COMPOSITION FOR USE IN A METHOD FOR MANUFACTURING PAPER PRINTABLE WITH AN INKJET PRINTER FOR USE AS A DECOR PAPER

Abstract

A composition may be provided for use in a method for manufacturing a paper layer printable with an inkjet printer. The paper layer may be used as a decor paper in a laminate panel. At least one side of the paper layer may be coated with an inkjet receiver coating in at least two partial steps. A first layer of a first composition may be applied, and subsequently a second layer of a second composition may be applied. The first and the second compositions may at least include a binder. Each of the first and the second compositions may include a liquid substance being a water-based suspension of at least the binder. A dry matter content of the first composition may be of 8 to 25 percent by weight of the liquid substance, and/or a dry matter content of the second composition may be of 4 to 20 percent by weight of the liquid substance.

Claims

1. A composition for use in a method for manufacturing a paper layer printable with an inkjet printer, wherein the paper layer is for use as a decor paper in a laminate panel, wherein at least one side of the paper layer is coated with an inkjet receiver coating in at least two partial steps, wherein respectively a first layer of a first composition is applied, and subsequently a second layer of a second composition is applied; wherein the first and the second compositions at least comprise a binder; wherein each of the first and the second compositions is a liquid substance being a water-based suspension of at least the binder; and wherein a dry matter content of the first composition is of 8 to 25 percent by weight of the liquid substance, and/or wherein a dry matter content of the second composition is of 4 to 20 percent by weight of the liquid substance.

2. The composition according to claim 1, wherein the dry matter content as expressed by weight percentage is higher in the first composition than in the second composition.

3. The composition according to claim 1, wherein the first layer and the second layer differ in that they show one or more of the following properties: the first composition and the second composition comprise pigment and binder in a different pigment to binder ratio; and the first composition and the second composition comprise pigment and binder, wherein an average particle size of the pigments contained in the first composition is larger than an average particle size contained in the second composition.

4. The composition according to claim 3, wherein the first composition has a pigment to binder ratio which is larger than the pigment to binder ratio of the second composition.

5. The composition according to claim 3, wherein the pigment to binder ratio in the second composition is lower than 2.

6. The composition according to claim 4, wherein the pigment to binder ratio in the first composition is larger than 3.5.

7. The composition according to claim from 4, wherein the first composition has a pigment to binder ratio which is at least 20% larger than the pigment to binder ratio of the second composition

8. The composition according to claim 3, wherein the larger pigment particles are contained in the first composition.

9. The composition according to claim 8, wherein the pigment particles in the first composition have an average particle size between 1 and 20 micrometer.

10. The composition according to claim 8, wherein the pigment particles in the second composition have an average particle size between 100 nanometer and 1 micrometer.

11. The composition according to claim 1, wherein in the first and the second compositions the binder is the same or, at least a main constituent of the binder is the same.

12. The composition according to claim 1, wherein the first composition and/or the second composition includes an inorganic pigment.

13. The composition according to claim 1, wherein the first and the second compositions include silica particles as pigment, and/or the binder is polyvinyl alcohol.

14. The composition according to claim 1, wherein the first and the second compositions include amorphous and/or precipitated silica as pigment.

15. The composition according to claim 1, wherein the first and the second compositions include pigments that have an average particle size of 100 nm to 20 μm.

16. The composition according to claim 1, wherein the first and the second compositions include pigments that have an average surface area of 20 to 420 m.sup.2/g.

17. The composition according to claim 1, wherein the first and the second compositions include pigments that have an average pore volume of 0.5 to 2 ml/g.

18. The composition according to claim 1, wherein the first and the second compositions include pigments that have an average particle size between 2 and 7 μm, an average surface area of 300 to 420 m.sup.2/g, and an average pore volume between 1 and 2 ml/g.

19. The composition according to claim 1, wherein the first composition and/or the second composition comprises a cross-linker.

