JP2007511631A - Use of an aqueous dispersion of at least one biodegradable polymer comprising at least one stabilizer for the preparation of an aqueous film-forming composition - Google Patents

Abstract

  The invention relates to the use of an aqueous dispersion comprising an organic phase dispersed in an aqueous dispersed phase for the preparation of an aqueous film-forming composition having a solids content of at least 30%, said dispersion being a solid 94 to 99.5% on a dry basis, based on content, organic phase comprising at least one biodegradable polymer, and 0.5 to 6% of at least one stabilizer, said aqueous dispersion forming an aqueous film. It relates to the preparation of the composition.

Description

  The present invention relates to the use of an aqueous dispersion of at least one biodegradable polymer comprising at least one stabilizer for the preparation of an aqueous film-forming composition having a high solids content.

  The invention particularly relates to the use of the film-forming composition thus obtained for the preparation of an aqueous adhesive composition and an aqueous pigment composition.

  In the sense of the present invention, the term “aqueous film-forming composition” is understood to mean a composition capable of forming a film or coating by evaporation of the water initially present in said composition.

  In the sense of the present invention, an “aqueous adhesive composition” is an aqueous film-forming composition that can adhere to a support or can form a seal between two separate materials of the same or different nature. It is understood to mean a thing.

  This includes, among other things, temporary protective compositions for metal sheets, wood varnishes, anti-graffiti compositions, waterproof compositions for walls, textile finishing or sizing compositions, fertilizers, drugs, or seed coating compositions. Or an adhesive for leather, paper, wood, cloth (woven or non-woven), synthetic fiber, plastic, glass, and other materials.

  Such aqueous adhesive compositions exhibit a variable water content of 30 to 95% relative to the total weight of these compositions.

  Water acts as an inert dispersion medium or solvent for the components of these compositions and generally affects the viscosity and rheology of these compositions by coating, casting, spraying, dipping, or by brush, roller, block or otherwise. The use of a device makes it possible to make adjustments so that it can be easily applied to the surface or material to be coated or sized.

  Such adhesive compositions essentially comprise the binder and adjuvant in dissolved or simply dispersed form in water.

  In the sense of the present invention, the term “aqueous pigment composition” is also understood to mean a film-forming composition prepared in the form of an aqueous suspension of pigments, binders and adjuvants.

  The aqueous pigment composition may be, inter alia, coating colors, aqueous paints, and aqueous film-forming pigment preparations such as filler-containing adhesives.

  For example, in papermaking applications, these aqueous pigment compositions originate from the finished appearance of the paper (opaque, white, smooth, and glossy) and are responsible for its suitability for printing, particularly color printing.

  Water is an essential component of the pigment composition because it generally constitutes 30 to 95% of the total weight of the pigment composition. This is a mediator for all other ingredients.

  The pigment constitutes a solid filler of the aqueous pigment composition. This is generally a calcium carbonate, calcium sulfate, barium sulfate, calcium sulfoaluminate, kaolin, talc, titanium oxide, or plastic pigment type material.

  In the case of coating pigments, the pigment generally constitutes 80 to 92% by weight of the solid pigment (SC) of the aqueous pigment composition and generally coats or imparts smoothness to paper fibers. It has the role of providing optical properties (whiteness, opacity, gloss) or printing properties (in the case of coating colors or coating films).

  In the case of aqueous film-forming pigment preparations and paints, the amount of pigment generally depends on the type of formulation selected (matte, satin or glossy paint) of the aqueous pigment composition. It accounts for 10 to 95% by weight of the solids content, more commonly 35 to 95% by weight of the solids content.

  An adjuvant is an auxiliary product that is present in small amounts in an aqueous film-forming composition whether it is an aqueous pigment composition or an aqueous adhesive composition.

  In practice, these adjuvants introduced represent 0.3 to 5%, or even 1 to 3%, of the solids content of the aqueous film-forming composition.

  These generally fall into three categories.

  The first category is alkaline agents, dispersants (sodium hexametaphosphate, sodium polyacrylate), wetting agents, antifoaming agents (mineral oils, silicone products, fatty acid esters, fatty amines), or biocides (quaternary) It corresponds to the formulation of agents such as ammonium, phenols, anhydrides, dyes).

  The second category imparts excellent operability on equipment to the film-forming composition. This can be a rheology modifier (eg cellulose compounds, polyurethane thickeners), water retention acid (carboxymethylcellulose, starches and derivatives, caseins, proteins, polyols) or lubricants (calcium stearate, sulfonated oils). And polyols).

  This is because this aqueous film-forming composition may need to be applicable to equipment at high speeds (speeds that can exceed 1500 m / min for paper equipment).

  The third category makes it possible to improve or adjust the final properties of the aqueous film-forming composition. This includes insoluble agents (crosslinkers and resins such as urea-formaldehyde, melamine-formaldehyde, glyoxal, zirconium salts), optical brighteners (di-, tetra-, or hexa-sulfonated stilbene derivatives), agglomeration Corresponds to an agent or shade imparting dye (violet helio BNZ, unisperse blue).

The last component of the aqueous film-forming composition, whether it is an aqueous pigment composition or an aqueous adhesive composition, is a binder, which is generally
-In the case of coating colors, 5 to 90% of the solids content of the aqueous film-forming composition,
An aqueous pigment preparation, such as 5 to 90% of the solids content of the aqueous film-forming composition in the case of filler-containing adhesives, and a paint that does not contain any matte, satin or gloss paint In some cases 5 to 65% of the solids content of the aqueous film-forming composition,
Occupy.

  These serve in particular to ensure adhesion of the resulting coating following the pigment layer or water desorption.

  These amounts are selected in relation to the adhesive strength of the adhesive used, the nature of the pigment that is optionally introduced, and the concentration of the aqueous film-forming composition.

  The binder used is usually of natural origin, such as starch (wheat, corn) or protein (casein), or synthetic, such as polyvinyl alcohol or latex.

  In particular, latex (or “aqueous polymer dispersion”) is used, which corresponds to a colloidal dispersion of a synthetic polymer in the aqueous phase, ie a dispersion in which polymer microparticles are suspended in the aqueous phase. Sometimes referred to as a polymer emulsion or suspension.

  Conventional production of aqueous dispersions of synthetic polymers is mainly based on direct emulsion polymerization methods of synthetic monomers.

