RU2671327C2 - Resin impregnated coated article with improved aesthetic properties - Google Patents

Abstract

FIELD: paint industry.SUBSTANCE: invention relates to a coated article, to a method for producing a coated article, and to an ink composition suitable for use in a method for producing a coated article. Coated article comprises a base layer, a coating layer comprising a resin composition, and an attenuation layer, containing at least one reducing agent capable of at least partially discoloring the resin composition. In this case, said coating layer is in contact with said attenuation layer.EFFECT: effective improvement of the aesthetic properties of resin impregnated papers is provided.16 cl, 2 dwg, 1 ex

Description

FIELD OF THE INVENTION

The present invention relates to a coated product with improved aesthetic properties, to a method for producing said coated article, and to a paint composition suitable for use in said method for producing said article.

BACKGROUND OF THE INVENTION

Resin-impregnated papers / thin sheets have been used for decades as coatings in the wood industry. To obtain laminated boards or panels (e.g. plywood), a resin-impregnated substrate (mainly paper or kraft paper) is attached to the board when heated and under pressure, when the resin melts, providing a strong bond between the board and the impregnated paper and form the desired plate surface. Such coated slabs are widely used for various purposes, such as concrete formwork, flooring, building materials, and in the furniture or automotive industries.

In order to create a specific surface pattern, such a pattern can be printed on paper before being impregnated with resin. The pattern can vary widely and can range from simple letters in the names of brands and company logos by means of text and pictograms to complex decorative patterns and photographic images (hereinafter referred to in general terms as “patterns”). After drawing on the plate, the drawing is coated with an impregnation resin. Hence the aesthetic appearance of the pattern depends on the transparency and color of the resin.

In particular, in cases where the pattern is printed with a light or white pigment, the color of the resin (mainly reddish brown), in particular when phenolic resin is used, can cause an undesirable change in the color of the pattern. This problem is even more serious if the resin additionally contains dyes, colorants or pigments, such as iron oxide, carbon black.

An additional problem arises especially when using phenolic resins. Phenolic resins are the result of the interaction of phenol and formaldehyde, which takes place either under acidic or alkaline conditions. If a base-catalyzed mixture of phenol and formaldehyde contains one or more moles of formaldehyde per mole of phenol, a thermosetting resin (“resole”) is obtained. Such resins have a lack of aging, i.e. they darken when heated or cured otherwise. It is known that the degree of darkening depends on the curing temperature and the use of the resin and the exposure time at this temperature. After receiving the panels laminated with impregnated paper, the panels are still stacked hot and they retain a relatively high temperature for a long time (100 ° C and gradual decrease). Natural cooling of the panels is not uniform, i.e. the center of the panel and the center of the stack cool more slowly. This may result in an undesirable mottled or stained surface appearance of the impregnated product.

US Pat. No. 5,110,320 describes the use of an ammonium salt in a resin to reduce the darkening of a resol. Another known method of imparting color stability to phenolic resols comprises introducing a melamine formaldehyde resin into a formulation. Although this can give an improvement in aesthetic properties, it gives brittleness, increases the curing time and degrades the mechanical properties of the product.

Hence, there is still a need for an effective way to improve or maintain the aesthetic properties of resin-impregnated papers. The aim of the present invention, therefore, is to provide a resin impregnated coated article and methods for its preparation which overcome at least one of the above disadvantages.

SUMMARY OF THE INVENTION

This problem is solved by providing a coated product according to claim 1 of the claims and a method for producing such a product. Certain embodiments of the invention are the subject of other independent or dependent claims.

According to the present invention, there is provided a coated article that has at least three layers, namely, a first layer that is a base layer, another layer that contains resin (also called a “coating layer”), and a third layer comprising, according to at least one reducing agent. The reducing agent serves to bleach at least a portion of the resin. Said third layer is also called a “weakening layer."

Hence, the coated product according to the present invention contains at least three layers, namely:

a) the main layer

b) a layer containing resin, and

c) a layer containing a reducing agent,

moreover, the layer containing the reducing agent is in contact with the layer containing the resin.

The main aspect of the invention is the finding that the reducing agent eliminates at least partially the color of the resin (either the color of the resin itself, or the dyes or pigments contained therein). In addition, the reducing agent is able to counteract the darkening of the resin, regardless of its cause (for example, UV radiation or heating). In the context of the invention, this phenomenon is called “discoloration”, “color change” or “color exclusion”.

In one particular embodiment of the invention, the reducing agent may be incorporated into the ink used to print the pattern onto the base layer. The inventors were able to show that this does not adversely affect the printing method and print quality. Hence, the established materials, machines, and production methods can be applied in the method according to the present invention.

In this embodiment of the invention, at least one reducing agent comes into contact only with parts of the resin layer, namely, those parts of the resin layer that cover the pattern. Only such parts are discolored by the reducing agent, and the pattern retains its desired appearance. Hence, a particular advantage of this embodiment of the invention is that it provides spatially selective exclusion of the color of the resin layer. The color of the resin layer can be determined either by the color of the resin itself, or by the color of the dyes or pigments contained therein.

In another embodiment of the invention, the pattern may be printed on a base layer (e.g., paper), and then the reducing agent is applied to the printed pattern. Although this option requires an additional preparation step, it may be preferable in some cases, for example, if the paint and reducing agent are not compatible enough.

