MXPA99010225A

MXPA99010225A - Water retaining and optical brighteners activating polymeric composition, paper coating colours and coated paper

Info

Publication number: MXPA99010225A
Application number: MXPA/A/1999/010225A
Authority: MX
Inventors: Suau Jeanmarc; Egraz Jeanbernard; Ravet Georges; Capraogier Isabelle; Grondin Henri
Original assignee: Coatex Sa
Priority date: 1998-11-10
Filing date: 1999-11-08
Publication date: 2000-10-01

Abstract

Polymeric composition for regulating water retention, activation of whiteners and viscosity of paper sizes comprises polyvinylic alcohol and neutral or alkaline hydrosoluble polymer Aqueous polymeric composition, stable in liquid form, which enables regulation of water retention, activation of whiteners and viscosity of paper sizes, comprises at least a polyvinylic alcohol (PVA) and at least a neutral or alkaline hydrosoluble polymer. Aqueous polymeric composition, stable in liquid form, which enables regulation of water retention, activation of whiteners and viscosity of paper sizes, comprises at least a polyvinylic alcohol (PVA) and at least a neutral or alkaline hydrosoluble polymer;said PVA having Ostwald viscosity less than 5 mPa.s corresponding to degree of polymerisation less than 600;and degree of hydrolysis=70-100 mol.%measured from ester index corresponding to mol.%vinyl acetate groups=30 - 0. Independent claims are also included for an aqueous suspension or slurry of mineral fillers containing the composition for use in paper sizes;and a sheet of paper coated with the suspension or slurry.

Description

that's it.

POLYMERIC COMPOSITION FOR THE RETENTION OF WATER AND THE ACTIVATION OF OPTICAL POLISHERS, FORMULATIONS PAPER SCRAPERS, AND COATED PAPER SHEETS OBTAINED IN THIS WAY The present invention deals with the technical field of the coating of paper sheets. It is known that, in the techniques for coating sheets of paper, card stock or the like, a coating formulation or coating color is deposited on the base surface, the coating formulation containing one or more mineral substances for filling, one or more binders and various additives. Among these additives, water retention agents can be mentioned, do not confuse with the agents to retain fine powders or fillers in the wire fabrics. The purpose of the coating is to improve certain physical and optical characteristics of the paper, such as for example its satin, gloss, opacity, capacity to receive printing ink, homogeneity of the surface and other properties of great commercial importance. A paper coating formulation is generally composed of a substance for filling the REF: 31934 which can be one or more pigments, one or more polymeric binders and various additives such as in particular a lubricant such as calcium stearate, a wax or a fatty acid ester, possibly with antifoaming agents and the like well known for a specialist in the field. After deposition on the base surface, the coating formulation has a natural tendency to transfer all or part of the water-soluble components it contains to the base material. It is necessary to control the excessively fast migration, which would be dangerous for the physical and optical characteristics of the layer. Therefore, it is sought to retain the water in the composition or the coating formulation. This water retention must also be controlled in order to avoid changes in the rheology of the coating formulation which remains unused and is recycled in the coating process. The water retention agents usually used are natural or synthetic materials such as carboxymethylcellulose (CMC), starch, polyvinyl alcohols (PVA's) or certain types of latexes or emulsions of highly carboxylated polymers. or polycarboxylates, for example of the polyacrylate type. Such products are described, for example, in EP No. 0 509 878. A particular class of retention agent are the polymers commonly known as alkali-swelling, described in the above-mentioned EP patent, and as the prior art in the art. U.S. Patent No. 4,780,500 which will be explained later. Naturally, it is essential that the various additives do not degrade the other properties of the paper, such as its gloss, opacity, mechanical strength, etc. The important, main optical characteristics include opacity, satin and gloss, particularly in materials for printing use. In order to improve the brightness of a paper, the addition of optical brighteners is well known, these reinforce the gloss effect of the paper. These optical brighteners are usually, and not exhaustively, of a type which includes in its molecule a stybic site substituted by diamines and sulfonic groups. These optical brighteners convert part of the invisible UV radiation into visible light, generally in the range of blue to violet.

A non-exhaustive example of a disulfonic acid derivative, stybic as an optical brightener is the product "TINOPAL ™ (SPP Z or ABP Z or SK)" sold by Ciba. Another non-exhaustive example of an optical brightener, known is the product "BLANKOPHORMR (P or BPN)" sold by Bayer. The efficiency of these products usually depends on their "activation", which means in this case the use of a co-product which will be developed and mainly, will amplify the effect of brightness. It is now known that certain known water retention agents do not activate the optical brighteners. It is also known that certain products such as polyvinyl alcohols or CMCs are of limited use due to the high viscosities they develop in the coating formulation in parallel with the efficiency of their water retention. The paper manufacturer is thus in the presence of two properties which are eminently desirable to reinforce but which in most cases are antagonistic to each other.

Attempts have been made for at least ten years to optimize the effects of modern water retention agents, such as thickening polymers, and those of the activators of optical brighteners such as in particular PVA's and other additives. In EP 0 509 878, preparations are recommended which "may be completely free of synthetic or natural thickening agents" (page 2 line 52), which clearly reveals the disadvantages in the use thereof. U.S. Patent No. 4,780,500 discloses water retention agents consisting first of an acrylic acid monomer and secondly of an itaconic acid monomer, with molecular weights of 100,000 to 800,000. These two documents do not mention the problem presented by the optical brighteners. British Patent No. 1 467 127 mentions the possible use of PVA as a binder in coating compositions, in the same way as starch, casein, etc. It mentions the possible presence of optical brighteners (page 2 line 10) but without presenting the problem of its activation relative to water retention.