  This type of latex generally comprises particles of a polymer synthesized by direct emulsion polymerization of monomer pairs such as styrene / butadiene, styrene / butyl acrylate, methyl methacrylate / butadiene, or vinyl acetate / butyl acrylate type.

Each of these monomers becomes latex,
-Rigidity, gloss, or ink absorbency (for styrene, acrylonitrile, or methyl methacrylate),
-Resistance to solvents and oils (when acrylonitrile is used),
-Resistance to aging by UV light (when using methyl methacrylate, butyl acrylate or butadiene),
-Porous (when vinyl acetate is used),
-Bond strength or flexibility (when using butyl acrylate or butadiene),
Is granted.

  Generally, the synthetic latex thus used in the film-forming composition has a solids content of 45-60%, a density of approximately 1, a B-type viscosity of 100-300 mPa · s and a pH of 4.5-8.

  However, those skilled in the art are aware of the major drawbacks of this type of aqueous dispersion of synthetic polymers, which limit their use, which is why these synthetic products are not biodegradable. Or the fact that it cannot be composted and is difficult to regenerate.

  The lack of biodegradability presents serious environmental problems, particularly when disposing of waste by landfill.

  Thus, proposals have been made to use starch derivatives as binders. However, while starch is biodegradable, it has poor binding power and is water sensitive. This is particularly detrimental for applications of the film-forming composition in, for example, multi-color offset printing, washing out, or flexographic ink where water is applied to each station.

  In order to overcome this problem, aqueous dispersions of polymers prepared from biodegradable polymers have become the subject of intensive research and development.

  The term “biodegradable polymer” is understood to mean a polymer that is degradable under the action of microorganisms, in particular soil microorganisms, and even under the action of natural agents, in particular water.

  Aqueous dispersions of such biodegradable polymers are known but can generally be obtained only by the use of volatile organic solvents, as described, for example, in Japanese patent application 10-101911 and US Pat.

  In particular, US Pat. No. 5,774,844 discloses the use of aqueous dispersions of biodegradable polymers, particularly of the PHA type, to formulate adhesive dispersions that can be used for bonding non-woven materials.

  However, such aqueous dispersions are usually prepared by the use of toluene, ethyl acetate, acetone, a halogenated solvent, or another suitable volatile organic solvent.

  The term “volatile organic compound” is understood to mean any organic compound that has a vapor pressure of 10 Pa or higher at 25 ° C. or that has considerable volatility under given conditions.

  To the best of Applicants' knowledge, three types of methods are known to date that make it possible to obtain aqueous dispersions of at least one biodegradable polymer without the use of volatile organic solvents.

  The first type of current process involves the production by extrusion of a dispersion of a biodegradable polyester having a high solids content (SC) and a very high viscosity.

European Patent Application 1302502 regards in this respect at least 40% by treating a melt blend of a biodegradable polyester exhibiting a predetermined surface tension and an aqueous emulsifier with a predetermined additive by such an extrusion method at high temperature and pressure. A process for obtaining an aqueous dispersion having an SC of 5 and a viscosity of at least 1000 mPa · s, preferably 1500 to 10000 mPa · s is disclosed.

  This method involves introducing the downstream component of the aqueous emulsifier of the melt blend after melting the biodegradable polyester in an extruder. The blend is then kneaded at a temperature below 100 ° C.

  International patent application 97/49762 also discloses an aqueous dispersion of biodegradable polymers obtained by extrusion, which contains starch modified by esterification dispersed in an aqueous phase. This patent application also discloses a method for producing the aqueous dispersion without using a solvent.

  The method includes the steps of preparing a melt blend of polymers and optional plasticizer at a temperature of 100 to 180 ° C, and gradually adding water and a dispersant after the blend has been continuously stirred at an elevated temperature. .

  A second type of current method, which makes available an aqueous dispersion of at least one biodegradable polymer free of volatile organic solvents, is provided by the applicant and is dispersed in an aqueous dispersion phase. And an aqueous dispersion of at least one biodegradable polymer that includes an organic phase that is free of volatile organic compounds. The dispersed organic phase includes at least one viscosity reducing agent.

  These aqueous dispersions of at least one biodegradable polymer form the subject of patent applications that have been filed in France by the applicant on 12 September 2003 and have not yet been examined.

  These aqueous dispersions of at least one biodegradable polymer exhibit specific characteristics regarding solubility parameters and the ability to form hydrogen bonds, and include a viscosity reducing agent used in a specific weight ratio with the biodegradable polymer. .

  Viscosity reducing agents (or “plasticizers”), in this case, are heavy organic compounds, preferably biodegradable or compostable, that when introduced into a polymer, increase the viscosity and mechanical properties of the polymer. Breaks at least partially the interchain interactions responsible for adhesion.

  Furthermore, the absence of volatile organic compounds in these aqueous dispersions means that the content of the components of said aqueous dispersion, i.e. up to 5000 ppm, preferably up to 1000 ppm, more preferably up to 500 ppm, volatile Reflected in organic compound (or VOC) content.

  A third type of current method makes it possible to obtain an aqueous dispersion of at least one bacterial biodegradable polymer of various stable polyhydroxyalkanoate types directly from the microorganism containing it.

  This method is based on extraction by cell lysis followed by purification of natural particles of biodegradable polymer by chemical or enzymatic route, thus preparing an aqueous dispersion of biodegradable polymer free of volatile organic solvents. Can bring.

  A. Dufresne and E. Smain, in Macromolecules, 1998, 31, 6426-6433 discloses the preparation of an aqueous dispersion of poly (β-hydroxyoctanoate) or PHO from a microbial strain of Psudomonas Oleovorans Yes. Production is carried out by fermentation under controlled pH conditions and extraction of the aqueous PHO dispersion is carried out using sodium hypochlorite.

  The spontaneous stability of these aqueous PHO dispersions is explained by the presence of a particular protein, in this case a murine sac residue, around the polymer particles in the suspension.

  This type of process is also known for the preparation of aqueous dispersions of biodegradable polymers derived from microorganisms other than PHO, such as copolymers of hydroxyvalerate and hydroxybutyrate (PHBV).

  The use of aqueous dispersions of biodegradable polymers free of volatile organic solvents as binders in aqueous film-forming compositions makes it possible to use these aqueous dispersions of biodegradable polymers isolated from microbial strains in the state of the art. It has been developed using things.