The attenuation layer is a reservoir for the reducing agent. The bleaching effect according to the present invention can thus be maintained for a long period of time due to the continuous diffusion of the reducing agent from the attenuation layer to the coating layer or to the coating layer.

According to one particular embodiment of the invention, the reducing agent is capable of reducing the dye contained in the impregnating resin and therefore discoloring it. In this embodiment, the reducing agent thus serves as a decolorizing agent. Agents for bleaching dyes during reduction are known to a specialist in wastewater treatment in the field of dye production for a long time. From here, the specialist can choose the appropriate reducing agent for the dye in the resin layer, which should be discolored.

In a particular embodiment of the present invention, the coated article consists of three layers with a layer of a paper substrate impregnated with phenolic resin. The paper is printed (for example, the company logo) with ink containing a decolorizing dye agent, before impregnation, forming as a result a weakening layer. This coated product can be successfully laminated onto slabs or panels.

DETAILED DESCRIPTION OF THE INVENTION

The base layer according to the present invention may be elastic or rigid. Most preferably, the base layer is paper, in particular kraft paper. The base layer may be applied to the substrate layer. The backing layer can be selected from the group consisting of cardboard, plywood, particle board (particle board), fiber board (oriented fiberboard) (OSB), glued wood, laminated veneer lumber ( (LSHPM) (LVL)), parallel strand lumber ((PSL) (PSL)) and oriented strand lumber ((PML) (OSL)). A particularly preferred substrate is plywood.

The reducing agent preferably has a standard electrode potential E ⁰ ranging from -150 to -1500 mV. In order to be able to restore the dye, the standard electrode potential of a reducing agent (a bleaching agent dye) has a more negative potential than the standard electrode potential. In a preferred embodiment of the invention, the difference between the standard electrode potentials of the reducing agent and the dye is more than 0.5 V, preferably more than 0.75 V, and more preferably more than 1.0 V.

The reducing agent is preferably selected from the group consisting of reducing sugars, hydrides, organic acids and inorganic salts or mixtures thereof.

In a preferred embodiment, the reducing agent is preferably selected from the group consisting of dihydroxyacetone, glycolaldehyde, glycerol aldehyde, erythrose, threose, ribose, arabinose, xylose, lyxose, allose, altrose, glucose, mannose, gulose, idose, galactose, , lactose, maltose, cellobiose, diborane, lithium aluminum hydride, sodium borohydride, lithium borohydride, SnCl ₂ , SnF ₂ , Sn (oH) ₂ , sodium dithionite (reducing index of color index 1), thiourea dioxide (reducing index of color index 11), sodium hydroxide ffinate (color index 2 reducing agent), color index 3 reducing agent, color 4 index reducing agent, color 5 index reducing agent, color 7 reducing agent, color 8 index reducing agent, zinc formaldehyde sulfoxylate (color index reducing agent 6), color index reducing agent 9, color index reducing agent 10 , calcium formaldehyde carboxylate (color index reductant 12), sodium sulfite, sodium bisulfite, diisobutylaluminum hydride, oxalic acid, formic acid, ascorbic acid, (NH ₄ ) ₂ HPO ₃ , CuHPO ₃ , SnHPO ₃ and Al ₂ ( HPO ₃ ) ₃ , potassium hypophosphite, FeCl ₂ , FeCO ₃ , FeSO ₄ , amides, such as urea, organic amines, such as hexa-methylenetetramine, or mixtures thereof. Reducing agents for bleaching individual dyes are discussed in Part 1 of the Color Index (2004, fourth edition, www.colour-index.com ), the contents of which are hereby intentionally incorporated by reference.

Particularly preferred reducing agents are fructose, sodium dithionite, tin chloride, iron (II) sulfate and borohydride. Fructose is the most preferred reducing agent.

In one embodiment of the invention, the dye in the resin is an organic polycyclic dye, an organic monoazo dye, an organic diazo dye, an organometallic complex, or an inorganic pigment such as an oxide or a metal complex. Dyes can be perinone, anthraquinone, complexes of azo-dyes and thioindigo.

In a preferred embodiment, the dye in the resin of the coating layer is selected from the group consisting of acid yellow 23, acid red 18, acid yellow 36, acid black 194, direct red 239, reactive red 120, acid blue 9, acid red 27, acid red 51 , direct blue 199, direct red 254, reactive red 195, acid red 14, acid yellow 17, acid black 1, direct yellow 86, direct black 168, food black 2.

In a most preferred embodiment, the dye in the resin of the coating layer is acid black 2 and direct red 254.

In a preferred embodiment, the coated article comprises a coating layer with a dye and a reducing agent in the attenuation layer, as noted in the table below. Such “fumes” of dye and reducing agent are particularly preferred for obtaining effective bleaching in areas where the coating layer is in direct contact with the attenuation layer.