U.S. Patent No. 3,793,244 describes terpolymers of styrene, butadiene and itaconic acid as water retainers and does not mention PVA 's. British patent No. 1 271 282 describes - a mixture of latex of which one includes a high proportion of styrene. This latex mixture provides water retention but nowhere is the presence of the aforementioned PVA. U.S. Patent No. 3,687,884 discloses a latex with a vinyl acetate / acrylic acid backbone to which the styrene is grafted. U.S. Patent Nos. 5,231,145 and 5,240,771 state that it is possible, by grafting, to increase the amounts of PVA in the presence of copolymers subject to the condition that the copolymer is prepared by polymerization in the presence of the PVA. They also indicate that simple mixing of this polymer with PVA does not make it possible for a stable preparation to be produced. According to the invention, it has been discovered that, contrary to the information contained in the recent patents such as the patent EP 0 509 878 mentioned above, it is possible to use certain specially selected PVA 's in combination with one or more retention agents of water as a liquid, aqueous preparation which simultaneously optimizes the functions of water retention, the activation of the optical brighteners and the viscosity regulation of the coating formulations, without the degradation of the properties of water retention which could be • feared In addition, it should be noted that the polymeric, liquid, aqueous preparation is stable, that is, it remains homogeneous for several days of storage without agitation at room temperature, this stability being a vital condition for transport, use and sale of the product. preparation. The invention also makes it possible to control the rheology of the coating formulations, that is, to select the viscosity of the product according to the application requirements. Without wishing to be bound by any theory, the applicant considers that the selection criteria used in the selection of the PVA 's according to the invention ensure compatibility and stability with the water retention agent. According to the invention, an accurate selection of PVA's is used, defined by: a viscosity below 5 mPa.s and preferably in the range of 2 mPa.s and 4 mPa.s measured in accordance with the standard described below, which corresponds to a degree of polymerization of less than 600 and preferably in the range of 250 to 500. - a molar hydrolysis percentage of between 70 and 100 and preferably between 80 and 90, corresponding to a molar percentage of vinyl acetate structures varying from 30 to 0 and preferably from 20 to 10 measured on the basis of ester index (DIN 53401). In a preferred mode of implementation, the polymer composition or the polymer composition is characterized in that it contains a PVA percentage of more than 20% by weight and preferably more than 50%. The viscosity of the PVA is determined by means of a Prolabo Ostwald viscometer (instrument No. 4080) with a capillary length of 100 mm and a reservoir capacity of 10 ml. To do this, one starts by preparing a 4% aqueous solution. In this way, a quantity of PVA, weighed to within 1 mg, which corresponds to 2.105 g for a PVA at 1% humidity, 2.128 g for a PVA in 2% of water, is introduced in a 60 ml stoppered flask. humidity, 2,151 g for a PVA at 3% humidity of 2,174 g for a PVA at 4% humidity. Then 50 ml of distilled water are added, accurately measured using a pipette. The flask is capped and agitated using a magnetic stirrer with heating. The solution whose viscosity should be measured should be free of insoluble matter which could modify the rate of fluid flow in the capillary of the viscometer. Therefore, it may be necessary to filter or centrifuge the solution. The 4% solution prepared in this way, the viscosity is measured by means of the aforementioned viscometer immersed in a temperature controlled bath at 20 ° C ± 0.05 ° C. In the remainder of the present application, in order to simplify the text, the viscosity determined using this method will be called the Ostwald viscosity, in particular, for the viscosities claimed. The invention is also about the polymeric, aqueous, liquid, stable composition which activates the optical brightener and retains water, which contains at least one PVA (polyvinyl alcohol) and at least one polymer which is soluble in water at a neutral pH or alkaline characterized in that the water-soluble polymer is a dispersion copolymer having at least 20% (20% to 75%) by weight of monomers which include acid groups and more particularly carboxylic groups. The copolymer in the dispersion can be selected from the copolymers of at least one of the acid functional monomers such as acrylic and / or methacrylic, itaconic, citraconic, crotonic, fumaric, maleic, isocrotonic, mesaconic, sinapic, undecylenic or angelic and / or their respective anhydrides and / or the half esters of diacids, acrylamido-methylpropanesulfonic acid, the acid phosphates or sulfates of the acrylates and methacrylates of ethylene glycol, propylene glycol, butylene glycol, polyethylene glycol, polypropylene glycol and polybutylene and other glycols . The monomer or monomers without acid groups can be. select not exhaustively among the derivatives of the aforementioned acids such as in particular the methyl, ethyl, butyl, 2-ethylhexyl acrylates or methacrylates or of acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, and n-methylolacrylamide and among the monomers vinyl and / or styrenic such as for example vinyl acetate, styrene, methylstyrene, diisobutylene, divinylbenzene, methyl vinyl ester or vinylcaprolactam or mixtures thereof. These may also be selected from the oxyalkylated monomers with ethylenic unsaturation terminated by a straight or branched chain, such as linear or branched alkyl, aryl or alkylaryl groups having from 1 to 50 carbon atoms and in particular the di-, tri-groups. - and tetra-styrylphenol, nonylphenols and others. Finally, these monomers without acid groups can also be selected from monomers possessing at least two ethylenic unsaturations such as, in particular, but not exhaustively, the group comprising ethylene glycol dimethyl acrylate, trimethylolpropanetriacrilate, allyl acrylate, methylene-2 acrylamide, methylene-2-methacrylamide, tetraliloxyethane, triallylcyanurate, allyl ethers obtained from polyols such as pentaerythritol, sorbitol, sucrose or others. The invention is also about the polymeric, aqueous, stable liquid which activates the optical brightener and retains water, which contains at least one PVA (polyvinyl alcohol) and at least one water-soluble polymer, soluble in water at a neutral or alkaline pH characterized by the fact that the water-soluble polymer is a water-soluble polyurethane. The invention is also about the polymeric, aqueous, stable liquid which activates the optical brightener and retains water, which contains at least one PVA (polyvinyl alcohol) and at least one water-soluble polymer, soluble in water at a neutral or alkaline pH characterized in that the water-soluble polymer is a homopolymer or copolymer of a carboxylic acid used in an acid form completely and in solution in water. The invention is finally concerned with aqueous suspensions or slurries of mineral fillers containing the polymeric, aqueous, stable liquid according to the invention. These mineral fillers can be selected, for example, from natural calcium carbonates, such as in particular calcium carbonate, calcite or marble or synthetic calcium carbonates, dolomites, kaolins, talcum, titanium dioxide, satin white, mica, calcined clay, aluminum hydroxide or calcium sulfate and mixtures thereof. The specialist in the field traditionally prepares the coating formulations by mixing in water the aqueous suspensions of mineral substances for filling, one or more binding agents of natural or synthetic origin such as for example casein, starch, carboxymethylcellulose or polyvinyl alcohols or latex of the type of styrene-butadiene or styrene-acrylate or acrylic or vinyl or other latex. It is known that the coating formulations can also contain the usual additives such as rheology modifiers, organic fillers, anti-foaming agents, optical brighteners, bactericides, lubricants, alkali hydroxides and others. According to the invention, the paper coating formulations containing one or more filling substances, one or more polymer binding agents, water retainers, pigments, optical brighteners and various other papermaking additives are characterized by the fact that the water retention, the activation of optical brighteners and the viscosities of the coating formulations are regulated by a polymer composition according to the invention containing at least one polyvinyl alcohol (PVA) and at least one water soluble polymer at a neutral pH or alkaline. Other characteristics and advantages of the invention will appear more clearly in the reading of the following description and by reference to the subsequent examples which can not in any way restrict the invention.

EXAMPLE 1 This example is a comparison of the effectiveness of the known activators of the optical brighteners, such as CMC or certain PVA's, with the activation efficiency of the preparations according to the invention.

Test No. 1 For this test, which illustrates the prior art, the following coating formulation was prepared by mixing: - 100 parts, expressed in terms of dry matter, of the aqueous calcium carbonate suspension sold by Omya under the name "HYDROCARBMR CC". - 12 parts, expressed in terms of dry matter, of the latex of the styrene-acrylic type sold by BASF under the name "ACRONALMR S 360 D". - 0.5 parts, expressed in terms of dry matter, of the PVA solution sold by Clariant under the name "MOWIOLMR 3/83". - 0.5 parts, expressed in terms of dry matter, of the carboxymethylcellulose (CMC) sold by Metsa Serla under the name "FINNFIXMR 10" - 1 part of the optical brightener sold by Bayer under the name "BLANKOPHORMR P".

The dry matter content is of the order of 64% and the pH is of the order of 8 to 9 by adjusting with an aqueous solution of sodium hydroxide.

Test No. 2 For this test, which illustrates the prior art, the following coating formulation was prepared by mixing: - 100 parts, expressed in terms of dry matter, of the aqueous calcium carbonate suspension sold by Omya under the name "HYDROCARBMR CC" - 12 parts, expressed in terms of dry matter, of the latex of the styrene-acrylic type sold by BASF under the name "ACRONALMR S 360 D". - 0.5 parts, expressed in terms of dry matter, of the PVA solution sold by Clariant under the name "MOWIOLMR 6/98". - 0.5 parts, expressed in terms of dry matter, of the carboxymethylcellulose (CMC) sold by Metsa Serla under the name "FINNFIXMR 10" 1 part of the optical brightener sold by Bayer under the name "BLANKOPHORMR P".

