Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L53/00—Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
• • 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
  • C08F293/00—Macromolecular compounds obtained by polymerisation on to a macromolecule having groups capable of inducing the formation of new polymer chains bound exclusively at one or both ends of the starting macromolecule
  • C08F293/005—Macromolecular compounds obtained by polymerisation on to a macromolecule having groups capable of inducing the formation of new polymer chains bound exclusively at one or both ends of the starting macromolecule using free radical "living" or "controlled" polymerisation, e.g. using a complexing agent
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D153/00—Coating compositions based on block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Coating compositions based on derivatives of such polymers

Definitions

• the invention relates to a process for preparing a film or a coating on a substrate in which an aqueous dispersion of polymer particles or a coating composition containing said dispersion is applied to said substrate.
• this dispersion is prepared directly by a multistage dispersion polymerization process.
• the invention also relates to a film or coating obtainable by this method.
• the invention finally relates to the use of said dispersion in paints; compositions, formulations for coating textiles, leather, nonwovens; compositions, formulations, adhesives; compositions for coating paper.
• the technical field of the invention can be defined as that of aqueous dispersions of polymers or synthetic resins and more particularly that of aqueous emulsions of polymers.
• Dispersions and in particular aqueous emulsions of polymers can be defined as fluid systems which contain particles of polymers distributed in the form of a dispersed phase in an aqueous dispersion medium forming an aqueous continuous phase.
• the size, generally defined by their diameter, of the polymer particles is generally from 0.01 to 5 micrometers, preferably from 0.02 to 1 micrometer.
• the dispersions and aqueous polymer emulsions have the property of forming, during the evaporation of the aqueous dispersion medium, clear films of polymer, and this is why these dispersions and emulsions are widely used as binders, for example in coating.
• the type of dispersed polymer and the temperature at which film formation occurs determine whether an aqueous polymer emulsion forms after evaporation of water a coherent transparent film or an opaque layer. , brittle.
• the lowest temperature at which a transparent film without crack is formed is defined as the minimum temperature of filmification (TMF or "Minimal Temperature Filtration", "MFT” in English) of said dispersion, emulsion.
• TMF Minimum Temperature Filtration
• aqueous emulsions of polymers which essentially contain polymerized monomers whose corresponding homopolymers have glass transition temperatures (T v or T g in English) "low", that is to say, generally lower than ambient temperature (i.e., generally 20 to 25 ° C, e.g. 22, 23 ° C) can form polymer films at low temperatures.
• these emulsions have a TMF close to the T v of the polymer.
• the coatings, films obtained from these dispersions, emulsions generally have a low “blocking” temperature (TB).
• the "blocking" temperature that characterizes the film tack is generally defined as the temperature from which two parts of the same film adhere to one another when they are brought into contact with each other. other at a predetermined contact pressure for a certain period of time.
• the films adhere to each other and can no longer be separated without being damaged.
• acrylic monomers which have a glass transition temperature (T v ) below room temperature provide low temperature filmability and flexibility properties to the resulting films.
• T v glass transition temperature
• these films have an adhesive character, sticky, very marked as we increase the amount of acrylic monomers in the composition.
• aqueous emulsions of polymers which contain essentially polymerized monomers whose corresponding homopolymers have glass transition temperatures (T v or T g in English) "high” that is to say generally greater than 50 ° C. C, have high "blocking" temperatures, that is to say generally greater than 50 ° C.
• methacrylic monomers such as methyl methacrylate, or styrene monomers such as styrene whose glass transition temperature (T v ) is greater than 50 ° C., give the film obtained from the aqueous dispersion hardness properties. resistance to blocking.
• aqueous dispersions of polymers, synthetic resins must have a pronounced film-forming character. For this, it is necessary to develop aqueous dispersions whose minimum filming temperature (TMF), as defined above, is low.
• TMF minimum filming temperature
• the "blocking" temperature characterizing the film adhesive is, in fact, only slightly greater than the minimum temperature of filming (TMF) which is very troublesome in the most applications of these dispersions.
• the first method consists of adding plasticizers (or coalescing agents) to aqueous dispersions of hard polymers; -
• the second method proposes to copolymerize "soft" monomers (lower T v or equal to 10 0 C) and "hard” monomers (T v greater than or equal to 50 0 C);
• the third method consists in mixing aqueous dispersions of "hard” polymers with aqueous dispersions of "soft” polymers.
• the disadvantage of the first method is to increase the volatile compound content of the aqueous dispersion due to the addition of the plasticizer (or coalescing agent).
• the disadvantage of the second and third methods is that the minimum filming temperature and the "blocking" temperature vary in the same direction and of the same order of magnitude. This has the consequence of not effectively increasing the temperature difference between the minimum filming temperature and the "blocking"temperature; a temperature difference between the TMF and the TB is generally obtained of the order of 20 ° C., which is quite insufficient. To increase this temperature difference between TMF and TB, multi-step polymerization techniques were then developed.
