MXPA06005399A - Composition containing a synthetic resin and a filler, methods for producing the composition and films obtained from this composition - Google Patents

Abstract

Composition containing (a) a synthetic resin and (b) a filler, the filler containing (b l) at least one inorganic substance having a specific surface area higher than or equal to 15 m2/g and (b2) at least one surface-active agent and/or one coating agent. Method for producing the composition. Use of the composition for the production of films, and films obtained starting with this composition.

Description

COMPOSITION CONTAINING A SYNTHETIC RESIN AND A MATERIAL OF FILLING, METHODS TO PRODUCE THE COMPOSITION AND FILMS OBTAINED FROM THIS COMPOSITION FIELD OF INVENTION The invention relates to compositions containing synthetic resins. It relates more particularly to compositions containing at least one synthetic resin and at least one filler material.

BACKGROUND OF THE INVENTION The packaging or packaging industry makes intensive use of synthetic resins, especially thermoplastic resins in the form of thin films. A technique commonly used to produce sheets of thermoplastic resin consists in the polymerization of a monomer in an aqueous phase, in the isolation of the solid resulting from the polymerization and in subjecting the collected resin to an extrusion process for film formed by blowing. This technique applies in particular to the production, for example, of thin films made of polyvinylidene chloride, intended for food packaging materials. These polyvinylidene chloride films have in fact the advantage of having low gas permeability, especially to the oxygen of the ambient air, which is favorable for the good preservation of the food. They additionally possess properties that are indispensable for the handling and sale of food, such as, for example, high flexibility and good mechanical strength. In order to improve certain properties of the polyvinylidene chloride films, the incorporation of mineral filler material into these is known, such as, for example, calcium carbonate. Thus, in international application WO 96/22329, a calcium carbonate powder is added to an emulsion of a polymer before the latter coagulates to form the resin. However, this known method is difficult to put into practice. The same in particular does not allow a uniform distribution of the calcium carbonate particles that will be obtained in the emulsion, these particles will preferably be adsorbed in small droplets of polymer which results in damage of larger droplets. The properties of the resin obtained from the method are therefore heterogeneous, which has harmful repercussions on the subsequent extrusion of the resin. Therefore the present problem is to provide compositions having the properties required to produce thin films intended for food packaging, namely with good thermal stability and with low oxygen permeability. Currently, special compositions have been found that simultaneously have these properties.

SUMMARY OF THE INVENTION The object of the invention therefore is to provide an improved composition having an optimum capacity to produce thin films having good thermal resistance and good oxygen barrier properties, preferably by the extrusion technique for film formed by blown. Accordingly, the invention relates to a composition containing: (a) at least one synthetic resin selected from homopolymers and copolymers of ethylene, propylene, styrene, vinyl chloride, vinylidene chloride, acrylic acid, alkyl acrylates, methacrylic acid , alkyl methacrylates, acrylonitrile, vinyl acetate, vinyl alcohol, isoprene, chloroprene, vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, copolymers of ethylene and alpha-olefins, copolymers of propylene and alpha-olefins other than propylene, chloride copolymers of vinylidene and vinyl chloride, copolymers of vinylidene chloride and alkyl acrylates, copolymers of vinylidene chloride and alkyl methacrylates, copolymers of styrene, butadiene and rubber, copolymers of acrylonitrile and butadiene, copolymers of styrene and acrylonitrile, copolymers of acrylonitrile , butadiene and styrene, copolymers of vinylidene fluoride and hexafluoropropylene or, polyesters, polyamides, polyurethanes, polycarbonates, polyphenylene ethers, polyimides, polyamideimides, polybenzimidazoles, polyalkylene oxides, polyether ether ketones, polyether sulfones, polyisocyanates, polyphenylene sulfides, and (b) at least one filler material containing (b) ) at least one inorganic substance having a specific surface area greater than or equal to 15 m2 / g and (b2) at least one surfactant and / or at least one coating agent.

BRIEF DESCRIPTION OF THE FIGURES Figure 1 represents the preferred method within the context of the invention, the inorganic substance is calcium carbonate precipitated by the carbonation of lime milk.