Test No. 3 For this test, which illustrates the prior art, the following coating formulation was prepared by mixing: - 100 parts, expressed in terms of dry matter, of the aqueous calcium carbonate suspension sold by Omya under the name "HYDROCARBMR CC" - 12 parts, expressed in terms of dry matter, of the latex of the styrene-acrylic type sold by BASF under the name "ACRONALMR S 360 D". - 1 part, expressed in terms of dry matter, of the carboxymethylcellulose (CMC) sold by Metsa Serla under the name "FINNFIXMR 10" - 1 part of the optical brightener sold by Bayer under the name "BLANKOPHORMR P".

Test No. 4 For this test, which illustrates the prior art, the following coating formulation was prepared by mixing: - 100 parts, expressed in terms of dry matter, of the aqueous calcium carbonate suspension sold by Omya under the name "HYDROCARBMR CC" - 12 parts, expressed in terms of dry matter, of the latex of the styrene-acrylic type sold by BASF under the name "ACRONALMR S 360 D". - 1 part, expressed in terms of dry matter, of the PVA solution sold by Clariant under the name "MO IOLMR 3/83". - 1 part of the optical brightener sold by Bayer under the name "BLANKOPHORMR P".

Test No. 5 For this test, which illustrates the prior art, the following coating formulation was prepared by mixing: - 100 parts, expressed in terms of dry matter, of the aqueous calcium carbonate suspension sold by Omya under the name "HYDROCARBMR CC" - 12 parts, expressed in terms of dry matter, of the latex of the styrene-acrylic type sold by BASF under the name "ACRONALMR S 360 D". - 1 part, expressed in terms of dry matter, of a dispersion copolymer of the prior art constituted by 37% by weight of methacrylic acid and 63% by weight of ethyl acrylate and known as Product no. 1. - 1 part of the optical brightener sold by Bayer under the name "BLANKOPHORMR P".

For the tests according to the invention (tests 6 to 13), the coating formulations according to the. invention were prepared by mixing: - 100 parts, expressed in terms of dry matter, of the aqueous calcium carbonate suspension sold by Omya under the name "HYDROCARBMR CC" - 12 parts, expressed in terms of dry matter, of the latex of the styrene-acrylic type sold by BASF under the name "ACR0NALMR S 360 D". - 1 part, expressed in terms of dry matter, of a polymeric composition according to the invention. - 1 part of the optical brightener sold by Bayer under the name "BLANKOPHORMR P".

The dry matter content is of the order of 64% and the pH is of the order of 8 to 9 by adjusting with an aqueous solution of sodium hydroxide. The polymeric composition for the activation of the optical brighteners and the water retention according to the invention is: Test No 6 A polymeric composition according to the invention consisting of 70% by weight of a PVA with an Ostwald viscosity of 3.5 Mpa.s and a molar hydrolysis percentage of 87.5% measured from the ester index (DIN 53401) and 30% by weight of a copolymer composed of 39% by weight of methacrylic acid, 55% by weight of ethyl acrylate and 6% by weight of a precondensate of ethylene glycol methacrylate and toluene diisocyanate condensed in nonylphenol with 50 ethylene oxide groups. This product according to the invention is referred to as product 2 in the remainder of this application.

Test No 7 A polymeric composition according to the invention consisting of 70% by weight of a PVA with an Ostwald viscosity of 3.5 mPa.s and a molar hydrolysis percentage of 87.5% measured from the ester index (DIN 53401) and 30% by weight of a copolymer composed of 37% by weight of methacrylic acid, 54% by weight of ethyl acrylate and 9% by weight of a precondensate of ethylene glycol methacrylate and toluene diisocyanate condensed in nonylphenol with 50 ethylene oxide groups. This product according to the invention is referred to as product 3 in the remainder of this application.

Test No. 8 A polymeric composition according to the invention consisting of 80% by weight of a PVA with an Ostwald viscosity of 3.5 mPa.s and a molar hydrolysis percentage of 87.5% measured from the ester index (DIN 53401) and 20% by weight of a copolymer composed of 42% by weight of methacrylic acid, 54.1% by weight of ethyl acrylate and 0.8% by weight of n-methylol acrylamide, 1.6% of ethylene glycol dimethacrylate and 1.5% of acrylamide. This product according to the invention is referred to as product 4 in the remainder of this application.

Test No. 9 A polymeric composition according to the invention consisting of 70% by weight of a PVA with an Ostwald viscosity of 3.5 mPa.s and a molar hydrolysis percentage of 87.5% measured from the ester index (DIN 53401) and 30% by weight of a copolymer composed of 37% by weight of methacrylic acid, 54% by weight of ethyl acrylate and 9% by weight of tristyrylphenol methacrylate with 25 ethylene oxide groups. This product according to the invention is referred to as product 5 in the remainder of this application.

Test No. 10 A polymeric composition according to the invention consisting of 70% by weight of a PVA with an Ostwald viscosity of 3.5 mPa.s and a molar hydrolysis percentage of 87.5% measured from the ester index (DIN 53401) and 30% by weight of a copolymer composed of 37% by weight of methacrylic acid, 63% by weight of ethyl acrylate. This product according to the invention is referred to as product 6 in the remainder of this application.

Test No. 11 A polymer composition according to the invention consisting of 70% by weight of a PVA with an Ostwald viscosity of 3.5 mPa.s and a molar hydrolysis percentage of 87.5% measured from the ester index (DIN 53401) and 30% by weight of a copolymer composed of 44% by weight of methacrylic acid, 15% by weight of butyl acrylate and 41% by weight of styrene. This product according to the invention is referred to as product 7 in the remainder of this application.

Test No. 12 A polymeric composition according to the invention consisting of 70% by weight of a PVA with an Ostwald viscosity of 3.5 mPa.s and a molar hydrolysis percentage of 87.5% measured from the ester index (DIN 53401) and 30% by weight of a polyurethane polycondensate of a lauric acid, diisocyanate and polyalkylene glycol. This product according to the invention is referred to as product 8 in the remainder of this application.

Test No. 13 A polymeric composition according to the invention consisting of 70% by weight of a PVA with an Ostwald viscosity of 3.5 mPa.s and a molar hydrolysis percentage of 87.5% measured from the ester index (DIN 53401) and 30% by weight of a polycondensate of polyurethane octanol, diisocyanate and polyalkylene glycol. This product according to the invention is referred to as product 9 in the remainder of this application.

Test No. 14 A polymeric composition according to the invention consisting of 70% by weight of a PVA with an Ostwald viscosity of 3.5 mPa.s and a molar hydrolysis percentage of 87.5% measured from the ester index (DIN 53401) and 30% by weight of an acrylic acid homopolymer in solution in an acid form completely. This product according to the invention is referred to as product 10 in the remainder of this application.

Test No. 15 A polymer composition according to the invention consisting of 70% by weight of a PVA with an Ostwald viscosity of 3.5 mPa. s and a molar hydrolysis percentage of 87.5% measured from the ester index (DIN 53401), 15% by weight of a copolymer composed of 37% by weight of methacrylic acid, 63% by weight of ethyl acrylate and 15% by weight of another copolymer composed of 44% by weight of methacrylic acid, 15% by weight of butyl acrylate and 41% by weight of styrene. This product according to the invention is referred to as product 11 in the remainder of this application.

