EP4093617B1 - Wet palette for water-based paint - Google Patents

Description

TECHNICAL AREA

The present invention relates to a wet palette for water-based paint (hereinafter referred to as "wet palette") which aims to extend the life of a water-based paint during a painting session or between painting sessions.

TECHNOLOGICAL BACKGROUND

In general, a wet palette comprises a box containing a foam or sponge saturated with water which, by capillarity, passes through a sheet of paper, for example greaseproof paper, on which a paint is positioned. The paint is then kept wet "in the open" during the painting session but also between painting sessions with a lid. Such a solution, in accordance with the preamble of claim 1, is for example described in the American patent US 5,715,933 A or in the US patent US 6,302,267 B1 .

The US patent US 3,874,499 A described, with reference to its figures 1 to 8, various embodiments of an artist's palette that maintains water-based paints in a fresh and usable condition during use or storage. The palette includes a palette surface that provides a controlled amount of moisture to paints applied thereto. A specific structure is provided that includes a palette base member having a textured surface, supplied with water by a reservoir positioned above the textured surface, and a cover sheet covering a majority of the textured surface. The cover sheet has an absorbent lower side positioned in contact with the textured surface, and a treated upper side that is permeable to water but substantially impermeable to pigments of water-based paints applied to the cover sheet. Water supplied to the textured surface by the reservoir passes by capillary action from the textured surface to the cover sheet and permeates the cover sheet to maintain a moisture level of the water-based paints. The cover sheet covering may in particular consist of a permeable and water-resistant wallpaper, the upper surface of which is treated with a water-permeable material preventing the permeation of pigments contained in water-based paints. In this case, an aqueous latex-based polymer emulsion is used to treat the upper surface of the covering sheet, which emulsion is applied in liquid form in order to form, after drying, a uniform layer on the upper surface of the covering sheet.

The solution described with reference to the figures 1 to 8 of the US patent US 3,874,499 A is therefore not based on the use of a wet palette comprising a water-retaining structure which is arranged in a container filled with water and which soaks up and moistens on contact with water, but on the use of a reservoir which must continuously supply water to the textured surface. This configuration is not suitable since the water supply to the entire textured surface cannot be ensured uniformly. This solution also requires that the covering sheet made of wallpaper be pre-moistened before being placed on the textured surface, in particular by saturating the covering sheet with water on both sides using a damp sponge or by passing it under a tap. The configuration of this palette is thus made more complex and its use more tedious and less than optimal.

The US patent US 3,874,499 A also describes, with reference to its figure 9, another embodiment of an artist's palette which does not require a reservoir supplying a textured surface at the base of the covering sheet. According to this other embodiment, the reservoir and the textured surface are replaced by a water-retaining base structure, formed of a rigid water-absorbent material, which base structure is treated or coated on its bottom and its side edges with a water-impermeable material in order to contain the water within the base structure. This other palette is used by pre-supplying water to the base structure, through its upper face, and distributing the water within the base structure, before applying the pre-moistened covering sheet to the upper face of the base structure.

The solution described with reference to Figure 9 of the US patent US 3,874,499 A is therefore not based on the use of a wet pallet comprising a water-retaining structure which is placed in a container filled with water and which becomes impregnated and moistened on contact with water, but on the use of a basic structure combining the functions of container and water-retaining structure. Such a basic structure, which is rigid moreover, turns out in practice to be too complex and expensive to produce, which is not desirable, especially since it is necessary to replace the water-retaining structure periodically.

The use of wallpaper as described in the US patent US 3,874,499 A proves in any event to be unsuitable in practice, this type of paper having too high a grammage typically exceeding 120 g/m2 and possibly approaching or even exceeding 200 g/m2. As explained above, the use of such wallpaper therefore requires that the covering sheet be previously moistened and saturated with water before the paint can be applied to the surface of this covering sheet, which makes its application difficult in practice.

The problems of state-of-the-art solutions involving water-permeable paper are multiple and depend on the papers used, which may have one or more of these defects. Laying the paper on the wet surface is difficult and very often the sheet of paper curls because the paper fibers in contact with the water relax.

Furthermore, relatively fragile, the paper ends up degrading to the point of forming small pieces of paper, like fine dust.

Depending on the paint, especially for very thin paint, "stirring" the paint causes it to penetrate the paper, which has the effect of staining the wet layer. In addition to losing paint, the sponge or foam is stained and the paper being slightly transparent, the work surface is therefore partially soiled and becomes unusable, making the paper difficult to clean and reuse. These papers therefore lead to overconsumption of paint, difficulty in cleaning and reusing these papers, and degradation of the sponges and foams.

