Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/14—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties characterised by function or properties in or on the paper
  • D21H21/28—Colorants ; Pigments or opacifying agents
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/34—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/41—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups
  • D21H17/44—Synthetic macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds containing ionic groups cationic
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/52—Epoxy resins
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/20—Macromolecular organic compounds
  • D21H17/33—Synthetic macromolecular compounds
  • D21H17/46—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H17/54—Synthetic macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen
  • D21H17/56—Polyamines; Polyimines; Polyester-imides
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
  • D21H17/63—Inorganic compounds
  • D21H17/66—Salts, e.g. alums

Definitions

• the invention relates to a method for producing a paper material, for example paper and cardboard, which is mass dyed, by using a food dye.
• known dyes are used to dye paper material (paper; cardboard) intended to come into contact with food products. More exactly, known dyes are used the specific use of which (dyeing of paper coming into contact with foodstuffs) is certified by certification bodies, such as for example the German ISEGA certification body.
• the aforesaid dyes although they are approved by the main sector regulations, are not "food dyes".
• the latter in Europe, are identified by a code comprising the letter "E” followed by a three-digit number (from 100 to 199).
• the possibility of using food dyes would be particularly desirable as it would confer an added value property to the paper material that is used in food packaging.
• paper or cardboard that are dyed with a food dye could not be limited to the manufacture of food packaging.
• the use of food dyes could in fact be extended, for example, to the manufacture of materials intended for objects for school and/or play use or to the manufacture of the so-called "tissues", i.e. thin paper products such as toilet paper, paper handkerchiefs and paper for household use.
• the chemical nature of the food dyes is such as to give the latter a reduced affinity to the cellulose fibres.
• a paper material is obtained that is dyed in a not sufficiently homogeneous manner, which compromises the aesthetic appearance of the product and accordingly significantly reduces the commercial value thereof.
• One object of the invention is to improve the known methods for producing mass dyed paper materials.
• Another object is to provide a method for producing a mass dyed paper material, in particular dyed paper and dyed cardboard, that enables food dyes to be used and an optimum interaction to be obtained between food dyes and cellulose fibres.
• a further object is to provide a method for producing a mass dyed paper material, in particular dyed paper and dyed cardboard, which enables a homogeneously dyed paper material to be obtained by using food dyes.
• Still another object is to provide a method for producing a mass dyed paper material, in particular dyed paper and dyed cardboard, which enables food dyes to be used and the environmental impact thereof to be reduced by limiting the discharge of dyes into the under-cloth water.
• a method for producing a mass dyed paper material as defined in claim 1.
• a method is made available for producing a mass dyed paper material, such as for example dyed paper or dyed cardboard, which enables the drawbacks of the prior art to be overcome.
• the used food dyes together with specifically selected fixing agents, are added to a paper mixture in quantities and according to an order that are such as to suitably overcome the drawback of the poor affinity between food dyes and cellulose fibres.
• a finished product paper or cardboard
• a good colour migration fastness of the paper in contact with water It is further possible to reduce the environmental impact managing to obtain sufficiently clean under-cloth water.
• a paper material for example a sheet of paper, is "mass" dyed when the dyes are added inside the mixture during processing, this ensuring that the produced sheet is homogenously dyed both internally and on the outer surfaces thereof (faces or sides of the sheet).
• the so-called mixture has to be first prepared, which is obtained from cellulose fibres.
• the cellulose fibres are mixed with water, pulped and refined using apparatuses of known type.
• the mixture is prepared by setting and selecting various parameters: type of raw material that is used, degree of refinement of the mixture and concentration of the mixture.
• the raw material can comprise: short cellulose fibres (for example, birch or eucalyptus cellulose), long cellulose fibres (for example, fir cellulose), cotton fibres, BCTMP (bleached chemi-thermomechanical pulp), recycled paper, etc.
• short cellulose fibres for example, birch or eucalyptus cellulose
• long cellulose fibres for example, fir cellulose
• cotton fibres for example, birch or eucalyptus cellulose
• BCTMP bleachached chemi-thermomechanical pulp
• the degree of refinement of the mixture is measured in °SR (Schopper-Riegler degrees) and influences the physical-mechanical properties of the paper material.
• the concentration of the mixture is expressed as a mass percentage composition, i.e. as the percentage ratio between the mass of the fibres contained in the mixture and the total mass of the mixture.
