System of surfacing compositions, method for the implementation thereof and paper and / or cardboard impregnated with said surfacing system

Abstract

The present invention relates to a system of surfacing compositions intended to be deposited successively on at least one main face of a sheet of paper and / or cardboard, said system comprising at least: - a first aqueous composition, the dry matter of which is composed, by weight, relative to the total weight of dry matter, of 40% to 90% of a dextrin which is derived from a starch, said starch having, by weight, relative to its total weight, an amylopectin content of greater than or equal to 70%, and from 10% to 60% of a hydrated talc; - a second coating color composition capable of and / or configured for conferring a barrier property with respect to water at least and intended to be deposited on top of said first aqueous composition. The present invention also relates to a surfacing method, and to a corrugated cardboard with liners impregnated with said surfacing system.

Description

[0001] Surfacing composition system, its implementation process and paper and / or cardboard impregnated with said surfacing system

[0002] technical field

[0003] The present invention relates to the field of packaging and in particular to the field of paper and / or cardboard, such as corrugated cardboard used for the transport, storage and protection of goods.

[0004] In particular, the present invention relates to a surfacing composition system capable of providing the final paper and / or cardboard with barrier properties, such as water or oil barrier properties, particularly for replacing non-recyclable and / or non-biodegradable plastic films. The present invention also relates to the method of implementing this surfacing composition system, as well as to corrugated cardboard coated with said surfacing composition system.

[0005] Technological background

[0006] There are many types of paper-based packaging, one of the best known and most commonly used being corrugated cardboard.

[0007] Due to its structure, corrugated cardboard allows for the replacement of solid cardboard with, generally, at least two flat sheets held equidistant by one or more corrugated spacers. Corrugated cardboard consists of at least one outer flat sheet, called the "cover," and at least one corrugated sheet forming a spacer, called the "flute." The covers contribute to the mechanical and climatic resistance of the packaging and serve as a medium for communication and / or information. The flutes ensure the rigidity of the packaging, but also maximum elasticity, as they act as shock absorbers in case of impacts.

[0008] Depending on the number of layers and flutes, there are different types of corrugated cardboard. For example, it is called "Single Face" (SF) when it consists of a layer and a flute bonded together at the flute ridges in contact with the layer; this type of cardboard is used for packaging, cushioning, and as a backing for various panels;

[0009] "Single Flute" (SC) when it is formed of a single SF face and a cover glued onto the free face of the flute;

[0010] "Double Fluted" (DC) when it combines two simple SF faces and a cover, and

[0011] “Triple Flute” (TC) when it combines three simple SF faces and a cover.

[0012] Due to their cellulose fiber composition, paper and cardboard, such as corrugated cardboard, are sensitive to water. For example, to give corrugated cardboard barrier properties, such as water or oil resistance, making it suitable for applications in the food and cosmetics industries, it is common practice to coat it with a plastic film. This plastic film can be made of polyethylene terephthalate (PET) or polyethylene (PE). Generally, the basis weight is between 15 and 50 g / m². 2 , preferably 20 to 30 g / m 2 is used to cover one side of the corrugated cardboard's outer sheet. However, the plastic film has the disadvantage of being non-biodegradable and complicates, or even prevents, the recycling of the corrugated cardboard thus coated.

[0013] One solution developed in the prior art is to coat corrugated cardboard with a coating that does not impair the cardboard's final recyclability. Such a coating can, for example, include an acrylic base / acrylic varnish. However, the use of such a coating presents some drawbacks. First, it has been observed that depending on the substrate (component of the linerboard) onto which the coating is applied, the performance in terms of barrier properties varies. It is therefore necessary to optimize the choice of this substrate (i.e., the material of the corrugated cardboard liner) according to the type of coating chosen. Indeed, the Applicant has noted that during its application, the coating penetrates the paper layer forming the liner of the corrugated cardboard, which is by definition porous, and thus fills the various voids / interstices present on the paper surface.He thus observed that certain areas of the coating (i.e., the ridges) were not covered by the coating, consequently affecting the barrier performance of the coated cardboard. To improve the coating coverage on the cardboard surface, one solution would be to apply a higher basis weight. However, this solution is relatively difficult to implement in terms of production and its cost is higher than that of plastic films. Indeed, for example, applying 8 g / m²... 2 acrylic varnish is equivalent to the cost price corresponding to the application of 32 g / m² 2 of plastic film, at a cost price ten times higher. Moreover, adding a significant weight also hinders the recyclability of the final product.

[0014] There is therefore a need in the state of the art to develop a new surfacing composition for any paper and / or cardboard which avoids all, or part, of the disadvantages described above.

[0015] In particular, there is a need in the state of the art to develop a new surfacing composition suitable for and / or configured to give paper and / or cardboard, such as corrugated cardboard, barrier properties, such as barrier properties to water, oil, oxygen, moisture, aromas, mineral oils, etc., without compromising its recyclability, as well as its mechanical performance.

[0016] There is also a need in the prior art to develop a new surfacing composition suitable for and / or configured to impart barrier properties to corrugated board, while still allowing the corrugation manufacturing process to continue after application. Therefore, it is desirable that the new surfacing composition not degrade the properties of the material forming the corrugated board.

[0017] Description of the invention

[0018] In this context, the Applicant focused on developing a new surfacing composition that would give paper and / or cardboard various barrier properties, including oil and water barrier properties useful, for example, in the food and cosmetics industries, while remaining environmentally friendly and thus not compromising its recyclability. It also focused on developing a new surfacing composition that could be easily implemented in the cardboard corrugation process.

[0019] As will be illustrated in the experimental section below, it has notably developed, in a surprising and unexpected way, a system of surfacing compositions which combines the use of two particular compositions, together making it possible to obtain barrier properties similar to those of plastic films and to considerably reduce the porosity of the paper substrate, especially compared to other comparative compounds tested.