  In particular, the patent application WO 91/13207 essentially contains polymers or copolymers consisting of β-hydroxyalkanoates (for example β-hydroxybutyrate and β-hydroxyvalerate) extracted especially from biomass of Alcaligenes eutrophus or Pseudomonas oleovorans. Discloses an aqueous dispersion comprising a colloidal suspension of irregularly shaped particles in water, and its use in the production of self-supporting films or biodegradable paper.

  This patent provides a microbial-derived latex that has the necessary characteristics for use as a binder for pigment compositions and exhibits the advantage of providing a biodegradable and reproducible coating film or coated paper. The possibilities are disclosed.

  However, the binding properties of the latex disclosed in this patent application are only shown by one family of polyhydroxyalkanoates, whose side chains contain 1 to 12 carbon atoms.

  Furthermore, while these latexes exist in the natural state in the form of essentially amorphous wet particles, they are highly crystalline, especially once dried and / or deposited on a substrate. Has the disadvantage of being placed in a state.

  Indeed, because of these crystallization tendencies of these latexes, it is essential on the one hand to promote agglomeration of the particles of the emulsion and on the other hand to obtain a dry film that exhibits suitable mechanical and optical properties. In application, it will not be used properly.

  In particular, the ability of aqueous polymer dispersions to form films requires that after water evaporation, complete interpenetration / dissolution of the dispersed polymer particles (a phenomenon called “aggregation”) is obtained.

  However, for certain applications in coating colors, coating films, or paints, the latex is maintained in an amorphous state to facilitate the dissolution of the particles on the substrate surface and is non-biodegradable or difficult to regenerate. It is essential to obtain mechanical and optical properties similar to those usually obtained with synthetic polymer latices.

  Therefore, the preparation of pigment compositions requires the use of soap or detergent type surfactants to improve the properties of this bacterial latex and precisely limit the effects of heat-induced crystallization of the latex. And this is further recommended in patent application WO 91/13207.

  For these reasons, the pigment composition disclosed in this international patent application is in the field of application targeted by the present invention due to the ability of the biodegradable polymer to crystallize strongly after degradation on a substrate. It does not seem appropriate for the practice of use.

  Furthermore, in this international patent application, only latexes with a solids content of 15 to 30% are envisaged for possible use for film formation, this being the rate of drying and the proportion in industrial machinery. Is a particularly disadvantageous condition.

  However, after water evaporates from the latex at ambient temperature, it was slightly improved by using chloroform type halogenated solvents and / or by exposing to vapors of these solvents during film drying. It is disclosed that a dense and transparent film with mechanical properties can be obtained.

  However, the need for the use of volatile organic solvents constitutes a second serious obstacle to the industrial application of this process.

  U.S. Pat. No. 6,022,784 discloses pigment compositions intended for the preparation of paints of poly (3-hydroxyalkanoates) having mono- or poly-unsaturated side chains of 6 to 16 carbon atoms extracted from Pseudomonas fluorescens The use as a binder in is disclosed.

  However, despite the fact that biodegradable polymers can be generally prepared in latex form, U.S. Pat. No. 6,022,784 discloses in practice with experiments that poly for solvent and quantity preparation. Only the use of organic solutions of (3-hydroxyalkanoates) (PHA).

  Petroleum ether, diethyl ether, or chloroform type organic solvents, toluene or xylene type aromatic solvents, or aliphatic solvents are recommended to dissolve the PHA prior to use as a binder.

However, this technical solution does not meet the desired environmental requirements because only solvent paint formulations provide.
US Pat. European patent application 1302502 A. Dufresne and E. Smain, in Macromolecules, 1998, 31, 6426-6433

  Preferably at least one biodegradation that is free of any volatile organic compounds, has a high solids content, can contain only biodegradable components, and is readily available for the preparation of aqueous film-forming compositions It is clear from all the above description that there is an unmet need to provide a film-forming composition comprising an aqueous dispersion of a functional polymer. Whether the film-forming composition is an aqueous pigment composition or an aqueous adhesive composition, such as a coating color, an aqueous film-forming pigment preparation, an adhesive, or an aqueous paint, is also cumbersome, difficult and complex Therefore, it is necessary to perform no complicated process.

  Applicant has addressed all these goals that were previously difficult to harmonize with at least one stabilizer present in sufficient but not excessive amounts for the production of such film-forming compositions. Has been credited with providing for the use of an aqueous dispersion of at least one biodegradable polymer comprising

The present invention, however, relates to the use of an aqueous dispersion comprising an organic phase dispersed in an aqueous dispersion phase for the preparation of an aqueous film-forming composition having a solids content of at least 30%. The dispersion is based on its solids content
-94-99.5% on a dry basis, organic phase comprising at least one biodegradable polymer, and -0.5-6% at least one stabilizer.

According to a particular embodiment of the invention, the dispersion used for the preparation of an aqueous film-forming composition having a solids content of at least 30% is based on its solids content,
-95 to 99.5% on a dry basis, organic phase comprising at least one biodegradable polymer, and -0.5 to 5% of at least one stabilizer.

  Preferably, the present invention provides an aqueous dispersion as defined above of at least 35% by weight on a dry basis, preferably 45 to 99.9% by weight, and even more preferably 50 to 75% by weight on a dry basis. It relates to the use for the preparation of an aqueous film-forming composition exhibiting a solids content.

  It has been the applicant's work to propose the use of this aqueous dispersion with such a high concentration of biodegradable polymer for the preparation of an aqueous film-forming composition having a high solids content.

  As explained above, in the case of conventional aqueous pigment compositions, the solids content is mainly provided by the pigment and is supplemented by a binder and, to a lesser extent, an adjuvant.

  However, Applicant, regardless of whether it is an aqueous pigment composition or an aqueous adhesive composition, the preparation of a stable aqueous film-forming composition from an aqueous dispersion of at least one biodegradable polymer is described above. It overturned the technical prejudice that it became more difficult and even impossible in practice as the dry content of the forming composition increased.

  This is due to the fact that aqueous dispersions of at least one biodegradable polymer of the state of the art generally exhibit excessively high viscosities.

  This promotes a strong interaction between the pigment and the components of the aqueous dispersion when it has a high solids content and is an aqueous pigment composition.

  In addition, strong interactions can cause phase conversion, greatly increasing viscosity and breaking the uniformity of the pigment composition.

  This increase in viscosity is very significant, making the pigment composition unsuitable for use in its coating color, aqueous film-forming pigment preparation, or aqueous paint.

  In order to avoid this phenomenon of phase inversion, Applicant is sufficient not to impair the excellent agglomeration of the dispersed organic phase particles in the aqueous dispersion that is a constituent of the film-forming composition. He credited the discovery of the need for an appropriate amount of stabilizer, not an excess.

