MXPA06013224A - Board comprising hydrotalcite. - Google Patents

Abstract

The invention relates to a process for producing board which comprises providing an aqueous suspension comprising cellulosic fibres; adding hydrotalcite to the suspension; dewatering the obtained suspension to provide a (i) single ply board; or (ii) a ply comprising cellulosic fibres and hydrotalcite, and attaching said ply to one or more plies comprising cellulosic fibres to provide a multi ply board comprising two or more plies. The invention further relates to board comprising one or more plies containing cellulosic fibres, wherein the board further comprises hydrotalcite distributed throughout at least one of said one or more plies. The invention also relates to a method for producing a packaging material, a packaging material per se and uses of the packaging material comprising board comprising one or more plies containing cellulosic fibres and hydrotalcite. The invention also relates to a procedure of making a package and the package per se which package comprises board comprising one or more plies containing cellulosic fibres and hydrotalcite.

Description

CARTON CONTAINING HYDROTALCITE FIELD OF THE INVENTION The present invention relates, in general, to paperboard containing cellulose fibers and hydrotalcite as well as the production thereof; the materials for packaging and the containers that contain the cardboard and the production of these as well as the uses of the materials for packaging of food products, pharmaceutical drinks, cosmetics and tobacco.

BACKGROUND OF THE INVENTION The containers are widely used throughout the world, for example to transport products and protect the contents of the containers. It has been shown that it is especially difficult to design containers to maintain the original properties of the content, such as food products, beverages, pharmaceuticals and cigars. The quality of the content can be reduced when the content itself changes over time, or by means of quality reducing substances that are supplied from or through the container. The content can be treated, for example, pasteurized, as in the case of milk, or dried, like flour. Usually, the containers are designed with different layers that are often They make different materials. Thus, each layer and each material has a specific and objective quality in this container, such as preventing the transfer of oxygen, water or steam to the contents of the container.

Packaging materials are often used to package solid and liquid food products and beverages, for example cereals, milk, juice, wine and water. These packaging materials are usually made of cardboard consisting of several layers or plywood of cellulosic fibers, combined with one or more layers of plastic material in direct contact with the food product or beverage. Despite the use of containers containing a combination of different materials, the content may acquire an unpleasant odor and / or taste after some time. The substances causing the unwanted odor and taste are usually the oxidation products that are formed during the production and storage of the cardboard. Since the packaging pieces are normally flat and opened when they are ready to be filled, the oxidation products can be transferred to the coated plastic within the packaging material.

It would be desirable to be able to provide carton packaging materials containing cardboard and containers having less undesirable or unpleasant odor and / or taste.

It would also be desirable to be able to provide improved processes for the production of these products.

SUMMARY OF THE INVENTION The present invention relates in general to a process for producing cardboard consisting of: (i) disposing of an aqueous suspension containing cellulosic fibers; (ii) adding hydrotalcite to the suspension; (iii) dehydrate the obtained suspension to obtain a single plywood board.

The present invention is also directed, in general, to a process for producing cardboard, which consists of: (i) disposing of an aqueous suspension containing cellulosic fibers; (ii) adding hydrotalcite to the suspension; (iii) dehydrating the suspension obtained to obtain a plywood containing cellulose fibers and hydrotalcite; and (iv) attaching the plywood to one or more plywood containing cellulosic fibers. to obtain a multilayer cardboard containing two or more sheets.

The present invention is also directed, in general, to a board containing one or more sheets having cellulosic fibers, wherein the board further has hydrotalcite distributed by at least one or more layers.

The present invention is further directed, in general, to a method for producing a packaging material consisting of: (i) disposing of cardboard containing one or more layers having cellulose fibers and hydrotalcite; and (ii) subjecting the board to one or more selected conversion operations of impregnation, varnishing, coating, laminating, metallizing, stamping, marking or swaging, folding, sheet locking, embossing and bending.

The present invention is also directed, in general, to a packaging material containing cardboard which comprises one or more layers containing cellulosic fibers and hydrotalcite, wherein it also has one or more slits, folds or markings.

The invention is also directed, in general, to a method for manufacturing a package, consisting of: (i) disposing of a piece of packaging material consisting of cardboard containing one or more layers having cellulosic fibers and hydrotalcite; (11) filling the packaging part with a solid or liquid content to form an unsealed package; and (m) sealing the obtained package.

The present invention is also directed, in general, to a container containing cardboard having cellulose fibers and hydrotalcite, wherein it also has a solid or liquid content.

The invention furthermore addresses the uses of the carton containing material, which consists of one or more layers having cellulose fibers and hydrotalcite, for packaging solid or liquid food products, beverages, pharmaceuticals, cosmetics, chocolates, cigars or tobacco. .

DETAILED DESCRIPTION OF THE INVENTION In accordance with the present invention, it has been found that problems that cause undesirable and unpleasant odor and / or taste of the carton and the packaging materials and carton-containing containers can be reduced by using hydrotalcite during production. of these as an additive for aqueous cellulose suspensions. It has also been found that the present invention reduces the negative effect in the cardboard manufacturing processes by the presence of disturbing and harmful substances present in the aqueous cellulosic suspensions, specifically problems caused by pitch, obstructions and low molecular weight organic substances, anionic . Furthermore, it has been found that the addition of hydrotalcite together with the additives used to manufacture cardboard also improves the performance of these additives if compared when hydrotalcite is not added. Examples of these additives for which improved performance can be observed include drainage and retention aids, sizing agents, and others. Preferably, hydrotalcite is used together with one or more drainage and retention aids consisting of at least one cationic polymer. Thus, the present invention makes it possible to obtain a reduction in odor and / or taste desired and unpleasantness of the carton and packaging materials containing improved drained cardboard (dehydration) and retention as well as better gluing in the cardboard manufacturing processes, while reducing the content of disturbing and harmful substances in the cellulosic suspension.