Dye in coating layer Reducer in weakening layer

Direct red 254 SnCl ₂ , FeSO ₄ , sodium dithionite,

Fructose

Acid Black FeSO ₄ , Fructose

Indigo sodium dithionite, sodium hypochlorite,

potassium permanganate

C.I. straight red 80 sodium borohydride

C.I. dispersed red 60 sodium borohydride, sodium dithionite

C.I. dispersed blue 79 sodium borohydride, sodium dithionite

C.I. dispersed orange 62 sodium borohydride, sodium dithionite

Not an azo dye such as: sodium hydroxymethanesulfinate

Disperse Blue 250, 354,

364 or 366;

solvent purple 8;

solvent blue 43,

solvent blue 57,

Lumogen F Blau 650;

lumogen F purple 570

According to a preferred embodiment of the invention, the reducing agent is part of the paint used to apply the pattern to the base layer. In this embodiment, the paint layer thus serves as a weakening layer. Hence, the present invention also relates to a paint (also called a paint composition) containing at least one coloring agent (dye or pigment, both referred to as a dye, unless otherwise specified) and at least one reducing agent. The dye in the ink is preferably not discolored by the reducing agent, or at least less discolored than the dye in the resin.

In one embodiment of the invention, the paint contains 0.5-20% (w / w), preferably 2-15% (w / w), more preferably 7.5-12.5 (w / w). ), and even more preferably 10% (w / w) of at least one reducing agent.

The composition preferably has a dry matter content of from 50% wt. up to 60% wt., preferably 55% wt. In this embodiment, approximately 10% (w / w) of a reducing agent (e.g., fructose) is particularly preferred. Binder is preferably casein.

The pigment in the paint can be any color, for example, black, yellow, orange, red, violet, cyan, brown or white pigment, where white pigment is preferred.

A non-limiting example of a suitable inorganic black pigment includes carbon black. Examples of carbon black pigments include those produced by Mitsubishi Chemical Corporation, Japan (such as, for example, carbon black No. 2300, No. 900, MCF88, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100, or No. 2200B), various carbon black pigments of the RAVEN series manufactured by Columbian Chemicals Company, Marietta, Ga. (such as, for example, RAVEN 5750, RAVEN 5250, RAVEN 5000, RAVEN 3500, RAVEN 1255 or RAVEN 700); various carbon black pigments of the REGAL series, MOGUL series or MONARCH series manufactured by Cabot Corporation, Boston, Mass.) MA7, MA8, MA100 or No. 2200B), various carbon black pigments of the RAVEN series manufactured by Columbian Chemicals (such as REGAL 400R, REGAL 330R, REGAL 660R, MOGUL L, MONARCH 700, MONARCH 800, MONARCH 880, MONARCH 900, MONARCH 1000, MONARCH 1100, MONARCH 1300 or MONARCH 1400); or various black pigments manufactured by Evonik Degussa Corporation, Parsippany, Ryu York (such as, for example, Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color Black S150, Color Black S160, Color Black S170, PRINTEX 35, PRINTEX U, PRINTEX V, PRINTEX 140U, Special Black 5, Special Black 4A or Special Black 4). A non-limiting example of an organic black pigment includes a black amine such as C.I. Pigment Black 1.

Other examples of inorganic pigments include metal and ceramic oxides, such as iron, zinc, cobalt, manganese or nickel oxides. Non-limiting examples of suitable inorganic pigments include pigments from the Shepherd Color Company (Cincinnati, Ohio) such as black 10C909A, black 10P922, black 1G, black 20A944, black 30C933, black 30C940, black 30C965, black 376A, black 40P925, Black 411A, Black 430, Black 444, Cyan 10F545, Cyan 10G511, Cyan 10G551, Cyan 10K525, Cyan 10K579, Cyan 211, Cyan 212, Cyan 214, Cyan 30C527, Cyan 30C588, Cyan 30C591, Cyan 385, Cyan 40P585, Cyan 424 , brown 10C873, brown 10P835, brown 10P850, brown 10P857, brown 157, brown 20C819, s green 10К637, green 187В, green 223, green 260, green 30С612, green 30С654, green 30С678, green 40Р601, green 410, orange 10Р320, StarLight FL37, StarLight FL105, StarLight FL500, violet 11, violet 11С, violet 92, yellow 10Р112 , yellow 10С242, yellow 10С272, yellow 10Р110, yellow 10Р225, yellow 10Р270, yellow 196, yellow 20Р296, yellow 30С119, yellow 30С236, yellow 40Р140 or yellow 40Р280.

In addition to the above inorganic pigments, which may have their surfaces fluorinated, as indicated here, the same indications can be used with organic pigments. The following is a list of organic pigments that can be processed as described here.

Non-limiting examples of suitable yellow pigments include the following: C.I. pigment yellow 1, C.I. pigment yellow 2, C.I. pigment yellow 3, C.I. pigment yellow 4, C.I. pigment yellow 5, C.I. pigment yellow 6, C.I. pigment yellow 7, C.I. pigment yellow 10, C.I. pigment yellow 11, C.I. pigment yellow 12, C.I. pigment yellow 13, C.I. pigment yellow 14, C.I. pigment yellow 16, C.I. pigment yellow 17, C.I. pigment yellow 24, C.I. pigment yellow 34, C.I. pigment yellow 35, C.I. pigment yellow 37, C.I. pigment yellow 53, C.I. pigment yellow 55, C.I. pigment yellow 65, C.I. pigment yellow 73, C.I. pigment yellow 74, C.I. pigment yellow 75, C.I. pigment yellow 81, C.I. pigment yellow 83, C.I. pigment yellow 93, C.I. pigment yellow 94, C.I. pigment yellow 95, C.I. pigment yellow 97, C.I. pigment yellow 98, C.I. pigment yellow 99, C.I. pigment yellow 108, C.I. pigment yellow 109, C.I. pigment yellow 110, C.I. pigment yellow 113, C.I. pigment yellow 114, C.I. pigment yellow 117, C.I. pigment yellow 120, C.I. pigment yellow 124, C.I. pigment yellow 128, C.I. pigment yellow 129, C.I. pigment yellow 133, C.I. pigment yellow 138, C.I. pigment yellow 139, C.I. pigment yellow 147, C.I. pigment yellow 151, C.I. pigment yellow 153, C.I. pigment yellow 154, C.I. pigment yellow 155, C.I. pigment yellow 167, C.I. pigment yellow 172 or C.I. pigment yellow 180.