  These stabilizers may be single or combined, natural or modified forms of proteins, starches, polyvinyl alcohols, rubbers, polymeric emulsifiers, celluloses, and polyols.

  These stabilizers include polymeric emulsifiers such as hydrophobic comonomers, high molecular weight cross-linked acrylic copolymers, especially cross-linked copolymers of acrylic acid and alkyl methacrylates of 10 to 30 carbon atoms (eg Pemulen marketed by Noveon). (Registered trademark)).

  The stabilizer is preferably a polyvinyl alcohol, gum arabic, xanthan gum or modified starch or cellulose having a degree of hydrolysis of 60 to 98%, preferably 70 to 90%, preferably esterified (methylated, carboxymethyl). , Acetylated, or alkyl succinylated) or etherified (cationic or hydroxypropylated) starch or cellulose.

  These stabilizers, in dry form in the aqueous dispersion, are 0.5 to 6% of the solid content of the aqueous dispersion, preferably 1 to 5.5%, more preferably 0.5 to 5%, very preferably. Must be present at a rate of 1.5 to 5%.

  Then, 94 to 99.5%, preferably 95 to 99%, of the biodegradable polymer can be introduced into the aqueous dispersion, which is still used for the preparation of the aqueous film-forming composition of the present invention. It becomes possible to obtain a highly concentrated aqueous dispersion that has never been achieved.

  This means that the Applicant does not have sufficient stability for the aqueous dispersion to be introduced as a binder in an aqueous film-forming composition having a high solids content with a stabilizer content of less than 0.5%. By finding out.

  At content above 5%, an excessively high content of stabilizer is detrimental to the cohesive properties required, for example, for the production of coating colors, aqueous film-forming pigment preparations, aqueous paints or aqueous adhesive compositions.

  The aqueous film-forming composition according to the invention is also characterized in that it is obtained by use of an aqueous dispersion, preferably free of volatile organic solvents, both in its content and in its treatment.

  The absence of volatile organic compounds in this aqueous film-forming composition means that the VOC content is the content of the components of said aqueous film-forming composition, i.e. up to 15000 ppm, preferably up to 5000 ppm, even more preferably up to This is reflected in not exceeding 1000ppm.

  However, the aqueous film-forming composition according to the present invention does not show any of the disadvantages of the preparations according to the prior art, and thus, with the problems of toxicity, additional costs, process complexity, equipment for liquid leakage avoidance, explosion. It makes it possible to avoid the need for the introduction of a prevention device or a device for the recovery of volatile organic solvents inevitable to affect the environment.

  Applicants have found that selecting an aqueous dispersion of a type that does not contain a volatile organic solvent is not a limiting factor and is notable in itself.

  Thus, each of the known types of methods for producing an aqueous dispersion of at least one biodegradable polymer described above may be suitable.

  This is because the selection of a given stabilizer in a given proportion allows the introduction of any type of biodegradable polymer into the aqueous dispersion.

  For the preparation of an aqueous-forming composition having a high solids content, the applicant optimally comprises an aqueous dispersion comprising 0.5 to 6% by weight of at least one stabilizer relative to the dry weight of the aqueous dispersion. The use of objects is recommended.

Advantageously, the Applicant has for the preparation of an aqueous forming composition having a high solids content according to the invention comprising an organic phase dispersed in an aqueous dispersed phase and free of volatile organic compounds, in particular two It is recommended to select one type of aqueous dispersion.

The first type corresponds to an aqueous dispersion developed by the applicant, which in its organic phase,
A solubility parameter of −15 to 28 (J · cm ⁻³ ) ^0.5 , preferably 16 to 23 (J · cm ⁻³ ) ^0.5 , more preferably 18 to 21 (J · cm ⁻³ ) ^0.5 , and 3.5 to 15 ( At least one viscosity reducing agent exhibiting a hydrogen bonding parameter δH of J · cm ⁻³ ) ^0.5 , preferably 4 to 13 (J · cm ⁻³ ) ^0.5 , even more preferably 5 to 10 (J · cm ⁻³ ) ^0.5 ,
-Containing at least one biodegradable polymer in a polymer / viscosity reducing agent weight ratio of 99.8 / 0.2 to 60/40, preferably 97/3 to 70/30, more preferably 92/8 to 70/30 .

  These aqueous dispersions exhibit a low viscosity even with a high solids content, so that they are exceptionally suitable for the preparation of pigment compositions with a high solids content according to the invention.

  Applicants are esters of alcohols and acids, optionally ethoxylated, preferably from the group of mono-, di-, or tri-esters of organic acids, carbonic acid, and phosphoric acids, sugars, or polyols. It is recommended to select a viscosity reducing agent.

  It may also be selected from the group consisting of saccharides, polyols (especially isosorbide), glycols or phenols, optionally ethoxylated ethers, glycols or ether esters of epoxidized triglyceride oils.

  It is desirable to select one that is biodegradable or compostable and is food grade.

  The viscosity reducing agent also advantageously exhibits a boiling point above 130 ° C., preferably above 150 ° C., and even more preferably above 200 ° C., thereby classifying it into a category of heavy solvents that are exceptionally suited for its function. Is done.

  Applicants have stated that the viscosity reducing agent is glycerol triacetate, isosorbide diacetate, isosorbide dibutyrate, isosorbide diisobutyrate, isosorbide dioctanoate, dimethyl isosorbide, ethyl lactate, butyl lactate , Tributyl citrate, triethyl citrate, bis (2-ethylhexyl) adipate, diisobutyl adipate, dibutyl phthalate, propionic acid, glycerol tributyrate, glycerol triisobutyrate, ethylene glycol dibenzoate, diethylene glycol dibenzoate, propylene glycol dibenzoate , Dipropylene glycol dibenzoate, triethylene glycol benzoate, dibutyl sebacate, diisobutyl sebacate, propylene Selecting from the group consisting of carbonate, polyethylene glycol 400, polyethylene glycol 600, caprolactone diols having a molecular weight of approximately 500, vegetable oil methyl esters, and dibasic esters of adipic acid, succinic acid, and / or glucaric acid. Especially recommended.