Depending on the papers used, especially greaseproof papers, paint or water tends to pool on the surface, making mixing and palette use difficult. This is due to too low a surface energy.

STATEMENT OF THE INVENTION

An object of the present invention is to provide a wet palette capable of keeping paint wet for as long as possible during a painting session and also between painting sessions.

Another object of the present invention is to prevent the sheet of paper used as a humidifying support from deteriorating, which would impair the quality of the painting.

Yet another aim of the invention is to prevent the paint and the pigments contained in the paint (particularly the finest ones) from penetrating into the sheet of paper, so as to make it more robust in use, or even to allow and facilitate its cleaning, if necessary, and its reuse in the best conditions.

An additional aim of the invention is to provide a wet palette which also allows thin layers of paint to be worked.

According to the invention as defined in claim 1, the wet palette for water-based paint comprises a flat container having a peripheral rim and which, in its operational state, contains water, a water-retaining structure, preferably a sponge or foam, which water-retaining structure is disposed in the flat container and arranged to soak up and moisten by contact with and absorption of the water contained in the flat container, and a sheet of water-permeable paper, positioned on the water-retaining structure, and which, in its operational state, is in contact with water-based paint applied to an upper face of the sheet of paper. A cover may be attached and placed on the flat container, thereby enclosing the water-retaining structure as well as the sheet of paper in order to preserve the paint between various painting sessions.

According to the invention, the sheet of paper is a sheet of one-sided coated paper - or "C1S" paper ("coated one side" in English terminology) - which is resistant to wet conditions ("WW"), paper which is normally used for labelling, in particular of glass or metal containers, and whose upper, coated face is used, in its operational state, as a support for the application of water-based paint.

Various papers are commercially available which have, in particular, varying degrees of water absorption and wet strength (WSR). The Applicant has carried out multiple tests in this regard using various types of papers, and wet strength (WSR) single-side coated (C1S) papers prove to be optimal candidates for application in the context of the invention due in particular to their good water absorption capacity (on the uncoated side), their good wet strength (WSR), the adequacy of the level of water permeability of the coating, and their good degree of impermeability to pigments usually contained in water-based paints. As mentioned above, wet strength (WSR) single-side coated (C1S) papers are usually used for labeling operations, in particular for glass or metal containers, for example for labeling glass bottles. In this context, the underside of these coated papers is normally not exposed to the environment, but typically coated with an adhesive allowing the application and adhesion of the paper to the container in order to form labels. To the knowledge of the Applicant, the use of this particular type of papers in the context of a wet pallet, namely as a humidifying support, has not been envisaged until now, much less described or suggested in the state of the art.

According to the invention, the single-sided coated paper sheet (C1S) is more particularly a sheet of machine-coated paper, or "MFC" paper ("Machine Finished Coated" in English terminology) or a sheet of chrome-coated paper, or "cast coated" paper, namely a paper whose coating is carried out using a polished chrome cylinder which gives the coating greater shine and a smooth surface.

In a preferred embodiment, the single-sided coated paper sheet (C1S) has a grammage defined according to the ISO 536 standard which is between 30 g/m ² and 100 g/m ² , preferably between 50 g/m ² and 100 g/m ² .

Wet strength (WSR) can be imparted to paper during its manufacture by the addition of reinforcing fibres or by appropriate treatment which prevents the paper sheet from tearing and disintegrating in water.

In one embodiment, the single-sided coated paper sheet (C1S) is preferably a wood-free paper sheet, which helps prevent any yellowing of the paper.

According to the invention, the single-sided coated paper sheet (C1S) has a COBB60 absorption index measured according to the ISO 535 standard on its lower face which is between 10 g/m ² and 25 g/m ² , as well as a dry tensile strength measured according to the ISO 1924-2 standard which is between 50 N/15mm and 100 N/15mm.

In one embodiment, the water-retaining structure is a smooth foam or sponge, especially a polyvinyl alcohol (PVA) foam or a polyurethane foam, which has the required characteristics such as high absorption capacity, the smooth surface limiting the development of mold.

The wet palette according to the invention can be used equally well with acrylic paint, gouache or any other type of water-based paint, such as watercolor.