Non-limiting examples of suitable purple or red or purple pigments include the following:

C.I. pigment red 1, C.I. pigment red 2, C.I. pigment red 3, C.I. pigment red 4, C.I. pigment red 5, C.I. pigment red 6, C.I. pigment red 7, C.I. pigment red 8, C.I. pigment red 9, C.I. pigment red 10, C.I. pigment red 11, C.I. pigment red 12, C.I. pigment red 14, C.I. pigment red 15, C.I. pigment red 16, C.I. pigment red 17, C.I. pigment red 18, C.I. pigment red 19, C.I. pigment red 21, C.I. pigment red 22, C.I. pigment red 23, C.I. pigment red 30, C.I. pigment red 31, C.I. pigment red 32, C.I. pigment red 37, C.I. pigment red 38, C.I. pigment red 40, C.I. pigment red 41, C.I. pigment red 42, C.I. pigment red 48 (CA), C.I. pigment red 48 (Mn), C.I. pigment red 57 (CA), C.I. pigment red 57: 1, C.I. pigment red 88, C.I. pigment red 112, C.I. pigment red 114, C.I. pigment red 122, C.I. pigment red 123, C.I. pigment red 144, C.I. pigment red 146, C.I. pigment red 149, C.I. pigment red 150, C.I. pigment red 166, C.I. pigment red 168, C.I. pigment red 170, C.I. pigment red 171, C.I. pigment red 175, C.I. pigment red 176, C.I. pigment red 177, C.I. pigment red 178, C.I. pigment red 179, C.I. pigment red 184, C.I. pigment red 185, C.I. pigment red 187, C.I. pigment red 202, C.I. pigment red 209, C.I. pigment red 219, C.I. pigment red 224, C.I. pigment red 245,

C.I. pigment violet 19, C.I. pigment purple 23, C.I. pigment purple 32, C.I. pigment violet 33, C.I. pigment violet 36, C.I. pigment violet 38, C.I. pigment violet 43 or C.I. pigment violet 50.

Non-limiting examples of blue or can organic pigments include the following:

C.I. pigment blue 1, C.I. pigment blue 2, C.I. pigment blue 3, C.I. pigment blue 15, C.I. pigment blue 15: 3, C.I. pigment blue 15:34, C.I. pigment blue 15: 4, C.I. pigment blue 16, C.I. pigment blue 18, C.I. pigment blue 22, C.I. pigment blue 25, C.I. pigment blue 60, C.I. pigment blue 65, C.I. pigment blue 66, C.I. blue cubic pigment 4 or C.I. blue pigment 60.

Non-limiting examples of green organic pigments include the following:

C.I. green pigment 1, C.I. pigment green 2, C.I. pigment green 4, C.I. pigment green 7, C.I. pigment green 8, C.I. pigment green 10, C.I. pigment green 36 or C.I. pigment green 45.

Non-limiting examples of brown organic pigments include the following:

C.I. pigment brown 1, C.I. pigment brown 5, C.I. pigment brown 22, C.I. pigment brown 23, C.I. pigment brown 25 and C.I. pigment brown, C.I. pigment brown 41 or C.I. brown pigment 42.

Non-limiting examples of orange organic pigments include the following:

C.I. pigment orange 1, C.I. pigment orange 2, C.I. pigment orange 5, C.I. pigment orange 7, C.I. pigment orange 13, C.I. pigment orange 15, C.I. pigment orange 16, C.I. pigment orange 17, C.I. pigment orange 19, C.I. pigment orange 24, C.I. pigment orange 34, C.I. pigment orange 36, C.I. pigment orange 38, C.I. pigment orange 40, C.I. pigment orange 43 or C.I. pigment orange 66.

The white pigment of the paint composition may be selected from the group consisting of calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, white satin, aluminum silicate, diatomaceous earth, calcium silicate, silicate magnesium, synthetic amorphous silicon dioxide, colloidal silicon dioxide, colloidal aluminum oxide, pseudoboehmite, aluminum hydroxide, alumina, modified alumina, lithopone, zeolite, hydrated halloysite, magnesium carbonate, hydr ksida magnesium and mixtures thereof. In a preferred embodiment, the white pigment is zinc sulfide, titanium dioxide (including rutile titanium dioxide), or a mixture thereof. In a preferred embodiment, the white pigment is titanium dioxide.

The choice of dye depends on the application and the ink used, whether it is based on an aqueous solvent, or based on hot melt, and on the type of printer: flexography, continuous ink jet or drop as needed, piezo or thermal ink jet.

In a preferred embodiment, the dye is suitable for flexography.

In the paint composition of the present invention, the solvent may be an aqueous solvent.