DETAILED DESCRIPTION OF THE INVENTION In the composition according to the invention, the synthetic resin is a polymeric resin. The term "polymer" is used as generally accepted, and invariably denotes a homopolymer, a copolymer or a combination of homopolymers and / or copolymers. The terms "synthetic resins", "polymer resins", "resins" and "polymers" will be used hereinafter to denote the same compound. Preferred are polymers based on vinyl chloride, vinylidene chloride, acrylic acid and their esters, methacrylic acid and esters thereof. More particularly, copolymers based on vinylidene chloride and vinyl chloride and copolymers based on vinylidene chloride and methyl acrylate are preferred. The vinylidene content of the copolymers based on vinylidene chloride and vinyl chloride in general is greater than or equal to 40% by weight, preferably greater than or equal to 45% by weight and more specifically greater than or equal to 70% in weigh. This content is usually less than or equal to 95% by weight and advantageously is less than or equal to 90% by weight. Values less than or equal to 85% by weight are particularly suitable. The vinylidene content of the copolymers based on vinylidene chloride and methyl acrylate is generally greater than or equal to 60% by weight, preferably greater than or equal to 65% by weight and more specifically greater than or equal to 75% by weight. weight. This content is usually less than or equal to 99% by weight and advantageously is less than or equal to 95% by weight. Values less than or equal to 92% by weight are particularly suitable. Copolymers based on vinylidene chloride and maleic anhydride or itaconic acid may also be suitable. The synthetic resins that participate in the composition according to the invention can be obtained by any known polymerization method, such as, for example, polymerization by aqueous emulsion, polymerization by aqueous suspension, solution polymerization or melt polymerization. Polymerization in aqueous suspension and aqueous emulsion polymerization are preferred. More particularly, aqueous emulsion polymerization is preferred. Among the various polymerization processes, radical polymerization and controlled radical polymerization processes are preferred in the presence of halogenated derivatives or derivatives of the xanthate type. The technique of emulsion polymerization is a well-known technique in the field of polymer production (PVDC and vinylidene chloride copolymers, Techniques de l'Ingénieur, Traite Génie des procedes, J. 6570). This is usually used for the production of vinyl polymers, especially polyvinyl chloride, polyvinylidene chloride and copolymers of vinyl chloride and vinylidene chloride. An aqueous polymeric emulsion used in this technique denotes an emulsion of the polymer in water or an aqueous solution. The emulsion may contain additives commonly used in the production of polymers by the emulsion polymerization technique. Commonly used additives comprise stabilizers, surfactants, polymerization initiators and plasticizers. The resins can be isolated by any known technique, such as, for example, filtration, centrifugation, spray and atomization. These isolation steps can be preceded by a coagulation step. The isolation technique preceded by a coagulation step is preferred. The stability of the emulsion will depend on the diameter of the polymer particles. The diameter is linked to various parameters, in particular the polymer used, the polymerization initiator, the surfactants used, the temperature and agitation and the presence of co-solvents and additives in the water and the presence or otherwise the water-soluble comonomers, inorganic or organic salts, anti-foaming agents or additives which by themselves constitute an emulsion or an dispersion. In practice, good results are obtained with aqueous emulsions in which the polymer particles can have a diameter less than or equal to 10 μm, preferably less than or equal to 5 μm. In particular, good results are obtained with polymer particles having a diameter less than or equal to 1 μm, preferably less than or equal to 0.75 μm and more particularly less than or equal to 0.5 μm. Polymer particles with a diameter less than or equal to 0.2 μm are particularly suitable. The polymer particles can have a diameter greater than or equal to 0.05 μm. Particles with a diameter greater than or equal to 0.07 μm are preferred. The suspension polymerization technique is a well-known technique for the production of polymers (PVDC and vinylidene chloride copolymers, Techniques de l'Ingénieur, Traite Génie des procedes, J. 6570). It is usually used for the production of vinyl polymers, especially polyvinyl chloride, polyvinylidene chloride and copolymers of vinyl chloride and vinylidene chloride. The aqueous polymer suspension used in this technique denotes a suspension of the polymer in water or an aqueous solution. The suspension may contain additives commonly used in the production of synthetic resins by the suspension polymerization technique. The additives normally used comprise stabilizers, surfactants, polymerization initiators and plasticizers.