  The biodegradable polymer is non-crystalline and includes polylactates (or PLA), polymerates (or PMA), polyhydroxyalkanoates (or PHA), polycaprolactones (PCL), polyesteramides ( PEA), aliphatic copolyesters (PBSA), and aliphatic coterephthalate copolyesters (PBAT), and celluloses or starches that are highly acetylated or rendered hydrophobic by the introduction of fixed fatty chains Selected from the group consisting of biodegradable polymers of the type that are in the form of homopolymers or heteropolymers, whether linear, branched, crosslinked, dendritic, or grafted, either alone or in combination Is done.

  Advantageously, the biodegradable polymer is a heteropolymer, preferably a di-, tri- or tetra-polymer, whose monomers are diols, caprolactones or acids and D-lactic acid, L-lactic acid, glycolic acid, tetramethylglycolic acid, malic acid, β-propiolactic acid, butyric acid, valeric acid, phthalic acid, terephthalic acid, succinic acid, adipic acid, sebacic acid, hexanoic acid, octanoic acid, decanoic acid, dodecane These are hydroxy acids selected from acids, tetradecanoic acid, hexadecanoic acid, and octadecanoic acid.

  Applicant recommends that at least two monomers be polymerized as a heteropolymer so that the first monomer is solid at ambient temperature and the second monomer is more fluid at this temperature. . In this case, an aqueous dispersion particularly suitable for film formation is obtained.

  The biodegradable polymer may be a random, alternating, chained, or block heteropolymer.

  Applicants have shown that the polymer's strong crystallizing properties were not recommended for aqueous dispersions intended to prepare aqueous film-forming compositions.

  It is therefore advantageous to select a biodegradable polymer that is present in the dispersion in an amorphous form, ie in an amorphous or semi-crystalline form, preferably in an amorphous form.

  Furthermore, Applicants recommend that the polymer in amorphous or semi-crystalline form be applied on a support and / or kept after drying.

  In the sense of the present invention, the “amorphous” form of the biodegradable polymer comprises up to 25% of the polymer in crystalline form. The “semi-crystalline” form includes up to 60% of the polymer in crystalline form.

  Optionally, functionalized biodegradable polymers are selected, preferably those functionalized with aldehyde type, fluorinated type, carboxylic acid type, amine type, and alcohol type groups.

  Finally, applicants have specifically identified PHA-type amorphous or semi-crystalline biodegradable polymers offered by Procter & Gamble under the trade name Nodax® and in particular Galactic® L68 by Galactic. We have found that PLA type biodegradable polymers provided under the trade name are particularly suitable.

  In particular, blends of Nodax® and amorphous or semi-crystalline PLA and / or starch that is highly acetylated or fully hydrophobic can be used.

  The presence of a given stabilizer in a certain proportion is necessary for the preparation of an aqueous dispersion suitable as a binder for the aqueous film-forming composition according to the invention.

This goal is easily achieved in this case by the following sequence of steps. What is said process?
1) A blend of the biodegradable polymer and the viscosity reducing agent is dissolved at a temperature higher than the glass transition temperature of the biodegradable polymer, and the ratio of the biodegradable polymer to the viscosity reducing agent is 99.8 / 0.2 to 60/40, preferably Providing an organic phase of the aqueous dispersion to be dispersed by obtaining a uniform polymer blend that is 97/3 to 70/30, more preferably 92/8 to 70/30;
2) Completely dissolve at least one stabilizer in the aqueous dispersion phase so that the stabilizer accounts for 0.5 to 6%, preferably 0.5 to 5% of the dry weight of the solids content of the aqueous dispersion. Process,
3) Simultaneously and continuously, the aqueous dispersion phase and the organic phase to be dispersed are introduced into the mixer of the emulsification unit, and the dispersed organic phase is at least the solid content of the aqueous dispersion. Pre-adjusting the flow rate of introducing the two phases to account for 80% by weight, preferably at least 90% by weight, and even more preferably 95% by weight; and
4) recovering the aqueous dispersion thus obtained,
including.

For the preparation of the aqueous dispersion, for example,
-Turbo mixer,
-Two facilities for the preparation of the organic phase to be dispersed (each comprising an insulated container, a capacity pump and an arrangement of insulated pipes);
An emulsification unit is used, such as that sold by Emulbitume (Tregueux-France) containing

  This type of equipment is used in a mixer at atmospheric pressure and at a flow rate of at least 100 l / h for the organic phase to be dispersed in a molten state containing one biodegradable polymer and a viscosity-reducing agent and for stabilizing the other. Allows the preparation of an aqueous dispersion by simultaneously contacting the aqueous dispersion phase containing the agent.

  A second group of aqueous dispersions comprising an organic phase dispersed in an aqueous dispersed phase, free of organic compounds, and usable for the preparation of an aqueous film-forming composition having a high solids content is extracted directly from microorganisms. Purified.

  For the preparation of the aqueous film-forming composition according to the present invention, the applicant adjusts the conditions for the purification of the native particles of the biodegradable polymer and adjusts its stabilizer content, in particular the protein content. Needs to be 1 to 5%, preferably 1 to 4% in terms of dry weight with respect to the dry weight of the polymer.

  This is because applicants generally have an aqueous film-forming composition in which the aqueous dispersion of bacterial polymer has a high solids content when the stabilizer content, especially the protein content, is less than 1%. This is because it has been found that it does not show a sufficient level of stability to be introduced as a binder.

  Above 5% content, too high a content of stabilizers, especially proteins, is an agglomeration property required for the production of coating colors, aqueous film-forming pigment preparations, aqueous paints, or aqueous adhesive compositions. Harmful to

  The protein content in the native particles of the bacterial polymer can be adjusted during the purification process by any method known per se to those skilled in the art.

  Applicants recommend the use of a type of purification method that utilizes sodium hypochlorite. The method comprises leaving a predetermined amount of stabilized protein for sufficient colloidal suspension to promote aggregation of native particles while digesting biomass without degrading polyhydroxyalkanoates. enable.

  Preferably, the solids content of the aqueous dispersion used for the preparation of the aqueous film-forming composition is 25 to 70% by weight, preferably 35 to 70% by weight, even more preferably 45 to 65% by weight. .

  An aqueous dispersion comprising an organic phase dispersed in an aqueous dispersed phase may comprise from 25 to 70% by weight, preferably from 35 to 70% by weight, and even more preferably from 45 to 65% by weight solid pigment, and its solids content 95 to 99.5% on a dry basis, organic phase comprising at least one biodegradable polymer, and 0.5 to 5% of at least one stabilizer, characterized in that it forms an aqueous film according to the invention It is clear that it is particularly suitable for the preparation of the composition.

