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
  • D21H21/50—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 form
  • D21H21/52—Additives of definite length or shape
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/52—Macromolecular coatings
• • 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
  • D21H19/52—Cellulose; Derivatives thereof
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/52—Macromolecular coatings
  • B41M5/5236—Macromolecular coatings characterised by the use of natural gums, of proteins, e.g. gelatins, or of macromolecular carbohydrates, e.g. cellulose
• • 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
  • D21H17/24—Polysaccharides
  • D21H17/25—Cellulose

Definitions

• the invention relates to the use of a water-insoluble microcellulose for coating color dispersions for coating printing substrates, in particular for paper and board.
• coating colors must have a very good running behavior. Not only increasing web speeds but also higher solids contents and novel pigments with theologically problematic particle morphology (for example PCC) and higher shape factor (for example talcum) make the running behavior extremely difficult and are a real challenge in recipe optimization.
• PCC structurally problematic particle morphology
• shape factor for example talcum
• the whiteness or brightness of the papers is a key technical parameter of the final product and more than ever a very powerful marketing tool.
• optical brighteners are increasingly used today.
• Brighteners must be known to be bound to suitable support materials (carriers, such as PVA, CMC), but because of a possible
• Viscosity increase with possible solids content reduction can be used only to a limited extent. In practice, therefore, especially at high brightener quantities - no longer the optimal brightener / carrier ratio can be set, which leads to a poorer whitening effect and to a graying, poorer light fastness and increased bleeding.
• a microcellulose with a narrow particle distribution which is produced especially for coating colors, very good water retention values and simultaneously higher solids contents of the coating color are obtained even at high web speeds and high temperatures.
• microcellulose particles result in a barrier layer or rapid immobilization of the coating color on the raw paper interface, which prevents the water from being washed away too quickly and also binders, cobinders and other additives.
• At high brightener doses can be achieved by partial replacement of PVA by microcellulose without solids content reduction by optimizing the brightener carrier ratio better brightening effect, light fastness with excellent bleeding fastness.
• Solids content, viscosity and water retention are the most important control variables for the "runability" of a coating color, which are mainly regulated by co-binder and thickener.
• the matching of these coating color criteria to the respective application method, base paper and working speeds is a necessary measure for achieving good running properties and optimum lines ,
• the main function of the co-binder and thickener is that they give the coating the desired viscosity and the necessary water retention even at higher temperatures (online mode) and higher
• Casein from cow's milk
• soy protein from seeds of the soybean plant
• starch oxidatively or enzymatically degraded starches of different origin
• HEC hydroxyethylcellulose
• Both CMC and HEC are obtained by chemical derivatization of the cellulose.
• Most natural products are supplied in powder or granular form. Often, these products must first be dissolved in separate preparatory steps and only then added to the coating color.
• Starch, soy protein and casein were used as binders in the early stages of paper coating. These products were characterized by the fact that, in addition to their binding power for the pigments, they also had the necessary thickening effect and water retention. Because of these properties, protein and especially starch are still used today as co-binder in addition to the more modern synthetic binders.
• Polyvinyl alcohol is prepared by polymerization of vinyl acetate followed by hydrolysis.
• Acrylate copolymers are produced by polymerization of suitable monomers such as acrylic acid and methacrylic acid and their esters, acrylonitrile, vinyl acetate, etc.
• suitable monomers such as acrylic acid and methacrylic acid and their esters, acrylonitrile, vinyl acetate, etc.
• the so-called "associative thickeners” are hydrophobically modified acrylate copolymers with some pronounced properties.
• the paper texture is weaker by the amount of water absorbed; the paper web can then easily tear under tensile stress. - No drastic change in the rheology of increasing solids contents and increasing viscosities with low water retention lead to dilatant flow behavior and thus to squeegee, bart formation on the blade, etc.
• the solids content of the coating in the circulation increases within a few hours, since excessive release of water to the paper also means a depletion of water-soluble polymers in the coating color. Especially with primers, this phenomenon is often encountered. In addition, there is a binder depletion, which can lead to Vertikianasproblemen. With the increase in the solids content of the coating color, a constant coating application becomes more and more difficult; Often you have to increase the blade pressure to keep the line weight. Interaction with pigments: thickening effect
• Thickeners should preferably have the following functions:
• hydrocolloids To develop their thickening effect, the hydrocolloids must be present in dissolved form.
• Whiteness, brightness, smoothness and gloss belong to optical properties that are perceived by the human directly through sense organs.
• the whiteness is also increased by the shift in hue from yellow to bluish.
• the brightness of the paper is also increased.
• the lightening effect only occurs when the optical brightener is fixed on a suitable carrier material or carrier or can "wind up".