• patents EP 184 091, EP 376 096, EP 609 756, EP 379 892 and US Pat. No. 5,744,540 describe methods for obtaining an aqueous dispersion of synthetic resins by a conventional two-stage aqueous emulsion radical polymerization process. successive steps, for example the first step of polymerizing a monomer or a mixture of soft monomers which have a glass transition temperature low, and the other step, for example the second step of polymerizing a monomer or a mixture of hard monomers which has a high glass transition temperature.
• the order in which these two polymerization sequences are carried out does not seem to play a preponderant role in the application.
• patent EP 379 892 describes the preparation of an aqueous resin dispersion during which the construction of the hard polymer takes place in the first stage and the soft polymer in the second stage, while the EP 184 patent 091 describes the opposite.
• the aqueous dispersions of synthetic resins resulting from these conventional, conventional, conventional radical polymerization steps have particular morphologies which are more generally referred to by the term "heart / bark".
• the core consists of the monomers or monomer mixture polymerized during the first step, while the bark is composed of the monomers or mixture of monomers polymerized during the second step.
• US-A-5,306,743 relates to aqueous dispersions of synthetic resins comprising latex particles having an average particle diameter of less than 140 nm, these particles being comprised of 5 to 45 % by weight of a core material having a T v greater than 60 0 C, and 95 to 55% by weight of a bark material having a temperature T v less than 80 0 C and less than 20 K at the core temperature.
• the dispersions prepared have TMF's of 0, 12, 21 and 25 ° C and TB's of 35, 40, 45, 50 and 55 ° C, the temperature difference between TB and TMF ranges from 25 ° C to 43 ° C. vs.
• the films obtained from the aqueous dispersions of synthetic resins polymerized by a conventional, conventional, multi-stage conventional radical polymerization process and which have said core-shell structure therefore have a temperature difference between the minimum temperature of filming and the blocking temperature. of the order of 40 0 C, which remains insufficient.
• US-B-6,710,112 discloses an aqueous polymer dispersion having a minimum film-forming temperature of less than 65 ° C and more than -35 ° C, preferably in the range of -20 ° C to 40 ° C and in particular in the range of 0 to 40 ° C., which comprises at least one film-forming polymer in the form of dispersed particles comprising a polymer phase P1 having a T v 1 and a different polymeric phase P2 having a T V 2.
• the polymer may be obtained by a conventional, conventional aqueous emulsion polymerization process comprising a polymerization step of a first charge of monomers M1 to give the polymer P1 and a polymerization step of a second charge of monomers M2. to give the polymer P2.
• the charge M2 is chosen to give a "hard" polymer of T V 2 greater than 30 ° C., preferably of more than 40 ° C., and in particular in the range of 50 to 120 ° C. and at least one chain transfer agent is used either in the polymerization of the charge M1 or in the polymerization of the charge M2.
• the dispersions prepared in the examples of this document have TMFs of 24 to 29 ° C which can not be considered low.
• WO-A-2007/017614 describes a process for the preparation of a polymeric material comprising a multiblock polymer which comprises at least one cycle of steps comprising: a) a step of synthesis of a block by controlled radical polymerization of one or more radically polymerizable monomers; and b) a polymerization step of unconverted monomers in step a).
• Step a) is preferably carried out by SFRP in the presence of a monofunctional or polyfunctional alkoxyamine acting as both an initiator and a control agent.
• Steps b) are carried out by conventional radical polymerization by adding to the medium in which the block was produced during step a) a conventional radical polymerization initiator. The temperature of this step is chosen to be lower than that of step a) to preserve the previously synthesized block as a living polymer.
• the process of this document is particularly suitable for the preparation of a polymeric material comprising an AB diblock copolymer, such as a diblock copolymer (n-butyl polyacrylate-b-polymethylmethacrylate).
• Example 5 of this document a latex containing both a copolymer of n-butyl acrylate and of methyl methacrylate obtained by controlled radical polymerization is thus prepared; a homopolymer of n-butyl acrylate, and a homopolymer of methyl methacrylate obtained by conventional radical polymerization.
• this document is essentially aimed at the preparation of a dry, solid polymeric material and not a dispersion. The polymers are recovered in this form in solid, dry form, and not in the form of a dispersion. It is mentioned that the solid, dry polymeric material prepared in this document can be applied as an additive in the field of coatings.
• the document FR-A-2 866 026 describes a radical polymerization process in mini-emulsion, microemulsion or emulsion using alkoxyamines.
• the process of this document produces (co) polymer latexes with controlled macromolecular architectures.
• the polymers obtained by the process of this document are living polymers carrying alkoxyamine functions and the process of this document allows the preparation of block polymers.