  The preparation of the aqueous film-forming composition according to the invention is carried out by blending its constituents by any method known per se to those skilled in the art and exemplified below.

  The aqueous film-forming composition thus obtained is particularly suitable for the production of aqueous pigment compositions, such as coating colours, aqueous film-forming pigment preparations or paints, or alternatively aqueous adhesive compositions.

Preferably, the aqueous pigment composition according to the invention exhibits a solids content equal to at least 30%, and
An aqueous dispersion of a biodegradable polymer belonging to one of the above groups as binder,
At least one adjuvant,
At least one pigment,
including.

Preferably, the aqueous adhesive composition according to the invention exhibits a solids content equal to at least 30%, and
An aqueous dispersion of a biodegradable polymer belonging to one of the aforementioned groups as the first binder,
As second binder, natural and modified starches, and natural and modified celluloses, preferably water-soluble,
At least one adjuvant,
-Any at least one pigment,
including.

  The water-based adhesive composition according to the present invention includes, inter alia, labeling, spiral mandrels, cardboard, bag making, wallpaper, carpets including laid carpets, backings, non-woven materials, tobacco, walls It may be an adhesive.

  It can also be a textile finish, varnish, temporary protective composition, anti-graffiti composition, coating composition or waterproofing composition.

  The aqueous adhesive composition can be easily diluted with water, depending on the method of application to the surface or material to be coated or sized.

  Other features and advantages of the present invention will become apparent as the following non-limiting examples are read.

(Example 1)
Three aqueous pigment compositions having a high solids content are prepared from three aqueous dispersions free of volatile organic solvents.

  The first aqueous dispersion (dispersion No. 1) is manufactured and marketed by Galactic, number average molecular weight of 68000 Da, polydispersity of 2.78, glass transition temperature of 55 ° C., 2380 Pa · s at 130 ° C. and It is prepared from Galastic® L68 which exhibits a complex viscosity of 34 Pa · s at 160 ° C., a crystallinity of approximately 0%, and a D-lactic acid polylactate content of 12.4% after hydrolysis.

  As an agent for reducing the viscosity of this polylactate, diethyl glycol dibenzoate having a boiling point of 236 ° C., marketed under the name Benzoflex® 2-45 by Velsicol, is used.

  The stabilizer chosen for the aqueous phase is polyvinyl alcohol with a degree of hydrolysis of 88 ± 1%, a viscosity of 25 ± 2 mPa · s and a purity of more than 94% marketed by TVP Japan Vam & Co. Ltd. Poval JP 18Y.

The method for producing an aqueous polylactate dispersion includes the following steps.
1) Preparation of organic phase to be dispersed
1300 g of Galastic® L68 type PLA pellets and 700 g of Benzoflex® 2-45 (ie the ratio of biodegradable polymer to viscosity reducing agent is 65/35) are electrically heated to 160 Introduce into a container maintained at ℃.
When these products are completely dissolved, the blend is homogenized by stirring.

2) Preparation of aqueous dispersed phase
135 g of polyvinyl alcohol Poval JP 18Y is dispersed in 3200 g of demineralized water with mechanical stirring at 80 ° C.

3) Preparation of aqueous dispersion Simultaneous blending of the organic phase to be dispersed and the aqueous dispersion phase is carried out by Emulbitume in a commercial laboratory emulsification unit.

  The organic phase and the aqueous phase are transferred to respective heat insulating containers whose temperatures are controlled at 160 ° C and 60 ° C.

  In order to adapt to the respective temperature and control the flow rate, the volume pump is started in a closed circuit, with a dispersed organic phase content of 97.2% and a stabilizer content of 2.8% relative to the solids content of the aqueous dispersion Get.

  After opening the valve, the organic and aqueous phases are conveyed simultaneously and continuously to an Atomix C turbomixer at 8900 rev / min.

Subsequently, second, third, and fourth aqueous polylactate dispersions are prepared by operations similar to those described above, except for the following.
-Dispersion No. 2 is stabilized with 85 g Poval JP 18Y, 3.5 g xanthan gum (Sigma Aldrich) and 32 g acetylated potato starch (AN = 1.8) extruded, manufactured and marketed by the Applicant Introduced as an agent,
-Dispersion No. 3 stabilizes 85 g Poval JP 18Y, 7 g xanthan gum (Sigma Aldrich) and 64 g acetylated potato starch (AN = 1.8) extruded, manufactured and marketed by the Applicant Introduced as an agent,
-For dispersion No. 4, 700 g of viscosity reducing agent Benzoflex (R) 2-45 is replaced with 325 g of diisobutyl adipate, extruded by the applicant, manufactured and marketed with 85 g of Poval JP 18Y and 7 g Xanthan gum (Sigma Aldrich) and 64 g of acetylated potato starch (AN = 1.8) are introduced as stabilizers and further adjusted to a pH value of 5.0 by addition of 1N sodium hydroxide.

  The production of two other dispersions by exactly repeating the production conditions of dispersion No. 1 is also tested, but the first one is added by adding 18 g Poval JP 18Y (ie on a dry basis). For the second is by adding 375 g of Poval JP 18Y (ie 7% for the stabilizer content / SC on a dry basis). In any case, in contrast to the other four preparations, it is impossible to obtain an aqueous dispersion or to produce an aqueous dispersion that exhibits a stability of several hours or more ( Immediate aggregation) is known.

  The characteristics of the four stable aqueous dispersions are summarized in Table 1 below.

  While stirring the aqueous pigment composition according to the present invention at 5000 rev / min for 2 minutes using a Dispermat mechanical stirrer, 8 g of demineralized water and dispersion Nos. 1, 2 and 2 having the characteristics described in Table 1 were gradually added. Or 35 g of any of 3 is prepared by gradually adding to 16 g of an aqueous pigment suspension of calcium carbonate having a solids content of 75% and commercially available from Omya under the Setacarb® trademark.

  These aqueous pigment compositions obtained with dispersions 1, 2, and 3, respectively, are referred to as PC1, PC2, and PC3. The main features are shown in Table 2 below.

  It can be seen that the aqueous pigment composition thus obtained is stable since no aggregation, coagulation, or phase conversion is observed. These pigment compositions further exhibit excellent film-forming properties and viscosities that are acceptable for use as aqueous film-forming pigment preparations.