Also claimed as independent claim 8 is the use of a wet strength (WSR) single-sided coated paper sheet (C1S), namely a machine coated paper sheet (MFC) or a chrome coated paper sheet, as a moistening support for a wet palette for water-based paint, the coated face of said single-sided coated paper sheet being used, in its operational state, as a support for the application of a water-based paint, in particular acrylic paint, gouache, or watercolor, the single-sided coated paper sheet (C1S) having a COBB60 absorption index measured according to ISO 535 on its lower face side which is between 10 g/m ² and 25 g/m ² , as well as a dry tensile strength measured according to ISO 1924-2 which is between 50 N/15mm and 100 N/15mm. This single-sided coated paper sheet (C1S) may preferably have the additional characteristics listed above.

• verser de l'eau dans le contenant plat puis disposer la structure rétentrice de l'eau dans le contenant plat, ou inversement, la structure rétentrice s'imprégnant et s'humidifiant par le contact et l'absorption de l'eau contenue dans le contenant plat ;
• disposer la feuille de papier perméable à l'eau sur ladite structure rétentrice de sorte que la face supérieure, couchée de la feuille de papier soit exploitée comme support pour l'application de peinture à l'eau ; et
• appliquer la peinture à l'eau sur la couche supérieure, couchée de la feuille de papier.

The invention also relates, according to claim 13, to a method of implementing the wet palette for water-based paint according to the invention, comprising the following steps:

• pouring water into the flat container and then placing the water-retaining structure in the flat container, or vice versa, the water-retaining structure becoming impregnated and moistened by contact with and absorption of the water contained in the flat container;
• arranging the water-permeable paper sheet on said retaining structure so that the upper, coated face of the paper sheet is used as a support for the application of water-based paint; and
• apply the water-based paint to the top, coated layer of the sheet of paper.

Other aspects of the invention are set forth in the remainder of this description.

SUMMARY DESCRIPTION OF THE DRAWINGS

The features and advantages of the invention will become more clearly apparent from reading the following detailed description of embodiments of the invention, which are presented solely as non-limiting examples and are illustrated by the attached drawings in which the figure 1 represents an exploded view of a wet pallet according to the present invention.

METHODS OF CARRYING OUT THE INVENTION

As illustrated in the figure 1 , the wet pallet comprises a flat container 1 having a peripheral rim which, in its operational state, contains water 4. A water-retaining structure 2, preferably a sponge or flat foam, is placed in the flat container 1 to soak up and moisten by contact with and absorption of the water 4 contained in the flat container 1. A sheet of water-permeable paper 3 is positioned on the water-retaining structure 2. In the operational state of the pallet, the sheet of paper 3 is in contact with a water-based paint 5, for example an acrylic paint, which is applied to the upper face of the sheet of paper 3. It will therefore be understood that the sheet of paper 3 here acts as a humidifying support making it possible to maintain the paint 5 in a moist state, while avoiding direct contamination by the paint 5 of the retaining structure 2.

According to the invention, the paper sheet 3 is a sheet of single-sided coated paper, or "C1S" paper, which is wet-strength ("WSR"), the coated upper face of which is used, in its operational state, as a support for the application of the water-based paint 5. As already mentioned, this particular type of paper is known and available on the market, however for a completely different application, namely the labeling of glass or metal containers, in particular glass bottles. The use of such a wet-strength (WSR) single-sided coated paper (C1S) as a moistening support for a wet palette has not, to the knowledge of the Applicant, been previously described or suggested in the state of the art.

In the example illustrated, it will be understood that the retention structure 2 is saturated with water 4 by capillarity, and that the water passes through the sheet of paper 3 and hydrates the paint 5, here of the acrylic type. The paint is therefore kept wet in the “open air” during the painting session, which allows it to be used beyond a few hours.

The use, according to the invention, of a sheet of one-sided coated paper (C1S) resistant to wet conditions (REH) as a humidifying support for the wet palette offers the advantage that the sheet of paper 3 has a coating, on its upper face, intended to receive the water-based paint 5 and whose water permeability is comparatively lower than the water permeability of the base of the sheet of paper 3 which is positioned in contact with the retention structure 2. In addition, the coating offers a good degree of impermeability to the pigments contained in the water-based paint 5. This therefore results in a directional structure which ensures, on the one hand, good humidification of the paint 5 and prevents, on the other hand, the penetration of the pigments contained in the paint 5 into the sheet of paper 3, thus preventing the soiling of this sheet of paper 3 and of the retention structure 2 located below.

It turns out that the wet strength (WSR) single-sided coated paper (C1S) is particularly suitable since it also allows for possible cleaning of the upper side of the sheet of paper 3 at the end of the painting session, and therefore reuse of the sheet of paper 3, thereby increasing the service life of the sheet of paper 3.

