Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
  • D21H19/56—Macromolecular organic compounds or oligomers thereof obtained by reactions only involving carbon-to-carbon unsaturated bonds
  • D21H19/58—Polymers or oligomers of diolefins, aromatic vinyl monomers or unsaturated acids or derivatives thereof
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F290/00—Macromolecular compounds obtained by polymerising monomers on to polymers modified by introduction of aliphatic unsaturated end or side groups
  • C08F290/02—Macromolecular compounds obtained by polymerising monomers on to polymers modified by introduction of aliphatic unsaturated end or side groups on to polymers modified by introduction of unsaturated end groups
  • C08F290/06—Polymers provided for in subclass C08G
  • C08F290/062—Polyethers
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H19/00—Coated paper; Coating material
  • D21H19/36—Coatings with pigments
  • D21H19/44—Coatings with pigments characterised by the other ingredients, e.g. the binder or dispersing agent
  • D21H19/62—Macromolecular organic compounds or oligomers thereof obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds

Definitions

• the present invention relates to a new thermo-thickening composition for coating baths, which can replace or be combined with the conventional thickening additives used in these baths.
• the present invention relates more particularly to a new thickening composition which improves the covering of the surface layer of cellulose supports and reduces the mottling of printing.
• the coating operation aims to specifically deposit this bath on the surface and to avoid its penetration into the support, there is also a significant absorption of the coating bath by the support. This results in a loss of coating efficiency since, to achieve the same level of property, a higher layer weight must be deposited to compensate for the layer absorbed by the support.
• the losses of quality induced are losses of opacity, smoothness and / or gloss.
• This absorption of the bath in the support is a defect all the more penalizing as the layer weights are low and it therefore becomes critical below the threshold of a layer weight of approximately 6 g / m 2 .
• the second type of defect corresponds to heterogeneities in the structure and composition of the layer coated on the support. Its most common and penalizing manifestation is the mottling or swarm of printing. Mottling is a phenomenon which manifests itself at the level of the printing of the layer by fluctuations in the printing results. This type of defect is notably caused by phenomena of migration of the bath in the support. For a bath not corresponding to the present invention, these phenomena migration and the defects they generate are in particular caused and amplified by the drying of the layer. Thus, the heating applied at the level of the layer to dehydrate it has the effect of reducing its viscosity, then amplifying the migration phenomena all the more.
• the coating bath compositions comprise, in addition to fillers, at least one thickening agent which has the main function of precisely controlling the viscosity and the water retention of the coating bath.
• thickening agent which has the main function of precisely controlling the viscosity and the water retention of the coating bath.
• They are generally cellulose derivatives such as carboxymethylcellulose or highly carboxylated synthetic alkali thickening polymers.
• these compounds have the disadvantage of having a viscosity which decreases significantly at a temperature above 45 ° C. They therefore promote migration phenomena during the dehydration operation and do not prevent the manifestation of the defects mentioned above.
• the present invention therefore aims to propose a new thickening composition for coating baths, useful in particular in that it makes it possible to avoid migration phenomena on drying and the defects which result therefrom.
• the present invention firstly relates to a heat-thickening composition based on at least one thermosensitive copolymer which makes it possible to overcome the problems mentioned above.
• heat-sensitive copolymer is understood to mean a polymer whose viscosity in an aqueous medium increases with temperature above a threshold temperature, unlike conventional polymers whose viscosity decreases continuously with the rise in temperature.
• the present invention takes advantage in particular of the ability of certain water-soluble polymer chains to associate locally above a certain threshold temperature. It follows the formation of a physical network of a high molar mass and therefore an increase in viscosity thus creating the thermo-thickening property.
• Copolymers of this type are in particular already known in the petroleum industry and more particularly in the field of drilling fluids.
• advantage is taken of the ability of the polyoxyalkylene chains, which are water-soluble at ambient temperature, to become hydrophobic at a temperature called critical temperature, greater than 100 ° C.
• copolymers selected according to the invention have the characteristic of having, in solution, an almost zero variation in turbidity beyond the critical temperature. This property means that the polymer solutions according to the invention retain, in the temperature range of their use, a degree of homogeneity which makes it possible to obtain a more regular and more uniform structure of the paper layers.
• the first subject of the present invention is a heat-thickening composition for coating baths comprising at least one thermosensitive copolymer characterized in that said copolymer has a comb structure and consists of a polymeric segment called backbone to which are grafted at least two segments polymeric sides, identical or different, with either the skeleton segment or the lateral segments having a lower critical solubility temperature, LCST, of between 30 and 80 ° C.