Hydrotalcite belongs to the group of materials known as clays. The term "hydrotalcite", when used herein, refers to hydrotalcite and hydrotalcite type clays that include double stratified hydroxide compounds, for example: manasseite, pyroaurite, sjrotrenite, stichiteite, barbertonite, takovite, reevesite, desautelsite, motukoreaite, wermlandite , meixnerite, coalingite, chloromagalumite, carrboidite, honessite, woodwardite, iowaita, hidrohonessitae, mountkeitita, etc. The hydrotalcite according to the invention can be obtained from natural hydrotalcites, synthetic hydrotalcites and natural or synthetic hydrotalcites chemically and / or physically modified. Natural hydrotalcites normally have a practically crystalline structure.

However, the hydrotalcites that are obtained by synthesis can also contain amorphous material that It has practically the same chemical composition as the crystalline structures. The amount of amorphous material present in synthetic hydrotalcite clays depends mainly on the reaction parameters used. The term "clay" when used herein refers to clays that have virtually crystalline structure and also to clays that contain crystalline and amorphous structures.

The clays are characterized by a stratified structure where the atoms within the layers (lamellae) are crosslinked by chemical bonds, while the atoms of the contiguous layers interact mainly by physical forces. The layers of the clay can be unloaded or loaded depending on the type of atoms present in the layers. If the layers have charge, then the space between these layers, also called the interlayer space, contains ions that have the opposite charge with respect to the charge of the layers. The term "cationic clay", when used herein, refers to clays having positively charged layers and anions present in the interlayer space. The term "anionic clay", when used herein, refers to clays having negatively charged layers and cations present in the space between layers. Normally the ions in the space between layers are interchangeable. Preferably, the hydrotalcite of the invention is cationic, that is, it is a cationic clay.

The hydrotalcite of the invention can have practically any anion, as an option, also water molecules, present in the interlayer space. Examples of common anions that may be present in the interlayer space may be N03", OH", Clr ", Br", I ", C032", S042", Si032", Cr042", B032", Mn04", HV04 and C104 ~, as well as support or intercalating anions such as V? 0286 ~ and M070246", acetate-type monocarboxylates, dicarboxylates such as oxalate and alkylsulfonates such as lauryl sulfonate; usually hydroxide and carbonate. The natural hydrotalcites of the invention commonly have carbonate anions in the interlayer space.

The layer or lamella of the hydrotalcite conveniently has at least two different metal atoms with different valency. Conveniently, one metal atom is divalent and the other metal atom is conveniently trivalent. However, the layer can also have more than two metal atoms. The charge of the layer is regulated by the ratio of the metal atoms that have different valences. For example, a higher amount of trivalent metals will cause a layer to have a high density of positive charge. Conveniently, the hydrotalcite of the invention has layers having divalent and trivalent metals in a ratio so that the total charge of the layers is cationic, and the layers have anions. Preferably, the layers consist mainly of divalent and trivalent metals in a proportion such that the total charge of the layers is cationic.

The synthetically produced and natural hydrotalcites according to the invention can be characterized by the general formula: [Mm 2¿ ++ R Mi 3+ / (O-viHjx) 2m + 2p] Xn / 2- ". BH20, wherein m and n, independent of each other, are integers having a value such that m / n is in the range from 1 to 10, preferably 1 to 6, more preferably 2 to 4 and more preferably values around 3; b is an integer having a value in the range from 0 to 10, conveniently a value from 2 to 6, and many times a value around 4; Xn / Zz "is an anion where z is an integer from 1 to 10, preferably from 1 to 6, conveniently Xn / z2" includes N03 ~, OH ", Cl", Br ", I", C032", S042", SIO32", Cr042", B032", Mn04", HV04 and C104", support and intercalating anions such as V? 0? 286" and M070246"acetate type monocarboxylates, bicarboxylates as oxalate and alkylsulphonates such as lauryl sulfonate, M2 + is a divalent metal atom, suitable divalent metal atoms include Be, Mg, Cu, Ni, Co, Zn, Fe, Mn, Cd and Ca, preferably Mg; M3 + is a trivalent metal atom, Suitable trivalent metal atoms include Al, Ca, Ni, Co, Fe, Mn, Cr, V Ti and In, preferably Al.

Preferably the divalent metal is magnesium and the trivalent metal is aluminum, converting the formula to: [Mgm2 + Aln3 + (OH) 2rn-.2n] Xp / Zz ". BH20.

The hydrotalcites according to the invention can be prepared by hydrothermal treatment (thermal solvo) of a slurry containing an aluminum source and a magnesium source. Examples of suitable hydrotalcites of the invention and methods for their preparation include those described in the publication of the international patent application No. WO 01/12550, the disclosure of which is incorporated herein by reference.

In a preferred embodiment of the invention, the hydrotalcite has a 3R2 space factor. In another preferred embodiment of the invention, the hydrotalcite has a 3R2 space factor, for example a 3R? Space factor. The differences between the 3R space factors? and 3R2 of a hydrotalcite are described in International Patent Application Publication No. WO 01/12550, the disclosure of which is incorporated herein by reference.