Preferably, the paper sheet 3 has a permeability at the coating level allowing to work with paints 5 with very fine particles and pigments. In this context, the coating can in particular have a microporous structure which makes it possible to limit the absorption of the paint 5 and the pigments in the paper, while allowing moisture to pass through.

Ideally, Paper Sheet 3 has a wet opacity (measured according to ISO 2471) that is greater than 80% so that moisture does not adversely affect the visual appearance of Paper Sheet 3.

The retaining structure 2 may advantageously be a smooth foam or sponge, in particular a polyvinyl alcohol (PVA) foam or a polyurethane foam, limiting the development of mold. An antifungal treatment of the sheet of paper 3 is in this regard also possible, or even appropriate.

The retaining structure 2 and the sheet of paper 3 preferably have identical shapes. In particular, the retaining structure 2 and the sheet of paper 3 can be advantageously embossed so as to create moisturizing basins arranged to receive a paint 5, in particular liquid.

In contact with water, ordinary paper relaxes and warps. It becomes relatively fragile and crumbles over time. Small pieces of paper can end up in the paint. The sheet of paper 3 according to the invention makes it possible to avoid these drawbacks. A thin, uncoated sheet of paper would in particular allow paint to penetrate, which would damage the retention structure. According to the invention, the sheet 3 is made of wet strength paper (WSR) in order to prevent the sheet of paper 3 from tearing and disintegrating in water, which would make it unusable. This wet strength (WSR) can be achieved during the manufacture of the paper by incorporating reinforcing fibers, for example synthetic, or by adding additives of the polyamide-amine-epichlorohydrin (PAE) type.

It is advantageous to use paper whose grammage (defined according to the ISO 536 standard) is between 30 g/m ² , or even 50 g/m ² , and 100 g/m ² , depending on the paint 5 used. The upper face of the sheet of paper 3 is also printable, which allows in particular the possible printing of guides or charts.

According to the invention, the single-sided coated paper sheet (C1S) has a COBB60 absorption index (measured according to ISO 535) on its lower, uncoated side, which is between 10 g/m ² and 25 g/m ² , as well as a dry tensile strength (measured according to ISO 1924-2) which is between 50 N/15mm and 100 N/15mm.

The single-sided coated paper sheet (C1S) may more particularly be, in a first variant, a machine-coated paper sheet, or "MFC" paper ("Machine Finished Coated" in English terminology). An example of such a machine-coated paper is for example marketed by the company Feldmuehle GmbH (www.feldmuehle-uetersen.com) under the name SaxaSet ^® with a grammage of 70, 75 or 80 g/m ² (SaxaSet ^® being a registered trademark of Feldmuehle GmbH).

The single-sided coated paper sheet (C1S) can alternatively be, in a second variant, a chrome-coated paper sheet, or "cast coated" in English terminology, namely a paper whose coating is carried out using a polished chrome cylinder which gives the coating a greater shine and a smooth surface. An example of such a chrome-coated paper is for example marketed by the company Zanders Paper GmbH (www.zanders.com) under the designation Chromolux ^® 900 E with a grammage of 80 or 90 g/m ² (Chromolux ^® being a registered trademark of Zanders Paper GmbH). This paper also has the advantage of being a wood-free paper, of high whiteness and good gloss on the coating side (i.e. a whiteness of around 89% according to ISO 2469 standard). and a gloss greater than 57% according to ISO 8254-2 standard), and which does not yellow and offers good robustness in use.

The above examples of wet strength (WSR) one-side coated papers (C1S) are given for illustrative purposes and other papers of similar categories (machine coated or chrome coated) could be used, particularly depending on the properties of the water-based paint 5 used.

Where appropriate, the lower face of the paper sheet 3 could be additionally treated or coated with a light coating in order to stabilize the paper sheet (and prevent, for example, the paper sheet 3 from rolling up on itself or stretching, in particular due to a differentiated absorption between the lower and upper faces) and/or in order to adjust the level of water absorption of the paper sheet 3.

Of course, the wet palette according to the invention can also include a cover or other similar element allowing the paint 5 to be hermetically sealed outside of painting session periods when the artist is not painting.

It will be generally understood that various modifications and/or improvements obvious to those skilled in the art may be made to the embodiments described in the present description without departing from the scope of the invention defined by the appended claims.