The diameter of the polymer particles is linked to various parameters, in particular the polymer used, the polymerization initiator, the surfactants used, the dispersing agents, both with respect to the chemical nature as well as the quantity, temperature and agitation. In practice, good results are obtained with aqueous suspensions in which the particles of the polymer can have a diameter less than or equal to 750 μm, preferably less than or equal to 500 μm. Polymer particles with a diameter less than or equal to 300 μm are particularly suitable. The particles of the polymer can have a diameter greater than or equal to 10 μm and more particularly greater than or equal to 50 μm. Polymer particles with a diameter greater than or equal to 80 μm are particularly preferred. The resins can be isolated by any known technique, such as, for example, filtration, centrifugal desiccation, vacuum drum drying, screening or centrifugation. Desiccation techniques are preferred. The inorganic substance used in the composition according to the invention can be any mineral material. This material may be a metal carbonate, silica, clays, aluminum oxides, magnesium silicates, talcs, zeolites, metal particles, vitreous particles as well as mixtures of at least two thereof. Alkaline earth carbonates are preferred. In particular, calcium and magnesium carbonates are preferred. Calcium carbonate is more particularly preferred. This can be a natural or synthetic calcium carbonate. The natural calcium carbonate can be natural calcite or aragonite, gypsum or marble. It can be ground beforehand in dry or in a suspension. Synthetic calcium carbonate is preferred. The synthetic calcium carbonate can be obtained by any means. Among these means, consideration can be given to the precipitation of calcium carbonate by carbon dioxide initiating with lime slurry (carbonation method) or precipitation by adding an alkali metal carbonate starting with whitewash (causticizing method) or precipitation by the addition of an alkali metal carbonate initiated with solutions containing calcium chloride. According to a preferred method within the context of the invention, the inorganic substance is calcium carbonate precipitated by the carbonation of lime milk. This preferred method is shown in Figure 1. The limestone coming from the container (1) is fed into the container (3) (oven) via a duct (2). The fuel and the oxidizer are fed into the container (3) via the conduit (4). In the container (3), the limestone is converted to quicklime (CaO) and carbon dioxide. The carbon dioxide leaves the container (3) via the conduit (5) and enters the container (10) (carbonator). The quicklime leaves the container (3) via the conduit (7) and enters the container (8) (hydrator). Water is injected into the container (8) via the conduit (6). In the vessel (8), the quicklime is converted to calcium hydroxide (Ca (OH) 2) by reaction with water. The suspension of calcium hydroxide (milk of lime) leaves the container (8) via the conduit (9) and enters the container (10) (carbonator). In the vessel (10), the calcium hydroxide is converted to calcium carbonate by reaction with carbon dioxide. Additives can be introduced into the container (10) via the conduit (11). The calcium carbonate suspension possibly containing the additives leaves the container (10) via the conduit (12) and enters the container (13) where the filtration, drying and grinding steps are carried out. The calcium carbonate thus treated leaves the container (13) via the conduit (14) and enters the container (15) (storage) before feeding into the packaging sector (17) via the conduit (16). According to the means that are particularly preferred within the context of the invention, calcium carbonate is precipitated by carbonation of the lime milk with a gas containing carbon dioxide. In this preferred medium, the lime slurry is generally obtained by dispersing quicklime into fine particles in water and the gas containing carbon dioxide advantageously is a rich gas, in particular a lime baking gas. The calcium carbonate precipitated in this way can optionally be isolated from the preparation medium by any known technique, such as, for example, filtration, atomization and centrifugation. Filtration and centrifugation techniques are preferred. The inorganic substance can be practically amorphous or practically crystalline. It should be understood that practically amorphous or crystalline means that more than 50% by weight of the substance is in the form of amorphous or crystalline material when analyzed by an X-ray diffraction technique. Practically crystalline substances are preferred. In the case where the inorganic substance is calcium carbonate, this may consist of calcite or aragonite or a mixture of these two crystalline phases. The calcite phase is preferred. The efficiency of the method according to the invention is influenced by the dimensions of the particles of the inorganic substance. In theory, the effectiveness of the method and the quality of the composition obtained from the method should be better the finer the particle size of the inorganic substance. According to the invention, a particle size for the inorganic substance characterized by a median particle diameter less than or equal to 1 μm is recommended. Particles with a diameter less than or equal to 100 nm are especially advantageous, diameters less than or equal to 50 nm are preferred. Particles with a diameter greater than or equal to 15 nm are particularly suitable. The median diameter of the particle is measured by the Lea and Nurse method (standard NF 11601/11602). According to the invention, a specific surface area for the inorganic substance that is greater than or equal to 15 m2 / g is recommended. The specific surface area of the particles of the inorganic substance is advantageously greater than 50 m2 / g. A specific surface area greater than or equal to 70 m2 / g is particularly recommended. The specific surface area of the particles of the inorganic substance in general is less than or equal to 100 m2 / g, in particular the values of the specific surface area less than or equal to 90 m2 / g are preferred. The specific surface area is measured by the BET standard method (ISO 9277, 1995-05-15).