• a first polymer is polymerized by the process of this document to obtain a living polymer block, and a block of another polymer is connected to this first block by placing the first block of living polymer in a polymerization medium. a second monomer, and so on.
• Residual monomers from the controlled radical polymerization can be converted using a conventional free radical initiator.
• the object of the present invention is to provide a process for preparing films or coatings, as well as films or coatings which meet these needs, among others.
• the object of the present invention is also to provide films or coatings prepared from aqueous dispersions of polymers and a process for preparing such films or coatings which do not have the disadvantages, defects and disadvantages of films and coatings, and processes to prepare these films and coatings of the prior art and that solve the problems of coatings and methods of preparation of these coatings of the prior art.
• the implementation of certain aqueous dispersions of polymer particles makes it possible to achieve this goal.
• the invention therefore relates to a method for preparing a film or a coating on a solid substrate, comprising at least one step of applying to the substrate an aqueous dispersion of polymer particles, consisting of a mixture of one part of one or more block copolymers and secondly one or more homopolymers and / or random copolymers; or a coating composition containing said aqueous dispersion.
• Each particle of the dispersion actually contains a mixture of one or more block copolymers and one or more homopolymers and / or copolymers that are generally random.
• the block copolymer or copolymers generally represent from 10 to 90%, preferably from 40 to 80% of the total of the polymers of the dispersion used, and the homopolymer (s) and / or random copolymers generally represent from 0.1 to 60%. % of the total polymers of the dispersion used.
• the aqueous dispersion is generally defined by a ratio (ratio) of polymer weight (s) (s) soft (s) / polymer (s) hard (s) generally lying in the range of 0.3 to 3, preferably 0.5 at 1.5. In order to calculate this ratio, we mean
• Polymer' means any polymeric segment, whether in the form of an isolated, separate, independent statistical copolymer or isolated, separate, independent homopolymer or a block copolymer block (eg polymeric example constituting block A, block B, or block A ').
• hard polymer is generally meant a polymer whose glass transition temperature T v (T g ) is greater than or equal to 50 0 C and by "soft” polymer a polymer whose glass transition temperature T v (T g ) is less than or equal to 10 0 C.
• the dispersions used in the process according to the invention are prepared directly by a specific dispersion polymerization process with which it is Surprisingly, it is possible to directly obtain such dispersions in which the ratio of soft polymer (s) to hard polymer (s) is in the aforementioned specific range.
• the dispersions used in the process according to the invention, and in particular those which have such a ratio of soft polymer (s) to hard polymer (s), are particularly suitable for producing films or coatings including TMF. is low, namely less than or equal to 10 0 C, preferably less than or equal to 5 ° C, more preferably less than or equal to 0 0 C, and of which, simultaneously the "blocking" temperature (TB) is at least 50 ° C.
• the dispersions used in the prior art which are obtained by simple mixing of dispersions, which are used to prepare coatings, films, do not make it possible to obtain a difference between the TB and the TMF of at least 50 ° C. . While the dispersions implemented according to the invention preferably obtained directly by the polymerization process described below make it possible to obtain a difference between the TB and the TMF of at least 50 ° C.
• the polymer mixture of the dispersion implemented according to the invention may comprise, for example, a triblock copolymer ABA 'or diblock AB, a random homopolymer or copolymer C, and optionally a homopolymer or random copolymer D.
• Blocks A, B, and A ' are homopolymers or copolymers, especially random ones.
• C may or may not be the same monomer (s) as B, and D may or may not be the same monomer (s) as A or A '.
• the ABA 'or AB block copolymer generally represents between 10-90% of the total of the polymers of the dispersion, C represents generally between 0.1% and 40% of the total of the polymers of the dispersion and D, if present, is generally between 0.1% and 40% of the total polymers of the dispersion.
• Block copolymer A-B-A 'or A-B is obtained by the controlled radical polymerization steps of the process described below.
• Block B can be a homopolymer or a copolymer.
• blocks A, A 'and D are hard, and blocks B and C are soft.
• the polymers C and D are generally obtained by free radical polymerization, conventional, conventional, generally in the context of one of the steps of the dispersion preparation process described below.
• the particles of the dispersions used in the process according to the invention generally have a particle size of less than 500 nm, preferably of 20 to 1000 nm.
• the molecular weight of the polymers constituting the dispersion is generally from 20,000 to 1,000,000 g / mol, preferably from 20,000 to 500,000 g / mol.
• a dispersion as defined above or a coating composition containing the aqueous dispersion as described above can be applied to the substrate.
• Such a coating composition generally comprises the dispersion described above and pigments, and / or solvents and / or fillers etc.
• the implementation of the dispersion described above, preferably prepared directly by the method described below, in coating compositions has never been described or suggested in the prior art.