In particular, the sheet of paper 3 may optionally be treated or coated with a light coating on its lower face in order to adjust as needed the degree of water absorption of the sheet of paper 3 and therefore the degree of humidity of this sheet, without this affecting the properties of the coating applied to the upper face where the paint is applied.

Finally, although reference has been made to the use of acrylic paint, the wet palette according to the invention can be used in conjunction with any other type of water-based paint, including but not limited to gouache or watercolor.

Claims (13)

1. Wet palette for water-based paint including:

   - a flat container (1) having a peripheral rim and which, in its operational state, contains water (4);

   - a retaining structure (2) for the water (4), preferably a sponge or a foam, which retaining structure (2) is placed in the flat container (1) and arranged to become impregnated and moisten by contact and absorption of the water (4) contained in the flat container (1); and

   - a sheet of paper (3) permeable to the water (4), positioned on said retaining structure (2), and which, in its operational state, is in contact with water-based paint (5) applied to an upper side of the sheet of paper (3),

   characterized in that the sheet of paper (3) is a sheet of one-side coated (C1S) paper, which is wet-strengthened (REH), the coated upper side of which is exploited, in its operational state, as a support for the application of the water-based paint (5), the sheet of one-side coated (C1S) paper being a sheet of machine-finished coated (MFC) paper or a sheet of cast-coated paper,

   and in that the sheet of one-side coated (C1S) paper has a COBB60 absorption index measured according to ISO standard 535 on the side of its lower side which is between 10 g/m² and 25 g/m², as well as a dry tensile strength measured according to ISO standard 1924-2 which is between 50 N/15 mm and 100 N/15 mm.
2. Wet palette according to claim 1, characterized in that the sheet of one-side coated (C1S) paper has a grammage defined according to ISO standard 536 which is comprised between 30 g/m² and 100 g/m².
3. Wet palette according to claim 2, characterized in that the sheet of one-side coated (C1S) paper has a grammage defined according to ISO standard 536 which is comprised between 50 g/m² and 100 g/m².
4. Wet palette according to any one of the preceding claims, characterized in that the sheet of one-side coated (C1 S) paper is a sheet of wood-free paper.
5. Wet palette according to any one of the preceding claims, wherein the retaining structure (2) is a smooth foam or a smooth sponge, in particular a polyvinyl alcohol (PVA) foam or a polyurethane foam.
6. Wet palette according to claim 5, wherein the retaining structure (2) is a polyvinyl alcohol (PVA) foam or a polyurethane foam.
7. Wet palette according to any one of the preceding claims, further comprising a lid arranged to be placed on the flat container (1) and enclose the retaining structure (2) as well as the sheet of paper (3) to preserve the paint between various painting sessions.
8. Use of a sheet of one-side coated (C1S) paper, which is wet-strengthened (REH), namely a sheet of machine-finished coated (MFC) paper or a sheet of cast-coated paper, as moistening support (3) of a wet palette for water-based paint, the coated side of said sheet of one-side coated (C1S) paper being exploited, in its operational state, as a support for the application of water-based paint (5),
   the sheet of one-side coated (C1S) paper having a COBB60 absorption index measured according to ISO standard 535 on the side of its lower side which is between 10 g/m² and 25 g/m², as well as a dry tensile strength measured according to ISO standard 1924-2 which is between 50 N/15 mm and 100 N/15 mm.
9. Use according to claim 8, characterized in that the sheet of one-side coated (C1S) paper has a grammage defined according to the ISO standard 536 which is comprised between 30 g/m² and 100 g/m².
10. Use according to claim 9, characterized in that the sheet of one-side coated (C1S) paper has a grammage defined according to the ISO standard 536 which is comprised between 50 g/m² and 100 g/m².
11. Use according to any one of claims 8 to 10, characterized in that the sheet of one-side coated (C1S) paper is a sheet of wood-free paper.
12. Use according to any one of claims 8 to 11, for the application of acrylic paint, gouache, or watercolor.
13. A method of implementing a wet palette for water-based paint according to any one of claims 1 to 7, comprising the following steps:

    - pouring water (4) into the flat container (1) then placing the retaining structure (2) for the water (4) in the flat container (1), or vice versa, the retaining structure (2) becoming impregnated and moistening by the contact and absorption of the water (4) contained in the flat container (1);

    - placing the sheet of paper (3) permeable to the water (4) on said retaining structure (2) such that the coated upper side of the sheet of paper (3) is exploited as a support for the application of water-based paint (5); and

    - applying the water-based paint (5) on the coated upper side of the sheet of paper (3).

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