[0020] Indeed, the experimental tests below show that the specific combination according to the invention, which was selected by the Applicant, is not arbitrary and has a different technical effect, namely it optimizes the barrier performance of the paper substrate, compared to other comparative compounds.

[0021] Summary of the invention

[0022] Thus, the present invention relates to a surfacing composition system intended to be successively deposited on at least one main face of a sheet of paper and / or cardboard, said system comprising at least:

[0023] - a first aqueous composition whose dry matter is composed, by mass, in relation to the total mass of dry matter, of 40% to 90% of a dextrin which is derived from a starch, said starch having, by mass, in relation to its total mass, an amylopectin content greater than or equal to 70%, and of 10% to 60% of a hydrated talc;

[0024] - a second coating sauce composition suitable for and / or configured to provide a barrier property at least to water and intended to be deposited on top of said first aqueous composition.

[0025] Other non-limiting and advantageous features of the surfacing composition system according to the invention, taken individually or in all technically possible combinations, are as follows:

[0026] - said dry matter of the first aqueous composition comprises, by mass, in relation to its total mass of dry matter, 55% to 85%, preferably 60% to 80% and typically 65% ​​to 75% of dextrin, and 15% to 45%, preferably 20% to 40% and typically 25% to 35% of hydrated talc;

[0027] - said starch has, by mass, in relation to its total mass, an amylopectin content greater than or equal to 80%, preferably greater than or equal to 90% and typically greater than or equal to 95%;

[0028] - the dextrin of said first aqueous composition is obtained by heating said starch to a temperature ranging from 80° to 100°C, preferably between 85° and 95°C for generally a period ranging from 10 minutes to 50 minutes, preferably from 20 minutes to 40 minutes;

[0029] - the dextrin of said first composition has a molecular mass by weight greater than or equal to 1,000,000 Da, and preferably greater than or equal to 3,000,000 Da, and typically ranging from 3,000,000 to 6,000,000 Da;

[0030] - hydrated talc is a hydrated magnesium silicate in the form of a slurry comprising, by mass, relative to the total mass of the slurry, a dry matter of between 55% and 70%;

[0031] - hydrated talc has a median particle size, D50, less than or equal to 6 pm, preferably less than or equal to 5 pm and typically less than or equal to 4 pm;

[0032] - the dry matter of said first aqueous composition represents, by mass, in relation to the total mass of the first aqueous composition, from 10% to 30%, preferably from 15% to 25% and typically 20%;

[0033] - the second coating sauce composition generally comprises at least one of the following compounds: acrylic, styrene butadiene, styrene acrylic, polyethylene, bio-polyethylene (Bio-Pe), polymers comprising by mass relative to their total mass more than 50% of PE-like polyester aliphatic chains, polyvinylidene chloride (PVDC), polyethylene terephthalate (PET), polyurethane (PU), ethylene vinyl alcohol (EVOH), starch, proteins, chitosan, waxes, polylactic acid (PLA), polyhydroxyalkanoates (PHA), polyethylene furanoate (PEF) or a combination thereof and typically comprises acrylic;

[0034] - The surfacing composition system includes a third composition intended to be deposited between said first aqueous composition and said second coating sauce composition and being suitable for and / or configured to impart oxygen barrier properties to the paper and / or board; preferably said third composition comprises a poly(vinyl alcohol) polymer. The present invention also relates to a method for surfacing a sheet of paper and / or board comprising at least one upper principal face and one lower principal face.

[0035] characterized in that it includes the application, on at least one of said principal faces, of the surfacing composition system as defined above by successively depositing the first aqueous composition, where applicable the third composition, and the second coating sauce composition.

[0036] Other non-limiting and advantageous features of the surfacing composition system according to the invention, taken individually or in all technically possible combinations, are as follows:

[0037] - the first aqueous composition is applied to at least one of the main faces of the said sheet of paper and / or cardboard, at a basis weight ranging from 3 to 10 g / m² 2 preferably ranging from 4 to 8 g / m³ 2 and typically ranging from 5 to 7 g / m³ 2 ;

[0038] - the second coating sauce composition is applied at a weight ranging from 2 to 25 g / m 2 preferably ranging from 4 to 12 g / m³ 2 and typically ranging from 6 to 8 g / m³ 2 ;

[0039] - said sheet of paper and / or cardboard is a corrugated cardboard cover, the main upper face and / or the main lower face of said cover is / are impregnated with the surfacing composition system by successively depositing the first aqueous composition, where applicable the third composition, and the second coating sauce composition.

[0040] The present invention also relates to a corrugated cardboard comprising:

[0041] - at least one cover, preferably at least two covers, each cover having a flat upper principal face and a flat lower principal face, and

[0042] at least one groove of sinusoidal section defining an alternation of straight sections, called ridges and inclined sections, said lower main face of the cover being bonded by gluing to groove ridges in contact with it, characterized in that at least said upper main face or said lower and upper main faces of said at least cover, is / are coated by the system of surfacing compositions as defined above, namely is / are coated successively by the first aqueous composition, where applicable the third composition and the second coating sauce composition.

[0043] Of course, the different features, variants and embodiments of the invention can be combined with each other in various ways as long as they are not incompatible or mutually exclusive.

[0044] In the present invention, unless otherwise specified, the term "comprises" and its derivatives shall be understood as non-limiting and not excluding the presence of other components or steps. In certain particular embodiments, the term "comprises" may be understood as "consisting essentially of" or "being made up of".

[0045] Unless otherwise specified, the intervals mentioned in the present invention are understood to include the limits.

[0046] Brief description of the figures

[0047] Furthermore, various other features of the invention become apparent from the attached description made with reference to the drawings which illustrate non-limiting embodiments of the invention and where:

[0048] [Fig. 1] represents different photographs of an oil barrier test carried out in the laboratory using the surfacing system according to the invention (a) and according to various comparative surfacing compositions (b) to (f);

[0049] [Fig. 2] represents a photograph of a comparative oil barrier test carried out on a pilot scale using the surfacing system according to the invention (a) and using only the coating sauce (b).

