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
• • 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
  • B41M5/502—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording characterised by structural details, e.g. multilayer materials
  • B41M5/506—Intermediate layers
• • 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
  • D21H19/66—Coatings characterised by a special visual effect, e.g. patterned, textured
• • 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
  • D21H21/30—Luminescent or fluorescent substances, e.g. for optical bleaching
• • 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
  • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
  • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
  • D21H23/22—Addition to the formed paper
  • D21H23/46—Pouring or allowing the fluid to flow in a continuous stream on to the surface, the entire stream being carried away by the paper
  • D21H23/48—Curtain coaters
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M2205/00—Printing methods or features related to printing methods; Location or type of the layers
  • B41M2205/38—Intermediate layers; Layers between substrate and imaging layer
• • 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
  • B41M5/5218—Macromolecular coatings characterised by inorganic additives, e.g. pigments, clays
• • 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
  • B41M5/5227—Macromolecular coatings characterised by organic non-macromolecular additives, e.g. UV-absorbers, plasticisers, surfactants
• • 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
  • B41M5/5254—Macromolecular coatings characterised by the use of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds, e.g. vinyl polymers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/24802—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/24802—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
  • Y10T428/24893—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.] including particulate material
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/24802—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
  • Y10T428/24893—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.] including particulate material
  • Y10T428/24901—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.] including particulate material including coloring matter
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
  • Y10T428/24802—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
  • Y10T428/24893—Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.] including particulate material
  • Y10T428/24909—Free metal or mineral containing
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31855—Of addition polymer from unsaturated monomers
  • Y10T428/3188—Next to cellulosic
  • Y10T428/31895—Paper or wood
  • Y10T428/31899—Addition polymer of hydrocarbon[s] only
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31855—Of addition polymer from unsaturated monomers
  • Y10T428/3188—Next to cellulosic
  • Y10T428/31895—Paper or wood
  • Y10T428/31899—Addition polymer of hydrocarbon[s] only
  • Y10T428/31902—Monoethylenically unsaturated
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31855—Of addition polymer from unsaturated monomers
  • Y10T428/3188—Next to cellulosic
  • Y10T428/31895—Paper or wood
  • Y10T428/31906—Ester, halide or nitrile of addition polymer

Definitions

• the present invention relates to an offset printable coated white sheet, at least the surface layer of which has a high fluorescence power by virtue of its composition. It also relates to its manufacturing process.
• fluorescent whitening agents also known as optical brighteners
• optical brighteners act by absorbing natural light in the interior of the room.
• ultraviolet as well as in the visible near below 420 ira, then re-emit light fluorescence at around 440 nm so in the blue or blue-violet part of the visible spectrum. They increase the whiteness of these leaves by moving strongly their shade from yellow to blue.
• the use of these fluorescent whitening agents, unsaturated organic molecules comprising two to six sulphonated groups has been abundantly described, in particular with regard to the need, at the level of the sheet, for a good fixation of these molecules. in their trans isomeric form which is only active.
• the weight of this layer after drying is at least 5 g / m 2 in dry weight per side to see an improvement in printability, preferably 10 g / m 2 per face and if we want a high level of offset printability, many more, possibly applied in several stages.
• the problem with such layers is that the fluorescent whitening agents are poorly fixed by the components of the layers and that it is difficult to increase the fluorescence without causing the counter-whitening effect called "greening" which corresponds to an evolution of the shade of the leaf lying from blue to green.
• This evolution can be quantified by the variation ⁇ a * of the tristimulus coordinate a * of the CIELAB space measured under the conditions of the ISO 11475: 2004 standard.
• Another problem is that the layers based on their weight per square meter act more or less as a UV filter of the incident light vis-à-vis the fluorescent whitening agent present in the base sheet.
• a first solution in the case of a paper sheet, is to confer on the fibrous base a high fluorescence power which is then more or less attenuated according to the composition and the layer thickness deposited thereon.
• this route uses a large amount of fluorescent whitening agent and limits the layer deposition to about 8 g / m 2 dry weight, per side if it is desired to maintain a high fluorescence power.
• Another solution is to introduce into the layer composition chemical substances which are a carrier for the fluorescent whitening agent, that is to say which play a role of fixing the agent analogous to that of cellulose.
• these support substances there may be mentioned starch, polyvinyl alcohol (PVA), carboxymethylcellulose (CMC), polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), etc. which are macromolecules rich in hydrophilic groups .
• PVA polyvinyl alcohol
• CMC carboxymethylcellulose
• PVP polyvinylpyrrolidone
• PEG polyethylene glycol
• the amount of whitening agent is limited, the amount of 0.2 to less than 1% by dry weight of fluorescent whitening agent and 0.3 to 2% by weight is usually used relative to the total dry weight of pigments. dry of substance support.