  Furthermore, starting from dispersion No. 2, to this dispersion No. 2, hydrogenated glucose syrup Polysorb® 70/12/12 marketed by the applicant is gradually added as an additional stabilizer. The mixture is added by simple agitation while increasing the amount to 1 to prepare new aqueous dispersions (dispersions No. 5 to No. 9).

  The amount of this syrup diluted to 59.5% SC and added to 100 g of dispersion No. 2 itself having 59.5% SC is the film of dispersion No. 5-9 at 20 ° C. and 90 ° C. Table 3 and Table 4 below together with the formation characteristics.

In fact, the stabilizer content, which is 0.5 to 5% of the SC of the aqueous dispersion on a dry basis,
-Obtaining an aqueous dispersion which is stable (no aggregation or solidification even over several months) and which further exhibits excellent film-forming properties and excellent water-resistant properties; and-preparation of aqueous film-forming pigments Preparing a pigment composition exhibiting rheological properties suitable for use as a product, while also exhibiting excellent film-forming properties;
It is clear that is possible.

(Example 2)
An aqueous pigment composition intended for a top coat / single coat type coating color formulation was prepared from Dispersion No. 4 of Example 1, which was prepared from a coated aqueous formulation prepared from a synthetic aqueous dispersion in the following manner: Compare.

1) “Topcoat / single coat” coating color formulation from dispersion No. 4 of Example 1 (coating color 1, according to the invention):
Less than:
-1115 g of calcium carbonate aqueous pigment suspension (commercially available under the trademark Setacarb® 80 OG by Omya, having 76% SC),
-328 g of an aqueous pigment suspension of kaolin (commercially available under the trademark Supragloss® 95 by Imerys, having 66% SC),
−340 g of dispersion No. 4,
-126 g polyol type plasticizer (manufactured and marketed by the applicant under the trade name Neosorb® 70/70, having 70% SC),
-12 g of dispersant (commercially available from Ciba under the trademark Dispex® N40),
-61 g of carboxymethyl cellulose type thickener (commercially available under the Finnfix® 10 trademark by Noviant, with 10% SC),
−10 g of insolubilizer (commercially available under the trademark Urecoll® S by BASF, with 56% SC), and −8 g of lubricant (under Nopcote® C 104 trademark by Nopco paper Technology) Commercially available, with a solids content of 48%),
Are added continuously with Rayneri mechanical stirring at 700 rev / min and stirred for 1 hour.
The solid pigment of the pigment composition is adjusted to 60% using demineralized water. The pH of this same pigment composition is adjusted to 9 using sodium hydroxide.
The viscosity measured with a B-type viscometer is 620 mPa · s at 30 ° C. and 100 rev / min.
The viscosity measured with a Hercules rheometer (DV-10 type model from Kaltec Scientific Inc.) is 42 mPa · s at a shear rate of 40000 s ⁻¹ .

2) Preparation of control “top coat / single coat” coating color from synthetic aqueous dispersion (coating color 2):
The preparation of the control pigment composition consists of a styrene butadiene type synthetic aqueous dispersion (solid pigment 50%; pH 5.7; type B viscosity 98 mPas), dispersion No. 4 marketed by Dow under the trademark Dow® DL 950.・ Same as above except that replaced by s).
The solid pigment of the pigment composition is adjusted to 60% with demineralized water. The pH of this same pigment composition is adjusted to 9 using sodium hydroxide.
The viscosity measured with a B-type viscometer is 580 mPa · s at 30 ° C. and 100 rev / min.
The viscosity measured with a Hercules rheometer (DV-10 type model from Kaltec Scientific Inc.) is 24 mPa · s at a shear rate of 40000 s ⁻¹ .

3) Coating of the coated paper and physical measurements These two pigment compositions were applied to the base paper surface at a basis weight of 39 g / m ² using a commercially available Helicoater® 2000 type coating device manufactured by Dixon. To coat. The coating performed is of the blade type (blade coating).

The adhesion amounts of these two pigment compositions are 19 g / m ² for the composition containing Dispersion No. 4 and 18 g / m ² for the composition containing the synthetic aqueous dispersion, respectively.

  These papers are then calendered using a RK 22 HU type laboratory calender machine manufactured by Ramisch & Co.

The calendering process is a process required to give a smooth and glossy appearance to the coated paper. The calendering conditions are one pass at 2.5 bar and 120 ° C.
Analysis after storage in an atmosphere control chamber (23 ° C./50% RH), the results are summarized in the table below.

  Paper coated with the coating color according to the invention containing dispersion No. 4 (coating color 1) is smoother, more porous and rigid than that with the coating color containing coating aqueous dispersion (coating color 2) Gives equivalent results, and gives better results for whiteness and opacity.

(Example 3)
The aqueous pigment composition PC1 obtained according to Example 1 is used as an adhesive aqueous film-forming pigment preparation as opposed to a control adhesive formulation.

The control adhesive formulation is 5000 rev / min for 2 minutes, the following:
-16 g pigment suspension Setacarb® 80 OG (commercially available from Omya, solids content 75%),
−8 g of demineralized water,
-35 g of latex Rhodopass® A 013P (equivalent to vinyl acetate marketed by Rhodia (SC 54%, pH 4.5, viscosity 6000 mPa · s) and plasticized with dibutyl adipate)
Prepared by blending.

  The adhesion performance between the aqueous pigment composition PC1 of Example 1 and the control formulation is comparatively evaluated by the FIPAGO test in which the adhesion progress is measured with a Strohlein apparatus.

  The principle of this test is to show the change over time in the breaking strength produced by the adhesive composition tested between two papers, one placed on a stationary support and the other attached to an articulated arm. It is to test.

The two sheets of paper are of the same quality and have dimensions of 20cm x 6cm, with the following main features:
- basis weight: 66g / m ^2,
- Cobb: 19g / m ^2,
-AFNOR porosity: 7.6 ml / min,
-Internal coupling (Scott coupling): 550 J / m ² ,
Have

  A value of 100 corresponds to the paper being inseparable, and a value of 0 corresponds to immediate separation.

The adhesion amount of the adhesive composition of 40g per paper 1 m ² (PC1 or control preparation), FIPAGO adhesion results shown in Table 6 below.

  It is clear that the adhesive pigment composition according to the present invention exhibits excellent adhesive properties even though it provides slower adhesion than the control adhesive formulation.