• This composition can be a painting; a composition for coating textiles, leather, nonwovens; a composition for coating the paper; an adhesive composition.
• the method according to the invention for preparing a film or a coating on a substrate comprises at least one step of applying to the solid substrate an aqueous dispersion as defined above or a coating composition containing said aqueous dispersion.
• Application of the dispersion or coating composition to the substrate can be by any method known to those skilled in the art.
• the method according to the invention may comprise only one step of application of dispersion or coating composition on the substrate or it may comprise several application steps (for example 2, 3, 5, ... 10 ) depending in particular on the desired properties and / or thickness of the film or coating.
• the method according to the invention may comprise, in addition to the one or more steps of applying the dispersion or the coating composition on the substrate, one or more other steps.
• This or these other steps may (in particular) be one or more steps of drying the applied dispersion or coating composition deposited on the substrate in order to form the film or coating on the substrate.
• the dispersion or coating composition which has formed a "wet" film or coating on the substrate is dried to form the final film or coating
• the "wet" film, before drying may have for example a thickness of 100 microns to 1000 microns, for example 200 microns to 400 microns.
• this application step is generally followed by a final drying step.
• the drying (s) can be performed at a temperature and for a time sufficient to form the film or coating on the substrate.
• the drying (s) can (for example) be carried out at room temperature (15 to 30 ° C., for example 20 to 25 ° C.) for a total period of 1 to 48 hours, for example 24 hours. hours or using any suitable heater.
• the drying (s) can (can) be carried out for a total duration of 24 hours and at a temperature of 25 ° C.
• the drying can be carried out in the open air or in a closed enclosure.
• a film (after drying) generally has a thickness of 100 ⁇ m to 1000 ⁇ m, for example 200 ⁇ m to 400 ⁇ m.
• a coating generally has a thickness of 100 ⁇ m to 1000 ⁇ m, preferably 200 ⁇ m to 400 ⁇ m.
• the thickness of a coating is generally greater than that of a film.
• the film thickness, "dry” coating after drying is generally less than the thickness of the film, "wet” coating before drying.
• a film is prepared by applying the dispersion while a coating is prepared by applying the coating composition.
• the invention further relates to the coating or film obtainable by the method of preparing a film or coating on a substrate described above.
• the invention also relates to the use of the aqueous suspension as described above in paints; compositions, formulations for coating textiles, leather, nonwovens; compositions, formulations, adhesives; compositions for coating paper.
• the aqueous dispersion described above being preferably obtained directly by the method described below, in particular when the ratio of polymer (s) soft (s) / polymer (s) hard (s) of this dispersion is in the range defined above, makes it possible to develop films or coatings having a TMF less than or equal to 10 0 C, preferably less than or equal to 5 ° C, more preferably less than or equal to 0 0 C, and whose blocking temperature (TB) is at least 50 ° C. higher than the TMF.
• a block copolymer comprising at least one block of T v less than or equal to 0 ° C., and at least one other block of T v greater than or equal to 50 ° C., such as a block copolymer poly (methyl methacrylate (PMMA) / poly (acrylate) butyl) (PABu) / poly (methyl methacrylate) with for example a PABu / PMMA ratio of 60/40);
• a glass transition temperature polymer T v greater than or equal to 50 ° C. such as poly (methyl methacrylate) (PMMA);
• the dispersion used in the process according to the invention may have the following composition:
• dispersion implemented may have the following composition:
• Block Copolymer Poly (methyl methacrylate) - Poly (butyl acrylate) - Poly (methyl methacrylate) - 72% PAB / 28% PMMA;
• the dispersion implemented may have the following composition:
• the dispersion used in the process according to the invention is generally prepared directly by a process comprising several radical polymerization steps of at least one radically polymerizable monomer, carried out in a dispersed polymerization medium comprising a continuous liquid aqueous phase and a liquid organic phase, wherein at least one of the steps is a controlled radical polymerization step and at least one of the steps is a conventional conventional radical polymerization step.
• This process comprises the combination of at least one controlled radical polymerization step and at least one conventional conventional free radical polymerization step.
• This method makes it possible to directly prepare aqueous polymer dispersions ensuring at low temperature, namely generally less than or equal to 10 ° C., preferably less than or equal to 5 ° C., more preferably less than or equal to 0 ° C. production of films or coatings, which satisfy the criteria specified above with regard to the difference between the "blocking" temperature TB and the TMF.
• This difference is at least 50 ° C., which is clearly greater than the difference between the TB and TMF of the films obtained from the dispersions of the art. prior reaching at most about 40 0 C.
• the dispersions implemented in the prior art were prepared for example by simple mixing, not by the specific process. In other words, this process makes it possible to directly prepare aqueous dispersions of polymers, synthetic resins which make it possible to produce low temperature films or non-stick coatings, the hardness and adhesion properties of which are in line with their uses in various formulations.