Alternatively, a water-soluble organic solvent having the ability to dissolve the solute and preferably selected from water-soluble solvents having a lower vapor pressure than water can be used. Examples thereof include polyhydric alcohols, such as ethylene glycol, propylene glycol, butanediol, pentanediol, 2-butene-1,4-diol, 2-methyl-2,4-pentanediol, glycerol, 1,2,6-hexantryol, diethylene glycol and dipropylene glycol; ketones such as acetonylacetone; esters such as Ƴ-butyrolactone, diacetin and triethyl phosphate, lower alkoxy lower alcohols such as 2-methoxyethanol and 2-ethoxyethanol, furfuryl alcohol, tetrahydrofurfuryl alcohol and thiodiglycol. In addition, the solvents used here include not only solvents that are liquid at room temperature, but also solvents that are solid at room temperature and, when melted when heated, can act as a solvent, and solvents that when used in combination with an aqueous solution or other solvent (s) may act as a solvent. Although the amount of water-soluble organic solvent used may be suitably determined, it is preferable, for example, 5-50% by weight. in relation to the total weight of the paint.

According to a preferred embodiment of the present invention, the paint composition may further comprise an additional organic solvent. Examples of additional solvents used herein include imidazole, methylimidazole, hydroxyimidazole, triazole, hikotinamid, dimethylaminopyridine, ε-caprolactam, 1,3-dimethyl-2-imidazolidinone, lactamide, sulfolane, dimethyl sulfoxide, 1,3-propanesultone, methyl carbamate ethyl carbamate, 1-methylol-5,5-dimethylhydantone, hydroxyethyl piperazine, ethylene urea, propylene urea, ethylene carbonate, propylene carbonate, dimethyl sulfoxide, N-methyl-2-pyrrolidinone, 2-pyrrolidinone, acetamide, formamide, dimethyl dimethyl dimethyl dimethyl dimethyl diamide. The introduction of an organic solvent can prevent, for example, the formation of a precipitate at low temperature and provide printing that is stably carried out under such conditions.

If necessary, additives may be added to the paint composition. Examples of additives are permeability accelerators, viscosity modifiers, binders, surface tension modifiers, hydrotropic agents, moisturizers, pH adjusters, anti-lubricant additives, chelating agents, preservatives and corrosion protection additives.

When the ink is used in a printing method in which the ink is charged, a resistivity modifier selected from inorganic salts such as lithium chloride, sodium chloride and ammonium chloride can be introduced.

Examples of suitable binders include aqueous dispersions of aromatic or aliphatic polyurethanes, proteins such as casein or casein derivatives, polyvinyl alcohols or polyvinyl alcohol derivatives, polymers or copolymers of acrylic acid or acrylic acid derivatives, such as, for example, acrylates, a poly (vinyl chloride copolymer) ) / poly- (vinyl acetate), polystyrene acrylate, maleic resin, rubber resin, phenolic resin, silicone resin, heat-drying linseed oil, oligomeric carbohydrates such as dextrin, natural rubber, gum arabic, shellac and cellulose derivatives. Casein and casein derivatives are particularly preferred. However, one skilled in the art makes a suitable choice of binders possible in principle.

Permeation accelerators used herein include lower alcohols such as ethanol, isopropanol, butanol and pentanol; cellosolves such as ethylene glycol monobutyl ether; carbitols, such as dylene glycol monobutyl ether; simple triethylene glycol monobutyl ether; and surfactants.

Surface tension modifiers used herein include diethanolamine, triethanolamine, alcohols such as glycerol and diethylene glycol, and nonionic, cationic, anionic or amphoteric surfactants.

Preferred hydrotropic agents used herein include urea, alkyl ureas, ethylene urea, propylene urea, thiourea, guanidine acid salts and tetraalkylammonium halides.

Humidifiers can also affect other properties of the ink composition and printed images made with it, such as viscosity, pH, surface tension, optical density and print quality. Such humectants typically include ethylene glycol, propylene glycol, diethylene glycols, glycerin, dipropylene glycols, polyethylene glycols, polypropylene glycols, alkanediols, amides, ethers, carboxylic acids, esters, alcohols, organosulphides, organosulphoxides, sulfones, derivatives of pyrrolides esters, amino alcohols and ketones. The amount of a particular additive varies depending on a number of factors, including the molecular weight of the pigment or dye, viscosity, the amount of any salt added, and the nature of the pigment or dye.

The paint composition of the invention contains the specified unlimited number of options.

Option 1

In one embodiment, the paint composition according to the present invention contains or consists of

5-20% (w / w) binder,

5-25% (w / w) dye / pigment,

1-15% (w / w) of one or more additives (optional),

0.5-20% (w / w) of a reducing agent.

The solvent may be, for example, water or alcohol, or a mixture thereof.

In one embodiment of the invention, the paint composition, as described above, contains 5-15% (w / w), more preferably about 10% (w / w). The binder is preferably casein and the reducing agent is reducing sugar, most preferably fructose.

Option 2

In yet another embodiment, the paint composition according to the present invention contains or consists of

2-30% (wt./wt.), More specifically, 5-20% wt. binder

30-70% (wt./wt.) Dye / pigment,

1-3% (w / w) of one or more additives (optional),

0.5-20% (w / w) of a reducing agent.

The solvent may be, for example, water or alcohol, or a mixture thereof.