Preferably, the hydrotalcite is used according to the invention as a slurry (suspension) or powder, which can be easily dispersed in water. The hydrotalcite suspension or powder may also contain other components, for example, dispersing and / or protective agents which may contribute to the total effect of the hydrotalcite. These agents can have a non-ionic, anionic or cationic nature. Examples of suitable protective agents or colloids include water-soluble cellulose derivatives, for example hydroxyethyl- and hydroxypropyl-, methylhydroxypropyl- and ethylhydroxyethyl cellulose, methyl- and carboxymethylcellulose, gelatin, starch, guar gum, xanthan gum, polyvinyl alcohol , etc. Examples of the appropriate dispersing agents may be the non-active agents ionics, for example ethoxylated fatty acids, fatty acids, alkylphenols or fatty acid amides, ethoxylated and non-ethoxylated glycerol esters, sorbitan esters of fatty acids, nonionic surfactants, polyols and / or their derivatives; anionic agents such as alkyl or alkylaryl sulfates, sulfonates, ether sulfonates, polyacrylic acid; and cationic agents such as etherquats obtained by the reaction of alkanolamines with mixtures of fatty acids and dicarboxylic acids, optionally alkoxylating the obtained esters and quaternizing the products, quaternized fatty acid amides, botains, dimethyldialkyl or dialkylarylammonium salts and cationic gemini dispersing agents.

According to the present invention, the board is produced by a process consisting of adding hydrotalcite to an aqueous cellulosic suspension and then dehydrating the obtained suspension to form the cardboard. In a preferred embodiment of the invention, the process produces a single-layer carton containing hydrotalcite which is preferably distributed throughout the board, more preferably having a substantially uniform distribution throughout the carton. The single-ply board contains only one layer containing cellulosic fibers.

In another preferred embodiment of the invention, the process produces a multilayer board having two or more layers having cellulosic fibers, wherein at least one of the two or more layers has hydrotalcite. Preferably, the hydrotalcite is distributed along at least two or more layers, more preferably it is distributed substantially uniformly along at least two or more layers, more preferably in at least one of the outer layers. The multi-layer paperboard according to the invention can be produced by forming at least one layer having cellulosic fibers and hydrotalcite and attaching at least one layer to one or more layers having cellulosic fibers to form a multi-layer paperboard. For example, the multilayer paperboard can be produced by forming individual layers separately into one or more continuous paper forming units and then embedding them together in the wet state. Examples of the appropriate multilayer board grades of the invention may be those having from 3 to 7 layers having cellulosic fibers and at least one of the layers having hydrotalcite.

In the process of the invention, the cardboard, for example the individual and multilayer cardboard grades, is they can submit to other process steps. Examples of suitable process steps include coating, for example cotton coating and pigment coating, printing and cutting. Accordingly, examples of the appropriate cartons of the invention may be coated paperboard, for example coated with cotton and / or pigment and printed cardboard.

The hydrotalcite can be added at any time in the production process of the cardboard starting from the moment where the wood chips are disintegrated until the moment in which the dehydration of the cellulose suspension is carried out.

According to a preferred embodiment of the invention, the hydrotalcite is added to the cellulose suspension of a pulp manufacturing process. The hydrotalcite can be added before or after the pulp manufacturing process, which can be the Kraft, mechanical, thermomechanical, chemomechanical, chemithermomechanical processes to manufacture the pulp. The hydrotalcite can be added just before the manufacturing process of the pulp or directly to the pulp manufacturing process, as it can be in the digester. However, it is preferred that the hydrotalcite it is added to the cellulose suspension after chemical digestion, for example after the brown paper pulp scrubber, or after the refining of the mechanical pulp (chemo). Normally, the cellulose pulp is bleached in a multi-stage bleaching process consisting of different bleaching stages and the hydrotalcite can be added to any bleaching sequence. Examples of the appropriate bleaching steps can be color bleaching steps, for example elemental chlorine and bleach steps with chlorine dioxide, bleaching steps without chlorine, for example the peroxide steps such as ozone, acid peroxide and peracetic acid, and combinations of chlorine and bleached without chlorine and oxidizing stages, optionally in combination with reducing stages such as dithionite treatment. The hydrotalcite can be added to the cellulose suspension directly for a bleaching step, preferably in the mixer before the bleaching tower, at any time between the bleaching and washing steps, and also in a washing step where the hydrotalcite can be partially separated, for example in the displacement section. Preferably, when the hydrotalcite is added to the cellulosic suspension of a manufacturing process of pulp, the pulp obtained subsequently is used in a cardboard manufacturing process.

According to another preferred embodiment of the invention, the hydrotalcite is added to a cellulosic suspension of a cardboard manufacturing process. The hydrotalcite can be added to the cellulose suspension at any time during the cardboard manufacturing process, such as thick pulp, thin pulp or white water before being recycled, for example before the feeding box of the thin paper pulp. Preferably, the hydrotalcite is added to the coarse pulp. The hydrotalcite can also be added to more than one point of the pulp and / or cardboard manufacturing processes. For example, the integrated pulp and cardboard factories, the hydrotalcite can be added in the process for the production of pulp, and optionally also in the cardboard production process, and it is possible to add one or more drainage and retention aids in the cardboard production process. These processes can include the dehydration of the cellulose suspension containing hydrotalcite, diluting the suspension obtained, adding one or more auxiliaries to the diluted suspension. of draining and retention and dehydrating the suspension containing the drainage and retention aids, unbleached Kraftliner, unbleached testliner, and recycled liner; fluting and fluting corrugated. Preferably, the paperboard has a grammage of at least 130 g / m2, more preferably a range of 140 to 600 g / m2 and more preferably from 150 to 450 g / m2. Preferably, the paperboard has a density density of from 120 to 1200 kg / m3, more preferably from 150 to 800 kg / m3, and more preferably from 200 to 600 kg / m3. The process can be used for the production of cardboard from different types of aqueous suspensions containing cellulose fibers, or aqueous cellulose suspensions. Preferably, the suspension contains at least 25% by weight, and more preferably at least 50% by weight of these fibers, based on the anhydrous substances. The cellulosic fibers may be based on bleached, unbleached pulps, they may be based on virgin and / or recycled fibers, and the suspension may be based on chemical pulp fibers such as sulphate pulps, sulfite and organ solve, mechanical pulp such as pulp thermomechanical (PTM), mechanical pulp chemotherapy (PCTM), more refined pulp and pulp of crushed wood, hardwood and soft wood, and may also be based on fibers recycled, as a choice of de-inked pulp (TDT) and mixtures of these. In multilayer cardboard grades the layers can be made of different types of pulp. Examples of suitable multilayer combinations with bleached cellulosic fibers may be the bleached chemical ink surface / in PDT, PCTM or mechanical pulp / bleached chemical pulp backing; and bleached chemical pulp surface / middle part PDT, PCTM or mechanical pulp / mechanical pulp backing; the optionally coated upper side and the optionally coated rear side.

