WO2005097380A1

WO2005097380A1 - An improved process for the manufacturing of decorative laminate

Info

Publication number: WO2005097380A1
Application number: PCT/SE2005/000484
Authority: WO
Inventors: Volker Kettler
Original assignee: Pergo Europe AB
Current assignee: Unilin Nordic AB
Priority date: 2004-04-07
Filing date: 2005-04-04
Publication date: 2005-10-20
Anticipated expiration: 2006-10-07
Also published as: SE527165C2; SE0400945D0; SE0400945L

Abstract

A process for the manufacturing of a decorative laminate having a base layer, a decorative layer and a wear layer. A decor is printed on a decor layer wherein the décor layer is constituted of paper which is impregnated with resin prior to the printing process. A bonding layer is arranged between said base layer and said decor layer. Said wear layer constitutes an abrasion resistant layer which is arranged on top of the decor layer, said wear layer comprising resin and hard particles, wherein said layers are bonded together through means of heat and pressure.

Description

An improved process for the manufacturing of decorative laminate.

The present invention relates to an improved process for the manufacturing of a decorative laminate with increased dimension stability of decor sections.

Products clad with thermosetting laminate is common in many areas nowadays. They are mostly used where the demands on abrasion resistance are high, and furthermore where resistance to different chemicals and moisture is desired. As examples of such products floors, floor skirting, table tops, work tops and wall panels can be mentioned. The thermosetting laminate most often consist of a number of base sheets with a decor sheet placed closest to the surface. The decor sheet can be provided with a pattern by desire. Common patterns usually visualise different kinds of wood or mineral such as marble and granite. The substrate carrying the decor often consist of a cellulose sheet on which the decor is printed. It is also known to use polymeric or polymer/cellulose blend materials as a decor carrier on which the decor is printed. The decor sheet is in most cases impregnated with a thermosetting resin. The dimension of the decor sheet will change during this process. This will cause problems in cases where decor matching is desired.

It has, through the present invention, been made possible to overcome the above mentioned problems and a decorative laminate where a radical improvement of manufacturing tolerances in respect of decor driven matching is achieved. The invention relates to a process for the manufacturing of a decorative laminate having a base layer, a decorative layer and a wear layer. A decor is printed on a decor layer. The decor layer is constituted of paper which is impregnated with resin prior to the printing process. A bonding layer is arranged between said base layer and said decor layer. The wear layer constitutes an abrasion resistant layer which is arranged on top of the decor layer, said wear layer comprising resin and hard particles. The different layers are bonded together through means of heat and pressure. According to one embodiment of the invention the printed decor comprises a printing ink while the wear layer comprises a thermosetting resin selected from the group consisting of; melamine-formaldehyde resin, phenol-formaldehyde resin, urea formaldehyde resin and mixtures thereof- An amount of amino resin is hereby mixed into the printing ink in order to increase the bond between the decor layer, printing ink and the wear layer when the layers are laminated together in a laminate press under increased temperature and pressure . The printing ink is suitably an alkyde based ink or a polyester-acrylate based ink. According to certain embodiments of the invention the amino resin is an etherified amino resin or a methylol amino resin.

According to preferred embodiments of the invention the main part of the base layer comprises a wood based board selected from the group consisting of; a particle board, a fibre board and a oriented strand board. The base layer may according to certain embodiments of the invention further comprise a supporting paper layer arranged between the board and the decor layer.

The wear layer may according to one embodiment of the invention be comprised of a high viscosity amino resin applied on top of the decorative layer prior to the lamination. According to another embodiment of the invention the wear layer is comprised of an amino resin / cellulose mixture. According to yet another embodiment of the invention the wear layer is comprised of one or more amino resin impregnated cellulose layer or layers. In preferred embodiments of the invention the wear layer also comprises hard particles with an average particle size in the range 50nm - 150μm in order to further improve the abrasion resistance. The upper portion of the wear layer may suitably be provided with hard particles with an average particle size in the range 50nm - 30μm while the inner portion of the wear layer is provided with hard particles with an average particle size in the range 31 μm - 150 μm. The smaller particles near the surface will improve scratch resistance while keeping wear of pressing equipment like press plates at a moderate level. The hard particles is preferably selected from the group consisting of; silicon oxide, silicon carbide and aluminium oxide. The wear layer is suitably provided with a surface structure that enhances the realistic impression of the decor during or after the lamination. This is suitably achieved by any known method of embossing.

According to one embodiment of the invention the bonding layer comprises a thermosetting resin. The thermosetting resin is suitably selected from the group consisting of; melamine formaldehyde resin, phenol formaldehyde resin, urea formaldehyde resin and combinations thereof. According to one alternative embodiment of the invention the bonding layer is comprises a thermoplastic resin. The thermoplastic resin may for example be a polyurethane based hotmelt glue.

