Method for manufacturing panels having a decorative surface

Abstract

Panels having a decorative surface may include a substrate and a top layer, and the top layer may include a paper layer having a printed pattern. A method for manufacturing such panels may involve providing the paper layer with a treatment that includes providing the paper layer with an ink receiving substance, and providing the treated paper layer with at least a portion of the printed pattern. The printed paper layer may be provided with thermosetting resin. Providing the portion of the printed pattern may involve depositing pigment containing inks on the treated paper layer using a digital inkjet printer. The printed pattern may be provided in a single continuous relative movement of the paper layer with respect to the digital inkjet printer. The pigments may be color pigments. The digital inkjet printer may include print heads with nozzles for firing droplets of the pigment containing inks onto the treated paper layer. The pigment containing inks may include a water vehicle that maintains a contact angle, at the interface between the droplets of pigment containing ink and the treated paper layer, between 0 and 90. The contact angle may be measured between the droplets and the treated paper layer. The droplets may have a volume of 15 picoliters or less. A definition of at least 200 dpi may be attained in the portion of the printed pattern.

Claims

1. A method for manufacturing panels having a decorative surface, wherein the panels include a substrate and a top layer, and the top layer includes a paper layer having a printed pattern, the method comprising: providing the paper layer with a treatment, including providing the paper layer with an ink receiving substance; and providing the treated paper layer with at least a portion of the printed pattern; providing the printed paper layer with thermosetting resin; wherein providing the portion of the printed pattern involves depositing pigment containing inks on the treated paper layer using a digital inkjet printer, wherein the printed pattern is provided in a single continuous relative movement of the paper layer with respect to the digital inkjet printer; wherein the pigments contained in the ink are color pigments; wherein the digital inkjet printer includes print heads with nozzles, and the depositing involves firing droplets of pigment containing inks from the nozzles onto the treated paper layer; wherein the pigment containing inks include a water vehicle that maintains a contact angle at the interface between the droplets of pigment containing ink and the treated paper layer, the contact angle being between 0 and 90; wherein the contact angle is measured between the droplets and the treated paper layer; wherein the droplets have a volume of 15 picoliters or less; and wherein a definition of at least 200 dpi is attained in the portion of the printed pattern.

2. The method of claim 1, wherein the thermosetting resin comprises additives, including a wetting agent.

3. The method of claim 1, wherein the thermosetting resin is provided in an amount wherein the dry weight of the thermosetting resin equals 40 to 250% of the weight of the paper layer.

4. The method of claim 1, wherein the thermosetting resin is a melamine formaldehyde resin with a formaldehyde to melamine ratio of 1.4 to 2.

5. The method of claim 1, wherein the contact angle is between 10 and 50.

6. The method of claim 1, wherein the pigment containing inks are UV curable and the method includes curing the droplets.

7. The method of claim 1, wherein the pigment containing inks comprise acrylic or methacrylic resin.

8. The method of claim 1, wherein the paper layer has a paper weight of between 50 and 100 grams per square meter.

9. The method of claim 8, wherein the paper layer has a mean air resistance according to the Gurley method of below 25 seconds.

10. The method of claim 1, wherein the method further comprises providing a further resin layer above the printed pattern after printing.

11. The method of claim 1, wherein the treated paper layer is fed from a roll, printed upon, and rolled back up again.

12. The method of claim 1, wherein the printed pattern covers the majority of a surface of the paper layer.

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 shows an embodiment of a paper layer that has been printed in accordance with the method of the invention;

(3) FIG. 2 illustrates some steps of a method in accordance with the invention; and

(4) FIGS. 3 and 4 show a decorative panel obtainable by means of the method of FIG. 2, wherein FIG. 3 is a perspective view of said panel, and FIG. 4 is a cross section at a larger scale along the line IV-IV in FIG. 3.

DESCRIPTION OF NON-LIMITING EMBODIMENTS

(5) FIG. 1 illustrates a decorative layer 1 for incorporation in a decorative panel, obtainable by means of a method in accordance with the invention. The decorative layer 1 comprises a paper sheet 2 provided with thermosetting resin 3. The thermosetting resin 3 satisfies or fills the paper core 4. The paper layer has been provided with a digitally printed ink layer 5 on the basis of pigment containing inks.

(6) FIG. 1 also clearly shows that at least at the side opposite the digitally printed ink layer the decorative layer 1 comprises a resin layer 6 outside the paper core 4. At the side that contains said digitally printed ink layer 5 a similar resin layer is not available, or at least the available resin layer is significantly thinner, for example less than half the thickness of the resin layer 6.