[0050] Detailed description

[0051] 1. The surfacing composition system. The present invention relates to a surfacing system intended to be successively deposited on at least one main face of a sheet of paper and / or cardboard, said system comprising at least:

[0052] - a first aqueous composition whose dry matter is composed, by mass, in relation to the total mass of dry matter, of 40% to 90% of a dextrin which is derived from a starch, said starch having, by mass, in relation to its total mass, an amylopectin content greater than or equal to 70%, and of 10% to 60% of a hydrated talc;

[0053] - a second coating sauce composition suitable for and / or configured to provide a barrier property at least to water and intended to be deposited on top of said first aqueous composition.

[0054] Due to its characteristics, the Applicant discovered, surprisingly and unexpectedly, that the first aqueous composition based on dextrin and hydrated talc improved the surface properties of any paper and / or cardboard onto which it was applied, thus facilitating the homogeneous and uniform application of the second coating composition. The paper and / or cardboard thus coated by the multilayer surfacing composition system according to the invention exhibits excellent barrier properties, particularly against water and oil.

[0055] According to the invention, "barrier property" means that the present surfacing composition system is capable of and / or configured to form a protective coating or surface that ensures impermeability, or at least prevents the main face(s) of the coated paper and / or cardboard sheet from becoming porous with respect to at least one of the following parameters: water, oil, humidity, mineral oil, oxygen, water vapor, and aromas. Preferably, the surfacing system exhibits barrier properties against at least two of these parameters, advantageously at least three, typically at least four, and generally exhibits barrier properties against all of them.

[0056] According to the invention, "paper" is defined as a cellulose-based material made from natural or processed plant fibers, reduced to a homogeneous pulp which has been spread and dried to form a thin sheet. According to the invention, "cardboard" is defined as a material of the same nature as paper, generally in sheets that are thicker and more rigid; cardboard commonly has a mass per square meter greater than 224 g. There are various types of cardboard, including cardboard formed by laminating different layers of paper and corrugated cardboard as described above (and whose definition falls within the scope of the present invention), namely, cardboard composed of at least one liner and at least one flute. This type of corrugated cardboard can be used for packaging food, cosmetics, or other goods.

[0057] "By dextrin" in the context of the present invention, we mean a polysaccharide obtained from a starch, said starch comprising, by mass, in relation to its total mass, at least 70%, preferably at least 80%, in particular at least 90% and typically 100% of amylopectin.

[0058] According to the invention, a value of "at least 70%" includes the following values ​​and all intervals between these values ​​(in %): 70; 71; 72; 73; 74; 75; 76; 77; 78; 79; 80; 81; 82; 83; 84; 85; 86; 87; 88; 89; 90; 91; 92; 93; 94; 95; 96; 97; 98; 99; 100.

[0059] In other words, the dextrin according to the present invention is derived from a starch comprising, preferably by mass, less than 30%, advantageously less than 20%, and typically less than 10% amylose. Generally, the dextrin according to the invention contains no amylose or only trace amounts (less than 5% by mass, preferably less than 3%, by mass). The Applicant has discovered that the presence of amylose in the starting starch renders the dextrin too viscous and unsuitable for the impregnation process.

[0060] Thus, according to one feature of the invention, the dextrin of said first composition is obtained by heating said starch to a temperature ranging from 80° to 100°C, preferably from 85° to 95°C, generally for a period ranging from 10 to 50 minutes, preferably from 20 to 40 minutes, or 30 minutes. According to the invention, a value "ranging from 80°C to 100°C" includes the following values ​​and all intervals between these values ​​(in °C): 80; 81; 82; 83; 84; 85; 86; 87; 88; 89; 90; 91; 92; 93; 94; 95; 96; 97; 98; 99; 100. At the end of this step, the dextrin is in powder form.

[0061] In general, the dextrin in powder form is then made into an aqueous solution to form the first aqueous composition according to the invention. For this purpose, the dextrin in powder form is heated in water at a temperature between 75°C and 115°C for a period of 30 to 60 minutes. According to the invention, a value "from 75°C to 115°C" includes the following values ​​and all intervals between these values ​​(in °C): 75; 76; 77; 78; 79; 80; 81; 82; 83; 84; 85; 86; 87; 88; 89; 90; 91; 92; 93; 94; 95; 96; 97; 98; 99; 100; 101; 102; 103; 104; 105; 106; 107; 108; 109; 110; 111; 112; 113; 114; 115.

[0062] In particular, the dextrin of said first composition has a molecular mass by weight greater than or equal to 1,000,000 Da and preferably greater than or equal to 3,000,000 Da. In general, the dextrin of said first composition has a molecular mass by weight less than or equal to 10,000,000 Da and typically ranging from 4,000,000 to 6,000,000 Da. According to the invention, a value of "molecular mass by weight greater than or equal to 1,000,000 Da" includes the following values ​​and all intervals between these values ​​(in Da): 1,000,000; 1,500,000; 2,000,000; 2,500,000; 3,000,000; 3,500,000; 4,000,000; 4,500,000; 5,000,000; 5,500,000; 6000000; 6500000; 7000000; 7500000; 8000000; 8500000; 9000000; 9500000; 10000000. As an example, the molecular weight distribution of dextrin can be as follows (measured by HPLC using 3 columns) as illustrated in Table 1 below:

[0063] [Table 1]

[0064] < < < < < <

[0065]

[0066] These molecular masses by weight are conventionally measured by size exclusion chromatography methods of the HPSEC-MALLS type ("High Performance SizeExclusion Chromatography coupled on-line with Multiple Angle Laser Light Scattering"). The corresponding measurement protocol is indicated in the introductory section of the examples supporting this application.