• the most important co-polymers which, among other properties, mainly fulfill a "carrier” function are polyvinyl alcohol, carboxymethylcellulose (CMC), polyethylene glycol (PEG), polyvinylpyrrolidone (PVP) starch, casein, MF resins and styrene-acrylate copolymers.
• CMC carboxymethylcellulose
• PEG polyethylene glycol
• PVP polyvinylpyrrolidone starch
• casein casein
• MF resins styrene-acrylate copolymers
• EP 0 499 578 B1 proposes a microcrystalline cellulose having an average particle size of 1 to 100 ⁇ m for the brightener improvement of optical brighteners.
• EP 0 710 742 A2 discloses a coating color for a printing substrate by the ink-jet printing method, which is essentially characterized in that a three-layer silicate is obtained by acid activation of a
• Alkali or Erdalkalismektits or by incorporation of metal oxide bridges in its layer structure is modified and contains about 10 to 50 parts by weight, preferably 20 to 25 parts by weight of binder and other additives.
• a coating ink for a printing substrate by the ink-jet printing method which consists essentially of a montmorillonite having a high swelling power and optionally a high surface area pigment such as synthetic silicic acid or calcium carbonate, and a water insoluble Contains binder.
• the high microcapillarity or specific surface area of the pigment particles results in excellent inkjet printability in the case of color printouts with good color brilliance, optical density of the colors and dot sharpness.
• the acid anionic, water-soluble inks are anchored by InkJet preferably at cationic interfaces by a rapid adsorption.
• the high capillarity of the pigments facilitates the separation of dyes and liquid by chromatographic effect.
• the larger dye molecules remain on the pigment surface, while smaller molecules, especially water and additives, are drawn into the interior of the pigments by the capillary forces.
• This requires a high microcapillarity with a defined pore radius and / or improved water resistance. Due to their high specific surface area of the very expensive silicates used today, their binder requirement is very high (up to 30 - 40 parts binder). In turn, binders are also expensive and, in turn, occupy a large portion of the surface, thus reducing the active surface area.
• a coating dispersion for coating paper and board contains a microcellulose with a narrow particle distribution and an average particle diameter (d 50%) of about 4 nm and a weakly anionic interfacial charge (zeta potentials of -17 to -20 mV), which has been specially developed for the coating process.
• microcellulose In addition to the high intrinsic water retention of the microcellulose, the water-affluent microcellulose particles result in a barrier layer or rapid immobilization of the coating color on the raw paper interface, which prevents the water and binder and other additives from being washed off too quickly. Like all hydrocolloids, microcellulose binds significant amounts of water molecules to their interface, increasing their diameter and volume and occupying more space in the aqueous phase of the coating.
• the investigations show that both the viscosity at low shear rates and at higher shear rates (high shear) with microcellulose decreases compared to starch and CMC in the coating color.
• the investigations also show a lower dynamic viscosity than in formulations with starch and CMC.
• the oscillatory measurement makes it possible to distinguish between elastic and plastic flow behavior.
• the stress on the coating color is increased by the above-mentioned increase of the deflection amplitude. As a result, the particles are moved against each other.
• a fully elastic system shows a shift angle of 0 °; a fully plastic system with a phase shift of 90 °.
• G ' Low values correspond to high mobility with significantly reduced forces between the particles.
• the lower the value of G " the higher the wet packing density and the faster the formation of the initial sediment layer which prevents the penetration of binder and fines into the substrate.
• the low storage modulus G * corresponds to previous experience, that is to say a rapid immobilization and barrier effect of the water-insoluble microcellulose at the paper and board interface prevents the coating ink from sagging due to steric hindrance as well as increased penetration of binders and other additives.
• the lower the value of G ' the higher the microcellulose packing density and the faster the formation of the sediment or barrier layer preventing the said negative penetration processes.
• the remaining coating color over the barrier layer remains mobile, d. H. it is easy to level.
• starch products are preferably used for surface sizing. With additional additives, certain effects are sought.
• the film-forming effect of the starch can be effectively improved by reducing the penetration depth or a saving of the strength can be achieved.
• the microcellulose Compared to CMC, which has hitherto been used as a regulator for the penetration depth of starch size press formulations, the microcellulose exhibits good water retention even at relatively high temperatures and, in addition, causes a barrier at the paper interface due to steric hindrance of the water-insoluble particles, which leads to increased penetration of the starch into the base paper prevents or controls accordingly.
• microcellulose has a very high substantivity for optical brightener (carrier effect), very good water resistance and an improvement in abrasion resistance (abrasion resistance).
• PVA is one of the most widely used carriers in the paper industry because of its excellent carrier effect for optical brighteners, used alone or in combination with CMC.
• an optimal ratio between whitener and carrier material (carrier) is a prerequisite for the efficient use of optical brighteners. Due to the increasing trend towards higher paper whiteness levels, more and more added amounts of optical brighteners are associated with high carrier application rates, which leads to very high viscosity increases in the coating color. This is currently counteracted by dilution with water (solids content reduction) or often too small amounts of carrier added in relation to the optical brightener to avoid the viscosity increases, but this leads to insufficient utilization of the brightener potential, lack of light fastness and bleeding fastness.
