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
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
  • D21H19/54—Starch
• • 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
  • D21H17/21—Macromolecular organic compounds of natural origin; Derivatives thereof
  • D21H17/22—Proteins
• • 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
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/38—Coatings with pigments characterised by the pigments
  • D21H19/385—Oxides, hydroxides or carbonates
• • 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
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
  • D21H19/50—Proteins

Definitions

• the present application relates to a paper or cardboard coating composition comprising a modified starch and a hydrolyzed wheat protein, and also to the method for obtaining such a composition.
• the application also relates to a method for coating or brightening paper or cardboard using such a composition, and to the coated paper or cardboard thus obtained.
• the application relates to the use of a hydrolyzed wheat protein in the replacement of latex in a paper or cardboard coating composition.
• Coating is a paper or cardboard finishing step which makes it possible to confer on a sheet of paper or on a cardboard a certain number of properties, such as opacity, gloss or whiteness or else to improve the printability for printing processes such as offset printing or photogravure.
• a composition referred to as coating color is applied to the surface of the paper or of the cardboard.
• This composition generally comprises at least one mineral or pigment filler, at least one binder and other additives such as, in particular, dispersants, rheology modifiers, lubricants, optical brighteners or antifoams.
• Latex typically synthetic latex of styrene-butadiene type, is the binder most widely used. Its function is to enable cohesion between the various elements of the composition and to bind them to the fibers. Synthetic latex is produced from petroleum resources which are by definition non-renewable. In order to reduce the number of chemical products used in this industry, and to reduce the consumption of petroleum-derived products and also the costs, the replacement of latex in coating colors represents a potential market but also a sizeable technical challenge. This is because it is very difficult to maintain the performance levels of a coating color while reducing the proportion of synthetic latex used.
• coating colors are intended to be applied to the surface of the paper or of the cardboard in very thin layers and at very high speed. Their application is carried out by means of a blade or a threaded rod which exerts very high shear forces at the surface of the paper.
• these shear forces lead not only, at the level of the application zone, to turbulences responsible for defects in the deposit, called “filaments” or “beads”, but also to an increase in the pressure exerted on the paper, increasing by the same token the risks of breakage and thus potentially hours of production interruption.
• the prior art proposes coating compositions which have a low dry matter content.
• the reduction of the dry matter of the composition (and thus the increase in the water content) in order to reduce the viscosity thereof is not an advantageous solution in the present application.
• the coating color has a natural tendency to transfer into the sheet of paper all or some of the water and of the water-soluble parts that it contains.
• This has several consequences, the first of which is the weakening of the paper or of the cardboard which, due to the excess water, can lose its integrity and can lead to breaking of the paper produced and thus hours of production interruption.
• the second is the loss of gloss of the paper observed following the migration of the water-soluble parts of the coating color into the paper.
• This migration leads to a third consequence which is the weakening of the cohesion of the layer of the paper, leading to problems during printing. Mention may, for example, be made of deposits of fibers or of mineral fillers originating from the coat on the blankets during offset printing. The final consequence of this excess water of the coating composition is the increase in energy and/or in time required to dry the paper or the cardboard obtained.
• a coating color which has both a high dry matter content and a low viscosity, beyond the solving of the abovementioned problems, is the small amount of coating color that needs to be laid.
• a coating color of low viscosity would also have the advantage of allowing very-high-speed coating, which constitutes a very clear industrial advantage.
• a new paper or cardboard coating composition has a dry matter content of between 45% and 80%, preferentially 50% and 78%, more preferentially 55% and 75%, comprising:
• paper or cardboard coating composition is intended to mean a composition that is particularly suitable for coating paper or cardboard. It is an aqueous formulation conventionally containing water, at least one mineral filler, one or more binders and also various additives.
• composition may comprise, in parts per 100 parts by weight of mineral filler:
• wheat protein denotes a water-insoluble protein fraction extracted from wheat flour via the wet process and subsequently dried, also known as wheat gluten.
• wheat proteins having an average molecular weight of between 7 and 1000 kDa are obtained by hydrolysis according to methods known well to those skilled in the art [Anfinsen, C. B. Jr. (1965), Advances in Protein Chemistry: v. 20, New York and London, Academic Press].
• the hydrolysis may be thermal, acid or enzymatic. Enzymatic hydrolysis is preferred.
• a wheat gluten that is particularly suitable is Solpro® 508 sold by Tereos Syral.
• the hydrolyzed wheat protein has a weight-average molecular weight of between 7 and 800 kDa, 5 and 500 kDa or 8 and 100 kDa, preferentially between 9 and 80 kDa, more preferentially between 10 and 70 kDa, even more preferentially between 12 and 50 kDa, even more preferentially between 13 and 40 kDa.