The cellulosic suspension may also contain mineral fillers of traditional types such as, for example, kaolin, china clay, titanium dioxide, chalk, talc and natural and synthetic calcium carbonates such as calcium sulfate, crushed marble and precipitated calcium carbonate.

Preferably, the hydrotalcite is added to the cellulosic suspension in an amount of from about 0.01% by weight to about 10% by weight, more preferably from about 0.06% by weight to about 5% by weight, calculated as anhydrous hydrotalcite in a suspension anhydrous cellulose During the process of the invention, hydrotalcite is preferably used together with one or more additional additives by addition to the aqueous cellulosic suspension prior to dehydration. Examples of suitable additional additives may be drainage and retention aids, cationic coagulants, sizing agents such as rosin-based sizing agents and cellulose-reactive sizing agents, eg, ketene dimers and succinic anhydrides, reinforcing agents in dry, wet reinforcing agents such as polymers formed by the reaction of polyamines and polyamitamine with epichlorohydrin, optical brighteners, dyes and others.

Examples of suitable drainage and retention aids may be organic polymers which may be selected from anionic, amphoteric, nonionic and cationic polymers, siliceous materials and mixtures thereof. The use of siliceous materials and organic polymers as drainage and retention aids, or as flocculating agents, is well known in the art. The term "drainage and retention aid" when used herein refers to a component (agent, additive) that when added to An aqueous cellulose suspension gives better drainage and / or retention than that obtained when the component is not added. Preferably, the hydrotalcite is used together with at least one cationic polymer. The term "cationic polymer" when used herein refers to an organic polymer having one or more cationic groups, preferably a total cationic charge. The cationic polymer can also contain anionic groups and such polymers are commonly known as amphoteric polymers.

Suitable polymers for use in the process can be obtained from natural or synthetic sources, and can be linear, branched or cross-linked. Examples of the appropriate polymers may be anionic, amphoteric and cationic polysaccharides, preferably starches; anionic, amphoteric and chain-growth polymers, preferably acrylamide-based cationic polymers, such as anionic and cationic acrylamide-based polymers, mainly linear, branched and cross-linked; as well as poly (cationic diallyldimethylammonium chloride); cationic polyethylene imines; cationic polyamines; cationic polyamidoamines and polymers based on vinylamide, anionic growth polymers in stages, preferably naphthalene-based condensation polymers, preferably anionic. Cationic starch and cationic polyacrylamide are particularly preferred polymers and can be used individually, together with one another or together with other polymers, for example, other cationic and / or anionic polymers. The molecular weight of the polymer is suitably greater than 1,000,000 and preferably greater than 2,000,000. The upper limit is not crucial; it can be around 50,000,000, usually 30,000,000 and conveniently around 25,000,000. However, the molecular weight of the polymers obtained from natural sources may be higher.

Examples of suitable silicon materials may be silica-based particles, anionic and anionic clays of the smectite type. Preferably, the silicon material has particles in the colloidal range of the particle size. Particles based on anionic silica, that is, particles based on SiO2 or silicic acid are preferably used and these particles are usually supplied in the form of colloidal aqueous dispersions, the so-called sols. Examples of silica-based particles Suitable may be colloidal silica or different types of polysilicic, homopolymerized or copolymerized acid. The silica-based sols may be modified or may contain other elements such as aluminum, boron, nitrogen, zirconium, gallium, titanium and the like, which may be present in the aqueous phase and / or in the silica-based particles. Examples of the appropriate silica-based particles of this type can be aluminum-modified colloidal silica and aluminum silicates. It is also possible to use mixtures of these appropriate silica-based particles. Examples of suitable drain and retention aids consist of anionic silica-based particles such as those described in US Patent Nos. 4,388,150; 4,927,498; 4,954,220; 4,961,825 4,980,025; 5,127,994; 5,176,891; 5,368,833; 5,447,604 5,470,435; 5,571,494; 5,573,674; 5,584,966; 5,603,805 5,688,482; and 5,707,493; which is incorporated herein by reference.

Examples of the appropriate anionic silica based particles can be those having an average particle size below about 100 nm, preferably below about 20 nm and preferably in the range from about 1 to about 10 nm. As an agreement in the chemistry of the silicas, the particle size refers to the average size of the primary particles, which may be added or not added. The specific surface area of the silica-based particles is suitably above 50 m2 / g and preferably more than 100 m2 / g. In general, the specific surface area can be up to about 1700 m2 / g and preferably up to 1000 m2 / g. The specific surface area is measured by titration with NaOH in a well known manner, for example as described by GW Sears in Analytical Chemistry 28 (1956): 12, 1981-1983 and in US Patent No. 5,176,891. The area thus determined represents the average specific surface area of the particles.