• a cellulose mixture having a mass equal to 500g which is declared to have a 5% concentration of fibres, will contain 25g cellulose.
• the mixture can vary from an initial 10-12% concentration to a 1% (or less) concentration, through several dilutions, as a function of the grammage that is desired for the paper or cardboard to be produced.
• the mixture can be added with chemical products (for example, dyes) that vary on the basis of the features that the finished product will have to have.
• chemical products for example, dyes
• Table 1 a possible plant on an industrial scale (paper mill) for producing paper is schematically exemplified (from upstream to downstream):
• Table 1 Pulper for pulping the cellulose Dyeing vat Refining the mixture in the refiner
• Pre-machine chest Machine chest (dyed mixture reserve)
• Constant level chest maintenance of constant feeding of mixture to the machine
• Fan pump (addition of water to the mixture coming from the constant level box and delivery to the selector via the fan pump)
• Selector sort of filtration of the mixture
• Headbox distributed of the mixture on the cloth
• Flat table formation of the sheet on the cloth and drainage of the water
• Cylinder system pressing and drying of the sheet
• the first fixing agent and the second fixing agent can be the same as or different from one another.
• the first fixing agent is different from the second fixing agent.
• the first fixing agent and the second fixing agent are added in predetermined w/w percentages, both expressed with respect to the w/w percentage of added food dye.
• the w/w percentages of the first fixing agent and of the second fixing agent vary on the basis of the type and concentration of dye that is used in the mixture.
• the food dye is added in a predetermined w/w percentage, which is expressed with respect to the total quantity of fibres contained in the mixture.
• the w/w percentage of dye to be used depends on the colouring intensity that it is desired to obtain and, as such, can be easily determined by the person skilled in the art.
• the w/w percentage of the first fixing agent and the w/w percentage of the second fixing agent are both comprised between 28% and 87% with respect to the w/w percentage of used dye.
• Table 2 shows, in correspondence with the type of dye, the quantity of each fixing agent to be used, expressed with a w/w % range with respect to the w/w percentage of used dye.
• Table 2 Type of dye First fixing agent (w/w %) Second fixing agent (w/w %) E102 64-87 64-87 E104 32-49 32-49 E110 51-69 51-69 E122 32-49 32-49 E124 43-58 43-58 E129 32-49 32-49 E132 51-75 51-75 E151 28-42 28-42
• the w/w percentage of both a first fixing agent and of a second fixing agent to be used is comprised between 32% and 49% with respect to the w/w percentage of the dye. If, for example, the E122 dye is used (namely, added) in a percentage that is equal to 2% (with respect to the total quantity of fibres contained in the mixture), the percentage of the fixing agents to be used (namely, to be added) with respect to the total quantity of fibres contained in the mixture can be calculated via the proportions set out below.
• the w/w percentage (with respect to the total quantity of fibres contained in the mixture) of the food dye is comprised between 0.01% and 7.5%.
• the term “food dye” refers to the so-called “active” food dye, namely to a solid food dye (powder or granules) that is used as it is, or to a solid food dye (powder or granules) that is dissolved in a liquid formulation (namely, solid dye dissolved in a solvent), or to a solid food dye (powder or granules) that is contained in a lacquer.
• the w/w percentage of a food dye that is added to the mixture thus corresponds to the w/w percentage of the solid food dye, which can be added as it is (namely, in solid form), or dissolved in a liquid formulation, or contained in a lacquer.
• the first period of time and the third period of time are at least 5 minutes, whereas the second period of time is at least 10 minutes.
• the food dye comprises a dye in powder or granules.
• the food dye comprises a liquid - namely solubilized (dissolved in a liquid formulation) - dye.
• the food dye comprises a lacquer dye (dye in the insoluble form thereof), such as for example E 102.
• Table 3 shows a list of known food dyes that are usable in the method according to the invention: Table 3 E 102 - Tartrazine - Food yellow 4 - Colour Index 19140 E104 - Quinoline yellow - Food yellow 13 - Colour Index 47005 E110 - Sunset yellow FCF - Food yellow 3 - orange yellow S - Colour Index 15985 E122 - Azorubine - Carmoisine - Food red 3 - Colour Index 14720 E124 - Ponceau 4R - Cochineal red A - Food red 7 - new coccine - Colour Index 16255 E129 - Allura Red AC - Food red 17 - Colour index 16035 E132- Indigotin - Indigo carmine - Food blue 1- Colour index 73015 E151 - Brilliant Black BN - Black PN - Food black 1 - Colour Index 28440
• the dyes of Table 3 are usable alone or in a mixture in the method according to the invention.
• the first fixing agent and the second fixing agent comprise: linear or branched cationic polyamines (such as for example: copolymer of epichlorohydrin and dimethylamine, copolymer of epichlorohydrin, dimethylamine and N-methylmethanamine; polymer of 1,2-ethanediamine with 2-(chloromethyl) oxirane and N-methylmethanamine; cyanoguanidine polymer with ammonium chloride and formaldehyde; polydiallyldimethylammonium chloride (polyDADMAC); poly(acrylamide-co-polydiallyldimethylammonium chloride).