• binder is intended to mean a compound having the function of sticking the particles of mineral filler (or pigments) to one another and of maintaining the coat at the surface of the paper.
• the composition comprises a binders/wheat protein ratio of from 1:5 to 5:1, preferentially from 1:3 to 3:1, more preferentially 1:2 to 2:1.
• the binders are at least one modified starch and one adhesive such as a synthetic adhesive; typically in a modified starch/synthetic adhesive ratio of from 1:5 to 5:1, preferentially from 1:3 to 3:1, more preferentially 1:2 to 2:1.
• modified starch is intended to mean any starch that has been chemically or physically treated.
• the molecules of modified starches can originate from a plant source such as cereals, tubers, roots, vegetables and fruits.
• the starch(es) can originate from a plant source chosen from corn, peas, potato, sweet potato, banana, barley, wheat, rice, oats, sago, tapioca and sorghum.
• modification reactions can be carried out for example:
• Suitable modified starches comprise, but are not limited to, pregelatinized starches, low-viscosity starches (for example, dextrins, hydrolyzed starches, oxidized starches), stabilized starches (for example, starch esters, starch ethers), crosslinked starches and starches which have received a combination of treatments (for example crosslinking and gelatinization treatments) and mixtures thereof
• Dextrins are the preferred modified starches.
• the term “dextrin” is intended to mean a modified starch obtained from native starch by dextrinization; typically, the dextrins according to some embodiments of the invention are not subjected to any other modification, in particular chemical modification.
• dextrins that are suitable for some embodiments of the present invention are, for example, white dextrins, generally obtained by transformation of starch at temperatures often of between 100 and 170° C., in the presence of a chemical agent or chemical agents, in particular of acid, in relatively high amounts; yellow dextrins, often obtained by transformation of starch at higher temperatures, generally of between 170 and 230° C., in the presence of a chemical agent or chemical agents, in particular of acid; finally, dextrins termed “British Gum” obtained solely by the action of heat, at high temperature, often above 230° C.
• a dextrin that is particularly suitable for some embodiments of the present invention is a wheat-based dextrin, typically the Mylofilm® 214 or Mylofilm® 218 dextrin sold by the company Tereos Syral.
• the particularly suitable modified starch has a weight-average molecular weight of between 20 and 300 kDa, preferentially 30 and 250 kDa, more preferentially between 35 and 233 kDa, even more preferentially between 40 and 200 kDa, even more preferentially between 42 and 150 kDa, and/or a viscosity of between 50 and 400 mPa ⁇ s (Brookfield, 70° C., 31% DM).
• the measurement, with a Brookfield viscometer, of the modified starch, such as, for example, of a dextrin, is performed in solution and is carried out on an RVDV-E model, the measurement is carried out at a speed of 20 rpm with spindle 3.
• the measurements are carried out at 70° C.
• the module is dipped in a composition of modified starch in suspension at 31% of dry matter up to the indicator line of the spindle; the value is recorded after 10 s of rotation.
• average molecular weight is intended to mean the weight-average molecular weight.
• this average molecular weight is measured by size exclusion chromatography (SE-HPLC) coupled with a UV detector regulated at the wavelength of 214 nm.
• SE-HPLC size exclusion chromatography
• the size exclusion chromatograph is equipped with a pump which circulates an eluent composed of a PBS phosphate buffer (0.1 M Na 2 HPO 4 —NaH 2 PO 4 with 0.1% of SDS) at a flow rate of 0.7 ml/min in a TSKG4000SWx1 column. This measurement is expressed in daltons.
• the preparation of a sample can be carried out by dissolving the product studied in a phosphate extraction buffer with 1% of SDS, followed by centrifugation to recover the supernatant.
• the average molecular weight is expressed in daltons and can be determined by those skilled in the art by size exclusion chromatography coupled with a detector of MALLS (Multi Angle Laser Light Scattering) type.
• the preparation of a sample can be carried out by dissolving 50 mg by dry weight of a modified starch and in particular of dextrin in a solvent consisting of a mixture of 90% (v/v) of DMSO (dimethyl sulfoxide) in deionized water containing 0.1% (w/v) of sodium nitrate. After stirring overnight, the mixture is preheated for 1 hour at 105° C. and then centrifuged for 15 min at 5300 g.