In addition to its particle size, the morphology of the inorganic substance also proves to be an important parameter in the quality and properties of the obtained composition. In the case where the inorganic substance is synthetic calcium carbonate, the particles may have the shape of needles, scalenohedron, rhombichedron, spheres, platelets or prisms. A rhombohedral configuration, which can be reduced to pseudo-cubes or pseudo-sphere, is preferred. In the case where the inorganic substance is calcium carbonate, it is worth noting that results have been obtained with calcium carbonate structures of nano-scale structure, nano-beams, nano-rosaries and nano-accordions-obtained through the method described and claimed in the patent application WO 03004414. The definitions of nano-beams, nano-rosaries and nano-accordions are provided in WO 03004414, page 5, line 33 to page 7, line 9 and are incorporated in the present as a reference. In the case where the inorganic substance is calcium carbonate, it is worth mentioning that the results have also been registered with microspheres, possibly hollow, which can be obtained by atomization. The surfactant can be selected from alkyl sulfates, aryl sulfonates, alkyl sulfosuccinates and mixtures of at least two thereof. It should be understood that the alkyl sulfates denote compounds from the group consisting of alkylsulfuric acids, the corresponding salts and mixtures of at least two thereof. The term "alkyl" represents a linear or branched aliphatic hydrocarbon group having a number of carbon atoms greater than or equal to one. This number of carbon atoms is preferably greater than or equal to 6. A number of carbon atoms greater than or equal to 10 is quite adequate. This number is usually less than or equal to 20 and more specifically less than or equal to 16. Preferred sodium, potassium or ammonium lauryl sulfates. In particular, sodium lauryl sulphate is preferred. It should be understood that the arylsulfonates denote compounds from the group consisting of arylsulfonic or alkylarylsulfonic acids or the corresponding salts and mixtures of at least two thereof. The term "aryl" represents a mono- or bicyclic aromatic hydrocarbon group having at least 6 carbon atoms and not more than 10 carbon atoms, such as, for example, phenyl and naphthyl groups. The term "alkylaryl" represents an alkyl radical as defined above covalently linked to an aryl residue as defined above. In a preferred process, the surfactant can be selected from the compounds represented by the following general formulas: (l-A) (l-B) wherein R1, R7, R9 and R10 are independently an individual bond, -O-, a -C? -Ci8-alkylene group or a -C2-C? 8 -alkenylene group (wherein in the alkylene or alkenylene chain, groups 1, 2 or 3 -CH2- can be optionally replaced by -O-); R2, R3, R4, R5 and R6 are independently -H, a -Ci-Ciß-alkyl group (wherein in the alkyl chain, groups 1, 2 or 3 -CH2- can be optionally replaced by -0-) , -OH, -F, -Cl, -CN, -C02H, -CO-C? -C6-alkyl, -C02-Ci-Ce-alkyl, -0-CO-C? -C5-alkyl, -N02, -NH2, -NH-C? -C6-alkyl or -N (C? -C6-alkyl) 2; R8 is -H or C? -C6-alkyl; and R11 and R12 are independently -H, a -Ci-Cig-alkyl group (wherein in the alkyl chain, groups 1, 2 or 3 -CH2- can be optionally replaced by -O-), -NH2, - NH-Ci-Ce-alkyl or -N (C? -C6-alkyl) 2. The term "alkylene" is to be understood as meaning divalent straight or branched chains such as, for example, -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2CH2CH2CH2-, -CH (CH3) -, -CH2CH (CH3) -, -CH2CH2CH (CH3) -, -CH = CCH3) CH2- and the like. The term "alkenylene" is to be understood to mean divalent linear or branched chains such as, for example, -CH = CH-, -CH2CH = CH-, -CH2CH2CH = CH-, -CH = C (CH3) -, -CH2CH = C (CH3) -, -CH = C (CH3) CH2- and the like. Preferably, in the compounds represented by the general formulas (IA) and (IB): R1, R7, R9 and R10 are independently an individual bond or a -Ci-Ce-alkylene group (wherein in the alkylene chain , groups 1, 2 or 3 -CH2- can be optionally replaced by -0-); R2, R3, R4, R5 and R6 are independently -H or a group C? -Ci8-alkyl (wherein in the alkyl chain, groups 1, 2 or 3-CH2 ~ can be optionally replaced by -0-); R8 is -H or Ci-Cg-alkyl; and R11 and R12 are independently a -C? ~ C12 alkyl group (wherein in the alkyl chain, groups 1, 2 or 3-CH2- can optionally be replaced by -0-). In a particularly preferred form: R1 and R7 are individual bonds, R2, R3, R5 and R6 are -H, R4 is -H or a group C? -C8-alkyl, R8 is -H, R9 and R10 are independently a bond individual or -CH2- and R11 and R12 are independently a -C? -C? 2-alkoxy group. The term "alkoxy" denotes an alkyl residue as defined above covalently bonded to an oxygen atom, such as, for example, -OCH 3, -OCH 2 CH 3 and the like. Among the arylsulfonates, sodium dodecylbenzenesulfonate is particularly preferred. Among the alkylsulfosuccinates, sodium dioctylsulfosuccinate is particularly preferred. The surfactant content of the filler material in general will be greater than or equal to 0.1% by weight, preferably greater than or equal to 0.5% by weight and more particularly greater than or equal to 1% by weight. This content is generally less than or equal to 20% by weight and more specifically less than or equal to 15% by weight. A content less than or equal to 5% by weight is particularly suitable. The coating agent may be selected from saturated or unsaturated fatty acids, the corresponding salts or any mixture of at least two thereof. The fatty acids have a number of carbon atoms in general greater than or equal to 6, preferably greater than or equal to 12 and more particularly greater than or equal to 14. This number of carbon atoms is usually less than or equal to 26 and more particularly less than or equal to 22. A number of carbon atoms less than or equal to 18 is particularly suitable. In particular, mixtures containing stearic, palmitic and oleic acids are preferred. These mixtures are also called "stearin" and are available commercially under the brands Priplus, Edenor, Pristerene, Undesa, Prifac, Radiacid, Safacid, Creraer, among others. This mixture, for example, referred to as technical grade stearic acid contains about 60-65% by weight of stearic acid and about 40-35% by weight of palmitic acid, the rest being mainly oleic acid. The content of the coating agent of the filling material in general is greater than or equal to 0.5% by weight, preferably greater than or equal to 1% by weight and more particularly greater than or equal to 2.5% by weight. This content is usually less than or equal to 25% by weight and more particularly less than or equal to 20% by weight. A content less than or equal to 15% by weight is particularly suitable. The content of the filling material of the composition may be greater than or equal to 0.5% by weight. This preferred content is greater than or equal to 1% by weight and more particularly greater than or equal to 2% by weight. This content is usually less than or equal to 10% by weight, more specifically less than or equal to 5% by weight. A content less than or equal to 3% by weight is particularly suitable. The composition according to the invention can be obtained by various methods. As a consequence, the invention therefore also relates to a method for the production of a composition containing at least one synthetic resin and at least one filler material, according to which a polymer is prepared and at least one is added a filler material thereto, the filler material contains (a) at least one inorganic substance having a specific surface area greater than or equal to 15 m2 / g and (b) at least one surfactant and / or at least one surfactant agent. coating. In the method according to the invention, the synthetic resin can be used in the form of a solid or an aqueous emulsion or an aqueous suspension. It is preferred to use the synthetic resin in the form of a solid or an aqueous emulsion. It should be understood that a solid synthetic resin means a resin isolated from the polymerization medium by any known technique, for example, filtration, centrifugation, spray, or atomization, it being possible for these operations to be preceded by a coagulation step. The solid may contain compounds other than the polymer itself, such as, for example, one or more additives used during the polymerization step. The water content of the solid may be lthan or equal to 1.5% by weight. This preferred content is lthan or equal to 0.8% by weight and more particularly lthan or equal to 0.3% by weight. It should be understood that an aqueous emulsion means the aqueous phase obtained from the emulsion polymerization procas described above. It should be understood that an aqueous suspension of the resin means the aqueous phase obtained from the suspension polymerization procas described above. In the method according to the invention, the filler material containing the inorganic substance and the surfactant or the coating agent can be formed as a dry solid or a wet cake or an aqueous suspension. Application in the dry solid state or in the aqueous suspension state is preferred. It should be understood that a dry solid means the solid filler material isolated from its preparation medium as described above and of which the water content may be lthan or equal to 10% by weight. This content of preference is lthan or equal to 5% by weight and more particularly lthan or equal to 3% by weight. A content lthan or equal to 1% by weight is particularly suitable. It should be understood that a wet cake means the solid filler material isolated from its preparation medium as described above and of which the water content may be lthan or equal to 70% by weight. This content of preference is lthan or equal to 50% by weight. This water content is usually greater than or equal to 10% by weight, more specifically greater than or equal to 30% by weight. It should be understood that an aqueous suspension means an aqueous suspension of solid matter that can be pumped as distinct from a wet filter cake. In the method according to the invention, the optimum content of the filling material to produce a stable suspension will depend on various factors, in particular the effective temperature and the particle size of the inorganic substance. In general, the concentration of the inorganic substance in the suspension may be greater than or equal to 30 g / 1 and preferably greater than or equal to 180 g / 1. This concentration in general is lthan or equal to 250 g / 1, more specifically lthan or equal to 180 g / 1. The surfactant containing the filler material can be used in the form of a solid or a solution or an emulsion or a suspension. It is preferably used in the form of a solution or an emulsion. It is possible to introduce the surfactant into the preparation medium of the filling material. The surfactant is preferably introduced in the form of a solution or an emulsion. The coating agent containing the filler material can be used in the form of a solid or a liquid or a solution or an emulsion or a suspension. It is preferred that it be used in the form of an emulsion or a molten solid. This can be introduced into the medium to prepare the filling material. The coating agent is preferably introduced in the form of an emulsion or a solid. According to a first variant according to the invention, the polymer is isolated in the form of a solid, the filler material is added thereto in the form of a dry solid and the combination is mixed substantially in the absence of the liquid. It should be understood that practically the absence of liquid means that the liquid content in the mixture in general is lthan or equal to 15 g / kg of the mixture, preferably lthan or equal to 8 g / kg and more particularly lthan or equal to 3 g / kg. It is preferred to add the filler material containing an inorganic substance and a coating agent. It is more preferred to add the filler material containing an inorganic substance and stearin. The mixing was carried out by any type of known means. Mixing in a mixer of the low speed type is preferred, high speed or planetary or in an extruder of the type of a screw or twin screws. Mixing in a mixer at low speed is more particularly preferred. According to a second variant according to the invention, an aqueous emulsion of the polymer is prepared and the filler material is added thereto and the emulsion is coagulated. The filler material can be added in the form of a dry solid, a wet cake or an aqueous suspension. The addition of the filler material in the form of an aqueous suspension is preferred. The coagulation of the aqueous emulsion consists of the decomposition of the colloidal stability of the emulsion by carrying out the coagulation of the polymeric particles that settle out as they agglomerate in entities that are between 10 and 1200 μm in size. Various means are known to carry out the coagulation of the emulsion. A preferred means is to add a coagulating agent to the emulsion. This is generally a suitable metal salt, for example, an aluminum salt. The concentration of the coagulating agent in the mixture of the aqueous emulsion and the aqueous suspension of the filling material may be less than or equal to 5% by weight, preferably less than or equal to 2% by weight and more particularly less than or equal to 1.5% in weigh. This concentration in general is greater than or equal to 0.05% by weight and more specifically greater than or equal to 0.10% by weight. A concentration greater than or equal to 0.15% by weight is particularly suitable. The composition collected after coagulation is normally subjected to drying before being stored for later use. All other things that are the same, in the method according to the invention, the quality and properties of the composition obtained after coagulation will depend on a combination of various parameters, among which are the content of the polymer in the emulsion, the concentration of the filler material in the suspension and the amount of suspension used. In an advantageous embodiment of the method according to the invention, the polymer emulsion contains at least 30 g / 1 and contains no more than 450 g / 1 of the polymer, and in a preferred form no more than 250 g / 1 of the polymer, the The suspension contains at least 25 g and not more than 250 g of filler material per kg of the aqueous suspension and the suspension is used in an amount sufficient for the composition in general to contain at least 0.5% of the filler material by weight, preferably at least 1% by weight and more particularly at least 2% by weight, and for the composition to contain no more than 10% of the filler material by weight, more specifically not more than 5% by weight and more particularly not more than 3 % in weigh. All other things will be the same, moreover, in the case of the production of the compositions containing polyvinylidene chloride, the crystalline morphologies of the calcium carbonate structured at the nanoscale as described above make possible an optimum incorporation efficiency in the composition. It should be understood that the efficiency of incorporation means the proportion of the calcium carbonate mass actually incorporated in the composition to be used in the suspension. As stated above, the suspension of the filling material used in the method according to the invention contains an inorganic substance and a surfactant and / or a coating agent. Without being bound by any particular theory, it is believed that this agent has the function of facilitating the dispersion of the particles of the filler material in the polymer emulsion. However, it has been observed that the choice of agent may have an influence on the properties of the composition and on those products produced with this composition. In particular, in the case of compositions containing polyvinylidene chloride, a suitable choice of agent may have a negative influence on the properties of the sheets produced with the composition, in particular on its thermal resistance and on its impermeability to oxygen in the air. Accordingly, in an advantageous embodiment of the method according to the invention, when the inorganic substance is precipitated calcium carbonate the suspension contains a surfactant which is an ionic compound. This compound is preferably compatible with the emulsion to which the suspension is added. In the case where the resin contains polyvinylidene chloride, the surfactant is advantageously selected from aryl sulfonates, alkyl sulfosuccinates, alkyl sulfates and mixtures of at least two thereof. The compositions obtained according to the invention have properties worthy of mention, superior to those of the known compositions. These properties worthy of mention can be observed particularly for the compositions comprising vinylidene chloride, in particular in relation to a better extrudability - by virtue of a better uniformity of the dispersion of the calcium carbonate in the composition and an improved porosity . The porosity of the composition is favorable on the one hand for a rapid drying in the coagulation method and on the other hand it makes possible the improved adsorption of additives during the subsequent treatment in an extruder. Furthermore, the films obtained, despite the increase in porosity measured in the compositions, maintain their good oxygen barrier properties, by virtue of the uniformity worth mentioning of the dispersion obtained. They have a better visual appearance. These properties make them particularly suitable for use in the food industry. The films obtained may also have a perception that is particularly suitable for medical applications. The invention therefore also relates to the use of compositions according to the invention for the production of films. In a preferred manner, those films can be obtained by extrusion of film by blowing. The invention therefore also relates to the films obtained by starting with the compositions according to the invention. The examples, which follow after the description, serve to illustrate the invention without however limiting the scope of the claims below.

