that it can be used in the manufacturing of laminate panel as it will be discussed below.

[0065] The printable substrate 1 comprises an amount of inkjet receiver coating 3 that is equal or lower than 5 g/m2 dry weight. This amount of inkjet receiver coating 3 has been found ideal to preserve the impregnation capacity of the paper 2.

[0066] It is generally noted that the dimensions of the represented paper sheet 2 and the inkjet receiver coating 3 is, in the figures, drawn out of scale in order to better illustrate the invention.

[0067] FIG. 2 shows that the inkjet receiver coating 3 comprises pigments 4. In the preferred embodiment the pigment substantially consists of silica particles. The inkjet receiver coating 3, further comprises a binder 5 preferably polyvinyl alcohol, a crosslinker, an ink reactive compound, more particularly a flocculating agent and/or a dispersant, such in accordance with the first aspect of the invention. It is clear however that the figures are also illustrative for many aspects of the present invention in the cases where an ink reactive compound, more specifically an ink destabilizing agent, other than a flocculating agent has been applied, such as for example a cationic metal salt.

[0068] FIG. 3 illustrates some step in a method for manufacturing a décor paper in accordance with the first independent aspect of the invention. FIG. 3 illustrates that the paper sheet 2 may be uncoiled from a starting roller 10 and coated with the ink receiver coating 3 in a coating station 11, to obtain the printable substrate 1. The printable substrate 1 is then fed to an inkjet printer 12. The printer 12, in this example, relates to a printer of the single pass type. The inkjet printer 12 is commanded for printing a décor on the printable substrate 1 thereby forming a décor paper 13. The décor paper 13 is optionally dried in a drier 14 and the décor paper 13 that is subsequently coiled up in a second roller 15.

[0069] FIG. 4 shows that, in accordance with a preferred embodiment, the ink receiver coating 3, may be obtained by applying a liquid substance 20 on the upper surface of the paper layer 2. The coating station 11 comprises reverse metering rollers 21. Such coating station 11 may initially apply an excess of the liquid substance 20, which is squeezed off to the desired weight by means of the rollers 21, which also may provide for a smooth coating surface. Preferably, the obtained half product is then dried, e.g. by means of a hot air oven, to reach a residual humidity level of preferably below 10%, or of about 7%. Such is here not illustrated, but this may be executed in a fairly similar way. It is clear that as an alternative to the coating station 11, other application techniques may be used, such as application by one or more gravure rollers, possibly also running in reverse, or with a size press or a film press, preferably in line with the paper machine.

[0070] FIG. 5 illustrates that, in this example, the inkjet printer 12 comprises a central cylinder 30 upon which the printable substrate 1 is partially wound and further comprises several printing units 31, each comprising one or more print heads, disposed radially around the central cylinder 30 and over the area of the printable substrate 1 to be printed. For example, the central cylinder 30 of the inkjet printer 12 comprises a radius between 800 and 950 mm, for example around 880 mm, and comprises a web angle above 270°, for example above 300°, preferably 320°. The printer 12, in this example, relates to a printer of the single pass type, wherein the provision of the printed pattern involves a relative motion of said inkjet printer 12, more particularly the printing unit 31, and said paper substrate 1 during printing in a printing direction D. In this case, the printing unit 31 and the print heads are at standstill, while the printable substrate 1 moves during ejection of inks. In this way, the printable substrate 1 gets printed during a single continuous movement of the printable substrate 1 relative the printer 12 or the rows of print heads.

[0071] As mentioned above, each printing unit 31 comprises a plurality of printheads and each printhead comprises a plurality of ejecting nozzle to eject the ink. Each nozzle can comprise a piezoelectric element that can be controlled through a controlling frequency for commanding the ejecting of the ink. Each printing unit 31 is dedicated to print one respective color. In the embodiment shown the printer is adapted to print with a set of inks having a minimum number of four colors, for example six colors. Preferably, said set of ink comprises cyan ink, magenta and/or red ink, yellow ink and black ink. Red ink is preferred above magenta ink for printing wood decors. In the example of the figures the set of inks further comprises a light red ink and a light black ink. Preferably said ink are printed according to a predefined sequence along the printing direction D that is configured to reduce the quantity of ink to be delivered on the printable substrate 1. As shown in FIG. 5, the preferred sequence starts with Cyan and ends with black or light black. Preferably the sequence is cyan (C), red (R), light red (1R), yellow (Y), black (K) and light black (1K).

[0072] Preferably the inks are water-based pigmented inks.

[0073] The printer 12 is configured to print one or more decorative patterns 16 (FIG. 6), preferably wood or stone décor, on the printable substrate 1 in a continuous manner for a first predetermined time period. This prolonged solicitation on the nozzle can cause the forming of residual vibrations in the nozzles leading to printing defects. According to the method of the first independent aspect of the invention, the printer is configured for interrupting the jetting of the ink for a second predetermined time period. In the embodiment shown in the figures, the jetting is interrupted in all the nozzles of all the printheads simultaneously so that a technical area 17 is formed on the printed paper 13, in the example an unprinted area. Said technical area has a length L, parallel to the printing direction, that is lower than 10 mm During said second predetermined period it is possible to relax the stress on the nozzles so to restore the printing quality. At the end of the second time period the jetting of the ink reprises for printing the decorative pattern 16 for another first time period.