Test No. 16 A slurry of calcium carbonate "HYDROCARBMR CC" from Omya containing the polymer composition consisting of 70% by weight of a PVA with an Ostwald viscosity of 3.5 mPa.s and a molar hydrolysis percentage of 87.5% measured from the ester index (DIN 53401) and 30% by weight of a copolymer composed of 37% by weight of methacrylic acid and 63% by weight of ethyl acrylate. This product according to the invention is referred to as product 12 in the remainder of this application. All the coating formulations prepared in this manner are subjected to a test to measure water retention, using the method described below. The coating formulation is subjected to a pressure of 7 bars (100 psi) in a normal cylinder equipped with a filter paper surface which allows water to pass through.

A value is measured: • the volume of water collected after 20 minutes (ml). The smaller the volume of water collected after 20 minutes, the better the water retention. This is achieved by using an API Fluid Loss Measurement filter press (Figure 1) supplied by Baroid. This essentially consists of a stirrup structure equipped with a clamping screw to immobilize the three sections of the filter body. The filter body comprises: • a perforated base part with a hole and equipped with a projection through which the filtrate flows. The base supports a metal sieve with a 60 to 80 mesh in which a paper filter with a diameter of 90 mm (WhatmanMT No. 50) is placed. An equivalent filter is DURIEUX BLEUMR No. 3. • a 128 mm high cylinder with an internal diameter of 76.2 mm • a lid with a compressed gas supply. A seal relative to the cylinder is provided by a flat seal of the same type as those located in the base.

To use the filter press, assemble in the following order: • the seal on the base • the metal sieve on the seals • the paper filter on the metal sieve • the second seal on the paper filter • assemble the cylinder to the base, immobilize the bayonet system Fill with the coating formulation (approximately 480 g, up to about 3 cm from the top of the cylinder). Mount the cover to the cylinder, place a seal between them. Place the assembly on the stirrup structure, immobilize using the screw. Place a measuring cylinder under the projection. Apply a pressure of 7 bars, start the chronometer simultaneously. After 20 minutes, observe the volume of fluid collected in the measuring cylinder (in ml). The precision of the result obtained is + 0.2 ml. The following procedure is used to take a direct measurement of 100% UV light brightness of coated papers in accordance with the TAPPI 452 ISO 2470 Standard used in this example. For each test, a 21 cm x 29.7 cm sheet of chemical pulp paper with a specific gravity of 41 g / m2 is used. The coating formulation to be tested is applied using a laboratory coater with replaceable rotating blades (sold by Erichsen under the name Mpd. KCC 202 MR). Each sheet of paper thus coated at 14-15 g / m2 is dried in a JOUAN ventilated oven for 5 minutes at 50 ° C and then subjected to light radiation at a wavelength of 457 nm using a Data spectrophotometer. Color Elrepho 3000 in order to determine the brightness. The brightness precision obtained is ± 1. The Brookfield viscosity of the coating formulations is also measured at 10 and 100 rpm and 25 ° C, using a Brookfield DV-1 viscometer equipped with the appropriate spindle. The results are shown in Tables la and Ib lines below. or W CO K3 THE An examination of Tables la and Ib shows that only the coating formulations according to the invention show both good gloss and good retention, this when using an individual product according to the invention instead of two as in the prior art. Test No. 5 of the previous technology, which only uses one product, shows good retention but poor brightness. An examination of Tables la and Ib, in particular a comparison of Test 1 and Test 12, also shows that the coating formulations according to the invention allow the desired Brookfield viscosity to be selected while retaining water retention. and the activation of the optical brighteners.

EXAMPLE II In a second group of tests (Numbers 17 to 32) the operations and measurements of Example I were repeated, using the same operating procedure and the same equipment but replacing the 100 dry parts of calcium carbonate in Example I with 70 dry parts of an aqueous solution of calcium carbonate (Hydrocarb ™ 90ME of Omya) and 30 dry parts of kaolin (Hydragloss ™ 90 of Huber). The different tests were: Test No. 17 This test illustrates the prior art and uses the following stucco formulation mixture: - 100 parts, expressed in terms of dry matter, composed of 70 parts by dry weight of an aqueous solution of calcium carbonate (HydrocarbM 90ME of Omya) and 30 dry parts of kaolin (Hydragloss 90 of Huber). - 12 parts, expressed in terms of dry matter, of a latex of the styrene-acrylic type sold by BASF under the name "ACRONALMR S 360 D". - 0.5 parts, expressed in terms of dry matter, of a PVA solution sold by Clariant under the name "MO IOLMR 3/83". - 0.5 parts, expressed in terms of dry matter, of carboxymethylcellulose sold by Metsa Serla under the name "FINNFIXMR 10" - 1 part of an optical brightener sold by Bayer under the name "BLANKOPHORMR P".

Test No. 18 For this test, which illustrates the prior art, the following coating formulation was prepared by mixing: - 100 parts, expressed in terms of dry matter, consisting of 70 parts by dry weight of the aqueous calcium carbonate suspension sold by Omya under the name "HydrocarbM 90ME" and 30 parts by dry weight of kaolin in the form of Hydragloss 90 of Huber. - 12 parts, expressed in terms of dry matter, of the latex of the styrene-acrylic type sold by BASF under the name "ACRONALMR S 360 D". - 0.5 parts, expressed in terms of dry matter, of a PVA solution sold by Clariant under the name "MOWIOLMR 6/98". - 0.5 parts, expressed in terms of dry matter, of the carboxymethylcellulose (CMC) sold by Metsa Serla under the name "FINNFIXMR 10". - 1 part of the optical brightener sold by Bayer under the name "BLANKOPHORMR P".

Test No. 19 For this test, which illustrates the prior art, the following coating formulation was prepared by mixing: - 100 parts, expressed in terms of dry matter, constituted with 70 parts by dry weight of the aqueous calcium carbonate suspension sold by Omya under the name "Hydrocarb® 90ME" and 30 parts by dry weight of kaolin in the form of Hydragloss® 90 of Huber. - 12 parts, expressed in terms of dry matter, of the latex of the styrene-acrylic type sold by BASF under the name "ACRONALMR S 360 D". - 1 part, expressed in terms of dry matter, of the carboxymethylcellulose (CMC) sold by Metsa Serla under the name "FINNFIXMR 10". 1 part of the optical brightener sold by Bayer under the name "BLANKOPHORMR P".

Test No. 20 For this test, which illustrates the prior art, the following coating formulation was prepared by mixing: - 100 parts, expressed in terms of dry matter, consisting of 70 parts by dry weight of the aqueous calcium carbonate suspension sold by Omya under the name "HydrocarbM 90ME" and 30 parts by dry weight of kaolin in the form of Hydragloss 90 of Huber. - 12 parts, expressed in terms of dry matter, of the latex of the styrene-acrylic type sold by BASF under the name "ACRONALMR S 360 D". - 1 part, expressed in terms of dry matter, of the PVA solution sold by Clariant under the name "MOWIOLMR 3/83". - 1 part of the optical brightener sold by Bayer under the name "BLANKOPHORMR P".

Test No. 21 For this test, which illustrates the prior art, the following coating formulation was prepared by mixing: - 100 parts, expressed in terms of dry matter, consisting of 70 parts by dry weight of the aqueous calcium carbonate suspension sold by Omya under the name "HydrocarbM 90ME" and 30 parts by dry weight of kaolin in the form of Hydragloss 90 of Huber. - 12 parts, expressed in terms of dry matter, of the latex of the styrene-acrylic type sold by BASF under the name "ACRONALMR S 360 D". - 1 part, expressed in terms of dry matter, of a dispersion copolymer of the prior art consisting of 37% by weight of methacrylic acid and 63% by weight of ethyl acrylate and known as Product no. 1. - 1 part of the optical brightener sold by Bayer under the name "BLANKOPHORMR P".