Method for preparing a solid polymer by the emulsion polymerization method An enameled autoclave (AC) having a volume of 67 liters was provided with a jacket with a capacity of 12 liters, the temperature of which was regulated by introducing steam at 2.94 kg / cm2 (3 bar) and water through two regulating valves operating according to the temperature measured in the reaction mixture, and - 12 liters of demineralized water were introduced, 2.26 mol of dodecylbenzenesulfonate were introduced. of sodium, - 4 g of ascorbic acid were introduced, vacuum was applied at 137.29 kg / cm2 (140 mbar) absolute for 10 minutes, - the autoclave was pressurized by introducing nitrogen at a relative pressure of 0.49 kg / cm2 (0.5 bar) for 10 minutes, vacuum was applied at 137.29 kg / cm2 (140 mbar) absolute, while the temperature of the container liner was being regulated at 15 ° C; - 8 kg of unstabilized vinylidene chloride (purity = at least 99.97%) and 2 kg of vinyl chloride were introduced. The reaction mixture was stirred at 40 rpm by means of a 3C impeller-type stirrer. At the same time, the reaction mixture was brought to a temperature of 43 ° C. Hydrogen peroxide (0.7 g) was introduced when the temperature reached 41 ° C. After 30 minutes, a solution of hydrogen peroxide at 5 g / 1 and a solution of ascorbic acid at 20 g / 1 were added at the same time to maintain a temperature difference between the internal temperature of the autoclave and the temperature of the shirt between 13 and 25 ° C. After at least 1 hour and no more than 12 hours of polymerization, the injection of hydrogen peroxide was stopped when the pressure in the CA dropped by at least 0.34 kg / cm2 (0.35 bar) and the introduction of hydrogen peroxide was stopped when the pressure drop reached 0.53 kg / cm2 (0.55 bar). The reaction mixture was then heated to 50 ° C and the AC was placed under vacuum in order to remove the residual monomers in order to provide a level compatible with their use in food applications. Stirring was reduced to 20 rpm during this step. The reaction mixture was then cooled to 25 ° C. The polymer was isolated from the reaction mixture by means of a coagulation step. For 3 liters of the reaction mixture, the procedure of operation was as follows: a coagulation solution was added to cover the lower part of a container whose temperature was maintained by means of a water bath. This volume of 1 liter contained a concentration of 0.17 g of aluminum nitrate. The temperature was maintained between 10 ° C and 14 ° C according to the proposed final particle size. The reaction mixture and the rest of the coagulant solution were added simultaneously during the same period while the temperature was being maintained and while stirring was continued at 125 rpm using a curved blade agitator with six blades. This corresponds to: 31 of the reaction mixture at a concentration of 200 g / 1, 1 liter of a solution at 0.34 g / 1 of aluminum nitrate. This double addition was carried out for 30 min taking care to place the inlets for the reaction mixture and the coagulant solution diametrically opposite each other in the coagulation vessel. Once this step was completed and after having verified the amount of coagulation, a heat treatment was carried out by bringing the resin to 70 ° C for 90 minutes. The resin was then cooled to 30 ° C before being drained on a Büchner funnel under vacuum. The resin was extracted twice in 2 1 of demineralized water in such a way that it could be completely rinsed and drained each time on the funnel Büchner. At the end of the third drain under vacuum, the lid was introduced into the bowl of a small Retsch fluidized bed dryer and then dried by passing air at 30 ° C. After 2 hours, the resin dried and had a volatile matter content (water) of less than 0.3% on a weight / weight basis.