• DMSO dimethyl sulfoxide
• a volume of 100 ml of the supernatant is injected into a size exclusion chromatography apparatus, the mobile phase of which is for example composed of a mixture of 90% (v/v) of DMSO (dimethyl sulfoxide) in deionized water containing 0.1% (w/v) of sodium nitrate, at a flow rate of 0.5 ml/min and a temperature of 70° C., the columns used preferentially being a combination in series of Gram columns.
• the detector is for example an angle laser such as the New Generation 3-angle miniDawn Treos.
• the calibration is carried out with Viscotec P82 Shodex standards.
• the adhesive is preferentially synthetic.
• An example of synthetic adhesive suitable for the present invention is a latex, a vinyl acetate, polyvinyl alcohol, sodium carboxymethylcellulose and hydroxyethylcellulose.
• latex refers to an aqueous dispersion of polymer which corresponds to a colloidal dispersion of synthetic polymers in an aqueous phase, i.e. a dispersion of polymer microparticles in suspension in an aqueous phase, sometimes also referred to as polymer suspension or polymer emulsion.
• examples of latex suitable for the present invention are chosen from the group made up of styrene-butadiene latexes, polyvinyl alcohol latexes and acrylic copolymer latexes, preferentially latex of styrene-butadiene type.
• the mineral filler introduced is carried in the form of an aqueous suspension.
• this filler is a calcium carbonate suspended in water by means of a dispersing agent.
• a mineral filler that is particularly suitable for a coating composition comprises a sufficient degree of whiteness (greater than 80% of the whiteness of barium sulfate at 457 nm), a particle size distribution of from 0 to 10 ⁇ m at most (the average particle size being between 0.2 and 2 ⁇ m) and a minimum degree of agglomeration of the particles.
• the mineral filler can be chosen from the group made up of calcium carbonates, coating clay, calcined fine clay, alumina trihydrate, talc and titanium dioxide.
• calcium carbonate comprises ground calcium carbonate (GCC), that is to say a calcium carbonate obtained from natural sources, such as limestone, marble, calcite or lime.
• GCC ground calcium carbonate
• calcium carbonate obtained from natural sources, such as limestone, marble, calcite or lime.
• calcium carbonate also comprises precipitated calcium carbonate (PCC), that is to say a synthesized substance, generally obtained by precipitation following a reaction of carbon dioxide and calcium hydroxide (hydrated lime) in an aqueous environment or by precipitation of a source of calcium and of carbonate in water.
• PCC precipitated calcium carbonate
• composition according to some embodiments of the invention may also comprise other agents such as one or more dispersing agents.
• dispersing agent is intended to mean an agent having the function of maintaining the particles of mineral filler in a state of electrostatic dispersion.
• the dispersing agent is chosen from the group made up of sodium polyacrylate, tetrasodium polyphosphate, tetrasodium pyrophosphate, pentasodium tripolyphosphate, sodium tetraphosphate and sodium silicate.
• the composition may also comprise at least one lubricant, typically chosen from the group made up of sodium stearate, calcium stearate, sulfonated oils, sulfated tall oil fatty acid and polyethylene emulsions.
• at least one lubricant typically chosen from the group made up of sodium stearate, calcium stearate, sulfonated oils, sulfated tall oil fatty acid and polyethylene emulsions.
• the composition may also comprise at least one insolubilizing agent chosen from the group made up of urea resins, melamine resins, glyoxal, zinc compounds, formaldehyde and dimethylolurea.
• at least one insolubilizing agent chosen from the group made up of urea resins, melamine resins, glyoxal, zinc compounds, formaldehyde and dimethylolurea.
• a new method for producing the composition described may comprise the following steps:
• a new method for coating or brightening paper or cardboard may comprise the steps of
• the step of depositing said composition on a paper or cardboard substrate can be carried out by means of blade coating, pencil coating, a threaded rod, size press curtain coating or a film press or any other technique known to those skilled in the art.
• the depositing step is carried out at a temperature of between 25 and 60° C.
• said composition is applied to at least one face of said paper or cardboard substrate in an amount of between 3 g/m 2 and 15 g/m 2 , preferably between 5 g/m 2 and 10 g/m 2 .
• a new paper or cardboard is coated with a composition as described.
• a new use of a hydrolyzed wheat protein involves the replacement of latex in a paper or cardboard coating composition, said hydrolyzed wheat protein preferentially having an average molecular weight of between 7 and 1000 kDa.
• a combination of a hydrolyzed wheat protein and of a modified starch, and more particularly a dextrin, may be used in the replacement of latex, preferentially in a modified starch/wheat protein ratio of 1:5 to 5:1, preferentially of 1:3 to 3:1, more preferentially 1:2 to 2:1.