[0067] The first composition of the system according to the invention also includes a hydrated talc. Generally, talc is a hydrated magnesium silicate that may have the following formulation: Mg3Si4Ow(OH)2. It may correspond to the product marketed under CAS number 14807-96-6.

[0068] Preferably, the talc of the first composition has, by mass relative to its total mass, the following chemical structure:

[0069] - 25% to 45%, in particular 28% to 35% and typically around 31% of MgO; - 55% to 75%, preferably 65% ​​to 72% and typically 60% of SO2;

[0070] - less than 3%, preferably less than 2% and typically less than 0.1% of CaO; - less than 5%, preferably less than 3% and typically less than 0.5% of Al₂O₃; and

[0071] - less than 5%, preferably less than 3% and typically less than 2.1% of FeO.

[0072] According to one feature of the invention, the hydrated talc of the first composition has a particle size distribution on the micrometer scale. In particular, it preferably has a median particle size, D50, less than or equal to 6 pm, preferably less than or equal to 5 pm, and typically less than or equal to 4 pm. According to the invention, a value "less than or equal to 6 pm" includes the following values ​​and all intervals between these values ​​(in pm): 6.0; 5.5; 5.0; 4.5; 4.0; 3.5; 3.0; 2.5; 2.0; 2.0; 1.5; 1.0; 0.9; 0; 0.8; 0.7; 0.6; 0.5, etc.

[0073] In the context of the present invention, the median size D50 is measured according to ISO 13317.

[0074] According to another feature of the invention, the hydrated talc of the first composition has a particle size distribution in which at least 20%, preferably at least 25%, and typically at least 30% of the particles have a diameter less than or equal to 2 µm. According to the invention, a value of "at least 20%" includes the following values ​​and all intervals between these values ​​(in %): 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; etc.

[0075] In general, hydrated talc is in the form of a slurry (i.e., a thick suspension) comprising, by mass relative to the total mass of the slurry, a dry matter content of between 60% and 70%. Preferably, according to this embodiment, the hydrated talc has a dry matter content, by mass relative to the total mass of the hydrated talc in slurry form, of between 60% and 65%, and typically about 63%.

[0076] According to the invention, the first aqueous composition comprises a dry matter which is composed, by mass, relative to the total mass of said dry matter, of at least 40% to 90% of dextrin as defined above and 10% to 60% of hydrated talc.

[0077] Hereinafter, a value ranging "from 40% to 90%" includes the following values ​​and all intervals between these values ​​(in %): 40; 45; 50; 55; 60; 65; 70; 75; 80; 85; 90. Also, within the scope of the invention, a value "from 10% to 60%" includes the following values ​​and all intervals between these values ​​(in %): 10; 15; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 50; 52; 55; 58; 60.

[0078] In general, the dry matter of the first aqueous composition comprises, by mass, relative to the total mass of dry matter,

[0079] - 55% to 85%, preferably 60% to 80% and typically 65% ​​to 75% of the dextrin as defined above, and

[0080] - 15% to 45%, preferably 20% to 40% and typically 25% to 35% of hydrated talc.

[0081] Also, the dry matter of said first aqueous composition generally represents, by mass, relative to the total mass of the first aqueous composition, from 10% to 30%, preferably from 15% to 25%, and typically it represents 20%. In the context of the invention, a value "from 10% to 30%" includes the following values ​​and all intervals between these values ​​(in %): 10; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30.

[0082] Thus, as an example, the first aqueous composition may include, by mass, relative to its total mass, at least:

[0083] - 5% to 20%, preferably 8% to 18% and typically 14% to 15% of said dextrin; - 0.5% to 15%, preferably 2% to 12% and typically 5% to 6% of hydrated talc; - the remainder being water, namely about 70% to 90%, preferably 75% to 85% and typically about 80% water.

[0084] The surfacing composition system according to the invention is also characterized by the presence of a second composition, intended to be placed on top of said first aqueous composition, called coating sauce.

[0085] According to the invention, "above" means that the second composition is placed above said at least main surface of the sheet of paper and / or cardboard which has already been coated with said first composition; this may be a direct contact, namely the second composition is placed / coated or applied directly on the first composition once the latter has been applied / impregnated on said at least main surface, namely, it is in direct contact with it or it is placed above but without being in direct contact because it is possible to apply / impregnate one or more other intermediate compositions between the first composition and the second composition.

[0086] The second composition according to the invention is a coating sauce composition. Preferably, it does not impair the recyclability of the paper and / or corrugated board or is at least environmentally friendly. For the purposes of this invention, "recyclable" means achieving a grade of A+, A, or B according to standard UNI 117432019 and the ATICELCA rating table.

[0087] According to one feature of the invention, the second coating sauce composition generally comprises at least one of the following compounds: acrylic, styrene butadiene, styrene acrylic, polyethylene, bio-polyethylene (Bio-Pe), polymers comprising by mass relative to their total mass more than 50% of PE-like polyester aliphatic chains, polyvinylidene chloride (PVDC), polyethylene terephthalate (PET), polyurethane (PU), ethylene vinyl alcohol (EVOH), starch, proteins, chitosan, waxes, polylactic acid (PLA), polyhydroxyalkanoates (PHA), polyethylene furanoate (PEF) or a combination thereof and typically comprises an acrylic base.

[0088] Advantageously, the coating sauce comprises one or more of the following compounds: bio-polyethylene (Bio-Pe), starch, chitosan, waxes, polylactic acid (PLA), polyhydroxyalkanoates (PHA) or a combination thereof.

[0089] As an example, the coating sauce suitable for the present invention may correspond to the following commercial product: VC2240®, marketed by the Michelman company.

[0090] In particular, the second coating sauce composition may also include at least: pigments and / or one or more fillers.

[0091] These compounds are well known to those skilled in the art and will not be described in further detail below.