• LCST critical solubility temperature
• segment covers either a linear sequence or a branched sequence.
• skeleton polymer segment which has a lower critical solubility temperature, LCST, of between 30 and 80 ° C.
• polymeric lateral segments which have a lower critical solubility temperature, LCST, of between 30 and 80 ° C.
• thermo-thickening composition claimed comprises several copolymers as defined above. These copolymers are arranged therebetween so as to form a crosslinked structure in which their polymeric segments having the lower critical solubility temperature, LCST, represent the crosslinking nodes and at least part of their segments having no lower critical temperature of solubility between 30 and 80 ° C establish connections between said nodes.
• LCST lower critical solubility temperature
• the segment which does not have the required LCST namely between 30 and 80 ° C, is for its part water-soluble at least in this temperature range.
• the polymer segments having a lower critical solubility temperature exhibit a water-soluble character at a temperature below their LCST.
• the polymer segments which do not have a lower critical solubility temperature in the temperature range concerned they are water-soluble at least in the temperature range of use of the heat-thickening composition, preferably between + 10 ° C to + 100 ° C.
• the polymer segment having no critical temperature it is more preferably a polymer of water-soluble ethylenic type.
• water-soluble polymers can be derived from the (co) polymerization of water-soluble ethylenic monomers.
• These monomers can be in particular of vinyl type, acrylic, styrenic, diene or also of vinyl ester type.
• vinyl monomers examples include vinyl sulfonic acid, methallyl sulfonic acid or their salts.
• acrylic monomers examples include the acid
• styrenic monomers examples include styrene sulfonic acid, vinyl benzoic acid or their salts.
• hydrosoluble monomers mentioned above can also be combined with or substituted for them hydrophobic monomers, the units of which, once incorporated in the polymer chain, can be transformed, in particular by chemical treatment such as hydrolysis, into water-soluble units.
• hydrophobic monomers the units of which, once incorporated in the polymer chain, can be transformed, in particular by chemical treatment such as hydrolysis, into water-soluble units.
• hydrophobic monomers for example, methyl (meth) acrylate, ter-butyl (meth) acrylate, glycidyl (meth) acrylate and vinyl acetate.
• any organosoluble monomers can also be used and incorporated into the polymer chain in the form of hydrophobic units. Present in small quantities, in the polymer segment, they make it possible to control the solubility in water of the corresponding copolymer.
• the different monomers are selected so that the corresponding polymer segment has a solubility in aqueous medium according to the invention.
• This adjustment of the relative amounts of corresponding monomers is within the competence of a person skilled in the art.
• the monomers such as acrylic or methacrylic acid, acrylamides and their derivatives, acids fumaric and maleic and sulfonated monomers such as 2-acrylamide-methyl-propane sulfonic acid (AMPS) and its alkaline salts and vinylsulfonate.
• AMPS 2-acrylamide-methyl-propane sulfonic acid
• this type of polymer segment has a molecular weight at least greater than 1,000 and preferably at least greater than 20,000.
• these polymer segments result from the polymerization of acrylic acid (AA) and / or 2-acrylamide-methyl-propane sulfonic acid (AMPS).
• AA acrylic acid
• AMPS 2-acrylamide-methyl-propane sulfonic acid
• polymer segments having a lower critical temperature for LCST solubility of between 30 and 80 ° C. they are derived from polyoxyalkylene polymers.
• the different oxyalkylene unit (s) present in the polyoxyalkylene polymer have at most 6 carbon atoms.
• the segments presenting a critical temperature consist of oxyethylene units (OE) and / or oxypropylene units (OP).
• the OE and OP motifs can be arranged in the thermosensitive polymer segment in statistical, block or sequenced form.
• the thermosensitive polymer segment can for example have a star structure. It turns out to be possible to adjust the critical solubility temperature in particular through the length and the composition of these polymer segments.
• the segments having a critical temperature according to the invention consist of at least 5 oxyalkylene units.
• a macromonomer designates a macromolecule carrying one or more ethylenic functions (co) polymerizable by the radical route.
• the grafting of the lateral polymer segments onto a so-called skeleton polymer segment can be carried out according to conventional techniques familiar to those skilled in the art (European Polymer Journal 4, 343 (1968); US 3,719,647). Among these conventional techniques, mention may be made in particular of those known as direct grafting and copolymerization.