Method for preparing a solid polymer by the suspension polymerization method An enameled autoclave (CA) having a volume of 67 liters was provided with a jacket with a capacity of 12 liters, the temperature of which was regulated by introducing steam at 2.94 kg. / cm2 (3 bar) and water through two regulating valves that work according to the temperature measured in the reaction mixture, and - 17 liters of demineralized water were introduced, lauroyl peroxide flakes (100 g) were introduced, 30 g of a dispersant of the methylpropoxycellulose type, such as, for example, Culminal C3550, prepared in demineralised water to give a concentration of 10 g / 1, was introduced, vacuum was applied at absolute 137.29 kg / cm2 (140 mbar) for 10 minutes , the autoclave (CA) was pressurized by introducing nitrogen at a relative pressure of 0.49 kg / cm2 (0.5 bar) for 10 minutes, - vacuum was applied at 137.29 kg / cm2 (140 mbar) absolute, while so that the temperature of the container jacket was being regulated at 15 ° C: 9 kg of unstabilized vinylidene chloride (purity = at least 99.97%) and - 1 kg of methyl acrylate was introduced. The reaction mixture was stirred at 40 rpm by means of a stirrer of the Impeller 2B type. At the same time, the reaction mixture was brought to a temperature of 75 ° C. When the reaction was finished, the temperature difference between the jacket and the reaction mixture was reduced until it was less than 2 ° C, and it was left for a period of 15 minutes before the reaction mixture was cooled. Once the resin had been obtained, a step was carried out to remove the residual monomers by distillation: the suspension, a mixture of water and resin, was brought to 100 ° C by heating and a vacuum was created in the autoclave. After 2 hours of distillation, the reaction mixture was cooled by introducing water into the jacket and drained over a filter in a Büchner funnel under vacuum. The resin was extracted twice in 2 liters of demineralized water so that it could be completely rinsed and drained each time over the Büchner funnel. At the end of this third draining under vacuum, the cake was placed in the bowl of a small Retsch fluidized bed dryer and then dried by passing air at 30 ° C. After 2 hours, the resin dried and had a volatile matter content (water) below 0.3% on a weight / weight basis.