[0092] As mentioned above, the surfacing composition system according to the invention may also include at least one intercalated third composition intended to be disposed above the first composition and below said second composition.

[0093] Preferably, this third composition is suitable for and / or configured to give the paper and / or cardboard oxygen barrier properties.

[0094] As an example, the third composition includes at least one biodegradable material and may preferably include a polymer of a poly(vinyl alcohol) nature.

[0095] 2. Surfacing method The present invention also relates to a method for surfacing a sheet of paper and / or cardboard.

[0096] Of course, the different embodiments described above for the surfacing composition system also apply to this surfacing process and will not be repeated below.

[0097] Thus, the surfacing process for a sheet of paper and / or cardboard comprising at least one upper principal face and one lower principal face is characterized in that it comprises the application, on at least one of said principal faces, of the surfacing composition system as defined above by successively depositing:

[0098] (i) the first aqueous composition,

[0099] (ii) where applicable, the third composition, and

[0100] (iii) the second bedding sauce composition.

[0101] In general, the first aqueous composition is usually prepared by following these steps:

[0102] (a) the preparation of dextrin in the form of an aqueous suspension;

[0103] (b) the preparation of the composition of hydrated talc;

[0104] (c) the mixture of the dextrin obtained at the end of step (a) with the hydrated talc obtained at the end of step (b).

[0105] For step (a) above, as mentioned above, the dextrin is first obtained from and / or is produced by the processing of a starch having, by mass relative to its total mass, an amylopectin content greater than or equal to 70%, preferably greater than or equal to 80% and typically greater than or equal to 90%. For this purpose, the starting starch is generally heated to a temperature ranging from 80° to 100°C, preferably between 85° and 95°C, generally for a period ranging from 10 to 50 minutes, preferably from 20 to 40 minutes, so as to obtain a dextrin powder.

[0106] This dextrin powder is suspended. To do this, the dextrin in powder form is cooked / heated in water. According to one process feature, the dextrin mass content, relative to the total mass of the suspension, can be between 15% and 30%, so as to obtain a first aqueous composition whose dry matter comprises, by mass relative to the total dry matter mass, from 40% to 90% dextrin. According to another feature of the invention, the dextrin in powder form is heated to a temperature generally between 75°C and 115°C, for a period of 60 minutes or less, preferably from 30 to 60 minutes.

[0107] For step (b) above, the hydrated talc is put into slurry form at a dry matter mass content generally ranging from 55% to 70%, such as 63% by mass.

[0108] For step (c) above, the cooked / heated dextrin obtained at the end of step (a) above is maintained between 70°C and 90°C and is mixed with the hydrated talc obtained at the end of step (b) (i.e. it is unheated) generally for a period of 15 to 60 minutes.

[0109] Once prepared, the first aqueous composition can be applied to the surface of the paper and / or board to be coated (step (i) above). To do this, the surface of the paper and / or board to be coated and / or impregnated is passed through an impregnation station equipped with a bath suitable for holding said first aqueous composition. In this bath, the first composition is generally at a temperature between 40°C and 95°C, preferably between 50°C and 80°C, and typically between 65°C and 75°C, such as 70°C. This step (i) can, for example, be carried out in an impregnation station more commonly known as a size press, such as a size press or a film press. These machines are used to manufacture, among other things, corrugated board.

[0110] According to one feature of the invention, the first aqueous composition is applied to the surface of paper and / or cardboard to be coated, with a basis weight ranging from 3 to 10 g / m². 2 , preferably 4 to 8 g / m2 and typically 5 to 7 g / m³ 2 .

[0111] According to the invention, "a weight ranging from 3 to 10 g / m² 2 » includes the following values ​​and all intervals between these values ​​(in g / m 2 ): 3; 3.5; 4.0; 4.5; 5.0; 5.5; 6.0; 6.5; 7.0; 7.5; 8.0; 8.5; 9.0; 9.5; 10.0. By way of example, the impregnation concentration (% solids) of the first aqueous composition on said at least one of said principal faces ranges from 10% to 30%, preferably from 15% to 25% and typically from 18% to 22%.

[0112] Once the initial coating has been applied to the surface, a drying phase typically takes place. This drying phase can last at least 10 seconds at a temperature between 90°C and 200°C.

[0113] Once dried, a roll of paper is obtained upon exiting the impregnation station. This roll can be coated directly with the second composition, or, if necessary, the third composition, or it can be stored. For example, storage can last from a few hours to a few weeks, pending the application of the second composition, and, if applicable, the third composition.

[0114] Next, the second coating sauce composition (step (iii) above) is generally applied. The coating sauce is usually ready-to-use and homogenized before application.

[0115] Application (ii) is carried out on the roll obtained at the end of step (i) using a different machine than that used in step (i), namely a machine capable of and / or configured to apply a coating. Such a machine could be a Mayer bar coater. Other coating processes may be suitable, such as curtain coating, flexographic, gravure, slot die, etc.

[0116] To do this, once the second composition is prepared, it can be applied to the surface of paper and / or cardboard previously impregnated with the said first composition, or even, where applicable, with the said third composition (arranged in the coating machine in the form of a roll).

[0117] According to another feature of the invention, the second coating sauce composition is applied at a weight ranging from 2 to 25 g / m². 2 , preferably 4 to 12 g / m 2 and typically 6 to 8 g / m³ 2According to the invention, "a weight ranging from 2 to 25 g / m² 2 » includes the following values ​​and all intervals between these values ​​(in g / m 2 ): 2.0; 2.5; 3.0; 3.5; 4.0; 4.5; 5.0; 5.5; 6.0; 6.5; 7.0; 7.5; 8.0; 8.5; 9.0; 9.5; 10.0; 10.5; 11.0; 11.5; 12.0; 12.5; 13.0; 13.5; 14.0; 14.5; 15.0; 15.5; 16.0; 16.5; 17.0; 17.5; 18.0; 18.5; 19.0; 19.5; 20.0; 20.5; 21.0; 21.5; 22.0; 22.5; 23.0; 23.5; 24.0; 24.5; 25.0. Similarly, the third composition is prepared by mixing the polymer in water (such as a poly(vinyl alcohol) polymer) at a mass concentration of 5% to 15%, preferably 8% to 12%, and typically 10%. This mixture is then cooked between 85°C and 95°C for 45 to 60 minutes. The composition is then stored at room temperature, between 15°C and 30°C.