20. The composition according to claim 19, wherein the cross-linker is chosen from the group consisting of aldehydes, aziridines, isocyanates, epoxides, and borates.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0090] With the intention of better showing the characteristics according to the invention, in the following, as an example without limitative character, an embodiment is described, with reference to the accompanying drawings, wherein:

[0091] FIG. 1 schematically shows an embodiment of a paper layer that has been provided with an inkjet receiving coating in accordance with the method of the first aspect of the invention;

[0092] FIGS. 2 and 3 on a larger scale provide a view on the area F3 illustrated in FIG. 1, wherein, in the case of FIG. 2, only said first layer has been applied to the paper layer;

[0093] FIG. 4 shows some steps in a method in accordance with the fifth aspect of the invention;

[0094] FIG. 5 shows in perspective a panel obtained by means of the method of FIG. 4;

[0095] FIG. 6 shows a view according to the line VI-VI indicated on FIG. 5;

[0096] FIG. 7 shows a piece of equipment for use amongst others in the first aspect of the invention; and

[0097] FIG. 8 schematically shows a top view on a printer operated in single-pass mode.

DESCRIPTION OF NON-LIMITING EMBODIMENTS

[0098] FIG. 1 schematically illustrates a treated paper layer 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, that comprises a first layer 4 with a first composition and a second layer 5 with a second composition. 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 below 30 seconds.

[0099] It is generally noted that the dimensions of the represented paper sheet 2 and the layers 4-5 is, in the figures, drawn out of scale in order to better illustrate the invention.

[0100] FIGS. 2 and 3 show that the inkjet receiver coating 3 comprises pigments 6 and binder 7. The composition of the first layer 4, as well as the composition of the second layer 5 both comprise binder, such in accordance with the first aspect of the invention.

[0101] FIG. 2 illustrates a halfproduct 8 wherein only the first layer 4 has been applied to the paper sheet 2. The binder 7 is partially absorbed into the paper sheet 2, and such in a non-uniform manner. At the surface 9 loose and/or badly bound pigments 6 are present. Such pigments 6 give rise to dust release upon further processing of such halfproduct 8. The obtained surface 9 of the first layer 4 also suffers from unevenness.

[0102] FIG. 3 shows the paper layer 1 wherein also the second layer 5 has been applied on top of the first layer 4. FIG. 3 shows that the second layer 5 evens out the surface 9, leading to a more uniform surface 10 of the second layer and of the paper layer 1. The composition of the second layer 5 has in this case a lower pigment to binder ratio than the composition of the first layer 4.

[0103] It is noted that FIG. 3 is an example of the third and fourth aspect of the present invention, wherein at the surface of the treated paper layer less than 10 weight percent of the total pigment 6 is unbound or free and wherein the surface 10 of the second layer is essentially, and in this case completely, formed by binder 7.

[0104] FIG. 4 illustrates a method for manufacturing laminate panels 11 of the type shown in FIGS. 5 and 6. The method forms an illustration of the fifth independent aspect of the invention as described in the introduction of the present patent application. The obtained decorative panels 11 at least comprise a substrate 12 and a top layer 13. The top layer 13 comprises a paper layer 1, manufactured in accordance with the first aspect, and provided with a printed pattern or a digitally printed ink layer 14 representing a wood pattern, as is the case here. The method of the example embodiment comprises at least the step S1 of providing said paper layer 1 having the inkjet receiving layer and the printed pattern with thermosetting resin 15. Hereto the paper layer 1 is taken from a roll 16 and transported to a first impregnation station 17 where said paper layer is immersed in a bath 18 of said resin 15, more particularly a mixture of water and resin 15. The paper layer 1 is then allowed to rest while in this case being transported upwards. The resting allows for the resin 15 to penetrate the paper core. The paper layer 1 then comes into a second impregnation station 19 where the paper layer 1 is, in this case, again immersed in a bath 18 of resin 15, more particularly a mixture of water and resin 15. A set of squeezing rollers 20 allows to dose the amount of resin 15 applied to the paper layer 1.