Procedure for the preparation of a dry uncoated precipitated calcium carbonate (PCC) A stream of carbon dioxide gas containing 30% by volume C02 was introduced into a 40 liter reactor that contained a whitewash with a lime concentration of 180 g / 1, at a temperature of 20 ° C and a flow rate of 16 m3 / h. After approximately 90 minutes, 100% of the calcium hydroxide had been converted to calcium carbonate. The PCC was recovered by filtration and dried at about 105 ° C and the solid was then ground in an Alpine type crusher. The solid had a specific surface area of about 20 m2 / g. By proceeding in the same manner in the presence of varying amounts of citric acid in the reaction mixture, solids were obtained having a specific surface area of about 66 m2 / g or about 80 m2 / g.

Procedure for the preparation of dry-coated PCC A stream of carbon dioxide gas containing 30% by volume C02 was introduced into a 40-liter reactor containing water with lime with a lime concentration of 180 g / l, at a temperature of 20 ° C and a flow rate of 16 m3 / h. After approximately 90 minutes, 100% of the calcium hydroxide had been converted to calcium carbonate. The suspension of the PCC obtained was brought to approximately 80 ° C and then an aqueous emulsion of stearin was added, also brought to 80 ° C. A stearin content of the emulsion was calculated to obtain a content of about 3 to 12% by weight based on dry calcium carbonate. The system was stirred for approximately 30 minutes before filtering, then dried at 105 ° C and finally ground. The aqueous emulsion of stearin could have been replaced by a solution of sodium dodecylbenzenesulfonate, the concentration will be calculated to obtain a content of about 1 to 4% by weight based on dry calcium carbonate.