Test No. 22 For this test, which illustrates the invention, the following coating formulation was prepared by mixing: - 100 parts, expressed in terms of dry matter, consisting of 70 parts by dry weight of the aqueous calcium carbonate suspension sold by Omya under the name "HydrocarbM 90ME" and 30 parts by dry weight of kaolin in the form of Hydragloss 90 of Huber. - 12 parts, expressed in terms of dry matter, of the latex of the styrene-acrylic type sold by BASF under the name "ACRONALMR S 360 D". - 1 part, expressed in terms of dry matter, of a polymeric composition according to the invention, referred to as Product no. 13 - 1 part of the optical brightener sold by Bayer under the name "BLANKOPHORMR P".

The polymeric compound according to the invention, referred to as Product no. 13, is composed of 70% by weight of a PVA with a viscosity of Ost ald equal to 3.5 mPas. s and a molar hydrolysis percentage equal to 88 measured from the ester index (DIN 53401) and 30% by weight of a compolymer composed of 37% by weight of methacrylic acid and 63% by weight of ethyl acrylate.

Test No. 23 This test illustrates the invention and implements a coating formulation according to the invention, by mixing the same constituents as in the Test No. 22 except for the preparation according to the invention. In the case of this test, the polymer composition according to the invention is Product no. 6 according to the invention.

Test No. 24 This test illustrates the invention and implements a coating formulation according to the invention, by mixing the same constituents as in Test No. 22 except for the composition according to the invention. In this test, the polymer composition according to the invention consists of 70% by weight of a PVA with an Ostwald viscosity equal to 3 mPa.s and a molar hydrolysis percentage equal to 83 measured at the base of the ester index ( DIN 53401) and 30% by weight of a copolymer composed of 37% by weight of methacrylic acid and 63% by weight of ethyl acrylate. This product of the invention is referred to as Product No. 14.

Test No. 25 This test illustrates the invention and implements a coating formulation according to the invention, by mixing the same constituents as in Test No. 22 except for the composition according to the invention. In this test, the polymer composition according to the invention consists of 70% by weight of a PVA with an Ostwald viscosity equal to 5 mPa.s and a molar hydrolysis percentage equal to 88 measured at the base of the ester index ( DIN 53401) and 30% by weight of a copolymer composed of 37% by weight of methacrylic acid and 63% by weight of ethyl acrylate. This product of the invention is referred to as Product No. 15.

Test No. 26 This test illustrates the invention and implements a coating formulation according to the invention, by mixing the same constituents as in Test No. 22 except for the polymeric composition according to the invention.

In this test, the polymer composition according to the invention consists of 70% by weight of a PVA with an Ostwald viscosity equal to 4 mPa.s and a molar hydrolysis percentage equal to 88 measured at the base of the ester index ( DIN 53401) and 30% by weight of a copolymer composed of 37% by weight of methacrylic acid and 63% by weight of ethyl acrylate. This product of the invention is referred to as Product No. 16.

Test No. 27 This test illustrates the invention and implements a coating formulation according to the invention, by mixing the same constituents as in Test No. 22 except for the polymeric composition according to the invention. In this test, the polymer composition according to the invention consists of 70% by weight of a PVA with an Ostwald viscosity equal to 4 mPa.s and a molar hydrolysis percentage equal to 98 measured on the basis of the ester Index ( DIN 53401) and 30% by weight of a copolymer composed of 37% by weight of methacrylic acid and 63% by weight of ethyl acrylate.

This product of the invention is referred to as Product No. 17.

Test No. 28 This test illustrates the invention and implements a coating formulation according to the invention, by mixing the same constituents as in the Test No. 22 except for the polymer composition according to the invention. In this test, the polymer composition according to the invention is constituted of 70% by weight of a PVA with an Ostwald viscosity equal to 3.5 mPa.s and a molar hydrolysis percentage equal to 87.5 measured on the basis of the Index of ester (DIN 53401) and 30% by weight of an acrylic acid homopolymer. This product of the invention is referred to as Product No. 18.

Test No. 29 This test illustrates the invention and implements a coating formulation according to the invention, by mixing the same constituents as in Test No. 22 except for the polymeric composition according to the invention. In this test, the polymer composition according to the invention consists of 20% by weight of a PVA with an Ostwald viscosity equal to 3.5 mPa.s and a molar hydrolysis percentage equal to 87.5 measured at the base of the ester index ( DIN 53401) and 80% by weight of a copolymer composed of 37% by weight of methacrylic acid and 63% by weight of ethyl acrylate. This product of the invention is referred to as Product No. 19.

Test No. 30 This test illustrates the invention and implements a coating formulation according to the invention, by mixing the same constituents as in Test No. 22 except for the polymeric composition according to the invention. In this test, the polymer composition according to the invention consists of 40% by weight of a PVA with an Ostwald viscosity equal to 3.5 mPa.s and a molar hydrolysis percentage equal to 87.5 measured on the basis of the ester Index ( DIN 53401) and 60% by weight of a copolymer composed of 37% by weight of methacrylic acid and 63% by weight of ethyl acrylate. This product of the invention is referred to as Product No. 20.

Test No. 31 This test illustrates the invention and implements a coating formulation according to the invention, by mixing the same constituents as in Test No. 22 except for the polymeric composition according to the invention. In this test, the polymer composition according to the invention is constituted by 60% by weight of a PVA with an Ostwald viscosity equal to 3.5 mPa.s and a molar hydrolysis percentage equal to 87.5 measured on the basis of the ester Index ( DIN 53401) and 40% by weight of a copolymer composed of 37% by weight of methacrylic acid and 63% by weight of ethyl acrylate. This product of the invention is referred to as Product No. 21.

Test No. 32 This test illustrates the invention and implements a coating formulation according to the invention, by mixing the same constituents as in the Test No. 22 except for the polymer composition according to the invention. In this test, the polymer composition according to the invention consists of 70% by weight of a PVA with an Ostwald viscosity equal to 3.5 mPa.s and a molar hydrolysis percentage equal to 87.5 measured at the base of the ester index ( DIN 53401) and 15% by weight of a copolymer composed of 42% by weight of methacrylic acid and 54.1% by weight of ethyl acrylate, 0.8% by weight of n-methylol acrylamide, 1.6% of ethylene glycol dimethylacrylate and 1.5% of acrylamide, and 15% by weight of another copolymer composed of 37% by weight of methacrylic acid and 63% by weight of ethyl acrylate. This product of the invention is referred to as Product No. 22. The results are shown in Tables Ila and Ilb below in the present.

OR Lp Lp t As in the previous example, an examination of Tables lia and Ilb shows that only the coating formulations according to the invention show both good gloss and good retention, this when using an individual product according to the invention instead of two as in the prior art. In a similar way, an examination of Tables lia and Ilb shows that the coating formulations according to the invention allow the desired Brookfield viscosity to be selected while retaining the water retention and activating the optical brighteners. Therefore, the conclusion is identical to that of the previous example but for a coating formulation including pigments such as calcium carbonate and kaolin.