• microcellulose is not a completely equivalent substitute for PVA, very high carrier amounts and brightener amounts without viscosity increase or dilution of the coating color by the combined use of PVA and microcellulose with the advantages of high light fastness, a high brightening effect and above all a high bleed fastness can be implemented because the water-insoluble microcellulose is the steric reason for the
• Digital printing papers for example color laser printing papers
• Digital printing papers often suffer from a lack of toner transfer or toner adhesion.
• microcellulose With microcellulose, a significant improvement in toner adhesion was observed with appropriate calendering conditions.
• the invention further provides a process for the preparation of a cationic microcellulose dispersion which is preferably used for specialty papers, such as inkjet papers.
• the process of cationization is carried out by initially introducing the anionic microcellulose in an aqueous medium and adding one or more cationic additives to this medium while stirring, depending on the desired charge density.
• a zeta potential of + 5 mV to + 90 mV results.
• the cationic or cationized water-soluble polymers are generally characterized by containing quaternary nitrogen atoms in the main chain and / or in the side chains.
• polymeric diallyl compounds examples include polymeric diallyl compounds, melamine-formaldehyde resins, epichlorohydrin resins, dicyandiamide resins, quaternary acrylates and inorganic polymers such as Polyaluminum hydroxychloride (PAC), cationically modified polyacrylamides (PAA), polyamidoamines (PAAM), polyamines (PA) and polyethylenimine (PEI).
• Poly (diallyldimethylammonium chloride) polyDADMAC
• polyDADMAC which preferably has a molecular weight of from 60.00 to 120,000, has proved particularly suitable.
• the cationic microcellulose thus prepared may be applied to the base paper in the present form or may be applied in admixture with various pigments without binder addition such as, for example, kaolin, GCC, PCC, precipitated silicates, bentonites or other pigments.
• various pigments such as, for example, kaolin, GCC, PCC, precipitated silicates, bentonites or other pigments.
• cationic formulations up to 100 parts of the cationic microcellulose can be used.
• the active ingredient content can be set individually according to customer requirements and is 10% dry matter in the application examples.
• Coating pigments used are commercial pigments and mixtures thereof, such as, for example, kaolin, ground calcium carbonate (GCC), precipitated calcium carbonate (PCC), talc, precipitated silicates, titanium dioxide and aluminum hydroxides.
• GCC ground calcium carbonate
• PCC precipitated calcium carbonate
• talc precipitated silicates
• titanium dioxide titanium dioxide
• aluminum hydroxides Both the base binder and the special binder are polymer dispersions (manufacturers for example BASF AG or Dow Chemical), which are found on the market with a wide variety of product properties. Combinations and copolymers are found which have been prepared with very different starting materials (monomers) (for example butadiene styrene, acrylic acid ester styrene, acrylic acid ester vinyl acetate, etc.). As Cobinder the products described in the patent can be used.
• Suitable optical brighteners are derivatives of diaminostilbenesulfonic acids, which are preferably used in the paper industry. There are both disulfo-, tetrasulfo- or Hexasulfoaufheller used (manufacturer Clariant AG, Bayer or Ciba Geigy). As crosslinkers are preferably modified glyoxal, epoxy resins, urea and melamine-formaldehyde resins and zirconium derivatives used.
• the classical leveling agents (lubricants) are predominantly dispersions of calcium stearates, ammonium stearates, wax emulsions and PEG.
• the base paper is wood-free, wood-containing and up to 100% recycled paper containing base paper or paperboard.
• the print carrier has a basis weight between 30 g / m 2 otro and 350 g / m 2 otro.
• Applicants may be used which include, for example, film presses, curtain coater, spray coating, roller coating, bar coating, blade coater, speed coater, Massey process, flooded nip, and the like.
• the coating speed of the coating color dispersion takes place at a speed between 150 m / min and 2000 m / min.
• Papers are suitable for a variety of printing processes as known in the art. These may be, for example, the offset printing method, the gravure printing method, inkjet method, flexo printing method, heat set method, cold set method, laser printing method and the like. Another aspect of the invention is that the coated paper according to the invention has an excellent recycling behavior.
• base paper a 46 g serving / m 2 wood-containing base paper and a 42g / m 2 base paper, which was prepared with 100% recycled paper.
• a high performance disperser was used to prepare the coating.
• Binder (BASF), cobinder, microcellulose and other additives were added successively to the GCC slurry (Omya) with stirring, the pH was adjusted with NaOH, and the viscosity was adjusted with residual water.
• the microcellulose products are in the company publication J. Rettenmaier u. Sons, Rosenberg described in detail.