• linear or branched cationic polyamines such as for example: copolymer of epichlorohydrin and dimethylamine, copolymer of epichlorohydrin, dimethylamine and N-methylmethanamine; polymer of 1,2-ethanediamine with 2-(chloromethyl) oxirane and N-methylmethanamine; cyanoguanidine polymer with ammoni
• a predetermined w/w percentage of an auxiliary agent is added before adding the second fixing agent, where the aforesaid w/w percentage is expressed with respect to the total quantity of fibres contained in the mixture.
• the auxiliary agent can enable cleaner under-cloth water to be obtained and can partially cooperate in dyeing the mixture, but is not indispensable for carrying out the method according to the invention.
• the auxiliary agent can be selected on the basis of the type of finished product to be obtained.
• tissue toilet paper, paper handkerchiefs and paper for household use
• aluminium sulphate or aluminium polychloride (PAC) are usable
• fine paper printing and writing paper
• aluminium polychloride and alkyl ketene dimer (AKD) are usable.
• the auxiliary agent comprises aluminium sulphate and the corresponding w/w percentage is comprised between 0.2% and 0.9%.
• the auxiliary agent comprises aluminium polychloride and the w/w percentage is comprised between 0.1% and 0.5%.
• the auxiliary agent comprises alkyl ketene dimer and the w/w percentage is comprised between 0.5% and 2%.
• the auxiliary agent comprises hexanedioic acid polymer with chloromethyl oxirane and N-(2-aminoethyl)-1,2-diaminoethane and the w/w percentage is comprised between 0.5% and 2%.
• the Applicant has replicated - on the laboratory scale - a known procedure for the industrial production of paper, by applying the method according to the invention for dyeing the mixture.
• a cellulose mixture was used having the properties shown in the following Table 4: Table 4 Type of cellulose 50% short fibre cellulose + 50% long fibre cellulose % cellulose in the mixture 5 Degree of refinement 28°SR Water hardness 20°F pH 7
• the so-called sheet former was used.
• This instrument is composed of different parts: a column formed by an upper graduated transparent container and a lower part comprising a water discharging unit. Between the two parts, there is a frame with a filtering net.
• the sheet former is connected to the mains water supply and to a vacuum pump.
• the drying system which is composed of a suitable plate, is placed next to the column.
• the method according to the invention enables the predetermined objects to be reached.
• the method according to the invention it is possible to mass dye paper materials in an optimum manner, in particular paper and cardboard, also using food dyes. This enables suitable conditions to be reached both for the dyed paper materials to be used in the food packaging and for dyed paper products intended for school and/or play use, as well as for thin paper products such as toilet paper, paper handkerchiefs and paper for household use.
• the method according to the invention enables the impact of the dyes on the environment and on the human organism to be reduced.
• the dyes that are used by the method according to the invention - namely the food dyes - are such as to ensure a good environmental safety profile also at the end of life of the dye/finished product.
• the available PNEC (predicted no-effect concentration) values, LC50 96/h (fish acute toxicity test) and EC50 48/h (invertebrate acute toxicity test), together with the absence of metals linked to the dye molecule, enable a minimum impact for both the marine and land environment to be produced.
• the dyes used by the method according to the invention are further such as to ensure the safety of the end user (human subject) also in the case of accidental contact and/or swallowing.
• the used food dyes belong to the range of the food dyes that are authorized for use in human diet.
• Such dyes according to the data present in bibliography ( Sax's Dangerous Properties Of Industrial Materials, 11th edition - European Chemical Agency, Information on Chemicals Database ), have values of oral LD50 that exceed on average 1000 mg/kg/day. This datum thus justifies a substantial "non-toxicity" condition of the paper finished product in the event of accidental swallowing, which condition is further supported by the low concentrations of dye (0.01 % - 7.5 %) that are requested by the method according to the invention for dyeing the mixture.
• an accidental and/or prolonged contact with the skin and/or the mucosae does not have foreseeable risks for the end user, as none of the used dyes shows sensitizing and/or irritating properties for the skin, eyes and/or mucosae.
• the method according to the invention has been disclosed through an example on the laboratory scale, the person skilled in the art is able to appropriately select suitable apparatuses and suitable quantities of raw materials and additives for carrying out the method according to the invention on an industrial scale.
• the method according to the invention can be combined with other methods that are known to the person skilled in the art and are used for dyeing paper material, for example surface dyeing methods.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Inorganic Chemistry (AREA)
• Paper (AREA)

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Citations (7)

• 2022
  • 2022-06-09 IT IT102022000012278A patent/IT202200012278A1/it unknown
  • 2022-08-04 EP EP22188829.0A patent/EP4290007A1/fr active Pending

Patent Citations (7)

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