EXAMPLE III In a third group of tests (numbers 33 a 43) were repeated, using the same operating procedure and the same equipment, the operations and measurements of Example I but replacing the 100 dry parts of calcium carbonate with 70 parts by dry weight of an aqueous suspension of calcium carbonate (HydrocarbMR 90ME from Omya) and 30 parts by dry weight of CIO talc from Mondo Minerals. The various tests were: Test No. 33 This test illustrates the prior art and uses the following coating formulation when mixing: - 100 parts, expressed in terms of dry matter, composed of 70 parts by dry weight of an aqueous solution of calcium carbonate (HydrocarbM 90ME of Omya) and 30 parts by dry weight of Cio talc of Mondo Minerals. - 12 parts, expressed in terms of dry matter, of a latex of the styrene-acrylic type sold by BASF under the name "ACR0NALMR S 360 D". - 0.5 parts, expressed in terms of dry matter, of a PVA solution sold by Clariant under the name "MOWIOLMR 3/83". - 0.5 parts, expressed in terms of dry matter, of carboxymethylcellulose sold by Metsa Serla under the name "FINNFIXMR 10" - 1 part of the optical brightener sold by Bayer under the name "BLANKOPHORMR P".

Test No. 34 For this test, which illustrates the prior art, the following coating formulation was prepared by mixing: - 100 parts, expressed in terms of dry matter, consisting of 70 parts by dry weight of the aqueous calcium carbonate suspension sold by Omya under the name "HydrocarbM 90ME" and 30 parts by dry weight of Cio talc from Mondo Minerals. - 12 parts, expressed in terms of dry matter, of the latex of the styrene-acrylic type sold by BASF under the name "ACRONALMR S 360 D". - 0.5 parts, expressed in terms of dry matter, of the PVA solution sold by Clariant under the name "MOWIOLMR 6/98". - 0.5 parts, expressed in terms of dry matter, of the carboxymethylcellulose (CMC) sold by Metsa Serla under the name "FINNFIXMR 10" - 1 part of the optical brightener sold by Bayer under the name "BLANKOPHORMR P".

Test No. 35 For this test, which illustrates the prior art, the following coating formulation was prepared by mixing: - 100 parts, expressed in terms of dry matter, consisting of 70 parts by dry weight of an aqueous suspension of calcium carbonate sold by Omya under the name "HydrocarbM 90ME" and 30 parts by dry weight of Cio talc from Mondo Minerals. - 12 parts, expressed in terms of dry matter, of the latex of the styrene-acrylic type sold by BASF under the name "ACR0NALMR S 360 D". - 1 part, expressed in terms of dry matter, of the carboxymethylcellulose (CMC) sold by Metsa Serla under the name "FINNFIXMR 10 ' - 1 part of the optical brightener sold by Bayer under the name "BLANKOPHORMR P ' The dry matter content is of the order of 64% and the pH is of the order of 8 to 9 by adjusting with an aqueous solution of sodium hydroxide.

Test No. 36 For this test, which illustrates the prior art, the following coating formulation was prepared by mixing: - 100 parts, expressed in terms of dry matter, consisting of 70 parts by dry weight of the aqueous calcium carbonate suspension sold by Omya under the name "HydrocarbM 90ME" and 30 parts by dry weight of Cio talc from Mondo Minerals. - 12 parts, expressed in terms of dry matter, of the latex of the styrene-acrylic type sold by BASF under the name "ACRONALMR S 360 D". - 1 part, expressed in terms of dry matter, of the PVA solution sold by Clariant under the name "MO IOLMR 3/83". - 1 part of the optical brightener sold by Bayer under the name "BLANKOPHOR ^ P".

Test No. 37 For this test, which illustrates the prior art, the following coating formulation was prepared by mixing: - 100 parts, expressed in terms of dry matter, consisting of 70 parts by dry weight of the aqueous calcium carbonate suspension sold by Omya under the name "HydrocarbM 90ME" and 30 parts by dry weight of Cio talc from Mondo Minerals. - 12 parts, expressed in terms of dry matter, of the latex of the styrene-acrylic type sold by BASF under the name "ACRONALMR S 360 D". - 1 part, expressed in terms of dry matter, of a copolymer of the prior art consisting of 37% by weight of methacrylic acid and 63% by weight of ethyl acrylate and known as Product no. 1. - 1 part of the optical brightener sold by Bayer under the name "BLANKOPHORMR P".

Test No. 31 For this test, which illustrates the invention, the following coating formulation was prepared by mixing: - 100 parts, expressed in terms of dry matter, consisting of 70 parts by dry weight of the aqueous calcium carbonate suspension sold by Omya under the name "HydrocarbM 90ME" and 30 parts by dry weight of Cio talc from Mondo Minerals. - 12 parts, expressed in terms of dry matter, of the latex of the styrene-acrylic type sold by BASF under the name "ACRONALMR S 360 D". - 1 part, expressed in terms of dry matter, of a polymer preparation according to the invention, referred to as Product no. 2. - 1 part of the optical brightener sold by Bayer under the name "BLANKOPHORMR P".

Test No. 39 This test illustrates the invention and uses a coating formulation according to the invention, by mixing the same constituents as in Test No. 38 except for the polymeric composition according to the invention. In the case of this test, the polymer composition according to the invention is the -Product no. 3 according to the invention.

Test No. 40 This test illustrates the invention and implements a coating formulation according to the invention, by mixing the same constituents as in Test No. 38 except for the polymer composition according to the invention. In this test, the polymer composition according to the invention is Product no. 4 according to the invention.

Test No. 41 This test illustrates the invention and implements a coating formulation according to the invention, by mixing the same constituents as in the Test No. 38 except for the polymer composition according to the invention. In this test, the polymer composition according to the invention is Product no. 5 according to the invention.

Test No. 42 This test illustrates the invention and implements a coating formulation according to the invention, by mixing the same constituents as in Test No. 38 except for the polymer composition according to the invention. In this test, the polymer composition according to the invention is Product no. 6 according to the invention.

Test No. 43 This test illustrates the invention and implements a coating formulation according to the invention, by mixing the same constituents as in the Test No. 38 except for the polymer composition according to the invention. In this test, the polymer composition according to the invention is Product no. 7 according to the invention.

The results are shown in Tables Illa and Illb below.

THE Lp in An examination of Tables Illa and Illb leads to the same conclusions as Tables I or II but this time with a coating formulation with a filling substance composed of calcium carbonate and talc. Examples 34 and 42 differ by the use of an individual product according to the invention for Test No. 42 while Test 34 uses two products of the prior art.

EXAMPLE IV This example deals with the tests on the variation of the type of the optical brightener. The coating formulations for these tests were prepared by mixing: - 70 parts, expressed in terms of dry matter, of an aqueous solution of calcium carbonate sold by Omya under the name HydrocarbMR 90ME. - 30 parts by dry weight of kaolin in the form of Huber Hydragloss ™ 90. - 12 parts, expressed in terms of dry matter, of a latex of the styrene-acrylic type sold by BASF under the name AcronalMR S 360 D. - 1 part, expressed in terms of dry matter, of the Product no. 6 according to the invention. - 1 part of the different optical brighteners to be tested, except for Test No. 44 which is a control test in which optical brightener is not used.

The dry matter content is of the order of 64% and the pH is of the order of 8 to 9 by adjusting with an aqueous solution of sodium hydroxide. The different optical brighteners are: Test No. 45 The optical brightener sold by Bayer under the name BlankophorMR P.

Test No. 46 The optical brightener sold by Clariant under the name LeucophorTM CK.

Test No. 47 The optical brightener sold by Bayer under the name BlankophorMR PSK.

Test No. 48 The optical brightener sold by 3V Sigma under the name OptiblancMR P.

Test No. 49 The optical brightener sold by Ciba under the name TinopalMK ABP.

Test No. 50 The optical brightener sold by Ciba under the name TinopalTM STP.