The paint composition, as described above, contains 5-15% (w / w), more preferably about 10% (w / w). The binder is preferably casein and the reducing agent is reducing sugar, most preferably fructose.

Option 3

In yet another embodiment, the paint composition according to the present invention contains or consists of

2-6% (w / w) of the dye, preferably an acidic or direct dye,

5-15% (w / w) humidifier,

0.2-0.8% (w / w) of the first additive, for example, a surface tension modifier, such as triethanolamine,

0.05-0.2% (w / w) of one or more other additives, for example, a preservative or biocide,

0.5-20% (w / w) of a reducing agent.

The solvent may be water or an organic solvent, such as N-methyl-2-pyrrolidone or a mixture thereof.

The paint composition, as described above, may contain, for example, 5-15% (w / w), more preferably about 10% (w / w). The binder is preferably casein and the reducing agent is reducing sugar, most preferably fructose.

Option 4

In yet another embodiment, the paint composition according to the present invention contains or consists of

2-6% (w / w) dye / pigment,

5-15% (w / w) of one or more additives,

2.5-7.5% (w / w) of a binder, for example, a poly (vinyl chloride) / polyvinyl acetate copolymer,

0.5-20% (w / w) of a reducing agent.

The solvent may be non-aqueous, for example methyl ethyl ketone.

The paint composition, as described above, may contain, for example, 5-15% (w / w), more preferably about 10% (w / w). The binder is preferably casein and the reducing agent is reducing sugar, most preferably fructose.

Paint compositions are generally known to those skilled in the art, for example, from “Industrial Dyes”, 2003, K. Hunger (publisher), Wiley-VCH, chapter 5.6 “Ink dyes”, the contents of which are intentionally incorporated herein by reference, or from WO 2006 / 005513A1. In order to obtain a paint composition, as in the invention, the reducing agent can be mixed and / or dispersed with / in well-known paint compositions.

According to the present invention, well-known or unknown curable resins can be used to form a coating layer. In particular, the resin may be selected from the group consisting of phenol-formaldehyde resins, amino resins such as urea-formaldehyde and melamine-formaldehyde resins, epoxy resins, vinyl ester resins and polyester resins or mixtures thereof. In a particularly preferred embodiment, the resin comprises phenolic resins. In a most preferred embodiment, the resin in the coating layer consists only of a phenolic resin.

Resins can be modified or unmodified resins. Amino resins can be modified, for example, with glycol, caprolactam, acetoguanamine, benzoguanamine or para-toluenesulfonamide, during alkylation or esterification. Phenol-formaldehyde resins can be modified, for example, with urea, melamine, lignin, resorcinol, modified phenols, cresols, bisphenols, or other equivalent compounds. Any amino and phenolic resins known to those skilled in the art can be used as amino and phenolic resins. By combining various types of resins, for example phenolic resins and amino resins, together in a suitable ratio, the properties of the coating can be improved or optimized. In a resin mixture, any solvent in which the resin dissolves can be used as a resin solvent.

The resinous coating composition (also called the "resin composition") forming the coating layer may contain about 0.01-5 wt.%, More preferably about 0.02-3 wt.%, And most preferably about 1% wt. . dye A, and the preferred dose for direct red 254 is 0.2% wt., and for acid black 2-1.5% wt. Possible and preferred colorants have been indicated above.

The coating composition may further contain additives, for example, waxes, surfactants, softeners, hardeners, wetting agents, antifoam agents, diluents and / or alkalis. Preferred hardeners are sulfamic acid, ethanolamine hydrochloride, triethanolammonium sulfate, or combinations of hardeners, such as morpholine / para-toluene-sulfonic acid, N-methylethanolamine / SO ₂ or N-methyl-ethanolamine / ethanolamine / SO ₂ . Hardeners can be introduced during the impregnation process in amounts of 0.1-3% wt. Surfactants can be, for example, ethoxylated fatty acids or alkyl phenol ethoxylates, which can be used in amounts in the range of 0.2-1.0% by weight. Typical separating agents may be wax emulsions in amounts in the range of 0.2-2.0% by weight. Possible defoamers can be low-foaming combinations of special surfactants in amounts in the range of 0.2-1.0% wt.

The yield values of the resin compositions can vary from 2 to 20% and, preferably, from 4 to 8%, which can be achieved using modifiers. Such modifiers can be (but not limited to) di- and polyols, poly- (ether) diols and alkoxylated alcohols. Alkoxylated alcohols contain methoxylated, ethoxylated and propoxylated alcohols, diols and polyols. Preferred compounds belong to the group of C ₂ -C ₁₂ diols, such as 1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol. These diols, preferably, can be introduced in an amount of 8-20 m.h. per 100 m.h. pitches.

An ammonium salt may be introduced into the resin composition, in particular containing a phenolic resin. Preferred ammonium salts include ammonium aluminum hexafluoride, ammonium borhexafluoride, ammonium chloride, ammonium phosphate and ammonium citrate. Suitable ammonium-containing stabilizers are discussed in US 5110320, the contents of which are therefore given in its entirety. Particularly preferred stabilizers are ammonium aluminum hexafluoride, ammonium borhexafluoride, ammonium chloride, ammonium phosphate and ammonium citrate.