Preferably, the anionic silica-based particles have a specific surface area in the range from 50 to 100 m2 / g, more preferably from 100 to 950 m2 / g. The silica-based particle sols of these types also comprise modifications, for example with any of the elements mentioned above. Preferably, the silica-based particles are present in a sol having an S value in the range from 8 to 50%, preferably from 10 to 40%, containing silica-based particles with a specific surface area in the range from 300 to 1000 m2 / g, conveniently from 500 to 950 m2 / g and preferably from 750 to 950 m2 / g, the soles of which They can be modified as already mentioned. The S value can be measured and calculated as described by Iler and Dalton in J. Phys, Chem. 60 (1956), 955-957. The S value indicates the degree of aggregation or microgel formation and a lower S value indicates a greater degree of aggregation.

In yet another preferred embodiment of the invention, the silica-based particles are selected from polysilicic, homopolymerized or copolymerized acid, having a high specific surface area, suitably above about 1000 m2 / g. The specific surface area can be in the range from 1000 to 1700 m2 / g and preferably from 1050 to 1600 m2 / g. The sols of modified or copolymerized polysilicic acid may contain other elements as already mentioned. In the art, polysilicic acid is also known as polymeric silicic acid, polysilicic acid microgel, polysilicate and polysilicate microgel, all of which are comprised by the term polysilicic acid used at the moment. Aluminum-containing compounds of this type are commonly known as polyaluminium silicate and polyaluminium silicate microgel, which are comprised by the terms silica modified aluminum and aluminum silicate colloidal which are used herein.

Examples of the appropriate anionic clays of the smectite type include montmorillonite / bentonite, hectorite, beidelite, nontronite, saponite, laponite, preferably bentonite. Examples of the appropriate anionic bentonite clays can be described in US Patent Nos. 4,753,710; 5,071,512; and 5,607,552, which are incorporated herein by reference.

Examples of the appropriate cationic coagulants (also known as garbage binders and fixatives) include water-soluble organic polymeric coagulants and inorganic coagulants. The cationic coagulants can be used individually or together, that is, a polymeric coagulant can be used in combination with inorganic coagulants. Examples of the appropriate water soluble organic polymeric cationic coagulants can be cationic polyamines, polyamidoamines, polyethyleneimines, polymers of the condensation of dicyandiamide and polymers of the monomer mixture with ethylenic unsaturation or monomer, soluble in water which are formed from 50% to 100% mol of cationic monomer and from 0 to 50% mol of another monomer. The amount of cationic monomer is usually at least 80 mol%, conveniently 100%. Examples of the appropriate ethylenically unsaturated cationic monomers may be dialkylaminoalkyl (meth) acrylates and -acrylamides, preferably in quaternized form, and diallyl dialkylammonium chlorides, for example diallyldimethylammonium chloride (DADMAC), preferably homopolymers and copolymers of DADMAC. Organic polymeric cationic coagulants usually have a molecular weight in the range from 1000 to 700,000, conveniently from 10,000 to 500,000. Examples of suitable inorganic coagulants can be aluminum compounds, for example alum and polyaluminium compounds, for example polyaluminium chlorides, polyaluminium sulfates, polyaluminium silicate sulfates and mixtures thereof.

Examples of preferred drainage and retention systems according to the invention consist of: (i) anionic silica-based particles in combination with cationic polysaccharides, preferably starch, or non-cationic chain-growing polymers, preferably cationic acrylamide based polymer, optionally in combination with cationic coagulant; (ii) anionic silica-based particles in combination with anionic acrylamide-based polymer, optionally in combination with cationic organic polymer and / or cationic coagulant; (ii) bentonite in combination with cationic chain-growing polymers, preferably cationic acrylamide based polymer, as an option in combination with cationic coagulant; (iv) cationic polysaccharide, preferably cationic starch, in combination with stepped, anionic growth polymer, preferably the condensation polymer based on anionic naphthalene, as an option in combination with cationic coagulant; (v) polymer with chain growth, cationic, preferably polymer based on cationic acrylamide, in combination with polymer with stepwise, anionic growth, preferably condensation polymer based on naphthalene anionic, as an option in combination with cationic coagulant; (vi) cationic chain-growing polymer, preferably cationic acrylamide based polymer, in combination with cationic coagulant; and (vii) polymer with chain growth, cationic, preferably polymer based on cationic acrylamide, in combination with polymers based on anionic and cationic acrylamide, crosslinked.

The components of the drainage and retention aids can be added to the cellulosic suspension in the traditional way and in any order. When a siliceous material is used, it is preferred to add a cationic polymer to the suspension before adding the siliceous material, even if it is also possible to use the opposite order of addition. It is further preferred to add a cationic polymer before the shearing stage, which can be selected from pumping, mixing, kneading and others, and adding the siliceous material after the shearing step. When a cationic coagulant is used, it is preferred to introduce it into the suspension before introducing the cationic polymer and the siliceous material, if used. In other In one embodiment, the cationic coagulant and the cationic polymer can be introduced into the suspension at substantially the same time, separately or in a mixture, for example as described in US Patent No. 5,858,174, which is incorporated herein by reference.

If the hydrotalcite according to the invention is used together with a drainage and retention aid, the hydrotalcite can be added to the suspension before or after the addition of the drainage and retention aid. Preferably, the hydrotalcite is added before the addition of the drainage and retention aid (s). Preferably, the hydrotalcite is added to the thick pulp, or to the thin paper pulp. And the drainage and retention aid is added to the thin paper pulp. The hydrotalcite can also be added to the recirculated white water. If two or more drainage and retention aids are used, ie, a cationic polymer together with siliceous material, eg, silica-based particles, and optionally organic organic polymer, the hydrotalcite can be added to the suspension (pulp). cellulose, before, after or between the addition of drainage and retention aids, or together with any of the drainage and retention aids. The hydrotalcite it can also be added at different locations in the process, for example to the pulp and then again to the thin paper pulp before the addition of the drainage and retention aid.