Test No. 51 The optical brightener sold by Ciba under the name TinopalMR SPP.

Test No. 52 The optical brightener sold by Ciba under the name TinopalMR UP.

Test No. 53 The optical brightener sold by Ciba under the name Tinopal ™ SK.

These different coating formulations according to the invention are subjected to the viscosity, water retention and gloss measurements using the same operating procedures as the previous tests. The results are shown in Tables IVa and IVb below.

Lú An examination of Tables IVa and IVb shows that whichever optical brightener is used, the polymer composition according to the invention increases the brightness under UV light while retaining water retention.

EXAMPLE V In this example illustrating the invention, the proportion of the polymer composition relative to the amount of the optical brightener used in the coating formulation varies.

This involves preparing the coating formulations to be tested using the same operating procedures, the same equipment and the same amounts of the various components as in the previous example, except for the amounts of the optical brightener and the polymeric composition according to the invention, which varies by the different tests.

Test No. 54 This test, which illustrates the invention, uses 0.6 parts of the optical brightener sold by Ciba under the name Tinopal ™ ABP and 0.6 parts of the Product not. 6 according to the invention.

Test No. 55 This test, which illustrates the invention, uses 0. 6 parts of the optical brightener sold by Ciba under the name Tinopal ™ ABP and 0.8 parts of the Product no. 6 according to the invention.

Test No. 56 This test, which illustrates the invention, uses 0.6 parts of the optical brightener sold by Ciba under the name Tinopal ™ ABP and 1.0 parts of the Product not. 6 according to the invention.

Test No. 57 This test, which illustrates the invention, uses 0.6 parts of the optical brightener sold by Ciba under the name Tinopal ™ ABP and 1.2 parts of the Product not. 6 according to the invention.

Test No. 58 This test, which illustrates the invention, uses 0.8 parts of the optical brightener sold by Ciba under the name Tinopal ™ ABP and 0.6 parts of the Product not. 6 according to the invention.

Test No. 59 This test, which illustrates the invention, uses 0. 8 parts of the optical brightener sold by Ciba under the name Tinopal ™ ABP and 0.8 parts of the Product no. 6 according to the invention.

Test No. 60 This test, which illustrates the invention, uses 0.8 parts of the optical brightener sold by Ciba under the name Tinopal ™ ABP and 1.0 parts of the Product not. 6 according to the invention.

Test No. 61 This test, which illustrates the invention, uses 0.8 parts of the optical brightener sold by Ciba under the name Tinopal ™ ABP and 1.2 parts of the Product not. 6 according to the invention.

Test No. 62 This test, which illustrates the invention, uses 1.0 parts of the optical brightener sold by Ciba under the name Tinopal ™ ABP and 0.6 parts of the Product not. 6 according to the invention.

Test No. 63 This test, which illustrates the invention, uses 1. 0 parts of the optical brightener sold by Ciba under the name Tinopal ™ ABP and 0.8 parts of the Product no. 6 according to the invention.

Test No. 64 This test, which illustrates the invention, uses 1.0 parts of the optical brightener sold by Ciba under the name Tinopal ™ ABP and 1.0 parts of the Product not. 6 according to the invention.

Test No. 65 This test, which illustrates the invention, uses 1.0 parts of the optical brightener sold by Ciba under the name Tinopal ™ ABP and 1.2 parts of the Product not. 6 according to the invention.

Test No. 66 This test, which illustrates the invention, uses 1.2 parts of the optical brightener sold by Ciba under the name Tinopal ™ ABP and 0.6 parts of the Product not. 6 according to the invention.

Test No. 67 This test, which illustrates the invention, uses 1. 2 parts of the optical brightener sold by Ciba under the name Tinopal ™ ABP and 0.8 parts of the Product no. 6 according to the invention.

Test No. 68 This test, which illustrates the invention, uses 1.2 parts of the optical brightener sold by Ciba under the name Tinopal ™ ABP and 1.0 parts of the Product not. 6 according to the invention.

Test No. 69 This test, which illustrates the invention, uses 1.2 parts of the optical brightener sold by Ciba under the name Tinopal ™ ABP and 1.2 parts of the Product not. 6 according to the invention.

The results are shown in Tables Va and Vb below.

OO An examination of tables Va and Vb shows that whatever the dose of the optical brightener used, the polymer composition according to the invention increases the brightness under UV light while retaining water retention.

EXAMPLE VI In this example, which illustrates the invention, the nature of the binder is varied. For the purposes of this example, coating formulations were prepared for the test using the same operating procedure, the same equipment and the same amounts of the various constituents as in Example IV, except for the nature of the latex used in the different tests and the products proposed to act as water retainers and / or activators of optical brighteners.

Test No. 70 This test, which describes the prior art, involves successively adding 0.5 parts, expressed in terms of dry weight, of a PVA solution sold by Clariant under the name "MOWIOLMR 3/83", 0.5 parts, expressed in terms of dry weight, of CMC and 12 parts, expressed in terms of dry weight, of an acrylic styrene latex sold by BASF under the name "AcronalMR S 360 D".

Test No. 71 This test, which describes the invention, uses 1 part, expressed in terms of dry matter, of Product 6 according to the invention and 12 parts, expressed in terms of dry weight, of a styrene acrylic latex sold by BASF under the name "AcronalMR S 360 D".

Test No. 72 This test, which describes the prior art, involves successively adding 0.5 parts, expressed in terms of dry weight, of a PVA solution sold by Clariant under the name "MOWIOLMR 3/83", 0.5 parts, expressed in dry weight terms, of CMC and 12 parts, expressed in terms of dry weight, of a styrene-butadiene latex sold by Dow Chemical under the name "DL 980" and referred to herein as "styrene-butadiene 1".

Test No. 73 This test, which describes the invention, uses 1 part, expressed in terms of dry matter, of Product 6 according to the invention and 12 parts, expressed in terms of dry weight, of a styrene-butadiene latex sold by Dow Chemical under the name "DL 980" and referred to in this description as "styrene-butadiene 1".

Test No. 74 This test, which describes the prior art, involves successively adding 0.5 parts, expressed in terms of dry weight, of a PVA solution sold by Clariant under the name "MOWIOLMR 3/83", 0.5 parts, expressed in dry weight terms, of CMC and 12 parts, expressed in terms of dry weight, of a styrene-butadiene latex sold by Rhone-Poulenc under the name "Rhodopas ™ SB 123" and referred to herein as "styrene-butadiene 2" .

Test No. 75 This test, which describes the invention, uses 1 part, expressed in terms of dry matter, of Product 6 according to the invention and 12 parts, expressed in terms of dry weight, of a styrene-butadiene latex sold by Rhone-Poulenc under the name "Rhodopas ™ SB 123" and referred to in this description as "styrene-butadiene 2". The results are shown in Table VI below. 00 00 - J An examination of Table VI shows that it is possible to increase the brightness under UV light while retaining water retention, whatever the latex used in the coating formulation. The invention also concerns the use, in the preparation of the paper coating formulations of polymeric, aqueous, stable liquids which perform the functions of activation of the optical brighteners, water retention and regulation of the viscosity of the coating formulations, which they contain at least one polyvinyl alcohol (PVA) and at least one water-soluble polymer at a neutral or alkaline pH. The invention also relates to paper coating formulations of the type containing a filling substance, a polymeric binder, water retainers, pigments, optical brighteners and other papermaking additives, and appropriate mixtures of these additives depending on the knowledge of a specialist in the field, characterized in that the water retention, the activation of the optical brighteners and the viscosities are regulated by liquid, aqueous, stable polymer compositions containing at least one polyvinyl alcohol (PVA) and at least one Water soluble polymer at a neutral or alkaline pH.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates.

