Abstract
A paper for inkjet printing may have one side that is provided with an inkjet receiver coating. The inkjet receiver coating may comprise at least pigment and binder. A portion of free or unbound pigment may be less than 10 weight percent of the total amount of pigment in the inkjet receiver coating and/or the inkjet receiver coating may have a surface that is substantially free of pigment.
Claims
1. A paper for inkjet printing, wherein the paper at least at one side is provided with an inkjet receiver coating comprising at least pigment and binder; and wherein a portion of free or unbound pigment is less than 10 weight percent of the total amount of pigment in the inkjet receiver coating and/or wherein the inkjet receiver coating has a surface that is substantially free of pigment.
2. The paper according to claim 1, wherein the inkjet receiver coating comprises a first layer with a first composition and a second layer with a second composition; and wherein the first and the second compositions include the binder.
3. The paper according to claim 2, wherein the first layer and the second layer differ in that they show one or more of the following properties: the property that the first layer as well as the second layer comprise pigment and binder in a different pigment to binder ratio; the property that the dry weight of material applied for the first layer and the second layer is different; and the property that the first layer and the second layer comprise pigment and binder, wherein the average particle size of the pigments contained in the first layer is larger than the average particle size of the pigments contained in the second layer.
4. The paper according to claim 3, wherein the first composition has a pigment to binder ratio that is larger than the pigment to binder ratio of the second composition.
5. The paper according to claim 4, wherein the pigment to binder ratio in the second composition is less than 2.
6. The paper according to claim 5, wherein the pigment to binder ratio in the first composition is greater than 3.5.
7. The paper according to claim 1, wherein the pigment is silica particles, and/or the binder is polyvinyl alcohol.
8. The paper according to claim 1, wherein the paper has a Gurley value of between 60 and 120 seconds.
9. A method for manufacturing a laminate panel, wherein the panel comprises a substrate material and provided thereon a top layer with a printed decor; wherein the top layer is substantially formed from a thermosetting resin and one or more paper layers; and wherein the paper layers include a decor paper on the basis of a paper for inkjet printing according to claim 1.
10. The method according to claim 9, wherein the paper for inkjet printing is printed using an inkjet printer, is impregnated with an amount of the thermosetting resin, and is attached to the substrate material via a hot pressing treatment.
11. The method of claim 10, wherein the inkjet printer operates using water-based inks.
12. The method of claim 10, wherein the inkjet printer is of the single-pass type and/or is operated in single-pass mode.
13. The method of claim 10, wherein the inkjet printer operates using pigment containing inks.
14. A paper for inkjet printing, wherein the paper at least at one side is provided with an inkjet receiver coating comprising at least pigment and binder; and wherein the inkjet receiver coating has a surface that is substantially formed by the binder.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) 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:
(2) 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;
(3) 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;
(4) FIG. 4 shows some steps in a method in accordance with the fifth aspect of the invention;
(5) FIG. 5 shows in perspective a panel obtained by means of the method of FIG. 4;
(6) FIG. 6 shows a view according to the line VI-VI indicated on FIG. 5;
(7) FIG. 7 shows a piece of equipment for use amongst others in the first aspect of the invention; and
(8) FIG. 8 schematically shows a top view on a printer operated in single-pass mode.
DESCRIPTION OF NON-LIMITING EMBODIMENTS
(9) 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.
(10) 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.
(11) 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.
(12) 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 an 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.
(13) 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.
(14) 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.
(15) 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.
(16) In the example several doctor blades 21 are available for partially removing resin at the surface of the resin provided paper layer 1.
(17) 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.
(18) FIG. 4 also illustrates that the continuous paper layer 2 is cut to sheets 23 and stacked.
(19) 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.
(20) 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.
(21) 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.
(22) 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.
(23) 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.
(24) 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.