• the object of the present invention is to overcome the drawbacks of the prior art and these alternatives to obtain coated sheets appearing very white and offset-printable, in particular by offset inks drying in the open air, without noticeable defect of swirling .
• the invention thus provides a white coated sheet having a fluorescence power greater than 55, measured according to International Standard ISO 11475: 2004, by difference between the value of CIE whiteness under illuminant D65 and the value of this same whiteness CIE after interposition of a filter eliminating wavelengths less than 420 nm, and being printable by offset printing without a flaw, said coated sheet comprising at least one base sheet and a printable white surface layer whose pigmented composition comprises: at least white coating pigments and at least one coating binder, at least one fluorescent whitening agent in a total amount greater than or equal to 1% by dry weight relative to the dry weight of said pigments, at least one support substance of said whitening agent. a total amount by dry weight greater than 2% relative to the dry weight of said pigments.
• the coated sheet according to the invention is "offset-printable without mounded defects" that it does not present on its surface when it is printed by offset, in particular by in-line drying inks, noticeable mottling defect.
• This mocking defect can be evaluated in particular by the test described in the examples presented below which gives a mock index.
• Said coated sheet according to the invention has a high fluorescence power and therefore appears very white and moreover its surface is printable in offset, in particular by offset inks drying in the open air, without noticeable mottle defect.
• said layer of The surface should be as uniform as possible, even if the surface of the base sheet and / or sub-layers are very irregular. This regularity of the deposition of the layer makes it possible to have a layer of composition that is homogeneous on the surface after drying and to avoid the flaw of molding during printing.
• the support substance which is in fact water-soluble, migrates irregularly with water depending on the irregularities of the deposition of the layer, these irregularities are notably related to structural irregularities of the base on which it is applied and / or a certain uneven penetration of the layer, resulting in offset printing (especially with inks drying in the open air) a non-uniform ink-surface interaction , which gives an irregular appearance to the printing, which can explain the lack of mottle observed in the prior art when the support substances are used in greater quantity.
• said coated sheet may comprise at least one sublayer comprising pigments and at least one binder disposed under said surface layer.
• the weight of said surface layer is at least 5 g / m 2 dry, per side, preferably at least 10 g / m 2 , more particularly between 15 and 30 g / m 2 .
• this most surface-deposited layer comprises a large quantity of fluorescent whitening agent and of support substance, the base sheet and / or the sub-layers possibly having intrinsically low fluorescence power, even zero in order to reduce the cost of these fluorescent whitening agents and carrier substances whose price is high.
• the Applicant has unexpectedly found that the sheets according to the invention have a high fluorescence power, and that they do not exhibit offset printing of noticeable mottle defect.
• the total amount of fluorescent whitening agent in said surface layer is greater than 1 and less than or equal to 4% by dry weight relative to the total dry weight of said coating pigments, in particular between 1.5 and 3. %.
• the total amount of support substance in said surface layer is less than or equal to 10% by dry weight relative to the total dry weight of said coating pigments, in particular between 4 and 8%.
• the total amount of fluorescent whitening agent in said surface layer is equal to 1% by dry weight relative to the total dry weight of said coating pigments, and the total amount of carrier substance in said surface layer is greater than 5% by dry weight relative to the total dry weight of said coating pigments.
• said coated sheet according to the invention has a fluorescence power greater than 60, this power being measured according to the international standard ISO 11475: 2004 as previously described.
• said base sheet, optionally coated with one or more sub-layers has a fluorescence power of between 0 and 20.
• the coating pigments of said layer are chosen from calcium carbonates, kaolins, talcs, titanium dioxide and plastic pigments.
• the plastic pigments are hollow microspheres of a (styrene-acrylic) copolymer having an average size of between 1 and 0.1 ⁇ m.
• the surface layer comprises at least one coating binder chosen from acrylic polymers, styrene-butadiene polymers and possibly other monomers commonly used in coating, as well as other commonly used additives such as dyes. shading.
• the coating binders are employed as a stabilized aqueous dispersion (latex).
• the fluorescent whitening agent is more particularly chosen alone or as a mixture among the various derivatives of stilbene disulfonic acid having in all
• 2, 4 or 6 sulfonic groups especially as marketed. Possibly these may be commercial preparations already containing a very small amount of a carrier substance.
• the support substance is chosen alone or in a mixture from polyvinyl alcohols (PVA), carboxymethylcellulose (CMC), polyvinylpyrrolidone (PVP) and N-vinylformamide-based polymers.
• PVAs are preferably chosen from those having a high degree of hydrolysis, especially greater than 98%.
• the base sheet may be any fibrous sheet, particularly cellulosic and / or synthetic fiber based sheet, such as paper including cardboard.