[0074] As illustrated in FIG. 3, a visual camera 18 can be connected to the printer 12 and is configured to identify printing defects on the printed paper 13. Said visual camera 18, in the example, is connected to a control unit 19 connected to the printer 12. The control unit 19 can be configured to start the second time period on the basis on the identification of the printing defects.

[0075] FIG. 7 illustrates some steps of a method for manufacturing decorative panels 40 of the type shown in FIG. 7.

[0076] The obtained decorative panels 40 at least comprise a substrate 41, preferably made of MDF or HDF, and a top layer 42. The top layer 42 comprises a décor paper 13 formed by the printable substrate 1 of FIG. 1 provided with a printed pattern 16 or a digitally printed ink layer representing a wood pattern, as is the case here. FIG. 8 illustrate that the obtained decorative panel or laminate panel 40 can have the shape of a rectangular and oblong laminate floor panel, with a pair of long sides 43 and a pair of short sides 44. In this case the panel 40 is provided at its edges 43,44 with coupling means 45 allowing to lock the respective edges 43,44 together with the sides of a similar panel.

[0077] In the method of FIG. 7 the décor paper 13 is taken from the second roll 15 and transported to an impregnation station 50, where said décor paper 13 is immersed in a bath 51 of a thermosetting resin, more particularly a mixture of water and thermosetting resin composition. Preferably, said thermosetting resin is a melamine-based resin, for example melamine formaldehyde or urea formaldehyde resin. The décor paper 13 is then allowed to rest while in this case being transported upwards. The resting allows for the resin to penetrate the paper sheet 2. The décor paper 13 then comes into a second impregnation station 52 where the paper layer 1 is, in this case, again immersed in a bath 51 of resin. A set of squeezing rollers 53 allows to dose the amount of resin applied to the décor paper 13.

[0078] In the example several doctor blades 54 are available for partially removing resin at the surface of the resin provided décor paper 13.

[0079] The resin provided décor paper 13 is dried and its residual humidity level is brought to below 10%. In the example hot air ovens 55 are used, but alternatively other heating equipment can be used, such as microwave or infrared drying equipment.

[0080] FIG. 7 also illustrates that the continuous resin provided décor paper 13 is cut to sheets 56 and stacked. In the example described the technical areas 17 of the décor paper can be cut away so that only the portions comprising the printed pattern 16 are used to form the sheets 56.

[0081] The obtained sheets 56 of the resin provided décor paper 13 are taken up from the stack to be pressed in a short daylight press 57 between upper and lower press plates 58-59. Said stack comprises from bottom to top a counter layer 60, a plate shaped substrate 41, the abovementioned sheet 56 of the resin provided décor paper 13 and a wear layer 61, wherein the counter layer 60 and the protective layer 61 both comprise a paper sheet, in case of the wear layer 61 called overlay paper, and resin. The stack is then pressed and the press treatment results in a mutual connection between the constituent layers 60-41-56-61 of the stack, as well as in a hardening or curing of the thermosetting resin. More particularly here a polycondensation reaction of the melamine-based resin takes place, having water as a by-product.

[0082] The upper press plate 58 is a structured press plates that provides a relief in the melamine surface of the panel 40 during the same press treatment by bringing the structured surface into contact with the melamine of the protective layer 61.

[0083] The present invention is in no way limited to the hereinabove described embodiments, but such may be realized according to different variants without leaving the scope of the present invention.

[0084] Further, as is clear from the content of the description, the present invention relates to one or more of the items as listed below, numbered from 1 to 38:

[0085] 1.—A method for printing onto a décor paper and/or foil, said décor paper or décor foil being suitable for being used in decorative panels, said method comprising the steps of providing a printable substrate and the step of printing a pattern on said printable substrate, wherein said pattern is printed by ejecting droplets of ink by means of at least one inkjet printing head, wherein said head comprises one or more nozzles, wherein in that after a first predetermined time period the ejecting of the ink form the nozzles is interrupted for a second predetermined time period and/or a controlling frequency of the printhead is changed for a second predetermined time period.

[0086] 2.—The method according to item 1, wherein said second predetermined period of time is shorter than the first period of time, preferably at least 10 time shorter, more preferably at least 100 time shorter.

[0087] 3.—The method according to any of the preceding items, wherein said method is of a roll-to-roll type.

[0088] 4.—The method according to any of the preceding items, wherein a relative movement between the printing substrate and the printing head is performed during the printing steps.

[0089] 5.—The method according to item 4, wherein said relative movement is performed during the first predetermined time period and during said second predetermined time period.

[0090] 6.—The method according to any of the preceding items, wherein said change of the control frequency involves a reduction of the control frequency.

[0091] 7.—The method according to any of the preceding items, characterized in that it comprises the step of providing an ink receiver layer onto the printing substrate before the printing step is performed.