[0118] Once prepared, this can be applied to the paper and / or cardboard surface previously impregnated with the first composition (step (ii)). For this purpose, the paper surface previously impregnated with the first composition can also be coated using a coating machine, such as a Mayer bar coater (as is the case for applying the second composition).

[0119] According to another feature of the invention, the third composition is applied at a dry basis weight ranging from 2 to 7 g / m² 2 , preferably 2 to 6 g / m 2 and typically 3 to 5 g / m³ 2 .

[0120] Preferably, the surfacing composition system according to the invention is applied / impregnated on the main lower face and the main upper face of the sheet of paper and / or cardboard.

[0121] According to one feature of the invention, the sheet and / or cardboard corresponds to a corrugated cardboard cover (as mentioned in the description of the prior art above); preferably, the two main lower and upper faces of the cover are impregnated with the surfacing composition system according to the invention by successively depositing the first aqueous composition, optionally the third composition, and the second coating composition. 3. Corrugated cardboard

[0122] The present invention also relates to a corrugated cardboard comprising:

[0123] - at least one cover, preferably at least two covers, each cover having a main upper face and a main lower face which are flat and

[0124] - at least one sinusoidal flute defining an alternation of straight sections, called ridges and inclined sections, said lower main face of the cover being bonded by gluing to flute ridges in contact with it, characterized in that at least said upper main face or said lower and upper main faces of said at least cover, is / are coated by the system of surfacing compositions as defined above, namely is / are coated successively by the first aqueous composition, where applicable the third composition, and the second coating sauce composition.

[0125] Of course, the different embodiments described above for the surfacing composition system and / or for the surfacing process also apply to corrugated board and will not be repeated below.

[0126] The following examples help to better understand the present invention, without limiting its scope.

[0127] 4. Examples

[0128] In all subsequent tests, the molecular masses of the dextrins are determined by size exclusion chromatography, according to the following protocol:

[0129] - preparation of a sample by solubilization of the product, by heating at 100°C for 30 min in a dilution solvent consisting of a DMSO / NaNCl mixture (0.1M of NaNCl in the DMSO), said sample being able to present a concentration ranging from 2 to 10 mg of product per Ml of dilution solvent;

[0130] - use of a high-performance liquid chromatography (HPLC) instrument equipped with a pump, operating in isocratic mode, circulating an elution solvent

[0131] - 0.3 mL / min, from a refractometer, an 18-angle multi-angle light scattering laser detector heated to 35°C, for example a DAWN DSP detector from Wyatt, and a column thermostating oven heated to 35°C, for example equipped with SUPREMA type polyhydroxymethacrylate columns and whose elution solvent is for example an aqueous solution of sodium nitrate at 0.1 M, containing 0.02% by mass of sodium azide;

[0132] - injection into the device of a sample volume of approximately 100 IL.

[0133] - average molecular masses by weight and number can be determined from the spectra obtained, for example, by reprocessing the spectra in 1st order exponential, using ASTRA v.4 type analysis software.

[0134] 1 according to the invention

[0135] a) Preparation of the surfacing system according to the invention

[0136] This example relates to the preparation of a surfacing composition system according to the invention comprising the compounds mentioned in Table 2 below (percentages are expressed by mass): [Table 2]

[0137] >

[0138]

[0139] The first aqueous composition is prepared as follows: dextrin and hydrated talc are added to a Moulinex Compagnion XL type laboratory cooker, then demineralized water is added to reach a concentration of 20% dry matter. The mixture is then cooked at a temperature of 95 °C for 45 min.

[0140] b) Preparation of a sheet coated with the surfacing system according to the invention

[0141] The surfacing system was applied to paper as follows:

[0142] For this test, a Mathis Lab size press type SP was used. The rollers had a flexible coating, the linear pressure was 9.5 daN / cm, and the speed was 15 m / min. The press includes at least two shafts on which are mounted circular rotating tools that drive the cover sheet to be coated, as well as a bath / container for receiving a surfacing composition.

[0143] The first composition, as illustrated above, is placed in this bath / container at a temperature of 68°C. The paper sheet is a sheet bearing the reference W 135gsm Mets®, marketed by the Mets® paper mill in Kemi. It is a whitetop liner, composed of two layers. Both layers are composed of 100% virgin fibers. The white layer is mainly composed of birch pulp, while the brown layer is mainly composed of Scots pine. The paper contains starch by mass, and the white layer contains CaCCL fillers. As it passes through the bath, this liner sheet is coated on both its upper and lower surfaces with the first composition according to the invention. The impregnation is carried out at an impregnation concentration of 20.4%. The deposited basis weight is then 6 g / m². 2At the end of this step in the sizepress, a coated sheet is obtained. A drying step takes place for 10 seconds at 120°C with a contact dryer.

[0144] Following this drying stage, the porosity was reduced from 130 mL / min to 4 mL / min. To measure the porosity, the ISO 5636-3 standard and a Frank PTI porosimeter were used.

[0145] Then, the coating sauce is applied to the top surface of the previously prepared sheet using an RK Coater Mayer bar coater. The coating was applied using the standard RK Coater Mayer bar (number 1) at a speed of 3 m / min. These parameters were chosen to apply a coating sauce of 3 g / m². 2 Once the top surface is coated with the coating sauce, the sheet is dried in an oven at a temperature of 100°C for 1 minute.