The drainage and retention aid (s) according to the invention can be added to the pulp to be dehydrated in amounts that can vary within wide limits depending on, among others, the type and number of components, the type of cellulose suspension, the salt content, the type of salts, the content of the load, the type of load, the point of addition, the degree of closure of the white water and others. In general, the retention and drainage aids are added in amounts that give better drainage and / or retention than that obtained when the components are not added. The cationic polymer is usually added in an amount of at least about 0.001% by weight, often at least about 0.005% by weight, based on the anhydrous cellulose suspension, and the upper limit is usually about 3% and conveniently around 1.5%. The commonly applied addition amounts of the cationic polymer are from about 0.01% to about 0.5% by weight.

Anionic materials, for example siliceous materials, ie, particles based on anionic silica and anionic clays of the smectite type and anionic organic polymers are usually added in an amount of at least about 0.001% by weight, very often by at least about 0.005% by weight, based on the anhydrous cellulose suspension, and the upper limit is usually about 1.0% and conveniently about 0.6% by weight.

When a cationic coagulant is used in the process, it can be added in an amount of at least about 0.001% by weight, calculated as anhydrous coagulant in the anhydrous cellulose suspension. Conveniently, the amount is in the range from about 0.05 to about 3.0%, preferably in the range from about 0.1 to about 2.0%.

Moreover, the process can also be useful in the manufacture of cardboard from cellulose suspensions having high conductivity. In these cases, the conductivity of the suspension that is dehydrated on the mesh is usually at least 1.0 mS / cm, conveniently at least 2.0 mS / cm, and preferably at least 3.5 mS / cm. The conductivity it can be measured by standard equipment such as a WTW LF 539 instrument from the Christian Berner supplier. The aforementioned values are conveniently determined by measuring the conductivity of the cellulosic suspension that is fed to or is present in the box head of the carton machine or in another version, measuring the conductivity of the white water obtained by dehydrating the suspension.

The present invention also comprises cardboard manufacturing processes where white water is widely recirculated, or recycled, that is, with a high degree of white water closure, for example where 0 to 30 tons of potable water per tonne of cardboard is used. anhydrous produced, usually less than 20, conveniently less than 15, preferably less than 10, and notably less than 5 tons of potable water per tonne of cardboard.

The invention further relates to a method for producing packaging material consisting of having cardboard having one or more layers containing cellulosic fibers and hydrotalcite, as defined herein, and subjecting the paperboard to one or more selected conversion operations. printing, varnishing, coating, for example, plastic coatings, extrusion coating, barrier coating, lamination, for example lamination of sheet metal plastic laminated film, for example metallized aluminum foil lamination, stamping, ie, stamping of unprocessed parts , folding, marking, peeling, that is, waste removal, punching, that is, separation of the blanks, metal sheet locking, embossing and bending. The term "folding" when used herein also refers to grating and grooving. Preferably, one method consists of one or more conversion operations consisting of grating or folding, more preferably two or more operations consisting of grating or folding, for example cutting and shredding or folding.

The invention also relates to the packaging material consisting of cardboard containing one or more layers having cellulosic and hydrotalcite fibers, as defined herein, wherein it also has one or more folds. Folds, also known as stripes, slits or fold lines, make it easy to bend and form the packaging material before filling. The packaging materials of the invention may have one or more layers of plastic film, sheet metal, for example aluminum and / or a barrier coating.

The invention furthermore relates to a method for preparing a package consisting of having a blank of packaging material having cardboard containing one or more layers containing cellulose fibers and hydrotalcite, as defined herein; filling the blank with a solid or liquid content to obtain an unsealed package; and then seal the obtained container. Preferably, the packaging material has one or more slots, folds or markings. The term "blank", when used herein, means a packaging material or unfilled container. Preferably, the blank is bent and formed for filling. Examples of convenient methods for sealing can be glued and heat sealed.

Examples of the appropriate solid and liquid contents can be solid and liquid food products, for example tomato, soup and cream products; drinks for example milk, fruit juices, wines and water; pharmaceutical products; cosmetics; chocolates; cigars and tobacco. In a preferred embodiment, the invention also it consists in sterilizing the container and / or the contents. The term "sterilize" when used herein means reducing the amount of microorganisms. Examples of methods and means suitable for sterilization can be heat, for example rapid heating and cooling, chemical substances, for example hydrogen peroxide, irradiation, for example IR and UV irradiation. The filling can be done in sterile conditions.

The invention also relates to a package having cardboard containing one or more layers containing cellulose fibers and hydrotalcite, as defined herein, wherein it also has solid or liquid content. The invention further relates to the uses of packaging material consisting of cardboard, which has one or more layers containing cellulosic fibers and hydrotalcite, as defined herein, for packaging solid or liquid food products, pharmaceutical beverages, cosmetics , chocolates, cigars or tobacco.

Suitable packaging examples of the invention can be packaged for food products, beverage packaging, sterile packaging and aseptic packaging.

The invention is further illustrated in the following example, which, however, is not intended to limit the same. The parts and percent refer to the parts by weight and percent by weight, respectively, unless otherwise mentioned.

EXAMPLE 1 In this example, the effectiveness of the invention in reducing the unwanted, and / or unpleasant taste, aroma and / or smell of the paperboard was evaluated.