(Example 4)
Two types of matte water-based paint and two types of satin-finished water-based paints are prepared according to the composition described in Table 7 below, except that the styrene-acrylic bonded resin Repolem® 2423 (SC is 50%, 20 ° C. No. 1 and No. No.1 and No. 1 dispersions that act as a binding resin with a B-type viscosity of 10000 mPa · s, a pH of about 8, a minimum film formation temperature of + 15 ° C, and a glass transition temperature of + 18 ° C) Replace completely with equal weight by either .2

    The components of the paint are introduced in the order shown in Table 7 using a Dispermat® CV trademark dispenser designed according to certain procedures and specifically for the preparation of the paint.

  The characteristics of various matte and satin finish water-based paints are summarized in Table 8 below.

*: Measured by gap height (mm), corresponding to the pair of streaks where the separation can be recognized. With either dispersion No. 1 or No. 2, the matte or satin finish water-based paint It is clear that the non-biodegradable synthetic binding resin Repolem® 2423 can be completely replaced in the formulation without compromising on its physical stability and its basic properties.

  In contrast to the control paint, it is clear that the paint comprising dispersions No. 1 and No. 2 exhibits a preferred yield point for its application on the support.

(Example 5)
An aqueous adhesive composition according to the present invention is prepared from an aqueous dispersion of polylactate Galastic® L 68 without the use of organic solvents.

This aqueous dispersion is obtained according to the conditions described in Example 1 (dispersion No. 5) and comprises the following components:
・ Demineralized water: 40.86%
・ Polyvinyl alcohol Poval JP 18Y: 1.07%
・ Xanthan gum: 0.07%
・ Polylactate Galastic (registered trademark) L 68: 46.40%
・ Dipropylene glycol dibenzoate: 5.80%
・ Vegetable oil methyl ester: 5.80%

  This dispersion exhibits a B-type viscosity of 650 mPa · s for a solids content of 56%.

  An aqueous adhesive composition that can be used as a cigarette adhesive or a backing adhesive, is soluble in cold water in 700 g of demineralized water and is commercially available by the applicant under the name Dexylose® 250 Is prepared by dispersing 300 g.

  After mechanical stirring at 1500 rpm for 30 minutes, 300 g of the above aqueous dispersion is introduced.

  The pH value is then adjusted to 3 by adding sodium hydroxide solution.

  A uniform adhesive is thus obtained, which exhibits a B-type viscosity of 4200 mPa · s for a solids content of 35.2%.

  When the adhesion test was performed with the FIPAGO device, the fiber disaggregation of the paper was recorded only after 30 minutes from the start, so this highly biodegradable and repulpable adhesive is It has been found to have very good performance for use in backing.

Claims (13)

Use of an aqueous dispersion comprising an organic phase dispersed in an aqueous dispersed phase for the preparation of an aqueous film-forming composition having a solids content of at least 30%, said dispersion being based on its solid content ,
Use of the aqueous dispersion comprising 94-99.5%, on a dry basis, an organic phase comprising at least one biodegradable polymer and -0.5-6% of at least one stabilizer.   The film-forming composition has a solids content of at least 35% by weight on a dry basis, preferably at least 45 to 99.9% by weight on a dry basis, and even more preferably a solids content of 50 to 75% by weight on a dry basis. Use according to claim 1, characterized in that it is indicated.   Use according to claim 1 or 2, characterized in that the aqueous film-forming composition is an aqueous pigment composition or an aqueous adhesive composition.   4. Use according to any one of claims 1 to 3, characterized in that the aqueous dispersion is free of volatile organic compounds. The dispersed organic phase component of the aqueous dispersion is
A solubility parameter of −15 to 28 (J · cm ⁻³ ) ^0.5 , preferably 16 to 23 (J · cm ⁻³ ) ^0.5 , more preferably 18 to 21 (J · cm ⁻³ ) ^0.5 , and 3.5 to 15 ( At least one viscosity reducing agent exhibiting a hydrogen bonding parameter δH of J · cm ⁻³ ) ^0.5 , preferably 4 to 13 (J · cm ⁻³ ) ^0.5 , even more preferably 5 to 10 (J · cm ⁻³ ) ^0.5 ,
-Containing at least one biodegradable polymer in a polymer / viscosity reducing agent weight ratio of 99.8 / 0.2 to 60/40, preferably 97/3 to 70/30, more preferably 92/8 to 70/30 Use according to any one of claims 1 to 4, characterized in that.   Use according to any one of claims 1 to 4, characterized in that the aqueous dispersion is derived from microorganisms and contains 1 to 5%, preferably 1 to 4% of a stabilizer. Said aqueous dispersion is preferably of the following type:
Polylactates (or PLA), polymerates (or PMA), polyhydroxyalkanoates (or PHA), polycaprolactones (PCL), polyesteramides (PEA), aliphatic copolyesters (PBSA), and fats Family terephthalate copolyesters (PBAT) and celluloses or starches that are highly acetylated or rendered hydrophobic by the introduction of fixed fatty chains, alone or in combination, linear, branched Characterized in that it comprises a non-crystallized biodegradable polymer selected from the group consisting of biodegradable polymers that are in the form of homopolymers or heteropolymers that are not either crosslinked, dendritic, or grafted Use according to any one of claims 1 to 6.   The stabilizer is selected from the group consisting of proteins, starches, polyvinyl alcohols, rubbers, polymeric emulsifiers, celluloses, and natural or modified forms of polyols, alone or in combination. Use according to any one of claims 1 to 7.   9. The aqueous film-forming composition thus obtained is intended for the preparation of pigment coating colors, aqueous film-forming pigment preparations, and aqueous paints, according to any one of the preceding claims. Use of.   The aqueous film-forming composition is an aqueous adhesive composition, in particular for labeling, for spiral mandrels, for cardboard, for bag production, for wallpaper, for carpets including laid carpets, for backings, for non-woven materials, Characterized by the preparation of tobacco adhesives, wall adhesives, textile finishes, varnishes, temporary protective compositions, graffiti-preventing compositions, coating compositions or waterproofing compositions, Item 9. The use according to any one of Items 1 to 8. An aqueous dispersion comprising an organic phase dispersed in a dispersible aqueous phase,
At least one solid content of from 25 to 70% by weight, preferably from 35 to 70% by weight, even more preferably from 45 to 65% by weight, and based on the solids content, from 95 to 99.5% on a dry basis Aqueous dispersion characterized in that it exhibits an organic phase comprising a biodegradable polymer and 0.5 to 5% of at least one stabilizer.   An aqueous pigment composition comprising the aqueous dispersion according to claim 11.   An aqueous adhesive composition comprising the aqueous dispersion according to claim 11.