According to one special embodiment of the invention the decor is achieved by digitisation of an actual archetype or by partly or completely being created in a digital media. The digitised decor is stored digitally in order to be used as a control function and original, together with possible control programs, when printing the decor. The decor may accordingly be obtained by making a high resolution or selected resolution digital picture of the desired decor. This is suitably made by means of a digital camera or scanner. The most common decor will of course be different kinds of wood and minerals like marble, as these probably will continue to be preferred surface decoration in home and public environments. It is, however, possible to depict anything that is visible. The digitised version of the decor is then edited to fit the size of the supporting core. It is also possible to rearrange the decor in many different ways, like changing colour tones, contrast, dividing the decor into smaller segments and adding other decorative elements. It is also possible to completely create the decor in a computer equipped for graphic design. It is possible to create a simulated decor so realistic that even a professional will have great problems in visually separating it from genuine material. This makes it possible to make for example floor boards with an almost perfect illusion of a rare kind of wood, like ebony or rose wood and still preserving trees under threat of extermination. The digital decor is used together with guiding programs to control a printer. The printer may be of an electrostatic type or an ink -jet type printer. Most often the colours yellow, magenta, cyan and black will be sufficient for the printing process, but in some cases it might be advantageous to add white. Some colours are difficult to achieve using the colours yellow, magenta, cyan, black and white whereby the colours light magenta and light cyan may be added. It is also possible to add so called spot colours where specific colour tones are difficult to achieve or where only certain parts of the colour spectrum with intermixing shades is desired. The resolution needed is much depending on the decor that is to be simulated, but resolutions of 10 - 1500 dots per inch (dpi) is the practical range in which most decors will be printed. Under normal conditions a resolution of 300 - 800 dpi is sufficient when creating simulations of even very complex decorative patterns and still achieve a result that visually is very difficult to separate from the archetype without close and thorough inspection.

As mentioned above the translucent wear layer is suitably constituted of melamine-formaldehyde resin / cellulose blend, high viscosity melamine- formaldehyde or one or more sheets of cellulose which are impregnated with melamine-formaldehyde resin. This wear layer is joined with the core and decor under heat and pressure whereby the resin cures. It is advantageous to add hard particles with an average particle size in the range 50 nm - 150 μm to the wear layer. Larger particles, in the range 10 μm - 150 μm, preferably 30 μm - 150 μm is foremost used to achieve abrasion resistance while the smaller of the particles, in the range 50 nm - 30 μm, preferably 50 nm - 10 μm, is used to achieve scratch resistance. The smaller particles is hereby used on, or very close to, the top surface while the larger particles may be distributed in the wear layer. Also here the particles advantageously are constituted of silicon carbide, silicon oxide, aluminium oxide. The wear layer is hereby suitably pressed together with the rest of the decorative laminate in a continuos belt press with two steel belts. It is also possible to utilise a discontinuous process where one or a number of surface elements can be pressed at the same time.

Claims

1. A process for the manufacturing of a decorative laminate having a base layer, a decorative layer and a wear layer wherein a decor is printed on a decor layer wherein the decor layer is constituted of paper which is impregnated with resin prior to the printing process, that a bonding layer is arranged between said base layer and said decor layer, that said wear layer constitutes an abrasion resistant layer which is arranged on top of the decor layer, said wear layer comprising resin and hard particles, wherein said layers are bonded together through means of heat and pressure.

2. A process according to claim 1 wherein the printed decor comprises a printing ink and wherein the wear layer comprises a thermosetting resin selected from the group consisting of; melamine-formaldehyde resin, phenol-formaldehyde resin, urea formaldehyde resin and mixtures thereof, whereby an amount of amino resin is mixed into the printing ink in order to increase the bond between the decor layer, printing ink and the wear layer whereby the layers are laminated together in a laminate press under increased temperature and pressure.

3. A process according to claim 1 wherein the printing ink is an alkyde based ink.

4. A process according to claim 1 wherein the printing ink is a polyester-acrylate based ink.

5. A process according to claim 3 or 4 wherein the amino resin is a etherified amino resin.

6. A process according to claim 3 or 4 wherein the amino resin is a methylol amino resin.

7. A process according to claim 1 wherein the main part of the base layer comprises a wood based board selected from the group consisting of a particle board, a fibre board and a oriented strand board.

8. A process according to claim 7 wherein the base layer further comprises a supporting paper layer arranged between the board and the decor layer.

9. A process according to claim 1 wherein the wear layer is comprised of a high viscosity amino resin applied on top of the decorative layer prior to the lamination.

10. A process according to claim 1 wherein the wear layer is comprised of an amino resin / cellulose mixture.

11. A process according to claim 1 wherein the wear layer is comprised of one or more amino resin impregnated cellulose layer or layers.

12. A process according to any of the claims 9 - 1 1 wherein the wear layer also comprises hard particles with an average particle size in the range 50nm - 150μm.

13. A process according to claim 12 wherein the upper portion of the wear layer is provided with hard particles with an average particle size in the range 50nm - 30μm while the inner portion of the wear layer is provided with hard particles with an average particle size in the range 31 μm - 150 μm.

14. A process according to claim 13 wherein the hard particles is selected from the group consisting of; silicon oxide, silicon carbide and aluminium oxide.

15. A process according to claim 1 wherein the wear layer is provided with a surface structure that enhances the realistic impression of the decor during or after the lamination.

16. A process according to claim 1 wherein the bonding layer comprises a thermosetting resin.

17. A process according to claim 16 wherein the thermosetting resin is selected from the group consisting of; melamine formaldehyde resin, phenol formaldehyde resin, urea formaldehyde resin and combinations thereof.

18. A process according to claim 1 wherein the bonding layer is comprises a thermoplastic resin. A process according to claim 18 wherein the thermoplastic resin is a polyurethane based hotmelt glue.