A chemical substance that is present in the cardboard and causes unwanted taste, aroma and / or odor, n-hexanal, was chosen as the aromatic model substance, hereinafter "aromatic substance". The content of the aromatic substance was determined by the so-called hot method in which a sample consisting of 2.5 g of packaging material was placed in a container which was then sealed. After stirring for 5 minutes and then maintaining at 100 ° C for 40 minutes, a quantity of gas was recovered above the sample and immediately analyzed in gas chromatograph. The content of the aromatic substance in the amount of gas was calculated from the upper area of the chromatogram. The degree of taste, aroma and / or unwanted odor was given when the waste of the aromatic substance, which constitutes a shared percentage of the content of the aromatic substance transferred from the cellulose leaf or pulp containing hydrotalcite in relation to the corresponding content transferred from the leaf or pulp without additives. Thus, the content of the aromatic substance transferred from the leaf or pulp without the addition of hydrotalcite or paper chemicals was calculated.

The cardboard layers with and without hydrotalcite were produced in a pilot machine. The coarse cellulose suspension (thick pulp) was used based on the pulp of a cardboard factory for liquid packaging consisting of 30% bleached softwood pulp and 70% bleached hardwood pulp. The slurry was diluted with press water of bleached hardwood pulp to obtain a consistency of 15 g / L. The suspension obtained had a pH of 7 and conductivity of 0.8 mS / cm. The suspension was stirred and heated to 50 ° C. In one test, 50 kg / t of hydrotalcite (CC-22, Akzo Nobel Catalyst BV) was added to the suspension. The suspension was stirred for 30 minutes.

Before forming the sheet, the following additives were added to the suspension in the following order: 8% calcined clay; 1 kg / t of aluminum sulfate; 4 kg / t of cationic starch (Perlbond 970); 1.6 kg / t of rosin-based sizing agent (Eka Composize L44HT); 1.5 kg / t of aluminum sulfate; 1.5 kg / t of sizing agent based on alkenyl ketene dimer (Eka Keydime 28HF); 5 kg / t of cationic starch (Perlbond 970); and 2.5 kg / t of silica sol (Eka NP 442). The suspension was dehydrated to form a sheet having a basis weight of about 90 g / m2.

Directly after production, A4 sheets were wrapped in aluminum foil and sealed in air-tight plastic bags. After two weeks, the bag was analyzed with gas chromatography to determine the aromatic substance. Table 1 shows the amount of aromatic substance after storage for two weeks.

Table 1 Example 1 shows that the invention resulted in a 35% reduction in the content of the volatile aromatic substance in the gas phase.

Example 2 Cardboard was prepared as described in Example 1 except that the amount of hydrotalcite added was different. The cardboard obtained was analyzed to determine the load content, also known as ash retention. Table 2 shows the results.

Table 2 Table 2 shows that the loading level was higher when hydrotalcite was added to the process.

Example 3 In this example the sizing performance was evaluated. A cellulose suspension of a cardboard factory for liquid packaging was treated with hydrotalcite had the 3R2 stacking (CC-22, Akzo Nobel Catalyst BV) and with talc (DInntalc P05 Omya) respectively. The sizing, drainage and retention aids were added and the leaves prepared by hand (SCAN-C 26:76). The sizing of the leaves was measured as Cobb 60 values (SCAN-C 26:64).

The thick cellulose suspension (thick pulp) was used based on the pulp of a cardboard factory for liquid packaging (LPB) consisting of soft wood pulp and bleached hardwood. The suspension was stirred and heated to 50 ° C. Hydrotalcite and talc were added to the suspension which was stirred for 30 minutes. The slurry was then diluted with tap water to a consistency of 5 g / 1. The suspension obtained had a pH of 8 and conductivity of 0.7 mS / cm. Before preparing the leaf, 0.3 kg / ton of anhydrous pulp (Keydime C223, Eka Chemicals), 8 kg / ton of anhydrous cationic starch pulp (Perlbond 970) and 0.5 kg / ton of anhydrous particle based pulp were added. silica (Eka NP 590 Eka Chemicals). The sheets had a basis weight of approximately 73 g / m2. Table 3 shows the results of the sizing obtained by the addition of different amounts of talc and hydrotalcite to the pulp for cardboard for packaging liquids.

Table 3 The performance of the sizing was improved when hydrotalcite was used on talc. The cellulose sheet containing bleached and hydrotalcite pulp can be used as a layer of a single-layer paperboard and multilayer paperboard, for example the top layer and / or the backing.

Example 4 The sizing performance was evaluated with higher additions of hydrotalcite (CC-22, Akzo Nobel Catalyst BV) and talc (Finntalc P05 Omya), respectively. The sheets were prepared by hand and the sizing performance was measured as Cobb 60 values (SCAN-Para 12:64).

A thick cellulose suspension was used based on the pulp of an LPB factory consisting of pulp from White wood sulfate and hardwood bleached with hydrogen peroxide at a consistency of ~ 4%. This suspension was stirred and heated to 50 ° C. Hydrotalcite or talc was added to the suspension, which was allowed to stand for 20 minutes. The slurry was then diluted with bleaching filtrate at -3.9 g / L of consistency. To the AKD pulp, 1.6 kg / ton of rosin sizing, 1.6 kg / ton of alum, 5.0 kg / ton of cationic starch and 0.35 kg / ton of silica-based particles (Eka NP 590 Eka Chemicals) were added before prepare the leaves by hand (former Rapad-kothen former). The leaves had a basis weight of approximately 100 g / m2. Table 4 summarizes the results of the sizing obtained by the application of the sizing to the cardboard pulp for liquid packaging.

Table 4 Table 4 shows that the sizing performance was improved (lower Cobb 60 values) using hydrotalcite compared to talc. The cellulosic sheet containing bleached and hydrotalcite pulp can be used as a layer of a single layer board and multilayer board, for example the top layer and / or the backing.