• Viscosity 1130 1050 1080 (Brookf. 100 rpm)
• Viscosity behavior, brightener development, coating hold-out but above all the possibility of increasing the solids content over commercial cobinder such as starch or CMC has advantages.
• Viscosity and solids content development especially the carrier function of microcellulose for optical brightener compared to commercial carriers are determined.
• 2 different addition amounts of a tetrasulfo brightener with different carrier amounts were used.
• GCC CaCO 3
• Offset formulations with a pigment mixture calcium carbonate and kaolin Offset formulations with a pigment mixture calcium carbonate and kaolin.
• microcellulose according to the invention by increasing the solids content in comparison to other commercially available cobinders, permits a binder saving without impairing the other functions of cobinders.
• the base paper used was a 46 g / m2 wood-containing base paper.
• the coating is 12 g / m 2 .
• the binder savings which can be up to more than 2 parts binder depending on the formulation and solids content increase, is made possible by the lower penetration of the binder by the higher solids content and by the barrier action of the microcellulose at the paper's interface.
• Example 2 To prepare the coating colors as well as the rheological properties, application by hand wringer and calendering, the methods mentioned in Example 1 were used. At the same time were using the Haake viscometer
• the rotational viscometer with a coaxial cylinder system enables measurements in the defined shear gap.
• the speed of the rotating body and the dimensions of the shear gap can be the shear rate in the wide range up. Max. 4 10 4 s ⁇ 1 vary.
• the coat application weight is 10 g / m 2 .
• Microcellulose solids increases - with the advantages already described - without viscosity increase or other adverse effects is possible.
• the Haake viscosity of the individual formulations correlates with the Brookfield viscosity, with the formulations with the microcellulose tending to be slightly lower.
• high pressure gradients are created in front of the blade edge.
• Organic coating pigment is a reduction in the scraper pressure and a reduction in the delivery of water to the base paper (less weakening of the fiber structure) achieved as well as counteracts a hydraulic injection of the coating color in the base paper.
• Microcapillarity of the microcellulose become the anionic, water-soluble
• the capillarity of the microcellulose promotes the separation of dyes and liquid by the chromatographic effect.
• Microcellulose has an excellent water retention capacity, which has a correspondingly positive effect on the quality properties, especially of pigmented cationic streaks.
• microcellulose cationic coating colors provide excellent inkjet printability in both HP CP 1160, HP 895 Cxi, HP 950, Epson C 80, and Canon J750 inkjet prints that are significantly superior to conventionally coated and surface sized papers on color brilliance, optical density of Distinguish colors, point sharpness, bleeding and mottling.
• the coating colors are also characterized by rapid color drying (increase in smudge resistance) and higher water resistance. Due to the excellent water retention capacity of cationic microcellulose, even with pigmented, cationic coating colors with high inkjet
• the application unit Jetflow F with Stiff Blade was used as the application unit.
• Coating application weight 12 g / m 2 Coating application weight 12 g / m 2 .
• the coated paper rolls were then calendered on the 12-roll supercalender (Voith Sulzer).
• the parameters set for the calendering of the paper samples V1, V2 and V3 were:
• the calendering according to setting 2 corresponded to the calendering conditions of an offset paper and the setting 3 to the calendering conditions of a rotogravure paper.
• the non-calendered paper pattern (setting 1) was changed to V4, the setting 2 calendered paper samples to V4! and the paper pattern calendered with the setting 3 labeled V4I I.
• Coating weight (g / m2) 12.2 12.0 12.0 12.4 Coating viscosity
• V3-OS perfect no to easy repelling
• V3-SS perfect no to easy repulsion
• V4-SS perfect no to easy repulsion
• V4II-OS perfectly strong repulsion
• microcellulose in addition to the good running properties, results in no printability problems with regard to plucking despite the somewhat lower binder content. Rather, microcellulose gives rise to advantages in terms of offset in terms of repelling the printing ink. Only with strong gravure inking (V4 II), which are not common in offset, it comes to repel the ink. Despite the more thickening effect or greater increase in viscosity of PVA compared to the synthetic binders, there are advantages with solid content development. It can also be deduced from the investigations that the combination PVA / microcellulose has a good degree of whiteness or a good carrier effect for optical brighteners.
• the printing and processing experiments with the test papers V1-V4 were carried out with a digital printing line from Oce. It can come at 1000 pages per minute with double-sided printing at the offset formulation V1 because of the high static charge to running problems. In particular, the coated papers produced with microcellulose are characterized in terms of toner adhesion.

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• 2007
  • 2007-02-23 AT AT07711648T patent/ATE538246T1/de active
  • 2007-02-23 EP EP07711648A patent/EP1987195B1/fr not_active Not-in-force
  • 2007-02-23 WO PCT/EP2007/001582 patent/WO2007096180A2/fr active Application Filing

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