• the reaction medium consists of a dispersion which can be used as such, without any other drying or other step, for example to prepare a coating, film on a substrate or to be incorporated into a coating composition.
• the liquid aqueous phase comprises at least 50% by weight of water.
• the monomer (s) and the polymer (s) generally represent at least 50% by weight of the organic phase.
• the dispersed polymerization medium is in the form of an emulsion.
• the aqueous phase is the continuous phase of this emulsion, so that it is the organic phase which is dispersed in the form of droplets with a diameter generally of 1 to 1000 nanometers.
• emulsifying agent that is to say a surfactant for stabilizing the emulsion, it being understood that said emulsifying agent is not an alkoxyamine.
• emulsifying agent usual to this kind of emulsion can be used.
• the emulsifying agent may be anionic, cationic or nonionic.
• the emulsifying agent may be an amphoteric or quaternary or fluorinated surfactant. It may be chosen from alkyl or aryl sulphates, alkyl or aryl sulphonates, fatty acid salts, polyvinyl alcohols and polyethoxylated fatty alcohols.
• the emulsifying agent can be chosen from the following list:
• the emulsifying agent may also be a random or block amphiphilic copolymer, such as copolymers of sodium styrene sulphonate and in particular polystyrene-b-poly (sodium styrene sulphonate).
• the emulsifying agent may be introduced into the polymerization medium in a proportion of 0.1% to 10% by weight relative to the mass of monomer (s). Instead of being added the emulsifying agent can be synthesized in situ in the polymerization medium, more specifically in the case of an amphiphilic copolymer. It also represents from 0.1% to 10% by weight relative to the mass of monomers.
• the emulsion may be a miniemulsion or a microemulsion, that is to say an emulsion in which the organic phase forms droplets with a diameter generally less than 2 micrometers and generally ranging from 100 to 1000 nanometers. The state of miniemulsion is obtained thanks to a sufficient shear of the liquid and thanks to the presence in the miniemulsion of a hydrophobic polymer and a co-solvent.
• the hydrophobic polymer must be soluble in the organic phase, it preferably has a solubility in water at 25 ° C of less than 1.10 ⁇ 6 g / liter and has a weight average molecular weight of at least 100,000, for example ranging from 100,000 to 400,000.
• the hydrophobic polymer may be polystyrene, polymethyl methacrylate or butyl polyacrylate.
• the hydrophobic polymer may be introduced into the emulsion in a proportion of 0.5 to 2% by weight relative to the monomer to be polymerized.
• the co-solvent has a hydrocarbon chain of at least six carbon atoms, has a solubility in water of 25 ° C lower than 1.10 ⁇ 6 g / liter and is liquid at the polymerization temperature. If the cosolvent does not contain fluorine atoms, the hydrocarbon chain preferably comprises at least 12 carbon atoms.
• the co-solvent may be: hexadecane, stearyl methacrylate, dodecyl methacrylate or perfluorooctyl methacrylate.
• the shear sufficient to obtain the miniemulsion state can be achieved by vigorous stirring, for example obtained by ultrasound. Once the miniemulsion state is obtained, it is generally possible to reduce the shear by bringing it back to that usual for emulsions in general while maintaining the miniemulsion state.
• monomer any monomer polymerizable or copolymerisable radical.
• monomer naturally covers mixtures of several monomers.
• the monomer may be chosen from monomers having a carbon-carbon double bond capable of radical polymerization, such as vinyl, vinylidene, olefinic diene, and allylic monomers, etc.
• vinyl monomers is meant, inter alia, (meth) acrylic acids, (meth) acrylates, in particular alkyl (meth) acrylates, vinylaromatic monomers, vinyl esters, (meth) acrylonitriles, (meth) acrylamides and mono- and di- (alkyl) (meth) acrylamides, the acid maleic anhydride, and the monoesters and diesters of maleic anhydride and maleic acid.
• alkyl and alkoxy groups may be linear or branched and generally have from 1 to 18 C.
• the cycloalkyl groups generally have from 3 to 18 C
• the alkenyl groups are generally from 2 to 18 C
• the aryl groups are generally from 6 to 20 C
• the alkylene groups generally have from 1 to 18 C.