[0146] c) Forming the aforementioned cover sheet into corrugated cardboard

[0147] The cover, thus impregnated by the surfacing composition system according to the invention, was subsequently passed through an industrial corrugator of the BHS brand in order to glue it with a flute and obtain a corrugated cardboard.

[0148] It was found that the surfacing system according to the invention did not deteriorate the properties of the roofing material and, in particular, always allowed for excellent bonding between the groove crests and the underside of the roofing material during the corrugation process. Example 2 Comparative Tests

[0149] a) For this trial, the following compositions were tested (table 3)

[0150] [Table 3]

[0151] "

[0152]

[0153] b) The porosity results are illustrated in Table 5 below [Table 4]

[0154]

[0155] To measure porosity, the ISO 5636-3 standard and a Frank PTI brand porosimeter were used.

[0156] This test shows that the surface coating composition system exhibits the best barrier properties compared to the other compositions tested. Indeed, the porosity is extremely low.

[0157] c) Surface test

[0158] To demonstrate the effectiveness of the first composition, a paper (kraftliner, Viana kraftliner (KL) 135 g / m 2 (Produced at the Viana paper mill – this kraftliner is a two-layer liner) was surfaced with each of the different compositions of the examples described above, and then coated with the second coating composition of Example 1 (identical to the invention). The amount of coating applied is the same for all examples.

[0159] The coated sheets are as follows:

[0160] (a) kraftliner + composition 1 + 3 g / m 2 of composition 2 (invention);

[0161] (b) Kraftliner + 3 g / m 2 of composition 2 (sleeping sauce only);

[0162] (c) Kraftliner + Ex. comp 2 + 3 g / m 2 of composition 2;

[0163] (d) Kraftliner + Ex. comp 3 + 3 g / m 2 of composition 2;

[0164] (e) Kraftliner + Ex. comp 4 + 3 g / m 2 of composition 2;

[0165] (f) Kraftliner + Ex. comp 5 + 3 g / m 2 of composition 2.

[0166] An 1800-second oil Cobb test was then carried out following the ISO 535 standard. At the end of this Cobb test, a photo was taken to observe if there were any oil stains on the paper.

[0167] Fig.1 shows photographs of these different surfacing tests (a) to (f).

[0168] It appears that the system according to the invention (a) exhibits barrier properties similar to those of non-biodegradable latex and performs excellently compared to the other compounds tested. Indeed, this test shows that the surfacing system according to the invention exhibits an oil barrier effect. Conversely, for the comparative surfacing compositions, oil stains / droplets are visible on the paper surface. It appears that these comparative compositions do not provide a satisfactory oil barrier effect.

[0169] Example 3 Pilot Scale

[0170] a) Test according to the invention

[0171] For this test, the surfacing composition system was prepared as follows. The dextrin described in Table 2 above (i.e., composed of more than 95% amylopectin and a molecular weight of 5,000,000 Da) was cooked in an industrial jet cooker at a concentration between 20% and 25%, at a temperature of 95 °C for at least 30 minutes. The cooked dextrin was then mixed with hydrated talc in a mixing tank with stirring.

[0172] Once the mixture has been prepared, the characteristics of the first aqueous composition according to the invention are as follows:

[0173] [Table 5]

[0174]

[0175] It was applied to paper. For this, a Valmet pilot film press (no French name available) was used. The machine parameters were as follows: speed of 400 m / min, application temperature between 57 and 64°C, impregnation concentration of 20.4%, linear load of 20 kN / m, lower and upper metal bar diameters of 0.35 / 30 mm, lower bar load of 0.4 bar, upper bar load of 0.5 bar, and wet film basis weight on the lower and upper rolls of 17.5 g / m². 2 These parameters were chosen in order to deposit a basis weight between 6.0 and 7.0 g / m². 2 of the first aqueous composition according to the invention.

[0176] The paper used for this test is a kraftliner: Viana kraftliner (KL) 135 g / m 2Produced at the Viana paper mill, this kraftliner is a two-layer liner. The top layer is composed of 100% virgin maritime pine fibers and a small amount of eucalyptus. The second layer is a blend of high-quality post-consumer recycled fibers and virgin maritime pine and eucalyptus fibers. The overall ratio is 75% virgin fibers and 25% recycled fibers. This paper has not been pre-surfaced but contains cationic starch added in bulk during its manufacturing process.

[0177] At the end of this step in the size press, a cover sheet impregnated with the first aqueous composition according to the invention is obtained (having a density of 6 g / m² in the first composition). 2 ).

[0178] The sheet is then dried with an air turner, followed by an infrared oven at 260°C and four banks of hot air dryers at 180°C. The sheet temperature upon exiting the drying room is 110°C and its dryness is between 6 and 8%.

[0179] Then, the coating sauce, as defined in Table 2 above, is applied to the top surface of the previously prepared roll using a Valmet Mayer bar coating machine. The Mayer bar used has a diameter of 16 mm, the pressure exerted by the bar is 0.6 bar, and the machine speed is 350 m / min. These parameters were chosen to apply a coating sauce weight of 3 g / m². 2 at 4 g / m 2Once the top surface is coated with the coating sauce, the cover sheet is dried in a hot air dryer at a temperature ranging from 87°C to 93°C. It is then cooled and rewound to a final temperature ranging from 25°C to 35°C.

[0180] b) Comparative test (without the first aqueous composition according to the invention)

[0181] In order to quantify the effect of the first size-press optimization step, a comparative test was conducted. For this test, only the coating sauce (second composition) was applied to the same paper (namely Viana kraftliner 135 g / m² paper). 2 (having not received prior surfacing). This comparative example therefore did not undergo the size-press step (i.e., application of the first aqueous composition according to the invention). The coating parameters are exactly the same, and the deposited basis weight is also the same, namely a deposited basis weight ranging from 3 to 4 g / m².2 .