• Direct grafting consists in (co) polymerizing the monomer (s) chosen (s) by the radical route, in the presence of the selected polymer to form the skeleton of the final product. If the monomer / skeleton couple as well as the operating conditions are judiciously chosen, then there may be a transfer reaction between the growing macroradical and the skeleton. This reaction generates a radical on the skeleton and it is from this radical that the graft grows. The primary radical originating from the initiator can also contribute to the transfer reactions.
• the copolymerization firstly implements the grafting at the end of the heat-sensitive segment of a (co) polymerizable function by the radical route. This grafting can be carried out by usual methods of organic chemistry. Then, in a second step, the macromonomer thus obtained is copolymerized with the monomer chosen to form the skeleton and a so-called "comb" copolymer is obtained.
• the copolymer comprises 0.1% to 50 mol% and preferably 0.1 to 5.0 mol% of polymer segments having a lower critical solubility temperature (LCST) of between 30 and 80 ° C.
• LCST critical solubility temperature
• the copolymers of the invention advantageously exhibit a slight variation in turbidity as a function of the temperature, which distinguishes them from other polymers having the heat-thickening character.
• the polymers according to the invention exhibit a variation in insensible turbidity such that at a concentration equal to 2%, the variation in absorbance of the solution measured with a turbidimeter (662 Metrohm brand photometer) is less than 0.1 in the temperature range between 20 and 60 ° C.
• thermoplastic compositions comprising at least:
• a copolymer prepared from POE-POP-POE tri-block macromonomer and acrylic acid (respective molar percentages: 2.3%, 97.7%), preferably by direct grafting,
• POP-POE and acrylic acid (respective mol%: 2%, 98%), preferably by copolymerization.
• compositions according to the invention are particularly useful as a thickening agent in the paper coating industry and more particularly as an agent improving the homogeneity and the quality of the layer covering.
• they are introduced into the coating bath at rates of the order of 0.1 to 3 parts by weight expressed per 100 parts of fillers.
• This composition can be mixed with the other components conventionally used in coating baths.
• these components include fillers of the pigment type. These are mineral pigments such as kaolin, satin white, calcium carbonate, talc, titanium oxide or so-called plastic pigments. It can also be latex type binders, at a rate of 3 to 50 parts by dry weight per 100 parts of pigments.
• this coating bath composition can comprise other auxiliary agents of the slip agents type such as stearates, insolubilizing agents, coloring agents, optical brighteners, brighteners such as polyvinyl alcohol, sequestering agents, biocides, defoaming agents , etc.
• the coating bath composition comprises 40 to 75% by weight of dry extract and has a pH of between 6 and 10.
• the layers are coated on the surface with a cellulosic support according to conventional coating techniques.
• the presence of at least one copolymer as defined above in the coating bath makes it possible to improve the homogeneity of layer coverage.
• the copolymer contributes to the optimization of the immobilization of the paper layer and therefore makes it possible to effectively oppose the migrations generally occurring during the drying of the paper layer. This results in a significant improvement in the printing qualities of the paper layers.
• the present invention also relates to a coating bath for coating papers and / or cardboards comprising at least one thermo-thickening composition according to the invention.
• thermo-thickening composition as defined above in a coating bath or a coating bath according to the invention to obtain better layer coverage, to improve layer coverage for coating of paper and cardboard with low layer weight and / or improving the smoothness, opacity and / or gloss of coated paper and cardboard with low layer weight.
• coated papers or cardboards with a low layer weight mean papers or cardboards coated with a coating less than or equal to 6 g / m 2 .
• the present invention also relates to the use of a thermo-thickening composition according to the invention in a coating bath or a couchaga bath according to the invention for reducing and / or avoiding the flecking of the print.
• FIG. 1 Evolution of the turbidity of a copolymer according to the invention and of a control (methylcellulose) as a function of the temperature.
• the synthesis is carried out under nitrogen.
• Pluronic PE6400 ® 100 g, 0.033 moles
• maleic anhydride 3.596 g, 0.0366 moles
• the temperature is raised from 25 ° C to 60 ° C in 20 min, maintained at 60 ° C for 15 min, then increased to 140 ° C and maintained for 12 h.
• the macromonomer is then used as it is.
• PAntarox E-400 ® (marketed by RHODIA) (number average molar mass: approximately 3,200) are introduced into a 100 ml three-necked flask topped with a condenser and immersed in a heating oil bath. mass percentage of OE units: 39%; LCST: about 55 ° C) (100 g, 0.031 moles) and maleic anhydride (3.37 g, 0.0343 moles). The temperature is raised from 25 ° C to 60 ° C in 20 min, maintained at 60 ° C for 15 min, then increased to 140 ° C and maintained for 12 h. The macromonomer is then used as it is.