• the monomers in question may in particular be chosen from vinylaromatic monomers such as styrene or substituted styrenes, especially ⁇ -methylstyrene and sodium styrene sulfonate, dienes such as butadiene or isoprene, and acrylic monomers such as acrylic acid or its salts, alkyl, cycloalkyl or aryl acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, ethylhexyl acrylate or phenyl acrylate, hydroxyalkyl acrylates such as acrylate 2-hydroxyethyl acrylates, ether alkyl acrylates such as 2-methoxyethyl acrylate, alkoxy- or aryloxypolyalkyleneglycol acrylates such as methoxypolyethylene glycol acrylates, ethoxypolyethylene glycol acrylates, methoxypolypropylene glycol acryl
• aminoalkyl acrylates such as 2- (dimethylamino) ethyl acrylate (ADAME), amine salt acrylates such as chloride or [2- (acryloyloxy) ethyl] trimethylammonium sulphate or [2- (acryloyloxy) ethyl] dimethylbenzylammonium chloride or sulphate, fluorinated acrylates, silylated acrylates, phosphorus acrylates such as alkylenglycol phosphate acrylates, methacrylic monomers such as methacrylic acid or its salts, alkyl, cycloalkyl, alkenyl or aryl methacrylates such as methyl, lauryl, cyclohexyl, allyl or phenyl methacrylate, methacrylates of hydroxyalkyl such as 2-hydroxyethyl methacrylate or 2-hydroxypropyl methacrylates
• silylated methacrylates such as 3-methacryloylpropyltrimethylsilane, phosphorus methacrylates such as alkylen glycol phosphate methacrylates, methacrylate hydroxyethylimidazolidone, hydroxyethylimidazolididone methacrylate, 2- (2-oxo-1-imidazolidinyl) ethyl methacrylate, acrylonitrile, acrylamide or substituted acrylamides, 4-acryloylmorpholine, N-methylolacrylamide, chloride acrylamidopropyltrimethylammonium (APTAC), acrylamidomethylpropanesulfonic acid (AMPS) or its salts, methacrylamide or substituted methacrylamides, N-methylolmethacrylamide, methacrylamidopropyltrimethylammonium chloride (MAPTAC), itaconic acid, maleic acid or its salts,
• phosphorus methacrylates such as
• the monomers listed above can be implemented both during the controlled radical polymerization step (s), and during the conventional conventional process radical polymerization step (s) leading directly to the dispersions used according to the invention.
• at least one of the radical polymerization steps of this process for preparing the dispersion is therefore a controlled radical polymerization step.
• the controlled radical polymerization technique comprises several variants depending on the nature of the control agent that is used.
• the controlled radical polymerization step (s) is (are) a step (s) known as (s) of SFRP carried out in the presence of stable free radicals, which preferably uses nitroxides T as control agents and an alkoxyamine (this alkoxyamine is generally water-soluble but it can be organosoluble in the case a mini emulsion), for example a difunctional alkoxyamine, as an initiator.
• a monofunctional alkoxyamine having the following formula (I) can be used:
• R 1 and R 3 which may be identical or different, represent a linear or branched alkyl group having a number of carbon atoms ranging from 1 to 3;
• R 2 represents a hydrogen atom, an alkali metal, such as Li, Na, K, an ammonium ion such as NH 4 +, NBu 4 +, NHBu 3 +, a linear or branched alkyl group having a number of carbon atoms ranging from 1 to 8, a phenyl group.
• a preferred monofunctional alkoxyamine is 2-methyl-2- [N-tert-butyl-N- (diethoxyphosphoryl-2,2-dimethylpropyl) aminoxy] propionic acid which has the following formula (II):
• Ri, R2 and R3 are as defined above,
• Z represents an aryl group or a group of formula Zi [XC (O) J n , in which Zi represents a polyfunctional structure derived for example from a compound of the polyol type, X is an oxygen atom, an atom of nitrogen carrying a carbon group such as an alkyl group of 1 to 10 C or a hydrogen atom, or a sulfur atom; and • n is an integer greater than or equal to 2.
• the polyfunctional alkoxyamine may in particular be a difunctional alkoxyamine or dialkoxyamine, for example of formula:
• the alkoxyamine is generally water soluble but can in some cases be organosoluble.
• the controlled radical polymerization step or steps are generally carried out at a temperature of 20 to 180 ° C. and preferably of 40 to 130 ° C. This or these step (s) are generally carried out at a pressure sufficient to avoid the boiling of the phases of the emulsion and that its various constituents remain essentially in 1 emulsion.
• the controlled radical polymerization step or steps are generally carried out in an inert gas atmosphere, for example nitrogen.
• polymer in its most general sense so that it covers homopolymers, copolymers, terpolymers and polymer blends.
• block copolymers are linear or radial molecules consisting of alternating long homogeneous sequences, they can be diblock, triblock or multiblock.
• precursor monomer of a block for example of a block (A) and monomer precursor of a block (A ') is meant the monomers which, after polymerization, respectively constitute the repetitive units of the block (A) and the block (A ').
• T v or T g denotes the glass transition temperature of a polymer measured by DSC according to ASTM E1356.
• T v or T g of a monomer we also speak of the T v or T g of a monomer to designate the T v or T g of the homopolymer having a number-average molecular mass M n of at least 10,000 g / mol, obtained by radical polymerization of said monomer .