[0182] c) Oil absorption measurement and result

[0183] An oil absorption measurement was then performed on both samples while they were lying down. Oil absorption was measured according to ISO 535 for a duration of 1800 seconds (Cobb oil 1800). A photograph of the sample was taken immediately after the measurement to allow for visual comparison of the two samples.

[0184] As shown in Fig. 2, this pilot test demonstrates that the surfacing composition system according to the invention provides oil barrier properties to the coated paper sheet (Fig. 2(a)). In contrast, the comparative composition consisting only of the coating sauce does not exhibit satisfactory oil barrier properties (Fig. 2(b)).

[0185] Of course, various other modifications can be made to the invention within the scope of the attached claims.

Claims

DEMANDS 1. A surfacing composition system intended to be successively deposited on at least one principal face of a sheet of paper and / or cardboard, said system comprising at least: - a first aqueous composition whose dry matter is composed, by mass, relative to the total mass of dry matter, o 40% to 90% of a dextrin which is derived from starch, said starch having, by mass, relative to its total mass, an amylopectin content greater than or equal to 70%, and o of 10% to 60% of a hydrated talc, the hydrated talc has a median particle size, D50, less than or equal to 6 pm; and in which the dry matter of said first aqueous composition represents, by mass, from 10% to 30%, relative to the total mass of the first aqueous composition; - a second coating sauce composition suitable for and / or configured to provide a barrier property at least to water and intended to be deposited on top of said first aqueous composition.

2. A surfacing composition system according to claim 1, wherein said dry matter of the first aqueous composition comprises, by mass, relative to the total mass of dry matter, - 55% to 85%, preferably 60% to 80% and typically 65% ​​to 75% of the dextrin, and - 15% to 45%, preferably 20% to 40% and typically 25% to 35% of hydrated talc.

3. A surfacing composition system according to claim 1 or 2, wherein said starch has, by mass, relative to its total mass, an amylopectin content greater than or equal to 80%, preferably greater than or equal to 90% and typically greater than or equal to 95%.

4. A surfacing composition system according to any one of the preceding claims, wherein the dextrin of said first aqueous composition is obtained by heating said starch to a temperature ranging from 80° to 100°C, preferably from 85° to 95°C, generally for a period ranging from 10 minutes to 50 minutes, preferably from 20 minutes to 40 minutes.

5. Surfacing composition system according to any one of the preceding claims, wherein the dextrin of said first composition has a molecular mass by weight greater than or equal to 1,000,000 Da, and preferably greater than or equal to 3,000,000 Da, and typically ranging from 3,000,000 to 6,000,000 Da.

6. Surfacing composition system according to any one of the preceding claims, wherein the hydrated talc is a hydrated magnesium silicate in the form of a slurry comprising, by mass, relative to the total mass of the slurry, a dry matter of between 55% and 70%.

7. Surfacing composition system according to any one of the preceding claims, wherein the hydrated talc has a median particle size, D50, less than or equal to 5 pm and typically less than or equal to 4 pm.

8. System of surfacing compositions according to any one of the preceding claims, wherein the dry matter of said first aqueous composition represents, by mass, relative to the total mass of the first aqueous composition, preferably from 15% to 25% and typically 20%.

9. A surfacing composition system according to any one of the preceding claims, wherein the second coating sauce composition comprises at least one of the following compounds: acrylic, styrene butadiene, styrene acrylic, polyethylene, bio-polyethylene (Bio-Pe) or polymers comprising by mass relative to their total mass more than 50% of PE-like polyester aliphatic chains, polyvinylidene chloride (PVDC), polyethylene terephthalate (PET), polyurethane (PU), ethylene vinyl alcohol (EVOH), starch, proteins, chitosan, waxes, polylactic acid (PLA), polyhydroxyalkanoates (PHA), polyethylene furanoate (PEF) or a combination thereof and typically comprises acrylic.

10. A surfacing composition system according to any one of the preceding claims, comprising a third composition intended to be deposited between said first aqueous composition and said second coating sauce composition and being suitable for and / or configured to impart oxygen barrier properties to the paper and / or board, preferably said third composition comprising a polymer of a poly(vinyl alcohol) nature.

11. A method for surfacing a sheet of paper and / or cardboard comprising at least one upper principal face and one lower principal face, characterized in that it comprises the application, on at least one of said main faces, of the surfacing composition system according to any one of the preceding claims by successively depositing the first aqueous composition, where applicable the third composition, and the second coating sauce composition.

12. A surfacing method according to claim 11, wherein the first aqueous composition is applied to at least one of said principal faces of said sheet of paper and / or cardboard, at a basis weight of 3 to 10 g / m² 2 preferably ranging from 4 to 8 g / m³ 2 and typically ranging from 5 to 7 g / m³ 2 .

13. A surfacing method according to claim 11 or 12, wherein the second coating sauce composition is applied at a basis weight of 2 to 25 g / m² 2 preferably ranging from 4 to 12 g / m³ 2 and typically ranging from 6 to 8 g / m³ 2 .

14. A surfacing method according to any one of claims 11 to 13, wherein said sheet of paper and / or cardboard is a corrugated cardboard cover, the upper principal face and / or the lower principal face of said cover is / are impregnated with the surfacing composition system by successively depositing the first aqueous composition, optionally the third composition, and the second coating composition.

15. Corrugated cardboard comprising: - at least one cover, preferably at least two covers, each cover having a flat upper principal face and a flat lower principal face, and at least one sinusoidal flute defining an alternation of straight sections, called ridges and inclined sections, said lower main face of the cover being bonded by gluing to flute ridges in contact with it, characterized in that at least said upper main face or said lower and upper main faces of said at least cover, is / are coated by the system of surfacing compositions defined according to any one of claims 1 to 10, namely is / are coated successively with the first aqueous composition, where applicable with the third composition, and the second coating sauce composition.

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