• the synthesis is carried out under nitrogen.
• the temperature is brought from 25 ° C to 40 ° C in 20 min, then to 45 ° C in 10 min. It is then maintained at 45 ° C.
• Acrylic acid (17.346 g, 0.241 moles) and ascorbic acid (0.0166 g) are introduced separately continuously over 5 h, while the temperature is maintained at 45 ° C for 14 h in total.
• the complex formed during the polymerization is then separated from the aqueous phase, redissolved in basic water (pH: about 8.4; mass concentration: about 8.0%).
• the temperature is brought from 25 ° C to 40 ° C in 20 min, then to 45 ° C in 10 min. It is then maintained at 45 ° C.
• Acrylic acid (21, 164 g, 0.294 mol) and ascorbic acid (0.0153 g) are introduced separately continuously over 5 h, while the temperature is maintained at 45 ° C for 14 h in total.
• the complex formed during the polymerization is then separated from the aqueous phase, redissolved in basic water (pH: about 8; mass concentration: about 15.5%).
• Copolymer 4 (from macromonomer 2: 2 mol%:
• the synthesis is carried out under nitrogen.
• the temperature is maintained at 45 ° C for a total of 14 hours.
• composition according to the invention for thickening a coating bath.
• coating baths are prepared according to the same formulation in which the nature of the thickener is changed, from one test to another.
• the coating formulation used is a typical top layer formulation of woodfree paper comprising: parts
• the copolymers of the invention exhibit a slight variation in turbidity as a function of temperature, which distinguishes them from other polymers having the thermo-thickening character but manifesting a high turbidity when passing the LCST.
• This property is illustrated in FIG. 1, where the evolution of the turbidity of the copolymer 3 and of the control 2 (methylcellulose) is plotted as a function of the temperature.
• the measurements are carried out with a turbidimeter (662 Photometer from Metrohm brand) in "absorbance" mode on 2% aqueous solutions whose temperature is regulated between 20 and 60 ° C. using a thermostatically controlled bath.
• the viscosity of the baths is measured on a rheometer (Carri-med CSL100 manufactured by TA Instruments) in flow mode. The viscosity is recorded as a function of the temperature, keeping the imposed stress constant.
• FIGS. 2 to 5 where the measurements relating to the baths are shown, the characteristics of which are given in Tables 1 to 4.
• the stress imposed varies from sample to sample. It is adjusted for each of them so that the flow at 20 ° C takes place at a gradient of 10 s-1, to allow a direct comparison of the viscosity of the coating baths at this temperature.
• FIGS. 2 to 5 clearly show the thermo-thickening nature of the copolymers 1, 2 and 3. This property is preserved in the case of a mixture of the copolymer with carboxymethylcellulose.
• Control 2 is also thermo-thickening, only its variant of turbidity with temperature distinguishes it, in terms of properties, from the copolymers according to the invention.
• the coating baths are deposited on a pre-coated wood-free paper (LEYKAM PM9, 105 g / m 2 ) with a laboratory machine with a blade of the EUCLID TOOL ® brand.
• the quantity of bath deposited corresponds to a layer weight indicated in the tables.
• the quality of the homogeneity of the layer cover is judged by a "mottling" test.
• the prints are made on a Pr ⁇ fbau ® laboratory press.
• the printing conditions are those recognized by those skilled in the art to judge the heterogeneity of the printing rendering or "mottling".
• a strip of paper is printed with a metal wheel covered with an ink film. After a time of one second, during which the paper fixes a certain amount of ink, the unbound ink is removed by performing a counter-printing: the printed surface is wiped with a metal wheel coated with rubber. This wiping operation is repeated 3 times so as to eliminate the loose ink. Printing and counter-printing are carried out at a speed of 0.5 m / s under a pressure of 800 kN / cm.
• printing should result in a solid color distributed evenly across the paper. If this is not the case, there are heterogeneities of color, the "mottling", which is attributed to an irregularity in the structure of the layer (in the broad sense).
• the polymers according to the invention have an action on the homogeneity of the layer. Therefore, their effect is therefore judged according to the "mottling" criterion.
• the assessment is made according to the practices of the profession. It consists in making a judgment on the homogeneity of the printing coloring determined by visual observation. A score is assigned on a scale of 0 to 5, 0 being assigned to a completely homogeneous impression, and 5 to an impression exhibiting very significant color fluctuations. A panel of 5 people performs the rating; the values given in Tables 1 to 4 are the arithmetic mean of the results. In this context, the results must be compared within the same series (each series is the subject of a separate table) taking as reference the value of the control bath (control 1).