• styrene has a T v , T g of 100 ° C. because the homopolystyrene has a T v , T g of 100 ° C.
• a block polymer is prepared, which block may be in particular an AB diblock polymer or an ABA 'triblock polymer and preferably ABA if A and A' are identical.
• polymerization is carried out by controlled radical polymerization of a first precursor monomer or a first mixture of precursor monomers to form give a living polymer block B and a residual monomer or a mixture of residual monomers.
• the living polymer block B can be brought into contact with a second monomer or a second monomer mixture, the polymerization of which forms, gives a connected polymer block A. at the polymer block B, or two identical or different blocks of polymers A and A ', each connected to the polymer block B, and a residual monomer or a mixture of residual monomers.
• conventional conventional radical polymerization steps of converting a monomer or a mixture of monomers into polymers can be carried out, especially to remove residual monomers or monomer mixtures (as described in FR-A- 2889703 of ARKEMA).
• the realization of the blocks can be done following each other, in the same apparatus.
• the first monomer is consumed so as to produce the first block, it suffices to introduce the second monomer intended for the first block.
• realization of the second block without stopping the agitation and without cooling or other interruption.
• the constitution conditions of each of the blocks such as the temperature of the emulsion, may be adapted.
• block copolymers ABA ' preferably ABA, or A-B, A, A' and B, which may be indifferently independently of each other, hard or soft.
• soft polymer is understood to mean that this polymer, whether isolated, separated, independent, or that it constitutes a block of a block copolymer, has a glass transition temperature T g or T v generally less than or equal to 10 0 C.
• Block A may be a homopolymer or a copolymer, for example a random copolymer.
• Block A ' may be a homopolymer or a copolymer, for example a random copolymer.
• Block B may be a homopolymer or a copolymer, for example a random copolymer.
• the precursor monomer (s) of the B block are preferably chosen from alkyl acrylates (for example from 1 to 18C).
• the precursor monomer (s) of block A and block A ' are preferably chosen from alkyl methacrylates (for example from 1 to 18C) and styrene compounds and their derivatives, some of which have been mentioned above.
• Block A and block A ' are preferably chosen from rigid, hard blocks having a glass transition temperature T v greater than or equal to 50 ° C.
• Block B is preferably chosen from soft blocks having a glass transition temperature of less than or equal to 10 ° C.
• the following block copolymers can be obtained at the end of the controlled radical polymerization steps of the process.
• preferred preparation of the dispersion implemented according to the invention - poly (methyl methacrylate) -b- poly (butyl acrylate) b-poly (methyl methacrylate).
• the preferred method used to prepare the dispersion implemented according to the invention comprises, in addition to at least one controlled radical polymerization step as described above, at least one conventional conventional radical polymerization step.
• conventional conventional radical polymerization step it is meant that this step is a conventional radical polymerization step, conventional, and is not a controlled radical polymerization step as defined above.
• An example of a conventional, conventional preparation process is a process in a dispersed medium in the presence of a conventional conventional radical polymerization initiator at a temperature of less than or equal to 80 ° C.
• a generally homopolymer or copolymer is generally prepared.
• the controlled radical polymerization step (s) and the conventional conventional radical polymerization step (s) are generally carried out successively in the same reactor, the same chamber.
• the conventional, conventional radical polymerization step or steps are generally carried out in the polymerization medium resulting from the controlled radical polymerization step immediately preceding each of these conventional, conventional radical polymerization steps. Said polymerization medium generally comprising one or more residual monomers.
• the polymerization of the residual monomer or monomers which have not reacted during the controlled radical polymerization step is carried out. immediately preceding said step or each conventional conventional radical polymerization step.
• polymers C and D are obtained for example.
• C can be a homopolymer or a copolymer, preferably a random copolymer.
• D can be a homopolymer or a copolymer, preferably a random one.
• C and D may be the same or different from A and / or A 'and / or B as defined above.
• a preferred method for preparing the dispersion implemented according to the invention may thus comprise the following steps: a) a first controlled radical polymerization step in which the controlled radical polymerization of a first precursor monomer or a first mixture is carried out; precursor monomers to provide a living polymer block B and a residual monomer or a mixture of residual monomers; b) a second controlled radical polymerization step in which the living polymer block B is brought into contact with a second monomer or a second monomer mixture whose polymerization gives a block of polymer A connected to the polymer block B or two blocks of polymer. polymers A and A 'identical or different each connected to the polymer block B, and a residual monomer or a mixture of residual monomers.
• one or more conventional conventional radical polymerization steps can be carried out in which the polymerization of a monomer or a mixture of monomers is carried out to give one or more polymers.
• the monomer or monomer mixture polymerized during the conventional polymerization step or steps, conventional are generally the residual monomer or the residual monomer mixture resulting from the controlled radical polymerization steps or only one or more monomers added or a mixture of the said residual monomer (s) and one or more added monomers.