• said wheat protein or said combination of wheat protein with a modified starch is used in the replacement of from 1% to 40% of the latex of said composition, preferentially from 10% to 35%, more preferentially from 15% to 30%.
• a coating color was produced according to formulae R1 to R4 of table 1 below.
• the recipes are given in number of parts (as is standard practice in papermaking).
• the coating color is produced using a stirrer (IKA type) first of all by suspending the calcium carbonate in water at 79.7% (Hydrocarb® 90 supplied by the company Omya).
• the synthetic binder styrene-butadiene DL930 latex from the company Styron
• the concentration is adjusted with water in order to obtain a dry matter content of 70%.
• the stirring speed is adjusted to 1500 rpm; the pH is then adjusted to 9.
• the coating color is thus stirred for 10 min.
• the coating colors of table 1 were tested in coating tests.
• the viscosity of the coating colors is evaluated before coating of the paper.
• the measurement of the coating color with a Brookfield viscometer is carried out on an RVDV-E model; the measurement is carried out at a speed of 20 rpm with spindle 3. The measurements are carried out at 40° C.
• the module is dipped in the coating color up to the indicator line of the spindle, and the value is recorded after 10 s of rotation.
• the coating color is deposited on the paper in an amount of 6 g/m 2 on a single face using a DT blade coater coating pilot plant allowing drying combining infrared radiation and hot air.
• the coating speed is 20 m/min.
• the paper used is an 80 g/m 2 thin paper supplied by the company Fedrigoni.
• the paper thus coated is then stored in a humidity- and temperature-conditioned room (50% humidity, 23° C.) for 24 h before any test.
• the dry pick measurement is carried out according to the IGT W31 method (ISO 3783:2006). This measurement makes it possible to evaluate the strength of the layer. Indeed, the binders (synthetic or natural such as starch) are used to maintain the mineral fillers required for the paper printing properties. If the binding capacity is too low, the mineral fillers are picked from the paper during printing and are deposited on the inking roll, leading to frequent interruptions. The higher the dry IGT measurement, the higher the pick resistance of the layer.
• the coating colors were produced as in example 1 according to the formulae of table 3 in which the synthetic latex is replaced with proteins in an amount of 14% (R5), 30% (R6) and 43% (R7).
• the proteins tested are the following:
• the proteins are added to the coating color without prior dilution.
• the coating color is produced as in example 1, using a stirrer (IKA type), by suspending the calcium carbonate in water at 79.7% (Hydrocarb® 90 supplied by the company Omya).
• the synthetic binder styrene-butadiene DL930 latex from the company Styron
• the dextrin having been dissolved are then added to the calcium carbonate as previously specified.
• the protein is incorporated into the color in solution form or as powder, as appropriate.
• the concentration is adjusted with water in order to obtain a dry matter content of 70%.
• the stirring speed is adjusted to 1500 rpm; the pH is then adjusted to 9.
• the coating color is thus stirred for 10 min.
• the low-molecular-weight wheat protein hydrolyzates have only a limited effect on the viscosity of the composition obtained but do not make it possible to compensate for the reduction in latex starting from 30%. Indeed, at 30% replacement of the latex, a loss of pick resistance is observed (0.45 of IGT at 0% replacement; 0.5 at 14% replacement for 0.30 at 30% replacement).
• composition R5 the partially hydrolyzed wheat proteins allow a significant increase in pick resistance at 14% latex replacement (composition R5).
• the advantage of the hydrolyzed wheat proteins is that, contrary to the soy proteins, they are soluble enough to be directly added to the coating color and do not require a prior dilution adding a not insignificant amount of water and thus reducing the dry matter content of the coating color, thereby making it possible to vary quite freely the dry matter content of the composition.

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• 2015
  • 2015-02-23 FR FR1500337A patent/FR3032979B1/fr not_active Expired - Fee Related
• 2016
  • 2016-02-23 WO PCT/IB2016/050969 patent/WO2016135625A1/fr active Application Filing
  • 2016-02-23 BR BR112017015729A patent/BR112017015729A2/pt not_active Application Discontinuation
  • 2016-02-23 US US15/553,132 patent/US20180044858A1/en not_active Abandoned
  • 2016-02-23 BE BE2016/5128A patent/BE1023282B1/nl not_active IP Right Cessation
  • 2016-02-23 JP JP2017544638A patent/JP2018511712A/ja not_active Withdrawn
  • 2016-02-23 CN CN201680011610.9A patent/CN107532390A/zh active Pending
  • 2016-02-23 CA CA2975499A patent/CA2975499A1/fr not_active Abandoned
  • 2016-02-23 EP EP16707224.8A patent/EP3262232B1/fr active Active

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