• the base sheet can also be a sheet or a plastic film, for example a so-called synthetic paper based on an extruded polyolefin film of the brand POL Y ART ® or an extruded polypropylene based sheet manufactured and marketed by PRIPLAK ® .
• the base sheet may also be a complex of a fibrous sheet, especially a paper and a film or plastic sheet or a paper coated with an extruded plastic layer.
• the invention also relates to the method of manufacturing said coated sheet.
• an outline method such as the curtain coating method contributes to the objects of the invention, in particular in the case of a substrate. substrate with a not very regular surface. Indeed, this method makes it possible to obtain a surface layer deposited with a very regular thickness and thus avoids, during drying, the non-homogeneous migration of the water-soluble support substance, and to avoid the mottle defect during offset printing.
• the invention therefore also relates to a method of manufacturing said offset coated white sheet with the characteristics as described above according to the invention, comprising a step of forming said surface layer by depositing the pigmented composition defining it, and carried out in an aqueous medium, by a curtain coating on said base sheet, the latter being optionally coated with underlayer (s).
• this coating method applies to a fibrous base sheet, especially a paper.
• Curtain coating can be done online during paper making or offline.
• the process is such that the pigmented composition of said surface layer is deposited simultaneously with that of a pigmented sub-layer described above by means of a multilayer curtain coating head.
• the said underlayer (s) may be applied (s) by means of a gluing press for example on the paper machine on which the base of the paper is produced or offline for a plastic base sheet.
• the gluing press may be of the conventional type or it may be a modified model, for example a "Speedsizer” as marketed by Voith.
• Other coating methods may be used provided that they are suitable for the application of the desired layer weights, several sub-layers can be applied by different methods.
• a first underlayer may be coated in a size press and a second pigmented sub-layer may be applied by blade coating, for example.
• the total dry weight of all the layers of a sheet according to the invention is greater than 10 g / m 2 in sec per side and preferably 15 g / m 2 , or even 30 g / m 2 per side or more. .
• coated sheet according to the invention may comprise said surface layer on each of its faces.
• the fluorescence power is measured according to ISO 11475: 2004 by difference between the values of the CIE whiteness under illuminant D65 and the value of this quantity measured after the interposition of a filter eliminating wavelengths below 420 nm.
• the measurements of the diffuse reflectance factor in blue R457 according to ISO 2469: 1994 and ISO 2470: 1999 under illuminant D65 as well as the whitening power at 457 nm are indicated by difference with the value of diffuse reflectance.
• the greening ⁇ a * is calculated by the difference between the value of the trichromatic coordinate a * in the presence of the filter at 420 mm for the coated sheet without fluorescent whitening brightener and that under the same conditions of measurement for the coated sheet with a given percentage of fluorescent whitening agent.
• Example 1 in conjunction with Table 1, includes Comparative Examples Ic and Ic Example Id according to the invention.
• a surface pigmented composition made in an aqueous medium and essentially comprising: a mixture of calcium carbonate pigments (95 parts) and of talc (5 parts) - a copolymer binder (styrene-butadiene), in a proportion of 7% by dry weight relative to the dry weight of the pigments, a fluorescent whitening agent A, which is a stilbene disulfonated derivative marketed by 3Vsigma under the reference d OPTIBLANC NL, in dry weight relative to the total weight of the pigments as indicated in Table 1, a carrier substance for the bleaching agent, which is a
• the pigmented surface composition of the test Id according to the invention is deposited by curtain coating.
• Matt coated papers with a total coating weight of 47 g / m 2 dry per side are then obtained, as used for sheet-fed offset printing applications (sheet-by-sheet printing with air-drying inks). high quality.
• coated papers from tests la to Id are tested in offset printing on the Roland 4-color machine and their roughness index is evaluated as described above.
• Comparative test la illustrates a standard coated paper for offset printing, both in terms of its coating formulation and its coating process: It is found that the quality of printing is good but the fluorescence power is insufficient.
• Comparative test Ib shows the negative effect of the percentage increase fluorescent whitening agent which leads after greening, the opposite effect of that sought.
• Comparative test Ic shows that under standard coating conditions it is not possible to increase the percentage of carrier substance without unacceptably degrading the printability (mucking failure).
• the test Id illustrates the invention, a coated sheet appears very white because of a high fluorescence power and for which there is a good quality of offset printing without noticeable mottle defect.
• the coated paper Id according to the invention has a CIE whiteness of 136, a diffuse reflectance factor in the R457 blue of 107% and a bleaching power of 22%.
• Example 2 in conjunction with Table 2, includes Comparative Examples 2a and 2b and Examples 2c and 2d with surface compositions in accordance with those defined for the invention.
