Method of Producing Decorative Paper and Decorative Laminate Comprising Such Decorative Paper

Abstract

The invention relates to a method of producing decorative paper which is coated with at least one ink-fixing layer, which is printable and which can be impregnated with a thermosetting resin, in order to produce a high- or low-pressure decorative laminate. The inventive method comprises the following steps consisting in: (a) producing a base sheet of decorative paper using paper-making means; and (b) coating at least one of the faces of the base paper sheet with said at least one ink-fixing layer, by means of curtain coating. The invention also relates to high- or low-pressure decorative laminates comprising such decorative paper.

Description

EXAMPLES OF EMBODIMENTS:

Comparative example 1: According to a usual paper-making process, a plain white decorative paper, well smoothed, having a grammage of 80 g/m², a Gurley porosity of 20 s, a Bekk gloss of 20 s and an ash content of 38%, was produced. Such a paper is marketed by company Arjowiggins under the trade name Arjosave. This paper was printed as it was by ink jet printing on an Epson® 7600 printer. Next, it was impregnated with a melamine-formaldehyde thermosetting resin and laminated to form a laminated panel of the low-pressure type.

Comparative example 2: This same Arjosave plain white decorative paper was coated by the blade coating process with 10 g/m² by dry weight of a layer C1 composed of 28.6 parts of a binder made of a mixture of an aqueous solution of hydrophilic polyvinyl alcohol (PVA) and a polyvinyl acetate in stabilized aqueous dispersion (called latex), in proportions of 85/15 by dry weight respectively, and 100 parts of a coating precipitated calcium carbonate (PCC) . This paper was printed by ink jet printing on an Epson® 7600 printer. It was then, as in example 1, impregnated with a melamine-formaldehyde thermosetting resin and laminated to form a low-pressure laminated panel.

Comparative example 3: This same Arjosave paper was coated by the blade process with 10 g/m² by dry weight of a layer C2 composed of 28.6 parts of the binder of example 2 and 100 parts of a coating silica (amorphous) having a mean particle size of 5.3-6.3 μm and a specific surface area (BET) of 160 m²/g. This paper, was then, as in the previous examples, printed by ink jet printing on an Epson® 7600 printer. It was then impregnated with a melamine-formaldehyde thermosetting resin and laminated to form a low-pressure laminated panel.

Example 4 according to the invention: A sheet of this same white plain white paper marketed by the company Arjowiggins under the trade name Arjosave was produced on a paper-making machine of the Fourdrinier type. The sheet, after drying, had a grammage of 80 g/m², a Gurley porosity of 20 s, a Bekk gloss of 20 s and an ash content of 38%.

The sheet of paper thus obtained was reeled up.

In a second step, this paper is then coated by the curtain coating process on one of its faces with 10 g/m² by dry weight of a layer C2 identical to the one used in example 3.

The sheet of paper thus coated was printed by ink, jet printing on an Epson® 7600 printer.

The sheet was then impregnated with a melamine-formaldehyde resin in an aqueous medium.

This sheet was laminated to produce a low-pressure laminate according to the usual operating conditions.

Comparative example 5 (Reference Printing base): According to usual paper-making process, an unsmoothed plain white decorative paper was produced having a grammage of 80 g/m², a Gurley porosity of 20 s, a Bekk gloss of 140 s and an ash content of 38%. Such a paper is marketed by the company Arjowiggins under the trade name Arjoprint. This paper is printed by ink, jet printing on an Epson® 7600 printer. Next, it was, as in the previous examples, impregnated with a melamine-formaldehyde thermosetting resin and laminated to form a laminated panel of the low-pressure type.

Comparative example 6: This same Arjoprint paper is coated according to the blade process with 10 g/M² of the C2 layer identical to that used in example 3. It was then, as in example 5, printed and then impregnated with a melamine-formaldehyde thermosetting resin and laminated to form a low-pressure laminated panel.

Example 7 according to the invention:

A sheet of this same plain white paper marketed by the company Arjowiggins under the trade name Arjoprint was produced on a paper machine of the Fourdrinier type. The sheet, after drying, had a grammage of 80 g/m², a Gurley porosity of 20 s, a Bekk gloss of 140 s and an ash content of 38%.

The sheet of paper thus obtained was reeled up.