• a still more preferred method for preparing the dispersion implemented according to the invention may thus comprise the following steps: a) a first controlled radical polymerization step in which the controlled radical polymerization of a first precursor monomer or a first precursor monomer mixture to provide a living polymer block B, and residual monomer or residual monomer mixture; b) a first radical free radical polymerization step (conventional) in which the conventional radical polymerization of the residual monomer or residual monomer mixture of step a) is carried out to form a polymer C; c) a second step of controlled radical polymerization in which is put in contact the living polymer block B with a second monomer or a second monomer mixture whose polymerization gives a polymer block A connected to the polymer block B or two identical or different polymer blocks A and A 'each connected to the polymer block B and a residual monomer or a mixture of residual monomers; d) optionally, a second conventional radical polymerization step in which the conventional radical polymerization of the residual monomers of
• the polymer C generally comprises the same monomer (s) as those from which the B block is derived, and the polymer D comprises the same monomer (s) from which the block (s) originates.
• the controlled radical polymerization steps are preferably carried out with an alkoxyamine, more preferably with a difunctional alkoxyamine as described above.
• aqueous dispersions of polymer particles in other words aqueous dispersions of latex particles consisting of a mixture of one or more block copolymers. and on the other hand random homopolymers or copolymers.
• Example 2 Preparation in emulsion of a block copolymer latex PoIy (methyl methacrylate) -Poly (butyl acrylate) - PoIy (methyl methacrylate) whose weight ratio Acrylate of Butyl / Methacrylate is 70/30.
• the synthesis is done in 5 steps:
• the temperature of the reactor is then brought to 105 ° C. and 75.1 g of methyl methacrylate, degassed beforehand, are added continuously over a period of 2 hours at 105 ° C. The temperature is maintained by thermal regulation for two more hours after the end. of addition. The conversion of methyl methacrylate reaches 86%. The temperature of the reactor is then lowered to 80 ° C.
• the final latex which has the following composition: 75% block copolymer
• Example 3 Preparation in emulsion of a block copolymer latex PoIy (methyl methacrylate) -Poly (butyl acrylate) - PoIy (methyl methacrylate) whose weight ratio Acrylate of Butyl / Methacrylate is 60/40.
• n-dodecyl mercaptan At 80 ° C., 4.48 g of n-dodecyl mercaptan, 33.6 g of a 10% by weight aqueous sodium formaldehyde sulfoxylate solution and 67.2 g of 5% aqueous potassium persulfate solution are used. are added and the temperature is maintained by thermal regulation for 2 hours.
• the final latex which has the following composition:
• Example 4 Preparation in emulsion of a block copolymer latex PoIy (methyl methacrylate) - PoIy (butyl acrylate) - PoIy (methyl methacrylate) whose mass ratio Butyl Acrylate /
• Methacrylate is 40/60.
• n-dodecyl mercaptan 0.22 g of n-dodecyl mercaptan, 0.16 g of sodium formaldehyde sulfoxylate and 0.16 g of potassium persulfate are added and the temperature is maintained by thermal regulation for 2 hours.
• the final latex which has the following composition: 65% of block copolymer
• the TMF was determined on the aqueous emulsion of pure polymer.
• the wet film produced at a thickness of 400 ⁇ m.
• the latex film was dried at different temperatures. TMF is the temperature at which cracks begin to appear on the film.
• the aqueous emulsion of pure polymer is applied to a weakly adsorbent paper (Lenetta card).
• the wet film produced has a thickness of 200 microns.
• the latex film is dried for 24 hours at 25 ° C.
• Two strips of 20x100 mm of the paper covered with the polymer film are cut from the Lenetta card and superimposed on each other, perpendicular to each other so as to obtain a contact area of 2 cm 2 , with the faces covered with the polymer film in contact.
• the 2 strips are kept in contact under a weight of 2 kg for 4 hours at different temperatures.
• the blocking temperature (TB) is the temperature at which the surface of the films is deteriorated when the two strips are separated from each other.
• Table I The results of TMF and TB measurements are summarized in Table I below:
• the films prepared by implementing the process according to the invention which uses polymer latices prepared directly by the process described above all have low TMF temperatures, ie below 0 0 C, and high TB temperatures, ie above 50 0 C.
• the temperature difference between TMF and TB is therefore, in all cases, greater than 50 0 C for films prepared by the process according to the invention from these latices.
• the films prepared by a process not according to the invention using polymer latices as represented by the document US Pat. No. 5,603,743 do not simultaneously exhibit a TMF lower than 0 ° C. and a TB greater than 50 ° C. and the temperature difference between TMF and TB, which reaches a maximum of 43 ° C., is never greater than 50 ° C.

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