• Two aqueous pigment compositions for mat coating consisting of the same mixture of calcium carbonate pigments and a copolymer binder (styrene-butadiene) at a rate of 11% by dry weight relative to the dry weight of the pigments.
• a copolymer binder styrene-butadiene
• One of the surface compositions which is not in accordance with the invention, also comprises standard percentages according to the prior art (0.4%) of the carrier substance of Example 1 and of a fluorescent whitening agent B which is a tetrasulphonated stilbene derivative marketed by CLARIANT under the reference LEUCOPHOR LCPE.
• the other composition includes the same products but with quantities according to the invention.
• compositions are each coated at a rate of 15 g / m 2 dry per side on two fibrous bases (paper) of 120 g / m 2 weak (16) or strong (69) fluorescence power.
• Table 2 shows that, unlike the surface compositions according to the invention (tests 2c and 2d), it is not possible with a standard coating composition of the prior art (tests 2a and 2b) to reconcile a deposit of a layer compatible with the printability requirement, that is to say a layer comprising a low level of support substance so as not to have a mottle defect, and a high fluorescence power of the coated sheet (greater than 55 ), even taking as a basis a paper having a very high fluorescence power (test 2b).
• Example 3 in conjunction with Table 3, includes Examples 3a and 3b with surface compositions in accordance with those defined for the invention.
• Table 3 reports the results obtained by coating a fibrous base with the same pigmented composition as in Example 2, this time in the presence of 6% (by dry weight relative to the dry pigments) of the carrier substance and 2, 5% (dry weight relative to the dry pigments) of fluorescent whitening agent B.
• coated papers 3a and 3b according to the invention respectively have a whitening power of 22% and 25%.
• Example 4 comprises Comparative Examples 4a to 4d and Examples 4 to 4q with surface compositions in accordance with those defined for the invention. These examples show that, contrary to the usual conditions, the surface compositions conforming to those defined for the invention do not exhibit critical greening.
• a fibrous base previously surfaced and precoated, for a total layer weight of 15 g / m 2 dry per side, with pigmented compositions of calcium carbonate and a mixture of binders starch and copolymer (styrene-butadiene) ), said precoated base having a fluorescence power of 43, is coated at a rate of 12 g / m 2 per side, a surface pigmented composition made in an aqueous medium essentially comprising: calcium carbonate pigments, a copolymer binder (styrene) -butadiene) in an amount of 8% by dry weight relative to the weight of the pigments, a fluorescent whitening agent in an amount by dry weight relative to the total weight of the pigments as indicated in Table 4, a carrier substance in quantity by weight dry matter relative to the total weight of the pigments as indicated in Table 4.
• the fluorescent whitening agent can be the agent A (disulfonated stilbene derivative) or B (tetrasulphonated stilbene derivative) already mentioned in the preceding examples, or another agent C which is a hexasulfonated stilbene derivative marketed by ROBAMA under the reference of RESISTOL SLK (see Table 4).
• the best quality / cost compromise will be chosen industrially to achieve the desired fluorescence power with a greening ⁇ a * of less than 1, preferably less than 0.6.
• This example 5 in connection with Table 5, includes Examples 5a to 5c which illustrate the use of mixtures of carrier substances to produce pigmented compositions in accordance with those of the invention.
• Example 4 The coating conditions of Example 4 are repeated with 2% (by dry weight relative to the dry weight of the pigments) of the fluorescent whitening agent A (stilbene disulfonated derivative), 0.8% (by dry weight per relative to the weight of the dry pigments) of the PVA carrier substance described in the previous examples and 5% (by dry weight relative to the dry weight of the pigments) of one of the following carrier substances:
• coated papers 5a, 5b and 5c according to the invention respectively have a measurement of the reflectance factor R457 of 104% (for 5a), 104.5% (for 5b) and 105% (for 5%). c), and a whitening power respectively of 21% (for 5a), 21% (for 5b) and 22% (for 5c).
• This example 6 in conjunction with Table 6 illustrates the invention using as a base sheet a plastic sheet.
• the coating composition of Test 4o (9% of carrier substance PVA in dry weight relative to dry pigments and 1.5% in dry weight relative to to the dry pigments of the fluorescent whitening agent A (disulfonated stilbene derivative)) with a coating weight of 23 g / m 2 dry per side deposited on a plastic sheet (based on an extruded polyolefin film coated with a pigmented precursor) of 150 g / m 2 marketed by the company ARJOBEX Ltd under the trademark POLYART®, having a fluorescence power of 8.
• Table 6 shows that a sheet with a high fluorescence power is obtained.

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• Laminated Bodies (AREA)
• Duplication Or Marking (AREA)
• Inks, Pencil-Leads, Or Crayons (AREA)
• Macromonomer-Based Addition Polymer (AREA)

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