• copolymers 1, 2 and 3 introduced into coating baths the formula of which is given above, lead to paper layers whose printing properties are better, with respect to the "mottling" criterion, than those obtained using carboxymethylceliulose.
• the copolymer 1 can be used in combination with carboxymethylceliulose and lead to an improvement in the printing properties, with respect to the "mottling" criterion.
• copolymers 2 and 3 lead to an improvement in the printing properties, vis-à-vis the "mottling" criterion, for mass rates less than or equal to 1 part (value compared to 100 parts of pigments)
• composition according to the invention for improving the spreading and homogeneity properties of a paper layer.
• multilayer papers having the following structure are manufactured. Two additional layers are deposited on a LEYKAM PM9 support, pre-coated with a basis weight of 105 g / m2:
• each layer (A or B) is 11 g / m2.
• the paper is heated before removing the sleeping bath.
• the distance between the dryer and the coating head is 1 m.
• the measurements carried out to characterize the coated papers are measurements of gloss, speed of ink setting. This last quantity is obtained by a smear test: the higher the quantity of ink transferred to the macule, the lower the ink intake.
• the homogeneity of the ink setting speed is estimated by making a solid with Porometric ink.
• CLC6000 is a high speed coating machine from the company "Sensor et Simulation” " It is a styrene butadiene carboxylated latex.
• the heat-thickening polymer according to the invention introduced into the layer (A) has a significant influence on the properties of the upper layer:
• the structure of layer (A) can be controlled by the use of heat-thickening polymers according to the invention.
• the effect has repercussions on the properties of the upper layer (B) - according to a mechanism which involves the conditions of deposition and drying - with as a consequence an improvement in the spreading properties, a reduction in the migrations of the various constituents at l inside the layer, better homogeneity of the structure (these three properties being estimated respectively by the gloss, ink setting and uniformity of the print measurements).
• thermo-thickening polymers according to the invention to limit the migration phenomena which occur during the deposition and then the drying of a paper layer.
• multilayer papers having the following structure are manufactured. Two additional layers are deposited on a LEYKAM PM9 support, pre-coated with a basis weight of 105 g / m2:
• thermo-thickener • a layer B whose formula is representative of an upper layer of woodfree paper.
• a layer formula containing the thermo-thickener according to the invention is compared to a control formula, without the thermo-thickener.
• the starch contained in layer A mixes with the constituents of the upper layer (B) when the latter is deposited and then dried.
• thermo-thickener used in layer B, different layers A are made, with variable levels of starch. We reveal the amount of starch that migrates from the layer
• Threaded rod 1 which deposits a 6 micron film
• the iodine dyes on contact with the starch on the surface of the paper.
• the intensity of this coloration is obtained by a measure of reflectance at the wavelength of 540 nm). The lower the value obtained (the darker the color), the more a significant amount of starch is detected.
• the layers are removed with a threaded rod on a support heated to 150 ° C and isolated by blotting paper.
• the coating of layers A and B is carried out with a threaded rod and a grammage of 11 to 12 g / m 2 , for layer A and 10 g / m 2 for layer B.
• the dry coating extract is 52% . Table 6 below reports the specificities retained for each test and Table 7 of the results obtained.
• thermo-thickening polymer according to the invention is added to layer (B).
• thermo thickener therefore provides an economic advantage, since the cost of layer (A) can be reduced by adding more starch and less latex.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Paper (AREA)
• Paints Or Removers (AREA)
• Graft Or Block Polymers (AREA)

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• 1998
  • 1998-06-26 FR FR9808171A patent/FR2780422B1/fr not_active Expired - Fee Related
• 1999
  • 1999-06-24 AU AU42718/99A patent/AU4271899A/en not_active Abandoned
  • 1999-06-24 CN CN99809433A patent/CN1312830A/zh active Pending
  • 1999-06-24 EP EP99957638A patent/EP1095079A1/de not_active Withdrawn
  • 1999-06-24 WO PCT/FR1999/001525 patent/WO2000000528A1/fr not_active Application Discontinuation
  • 1999-06-24 ID IDW20010036A patent/ID27557A/id unknown
  • 1999-06-24 JP JP2000557288A patent/JP2003522210A/ja active Pending
  • 1999-06-24 BR BR9911567-0A patent/BR9911567A/pt not_active IP Right Cessation

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