Example 5 This example was made in a deinked pulp factory (DIP). An aqueous suspension of pulp from the DIP factory was treated with hydrotalcite (CC-2, Akzo Nobel Catalyst BV). The turbidity of the filtrate of the pulp was then measured.

The suspension of the pulp used was taken between the disc filter and the screw press in the DIP plant. The suspension of the pulp had a consistency of about 7%, and diluted with running water to ~ 4.2%. This pulp in suspension was stirred and heated to 50 ° C. The hydrotalcite was added to the suspension of the pulp which was left to rest for 30 minutes. The pulp suspension was then filtered through a GF / A glass fiber filter (hole diameter ~ 2 μm). The filtrate was analyzed to determine turbidity in a 2100P turbidity meter. Table 5 shows the results.

Table 5 The turbidity of the filtrate improved (decreased) when de-inked pulp was mixed with hydrotalcite before filtering. The cellulose sheet containing DIP and hydrotalcite can be used as a multilayer paperboard layer, for example the layer under the top and / or intermediate layer.

Claims (20)

1. A process for producing cardboard consisting of: (i) having an aqueous suspension having cellulosic fibers; (ii) adding hydrotalcite to the suspension; (iii) dehydrate the suspension obtained to obtain a single-layer paperboard, wherein the paperboard has a grammage of at least 130 g / m2.

2. A process to produce cardboard consisting of; (ii) having an aqueous suspension having cellulosic fibers; (ii) adding hydrotalcite to the suspension; (iii) dehydrating the obtained suspension to obtain a layer having cellulose fibers and hydrotalcite; and (iv) attaching the layer to one or more layers having cellulosic fibers to obtain a multilayer board having two or more layers.

3. The process of claim 1 or 2, characterized in that it further comprises adding a cationic polymer to the suspension.

4. The process of any of the preceding claims, characterized in that it also consists in adding a siliceous material to the suspension.

5. The process of any of the preceding claims, characterized in that it further consists in adding a sizing agent to the suspension.

6. A cardboard containing one or more layers having cellulosic fibers, wherein the paperboard has a grammage of at least 130 g / m2 and further has hydrotalcite distributed along at least one of one or more layers.

7. A method for producing a packaging material consisting of (i) disposing of paperboard having a grammage of 130 g / m2 and comprising one or more layers having cellulosic fibers and hydrotalcite distributed along at least one of a or more layers; and (ii) subjecting the paperboard to one or more conversion operations selected from: printing, varnishing, coating, laminating, metallizing, stamping, marking, folding, metal sheet locking, embossing and bending.

8. The packaging material consisting of a board having one or more layers having cellulosic fibers and hydrotalcite distributed along at least one of one or more layers, wherein it further comprises one or more slots, markings or folds.

9. A method for preparing a package consisting of: (i) disposing of a blank of a packaging material consisting of cardboard with one or more layers having cellulosic fibers and hydrotalcite distributed along at least one or more layers, (ii) a blank with a solid or liquid content to form an unsealed package; and (iii) sealing the obtained package.

10. A container consisting of cardboard having one or more layers having hydrotalcite cellulosic fibers distributed along at least one or more layers, wherein it also has a solid or liquid content.

11. The process of any of claims 1 to 5; the cardboard of claim 6, the method of claim 7; the packaging material of claim 8; the method of claim 9 or the package of claim 10; where the hydrotalcite has a Stacking 3R ?.

12. The process of any of claims 1 to 5; the carton of claim 6, the method of claim 7; the packaging material of claim 8; the method of claim 9 or the package of claim 10; where the hydrotalcite has a Stacking 3R2.

13. The process of any of claims 1 to 5, 11 and 12; the cardboard of any of claims 6, 11 and 12; the method of any of claims 7, 11 and 12; the packaging material of any of claims 8, 11 and 12; the method of any of claims 9, 11 and 12; or the package of any of claims 10 to 12; wherein the paperboard has one or more layers having cellulosic fibers.

14. The process of any of claims 2 to 5, 11 and 13; the method of any of claims 7, 11 to 13; The material for packaging any of claims 8, 11 to 13; the method of any of claims 9, 11 to 13; or the package of any of claims 10 to 13; where the cardboard has a grammage of at least 130 g / m2.

15. The process of any of claims 1 to 5, 11 to 14; the cardboard of any of claims 6 and 11 to 14; the method of any of claims 7 and 11 to 14; the packaging material of any of claims 8 and 11 to 14; the method of any of claims 9 and 11 to 14; or the package of any of claims 10 to 14; where the cardboard has a grammage of 150 to 450 g / m2.

16. The process of any of claims 1 to 5, and 11 to 15; the card of any of claims 6 and 11 to 15; the method of any of claims 7 and 11 to 15, the packaging material of any of claims 8 and 11 to 15; the method of any of claims 9 and 11 to 15; or the package of any of claims 10 to 15; wherein the paperboard has at least 50% by weight of cellulosic fibers.

17. The process of any of claims 1 to 5 and 11 to 16; the cardboard of any of claims 6 and 11 to 16; the method of any of claims 7 and 11 to 16; the packaging material of any of claims 8 and 11 to 16; the method of any of claims 9 and 11 to 16; or the package of any of claims 10 to 16; where the cardboard has an apparent density of 200 to 600 kg / m3.

18. The method of any of claims 9 and 11 to 17; or the package of any of claims 10 to 17; wherein the solid or liquid content is food products, beverages, pharmaceuticals, cosmetics, chocolates, cigars or tobacco.

19. The method of any of claims 9 and 11 to 18; wherein it also comprises sterilization.

20. The use of the packaging material of any of claims 8 and 11 to 17 for packaging solid or liquid food products, beverages, pharmaceuticals, cosmetics, chocolates, cigars or tobacco.