In a second step, the paper is coated by the curtain coating process on one of its faces with 10 g/m² by dry weight of a layer C2 identical to the one used in example 3.

The sheet of paper thus coated is printed by ink jet printing on an Epson® 7600 printer.

The sheet is then impregnated with a melamine-formaldehyde resin in an aqueous medium.

This sheet is laminated to produce a low-pressure laminate under the usual operating conditions.

Comparative example 8: This same Arjoprint paper is coated according to the blade process with 10 g/m² of a layer C3 composed of 28.6 parts of a polyvinyl acetate in the form of a latex and 100 parts of a coating silica (amorphous) having a mean particle size of 5.3-6.3 μm and a BET specific surface area of 160 m²/g. It is, as in example 6, printed and then impregnated with a melamine-formaldehyde thermosetting resin and laminated to form a low-pressure laminated panel.

The papers according to these examples were tested according to the tests described hereinafter and the results are given in table 1.

Results:

As can be seen in table 1, all the coated papers—represented by comparative examples 2, 3, 6 and 8 and examples 4 and 7 according to the invention—exhibited a very appreciable increase in ink intensity compared with the reference uncoated decorative papers, represented by example 1 in the case of a smoothed paper and by example 5 in the case of an unsmoothed paper.

It may be ascertained in view of the results given in table 1 that comparative examples 2, 3, 6 and 8 of coated papers had a very different performance from that of comparative examples 1 and 5 of reference uncoated papers in terms of resin-absorbtion capacity.

It should be noted that among all the coating tests, comparative example 2 exhibits a high degree of undercuring of the melamine-formaldehyde resin after lamination.

From example 8, it will be noted that the use of a layer of which the binder contained too much of non-hydrophilic binder (latex) resulted in a blistering phenomenon for the laminate, which is unacceptable.

The examples show that the invention makes it possible to obtain a decorative paper exhibiting at the same time an excellent aptitude for ink jet printing and good resin absorption, necessary for the subsequent impregnation of this type of paper.

The results of these tests show in addition that decorative papers derived from the process for producing decorative paper according to the invention (examples 4 and 7) carried out on a smoothed Arjosave substrate as well on a unsmoothed Arjoprint substrate, have at the same time a good aptitude for ink jet printing and good resin absorption according to the test described hereinafter.

In addition, the use of a non-hydrophilic polymer (of the latex type) mixed with a hydrophilic binder in the coating composition also proved to be possible, in proportions compatible with the requirements for impregnation and lamination of the coated sheet (absence of blistering).

Description of Tests and Conditions for Performing Same:

• • The grammage of the sheets was determined according to ISO standard 536 after conditioning according to ISO standard 187. It consisted of the grammage of the sheet treated with said pigmented composition but before impregnation with resin.
  • The air permeability, Gurley porosity method, was determined according to ISO standard 5636-5R (1990).
  • The impregnation speed is characterized by determining the time of penetration of the thermosetting resin through the sheet, this time being determined in the following manner:
    • a 56% by weight resin solution is prepared by dissolving the melamine-formaldehyde resin Madurit MW550 in powder form in distilled water heated to 45° C. The viscosity is adjusted so that it is of the order of 100 mPas (cps) at 20° C. on a Brookfield viscometer measured at 100 revolutions/min—shaft N°2,
    • the impregnation time of a sheet of paper is determined as follows:
      • two square (10×10 cm) samples are cut out per test; for testing each face, the face is referenced,
      • a watch-glass is filled with resin,
      • the paper square is deposited on the surface of the resin, with the face to be tested in contact therewith, and the chronometer is started at the same time,
      • the total strike-through time is noted which gives the penetration time of the resin.

The following tests were carried out on a particle panel onto which the decor film (sheet impregnated with resin) had been laminated:

• • The graphite test was carried out as follows: powdered graphite was mixed with oil so as to form a paste. This paste was spread over the visible face of the decor film. The panel was then cleaned with a damp sponge impregnated with a detergent. The cleaned surface was compared with a reference scale. The scale extended from 1 to 6, the lowest score being 1.

This graphite test made it possible to assess the porosity of the decor film after lamination and therefore its resistance to soiling. This property depends on several parameters including the degree of volatiles in the resin, the lamination, the decorative sheet.