Having described the invention as above, property is claimed as contained in the following:

Claims

1. A polymeric, aqueous, liquid and stable composition, which provides for the regulation of the activation of optical brighteners, water retention and viscosity in paper coating formulations, containing at least one polyvinyl alcohol (PVA) and at least one polymer soluble in water at a neutral or alkaline pH, characterized in that the PVA presents: an Ostwald viscosity less than 5 mPa.s, which corresponds to a degree of polymerization below 600 and a percentage of molar hydrolysis of between 70 and 100 measured at the base of the ester index (DIN 53401), which corresponds to a molar percentage of vinyl acetate structures ranging from 30 to 0.

2. A polymeric, aqueous, liquid and stable composition, which provides for the regulation of the activation of optical brighteners, water retention and viscosity in paper coating formulations, containing at least one polyvinyl alcohol (PVA) and at least one polymer soluble in water at a neutral or alkaline pH, according to claim 1, characterized in that the PVA has: - an Ostwald viscosity between 2 and 4 mPa.s, corresponding to a degree of polymerization of 250 to 500 and a molar hydrolysis percentage of between 80 and 90 measured on the basis of the ester index (DIN 53401), which corresponds to a molar percentage of vinyl acetate structures ranging from 20 to 10.

3. A polymeric, aqueous, liquid and stable composition, which provides for the regulation of the activation of optical brighteners, water retention and viscosity in paper coating formulations, containing at least one polyvinyl alcohol (PVA) and at least one Water-soluble polymer at a neutral or alkaline pH, according to any of claims 1 and 2, characterized in that it contains a PVA percentage greater than 20% by weight.

4. A polymeric, aqueous, liquid and stable composition, which provides for the regulation of the activation of optical brighteners, water retention and viscosity in paper coating formulations, containing at least one polyvinyl alcohol (PVA) and at least one Water-soluble polymer in a neutral or alkaline pH, according to claim 3, characterized in that it contains a PVA percentage greater than 50% by weight.

5. A polymeric, aqueous, liquid and stable composition, which provides for the regulation of the activation of optical brighteners, water retention and viscosity in paper coating formulations, containing at least one polyvinyl alcohol (PVA) and at least one water-soluble polymer at a neutral or alkaline pH, according to any of claims 1 to 4, characterized in that the water-soluble polymer is a dispersion copolymer containing more than 20% by weight of monomers with groups of acid.

6. A polymeric, aqueous, liquid and stable composition, which provides for the regulation of the activation of optical brighteners, water retention and viscosity in paper coating formulations, containing at least one polyvinyl alcohol (PVA) and at least one Water-soluble polymer at a neutral or alkaline pH, according to claim 5, characterized in that the water-soluble polymer is a dispersion copolymer containing from 20% to 75% by weight of monomers with acid groups.

7. A polymeric, aqueous, liquid and stable composition, which provides for the regulation of the activation of optical brighteners, water retention and viscosity in paper coating formulations, containing at least one polyvinyl alcohol (PVA) and at least one Water-soluble polymer at a neutral or alkaline pH, according to any of claims 5 and 6, characterized in that the acid groups are carboxylic groups.

8. A polymeric composition, aqueous, liquid and stable, which provides the regulation of the activation of the optical brighteners, the water retention and the viscosity in the paper coating formulations, which contains at least one polyvinyl alcohol (PVA) and at least one soluble polymer in water at a neutral or alkaline pH, according to any of claims 1 to 7, characterized in that the copolymer in the emulsion is selected from the copolymers of at least one of the acid functional monomers such as acrylic acid and / or methacrylic, itaconic, citraconic, crotonic, fumaric, maleic, isocrotonic, mesaconic, sinapic, undecylenic or angelic and / or their respective anhydrides and / or the half esters of diacids, acrylamido-methyl-propane-sulfonic acid, the phosphates of acid or sulfates of the acrylates and methacrylates of ethylene glycol, propylene glycol, butylene glycol, polyethylene glycol, polypropylene glycol and polybutylene glycol with at least one of the monomers without acid groups such as the derivatives of the aforementioned acids and the methyl, ethyl, butyl, 2-ethyl-hexyl acrylates or methacrylates or of acrylonitrile, methacrylonitrile, acrylamide, methacrylamide and n-methylolacrylamide, and possibly with vinyl and / or styrenic monomers such as vinyl acetate, styrene, ethylstyrene, diisobutylene, divinylbenzene, methyl vinyl ether or vinylcaprolactam or mixtures thereof or with one of the oxalkylated monomers with ethylenic unsaturation terminated by a chain, such as alkyl groups , linear or branched aryl or alkylaryl having from 1 to 50 carbon atoms and in particular the di-, tri- and tetra-styphenylphenol and nonylphenol groups or finally with at least one of the monomers possessing at least two ethylenic unsaturations such as dimethylacrylate ethylene glycol, trimethylolpropanetriacrilate, allyl acrylate, methylene-2-acrylamide, methylene-2-methacrylamide, tetraliloxydate no, triallylcyanurate, allyl esters obtained from polyols such as pentaerythritol, sorbitol, sucrose or mixtures thereof.

9. A polymeric, aqueous, liquid and stable composition, which provides for the regulation of the activation of optical brighteners, water retention and viscosity in paper coating formulations, containing at least one polyvinyl alcohol (PVA) and at least one Water-soluble polymer in a neutral or alkaline pH, according to any of claims 1 to 4, characterized in that it contains a water-soluble polyurethane.

10. A polymeric, aqueous, liquid and stable composition, which provides for the regulation of the activation of optical brighteners, water retention and viscosity in paper coating formulations, containing at least one polyvinyl alcohol (PVA) and at least one Water-soluble polymer at a neutral or alkaline pH, according to any of claims 1 to 4, characterized in that the water-soluble polymer is a homopolymer or solution copolymer of a carboxylic acid.

11. An aqueous suspension or slurry of a mineral substance for filling, characterized in that it contains polymeric, aqueous, stable liquids which perform the functions of activation of the optical brighteners, water retention and regulation of the viscosity in the paper coating formulations, in accordance with with any of claims 1 to 10.

12. An aqueous suspension or slurry of a mineral substance for filling containing liquid, aqueous, stable liquids that perform the functions of activation of the optical brighteners, water retention and regulation of the viscosity in the paper coating formulations, in accordance with the claim 11, characterized in that the mineral substance to be filled is selected from natural calcium carbonates such as calcium carbonate, calcite or marble or synthetic calcium carbonates, dolomites, kaolins, talcum, titanium dioxide, satin white, mica , calcined clay, aluminum hydroxide or calcium sulfate and mixtures thereof.

13. The use of polymeric, aqueous, stable liquids according to any of claims 1 to 10 in the preparation of coating formulations for paper.

14. The use of aqueous suspensions of mineral substance for filling according to any of claims 11 to 12 in the preparation of paper coating formulations.

15. The paper coating composition, characterized in that it contains polymeric, aqueous, liquid compositions that provide the functions of activation of the optical brighteners, water retention and viscosity regulation, according to any of claims 1 to 10.

16. The paper coating composition, characterized in that it contains an aqueous suspension or slurry of mineral substance for filling according to any of claims 11 to 12.

17. A sheet of coated paper, characterized in that it contains the paper coating composition according to any of claims 15 or 16.