(7) From FIG. 1 it is clear that the digitally printed ink layer 5 covers the majority of the papers surface. Such print might for example represent a wood pattern, a stone pattern or a fantasy pattern.

(8) FIG. 2 illustrates a method for manufacturing decorative panels 7 of the type shown in FIGS. 3 and 4. The obtained decorative panels 7 at least comprise a substrate 8 and a top layer 9. The top layer comprises a paper layer 2 with a printed pattern or a digitally printed ink layer 5 representing a wood pattern, as is the case here. The method comprises at least the step S1 of providing said paper layer 2 with thermosetting resin 3. Hereto the paper layer 2 is taken from a roll 10 and transported to a first impregnation station 11 where said resin 3, more particularly a mixture of water and resin 3, is applied at one side of the paper layer 2, in this case, by means of a dipping roller 12. The paper layer 2 is then allowed to rest while in this case being transported upwards. The resting allows for the resin 3 to penetrate the paper core 4. The paper layer 2 then comes into a second impregnation station 13 where the paper layer 2 is immersed in a bath 14 of resin 3, more particularly a mixture of water and resin 3. A set of squeezing rollers 15 allows to dose the amount of resin 3 applied to the paper layer 2.

(9) In the example an amount of applied resin 3 is removed again from the side that is to be provided with the digitally printed ink layer 5, in this case by means of a doctor blade 16.

(10) In a second step S2 the resin provided paper layer 2 is dried and its residual humidity level is brought to below 10%. In the example hot air ovens 17 are used, but alternatively other heating equipment can be used, such as microwave drying equipment.

(11) FIG. 2 also illustrates that the method at least comprises the step S3 of providing said resin provided paper layer 2 with a printed pattern, in this case a digitally printed ink layer 5 representing a wood pattern. Use is made of pigment containing UV curable inks, that are deposited on the paper layer 2 by means of a digital inkjet printer 18, in this case a single pass inkjet printer having print heads extending over the width of the paper layer 2. The dry weight of the total volume of pigment containing inks deposited on said paper layer 2 is lower than 15 grams per square meter. The inkjet printer is preferably a drop on demand printer that allows to pin cure the deposited droplets of UV curable pigmented ink. Preferably a further UV curing station 19 is provided downstream of the printer 18. After printing and curing the inks the continuous paper layer 2 is cut to sheets 20 and stacked. The obtained sheets 20 resemble the decorative layer 1 illustrated in FIG. 1.

(12) According to a non illustrated variant the step of the printing S3 and/or the curing of the ink might be carried out after the resin provided paper layer 2 is already cut to sheets 20.

(13) According to still another non illustrated variant, the resin provided paper layer 2 might be rolled up again before cutting it to sheets and/or before printing.

(14) FIG. 2 further illustrate that in a subsequent step S4 the obtained sheets 20 or the decorative layer 1 is taken up in a stack to be pressed in a short daylight press 21 between upper and lower press plates 22-23. Said stack comprises from bottom to top a counter layer 24, a plate shaped substrate 8, the abovementioned decorative layer 1 and a protective layer 25, wherein the counter layer 24 and the protective layer 25 both comprise a paper layer 2 and resin 3. The stack is then pressed and the press treatment results in a mutual connection between the constituent layers 1-8-24-25, including the substrate 8, of the stack, as well as in a hardening or curing of the available resin 3. More particularly here a polycondensation reaction of the melamine formaldehyde resin 3 takes place, having water as a by-product.

(15) The upper press plate 22 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 S4, by bringing the structured surface 26 of the upper press plate 22 into contact with the melamine of the protective layer 25.

(16) FIGS. 3 and 4 illustrate that the obtained decorative panel 7 can have the shape of a rectangular and oblong laminate floor panel, with a pair of long sides 27-28 and a pair of short sides 29-30 and having an HDF or MDF substrate 8. In this case the panel 7 is at long at least the long sides 27-28 with coupling means 31 allowing to lock the respective sides 27-28 together with the sides of a similar panel both in a direction R1 perpendicular to the plane of the coupled panels, as in a direction R2 perpendicular to the coupled sides and in the plane of the coupled panels. As illustrated in FIG. 4 such coupling means or coupling parts can basically have the shape of a tongue 32 and a groove 33, provided with additional cooperating locking means 34 allowing for said locking in the direction R2.

(17) The present invention is in no way limited to the above described embodiments, but such method may be realised according to several variants without leaving the scope of the invention as defined by the appended claims.