	TABLE 1
	Resin impregnation	Lamination
			Total strike-through		Curing	Observations
	Coating	Printing	(seconds): coated	Porosity	of resin	Appearance
	process	reproduction	face/uncoated face	(graphite test)	(° C.)	of panel
Comparative	—	Very pale	8/6	3.5	3	Good
example 1
Comparative	Blade	Good	>240/15	4	4.5	Matt
example 2
Comparative	Blade	Good	>240/13	4.5	2.5	Good
example 3
Invention	Curtain	Good	65/7	4	2.5	Good
Example 4
Comparative	—	Very pale	6/6	4.5	3	Good
example 5
Comparative	Blade	Good	>240/10	5	2.5	Good
example 6
Invention	Curtain	Good	40/8	4	2.5	Good
Example 7
Comparative	Blade	Good	>240/13	4	2.5	Quite a
example 8						number of
						blisters

Claims

1. A process for producing a decorative paper coated with at least one ink-fixing layer, printable and that can be impregnated with a thermosetting resin, for a high- or low-pressure decorative laminate, comprising the following steps: a. a sheet of base decor paper is produced by paper making route, thenb. at least one of the faces of said sheet of base paper is coated by curtain coating with at least said ink-fixing layer.

2. The process as claimed in claim 1, wherein said ink-fixing layer is printable by ink-jet printing.

3. The process as claimed in claim 1, wherein the ink-fixing layer contains at least one hydrophilic binder.

4. The process as claimed in claim 3, wherein said layer contains, in addition to said hydrophilic binder, a non-hydrophilic polymeric binder in a ratio of hydrophilic binder/non-hydrophilic binder of at least 70/30 by dry weight.

5. The process as claimed in claim 3, wherein the hydrophilic binder is a polyvinyl alcohol (PVA).

6. The process as claimed in claim 1, wherein the layer is not alkaline, in particular it is free from carbonates and alkaline buffers.

7. The process as claimed in claim 1, wherein the layer contains coating fillers chosen substantially from silicas.

8. The process as claimed in claim 7, wherein said silicas are essentially precipitated amorphous silicas.

9. The process as claimed in claim 1, wherein the quantity of layer deposited is comprised between 4 and 20 g/m2, in particular between 6 and 15 g/m2 by dry weight.

10. The process as claimed in claim 1, wherein said process includes a printing step, in particular of a decorative pattern, of the paper sheet coated with at least one ink-fixing layer coming from step b of said process.

11. The process as claimed in claim 10, wherein said ink-fixing layer is printed by ink jet printing, in particular at high resolution.

12. A decorative paper printable or printed, in particular by ink jet printing, and that can be impregnated with a thermosetting resin, obtained according to the process for producing a decorative paper such as defined in claim 1.

13. A printable or printed decorative paper that can be impregnated with a thermosetting resin such as defined in claim 1 wherein it has a resin-impregnation speed of less than 100 seconds, whatever its face, said speed being characterized by determining the time of penetration of the thermosetting resin through the sheet, this time being determined in the following manner: a 56% by weight resin solution is prepared by dissolving the melamine-formaldehyde resin Madurit MW550 in powder form in distilled water heated to 45° C. The viscosity is adjusted so that it is of the order of 100 mPas at 20° C. on a Brookfield viscometer measured at 100 revolutions/min—shaft N°2,and the impregnation time of a sheet of paper is determined as follows:two square (10×10 cm) samples are cut out per test; for testing each face, the face is referenced,a watch-glass is filled with resin,the paper square is deposited on the surface of the resin, with the face to be tested in contact therewith, and the chronometer is started at the same time,the total strike-through time is noted which gives the penetration time of the resin.

14. The paper as claimed in claim 13, characterized in that wherein said speed of impregnation is less than or equal to 65 seconds.

15. A process for producing an impregnated decorative paper for decorative laminates, characterized in that wherein a printed decorative paper as defined in claim 10 is impregnated with a thermosetting resin.

16. The process as claimed in claim 15, wherein the thermosetting resin is chosen from melamine-formaldehyde resins, urea-formaldehyde resins, benzoguanamine-formaldehyde resins, unsaturated polyester resins and mixtures thereof.

17. A high- or low-pressure laminated decorative panel or profile, wherein it comprises, as a decorative paper, a decorative paper such as obtained or defined in claim 10.