Preferably, phenol-formaldehyde resin is used to form a coating layer. By varying the type of catalyst and the molar ratio of formaldehyde (F) and phenol (P), two classes of PF resins can be synthesized: resoles and novolaks. Resoles are synthesized under alkaline conditions with an excess of formaldehyde (i.e., F / P> 1); novolacs are synthesized under acidic conditions with an excess of phenol (i.e., F / P <1).

In a first embodiment of the invention, said resin is novolak. Novolak is a phenolic resin, which by its nature is not reactive. It is obtained by the interaction of phenol with formaldehyde under acidic conditions with a molar ratio of formaldehyde / phenol below 1: 1, in particular, with a molar ratio of 0.75: 1 to 0.85: 1. This can give a linear polymer with a molecular weight of 1000-1500. Additional crosslinking may occur with the introduction of more formaldehyde, usually in the form of hexamine.

In yet another preferred embodiment of the invention, the resin is a resol, which is formed by the base-catalyzed reaction of phenol and formaldehyde and requires an excess of formaldehyde. For a resin solution, they interact at a low molecular weight of 300-700, so that the polymer is still soluble. Additional heating causes condensation reactions and gives a high molecular weight crosslinked polymer.

In a preferred embodiment, the rezol resin used for the coating layer has a molar formaldehyde / phenol ratio of from 1.6 to 2.5 and / or alkalinity in the range of 1.5-3%. The resol may contain well-known additives, such as, for example, urea or glycols.

As noted above, the base layer is preferably paper, most preferably kraft paper. The paper may have a weight of 20-150 g / m ² , preferably 30-80 g / m ² .

The impregnated paper can then be attached under pressure and when heated to a panel or board in order to provide a coated board or coated panel. In this embodiment, the plate or panel serves as a backing layer. Possible backing layers coated with impregnated paper according to the present invention are plywood, particle board, fiber board, oriented strand board ((OSB)), glued wood, laminated veneer lumber ((LSL) (LVL) ), parallel strand lumber ((ППСС) (PSL)) and oriented strand lumber ((ППСО) (OSL)). The most preferred option is a plywood panel. Covered slab or panel can be used in the woodworking industry, in particular, in the construction industry for concrete formwork.

In a particularly preferred embodiment of the invention, the coated article comprises the following structures; preferably, it consists of such structures:

a) a substrate layer, most preferably plywood;

b) paper with a printed ink composition containing one or more reducing agents;

c) a resin-containing coating layer covering at least partially the base layer.

Hence, in this embodiment, the coated article contains at least or consists of four layers: a substrate layer, paper, a weakening layer formed by printing ink, and a coating layer. The attenuation layer is in contact with the coating layer.

In yet another aspect of the invention, the use of a paint composition comprising a first dye or pigment and one or more reducing agents is provided to discolor the second dye in the resin composition, while the reducing agent is not affected or has little effect on the first dye or pigment.

In a preferred embodiment, the coloring matter of the paint does not substantially interfere with the reducing agent (s) in the paint. However, the reducing agent is still capable of reducing the coloring matter that is present in the coating layer.

In yet another aspect of the invention, there is provided a method for producing a coated article according to the present invention, which comprises the following steps:

i. providing a base layer, in particular paper;

ii. printing a pattern on a base layer with applying a paint composition with one or more reducing agents to said base layer;

iii. impregnating said base layer with a resin containing coating composition and

iv. optionally laminating said impregnated base layer onto a substrate layer.

The impregnation of the base layer can be carried out by traditional technology known to a person skilled in the art, for example, using bathtubs, rolls, doctor blades, air knife, metering roller, doctor blade or other. The resin compositions can be applied in one or more stages with drying and / or partial curing between the stages of application.

Coated products according to the present invention are described using the following illustrative drawings and examples, which should not be interpreted as limiting the scope of protection.

Description of drawings

The figure 1 shows schematically the structure of a coated product containing the layer (1) of the substrate, the main layer (2), the weakening layer (4) and the coating layer (3).

2 is a diagram showing a mechanistic principle. The starting point of the reaction is shown above. Coated product with uniformly distributed dye or pigment. Due to the reducing agent contained in the underlying attenuation layer, the coating layer is discolored only in areas adjacent to the attenuation layer.

Example 1

1. Printing on kraft paper

Kraft paper is printed using ink WM1A-002H (Woodline, Flint Group, Finland) having a viscosity of 14 s (measured according to DIN 4), which is equivalent to a viscosity of approximately 28 mPas. The rate of application of liquid paint is approximately 11 g / m ² . A well-known printing ink (such as, for example, known from WO2006 / 005513A1, see above) is modified in order to achieve the present invention with the introduction of 5, 10 and 15%, respectively, of fructose as a reducing agent. Fructose is dissolved in the paint when mixed. Modified ink is used to print a picture (company logo) on 80 g / m ² natural kraft paper.

2. Impregnation

In the second stage, printed kraft paper is saturated with a water-containing phenolic rezole resin having a formaldehyde / phenol molar ratio of 1.6 to 2.5, having an alkalinity of 1.5-3% and with drying to have a volatile content of 8% (5 min at 160 ºC). The resin contains red and black dyes, giving the resin and impregnated paper a deep reddish brown color.

3. The method of lamination

A thin sheet is obtained by pressing in a hot press 9 mm birch plywood using the pressing parameters: 5 min, 135 ºC and a pressure of 18 kg / cm ² . Visual assessment of the pressed samples yielded the following results:

- paints containing fructose have a lighter color than comparative paints;

- The best result is obtained with 10% fructose.