[0105] In the example several doctor blades 21 are available for partially removing resin at the surface of the resin provided paper layer 1.

[0106] In a second step S2 the resin provided paper layer 1 is dried and its residual humidity level is brought to below 10%. In the example hot air ovens 22 are used, but alternatively other heating equipment can be used, such as microwave drying equipment.

[0107] FIG. 4 also illustrates that the continuous paper layer 2 is cut to sheets 23 and stacked.

[0108] FIG. 4 further illustrates that in a subsequent step S3 the obtained sheets 23 or the paper layer 1 is taken up in a stack to be pressed in a short daylight press 24 between upper and lower press plates 25-26. Said stack comprises from bottom to top a counter layer 27, a plate shaped substrate 12, the abovementioned paper layer 1 and a protective layer 28, wherein the counter layer 27 and the protective layer 28 both comprise a paper sheet 2 and resin 15. The stack is then pressed and the press treatment results in a mutual connection between the constituent layers 1-12-27-28, including the substrate 12, of the stack, as well as in a hardening or curing of the available resin 15. More particularly here a polycondensation reaction of the melamineformaldehyde resin 15 takes place, having water as a by-product.

[0109] The upper press plate 26 is a structured press plates that provides a relief in the melamine surface of the panel 1 during the same press treatment of the step S3, by bringing the structured surface 29 of the upper press plate 26 into contact with the melamine of the protective layer 28.

[0110] FIGS. 5 and 6 illustrate that the obtained decorative panel or laminate panel 11 can have the shape of a rectangular and oblong laminate floor panel, with a pair of long sides 30 and a pair of short sides 31 and having an HDF or MDF substrate 12. In this case the panel 11 is at long at least the long sides 30 with coupling means 32 allowing to lock the respective sides 30 together with the sides of a similar panel both in a direction R1 perpendicular to the plane of the coupled panels, and in a direction R2 perpendicular to the coupled sides and in the plane of the coupled panels. As illustrated in FIG. 6 such coupling means or coupling parts can basically have the shape of a tongue 33 and a groove 34, provided with additional cooperating locking means 35 allowing for said locking in the direction R2.

[0111] FIG. 7 shows that, in accordance with a preferred embodiment, at least one of the first layer 4 and the second layer 5 of the inkjet receiver coating 3, may be obtained by coating in one of said two partial steps a liquid substance 36 to the paper sheet 2. In this case, the application of the first layer is illustrated. A device 37 comprising reverse metering rollers 38 is applied. Such device 37 may initially apply an excess of the liquid substance 36, which is squeezed off to the desired weight by means of the rollers 38, which also may provide for a smooth coating surface. Preferably, the obtained halfproduct 8 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%. The obtained treated paper is then further treated by applying the second layer 5 of the inkjet receiver coating 3. Such is here not illustrated, but this may be executed in a fairly similar way.

[0112] FIG. 8 illustrates that the paper layer 1 having the inkjet receiver coating of the first aspect of the invention may be printed by means of an inkjet printer 39, which, in this example comprises several rows 40 of print heads that extend over the area of the paper layer 1 to be printed. The printer 39, 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 39, more particularly the rows 40, and said paper layer 1 during printing in a printing direction D. In this case, the rows 40 and the print heads are at standstill, while the paper layer 1 moves during ejection of inks onto the paper layer 1, more precisely onto the inkjet receiver coating 3 applied to the paper sheet. The paper layer 1 gets printed during a single continuous movement of the paper layer 1 relative the printer 39 or the rows 40 of print heads. The obtained printed pattern 14 comprises, in the example, a wood motif having wood nerves 41 extending generally in the printing direction D. Preferably a drying station 42 is provided downstream of the printer 39. After drying the inks, the printed paper layer is preferably rolled up and used in the method illustrated in FIG. 4 as the roll 16.

[0113] The present invention is in no way limited to the above described embodiments, but such methods, equipment, paper layers and thermoplastic foils may be realized according to several variants without leaving the scope of the invention.