[0092] 8.—The method according to item 7, wherein said ink receiver layer is not provided during said second predetermined time period.

[0093] 9.—The method according to item 7, wherein said ink receiver layer is provided also during said second predetermined time period.

[0094] 10.—The method according to any of the preceding items, wherein said printing step is performed using a set of inks, preferably wherein said set of inks is of the type CMYK or CRYK.

[0095] 11.—The method according to any of the preceding items, wherein said set of inks comprises more than four inks, preferably six inks.

[0096] 12.—The method according to item 11, wherein said set of ink comprises a light red and/or a light black ink.

[0097] 13.—The method according to any of the items from 10 to 12, wherein said inks are printed onto the printing substrate according to a predetermined sequence, preferably said sequence is configured to reduce the amount of ink to be printed on the printing substrate.

[0098] 14.—The method according to item 13, wherein said sequence is CRYK or CMYK.

[0099] 15.—The method according to any of the preceding items, wherein during said second predetermined time period a technical area is formed on said printable substrate

[0100] 16.—The method according to item 15, wherein said technical area has a length along a printing direction, that is lower than 10 mm.

[0101] 17.—The method according to any of the preceding items, wherein in said technical area is an unprinted area.

[0102] 18.—The method according to any of the preceding items, wherein in said technical area a technical pattern is printed, preferably said technical pattern is configured to highlight printing defects.

[0103] 19.—The method according to any of the preceding items, wherein said second predetermined period starts only after completion of printing of a discrete number of printed patterns.

[0104] 20.—A method for printing onto a décor paper and/or foil, said décor paper or décor foil being suitable for being used in decorative panels, said method comprising the steps of providing a printable substrate and the step printing a pattern on said printable substrate, wherein said pattern is printed by ejecting droplets of ink by means of at least one inkjet printing head, wherein said head comprises one or more nozzles, wherein during said step of printing a print quality control operation is performed characterized in that said print quality control operation is configured to identify at least one predetermined printing defect and to send a signal to a printer control unit on the basis of said identification, and in that said printer control unit is configured to interrupt the ejecting of the ink for a predetermined time period and/or change a control frequency of the printhead for a predetermined time period.

[0105] 21.—The method according to item 20, wherein said second predetermined period of time is shorter than the first period of time, preferably at least 10 time shorter, more preferably at least 100 time shorter.

[0106] 22.—The method according to item 20 or 21, wherein said method is of a roll-to-roll type.

[0107] 23.—The method according to any of items from 20 to 22, wherein a relative movement between the printing substrate and the printing head is performed during the printing steps.

[0108] 24.—The method according to item 23, wherein said relative movement is performed during the first predetermined time period and during said second predetermined time period.

[0109] 25.—The method according to any of items from 20 to 24, wherein said change of the control frequency involves a reduction of the control frequency.

[0110] 26.—The method according to any of items from 20 to 25, characterized in that it comprises the step of providing an ink receiver layer onto the printing substrate before the printing step is performed.

[0111] 27.—The method according to item 26, wherein said ink receiver layer is not provided during said second predetermined time period.

[0112] 28.—The method according to item 27, wherein said ink receiver layer is provided also during said second predetermined time period.

[0113] 29.—The method according to any of items from 20 to 28, wherein said printing step is performed using a set of inks, preferably wherein said set of inks is of the type CMYK or CRYK.

[0114] 30.—The method according to any of items from 20 to 29, wherein said set of inks comprises more than four inks, preferably six inks.

[0115] 31.—The method according to item 30, wherein said set of ink comprises a light red and/or a light black ink.

[0116] 32.—The method according to any of the items from 20 to 31, wherein said inks are printed onto the printing substrate according to a predetermined sequence, preferably said sequence is configured to reduce the amount of ink to be printed on the printing substrate.

[0117] 33.—The method according to item 32, wherein said sequence is CRYK or CMYK

[0118] 34.—The method according to any of items from 20 to 33, wherein said second predetermined period starts only after completion of printing of a discrete number of printed patterns

[0119] 35.—A method for printing onto a décor paper and/or foil, said décor paper or décor foil being suitable for being used in decorative panels, said method comprising the steps of providing a printable substrate and the step of printing at least two printed patterns, or at least two groups of printed patterns, on said printable substrate, wherein said patterns are printed by ejecting droplets of ink by means of at least one inkjet printing head, wherein during said printing operation a relative movement between the printable substrate and the printing head in a printing direction is performed, wherein the method comprises the step of printing a technical area between said two printed patterns or between said two groups of printed patterns, preferably wherein said technical area has a length in said printing direction that is lower than 10 mm.

[0120] 36.—The method according to item 35, wherein said technical area is an unprinted area.

[0121] 37.—The method according to item 35 or 36, wherein said technical area comprises a technical printed pattern configure to highlight printing performances and/or possible printing defects.

[0122] 38.—The method according to item 35 or 37, wherein during forming of said technical area ejecting of the ink form the nozzles is interrupted and/or a controlling frequency of the printhead is changed, preferably reduced.