4. Analysis of aging

The pressed samples are subjected to heat treatment (70 ºC / 24 h). All samples show a darkened logo color. Paints containing fructose do not darken as much as comparative ones. Visually, a paint containing 10% fructose has the best appearance.

Claims (24)

1. A coated product that contains: a) a base layer, preferably paper; b) a coating layer containing a resin composition, in particular a phenolic resin; and c) a weakening layer containing one or more reducing agents capable of at least partially decolorizing the resin composition, wherein said coating layer is in contact with said attenuation layer. 2. The coated article of claim 1, wherein the attenuation layer comprises printing ink applied to a base layer. 3. The coated product according to claim 1 or 2, wherein said reducing agent has a standard electrode potential E ⁰ in the range from -150 to -1500 mV. 4. The coated product according to claim 1 or 2, wherein said reducing agent is selected from the group consisting of reducing sugars, hydrides, organic acids and inorganic salts. 5. The coated product according to claim 1 or 2, wherein said reducing agent is selected from the group consisting of dihydroxyacetone, glycolaldehyde, glycerol aldehyde, erythrose, threose, ribose, arabinose, xylose, lyxose, allose, altrose, glucose, mannose, gulose , idoz, galactose, thalose, fructose, lactose, maltose, cellobiose, diborane, lithium aluminum hydride, sodium borohydride, lithium borohydride, SnCl ₂ , SnF ₂ , Sn (OH) ₂ , sodium dithionite (color index reducing agent 1), thiourea color index 11), sodium hydroxymethanesulfinate (reductant color index 2) tsinkformaldegidsulfoksilata (reductant index colors 6) kaltsiyformaldegidkarboksilata (reductant index color 12) natriysulfita, natriybisulfita, diisobutylaluminum hydride, oxalic acid, formic acid, ascorbic acid, (NH _{4) 2} HPO _3, CuHPO _3, SnHPO ₃ and Al ₂ (HPO ₃ ) ₃ , alkali metal hypophosphite, FeCl ₂ , FeCO ₃ , FeSO ₄ . 6. The coated article of claim 1 or 2, wherein the resin is selected from the group consisting of phenolic resins, such as phenol-formaldehyde resins, urea-formaldehyde resins, melamine-formaldehyde resins, epoxies, vinyl ester resins and polyester resins, or mixtures thereof, preferably phenolic resins . 7. The coated article of claim 1 or 2, wherein the resin composition contains a colorant. 8. The coated product of claim 7, wherein said dye is selected from the group consisting of acid yellow 23, acid red 18, acid yellow 36, acid black 194, direct red 239, reactive red 120, acid blue 9, acid red 27 acid red 51, direct blue 199, direct red 254, reactive red 195, acid red 14, acid yellow 17, acid black 1, direct yellow 86, direct black 168 and food black 2. 9. The coated product according to claim 1 or 2, which further comprises a substrate layer, preferably selected from the group consisting of cardboard, plywood, chipboard, fiberboard, oriented strand board ((PIC) (OSB) ), glued wood, laminated veneer lumber ((LSL) (LVL)), parallel strand lumber ((PSL) (PSL)) and oriented strand lumber ((OSL)), preferably plywood. 10. The ink composition for printing on a substrate, preferably paper, containing a binder, a reducing agent and a dye or pigment, in which the reducing agent has a standard electrode potential E ⁰ from -150 mV to -1500 mV. 11. The paint composition of claim 10, wherein said reducing agent is selected from the group consisting of reducing sugars, hydrides, organic acids, and inorganic salts. 12. The paint composition according to claim 11, wherein the reducing agent is selected from the group consisting of dihydroxyacetone, glycolaldehyde, glycerol aldehyde, erythrose, threose, ribose, arabinose, xylose, lyxose, allose, altrose, glucose, mannose, gulose, idose, galactose, thalose, fructose, lactose, maltose, cellobiose, diborane, lithium aluminum hydride, sodium borohydride, lithium borohydride, SnCl ₂ , SnF ₂ , Sn (OH) ₂ , sodium dithionite (reductant color index 1), thiourea dioxide 11 -sulfinate (rebound ovitel color index 2) tsinkformaldegidsulfoksilata (reductant color index 6) kaltsiyformaldegidkarboksilata (reductant Color Index 12), sodium sulfite, sodium bisulfite, diisobutylaluminum hydride, oxalic acid, formic acid, ascorbic acid, (NH _{4) 2} HPO _3, CuHPO ₃ SnHPO ₃ and Al ₂ (HPO ₃ ) ₃ , alkali metal hypophosphite, FeCl ₂ , FeCO ₃ , FeSO ₄ . 13. The paint composition according to any one of paragraphs. 10-12, in which casein is a binder, and fructose is preferably a reducing agent. 14. The paint composition according to any one of paragraphs. 10-12, which contains 0.5-20% wt. reducing agent calculated on the sum of all components of the composition. 15. The use of a paint composition containing a reducing agent to discolour at least partially the resin composition applied to the base layer. 16. A method of obtaining a coated product, which contains the following stages: a) providing a base layer, preferably paper, b) applying a paint composition to a base layer, said paint composition containing one or more reducing agents, c) impregnation of the base layer b) a resin composition, and d) optionally, laminating the base layer c) onto a substrate layer.

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