Process for the production of films The resin was premixed first of all in the presence of various additives such as, for example, a plasticizer, liquid hot stabilizers and a wax. This premix was then introduced into a stirred extruder fitted with a parison. The tubular parison collected from the hot extruder at 150 ° C was converted into a film by blowing. Before extrusion: 4% by weight of dibutyl sebacate; 1.2% epoxidized soybean oil; they could have been mixed at 70 ° C.

Methods for analyzing the properties of resins and films Incorporation efficiency The incorporation efficiency (IE) of calcium carbonate in the composition is expressed as a percentage by weight of calcium carbonate (in 'dry state' used (in dry state or in suspension). The incorporation efficiency was calculated by determining the calcium content of the mixture by dissolving the resin in an aliquot of heated tetrahydrofuran. 60 ° C, then adding an aqueous solution of hydrochloric acid. The aqueous phase obtained was separated by filtration and then analyzed by ICP-AES or by colorimetry.

DOP Porosity DOP porosity was measured by the adsorption of a plasticizer (dioctyl phthalate) in the pores of the composition. The ability of the composition to adsorb a plasticizer and to undergo extrusion is proportional to the DOP porosity. An aliquot of known mass of the composition in contact with the same amount of dioctyl phthalate was placed. After a contact time of 30 minutes at room temperature, the whole was placed in a filter cartridge from which the filtration threshold maintained the polymer particles. The filtration was carried out on centrifugation (30 seconds) and the amount of DOP recovered was weighed and the porosity provided corresponded to the percentage of DOP incorporated in the resin in relation to the amount used in the initial mixture.

FFD or free-flowing density This involved placing a 250-g mass of the resin in a cylinder at a height and closed by a pivot-actuated disc. A cylinder with a known volume was placed under this tube and operated as a receiver for the resin that flowed under gravity when the disk plug moved to the side. The excess resin was scraped off by passing a ruler resting on the edge of the receiving test tube. The mass of the resin contained was then weighed and the FFD deduced from the ratio of resin mass / volume of the receiving test tube.

Particle size distribution In the case of the resin emulsion, the particle size distribution was obtained by screening the resin through a series of screens from which the thresholds were obtained, from the thickest to the thinnest, 850 μm, 500 μm, 350 μm, 250 μm, 104 μm and 44 μm. For the resin suspension, which had spherical particles, it was subjected to light scattering which was used using a Malvern or Coulter brand apparatus. A curve was obtained from which it was possible to extract the data, dio, dso, and dioxide, for example it is understood that they provided the necessary diameter for a screening that could only allow 10% of the resin mass to pass. The median diameter was denominated d50- The distribution will be provided by the data of the section corresponding to the index obtained according to the proportion (dgo-d? O) / d50. The particle size distribution of the composition resulting from the second variant according to the invention was determined by a screening method as described above. The median diameter dm, the diameter dso and the particle size distribution? of the composition were also calculated, these parameters will be defined by the equations: d90-d 10 x50 where: n denotes the weight of the diameter particles; n denotes the total weight of the composition (=? n¿); d90 denotes the diameter of the screen through which 90% by weight of the composition passes; gave denotes the diameter of the screen through which passes 10% by weight of the composition; and d5o denotes the diameter of the screen through which 50% by weight of the composition passes.

Thermal stability The thermal stability (TS) was measured at 160 ° C in a twin cam mixer (a master and a slave) of the Brabender brand. The color changes of the mixture and the torque to which the slave cam was subjected were recorded. The thermal stability, which was measured in minutes, corresponds to the period necessary to observe a break in the slope of torque decrease, a break that revealed a three-dimensional reorganization of the product and therefore an irreversible degradation before carbonizing.

Oxygen permeability Once a film was obtained, its thickness was measured by light filtration (infrared spectroscopy). The film was then placed hermetically on the upper side of a cell included in a double network. A stream of pure oxygen circulated underneath and a stream of nitrogen circulated above, the incoming oxygen had traveled through the film. This oxygen was then analyzed columbometrically, and the amount that had migrated for 24 h, was separated from a transient period, multiplied by the thickness of the film in microns in order to define the intrinsic permeability in g of oxygen / day. μm, and it is at 25 ° C and at a humidity of 85% (standard D-3985-81 ASTM).

First variant according to the invention In each example, the solid polymer had been obtained from a suspension polymerization according to the procedure detailed above. The solid polymer and the filler material were mixed by the following procedure. 500 g of the polymer in pulverized form was placed in a slow-speed premixer having a capacity of 1 kg and provided with a system to maintain the temperature of the mixture. This resin was stirred for 30 minutes in such a way that its temperature was brought to 50 ° C and then 7.5 g of dry filler material (precipitated calcium carbonate, PCC) was added and stirring was carried out continuously while continuing to maintain the temperature for 6 hours. Once mixing was completed, care was taken when transferring the product to a screen of hard agglomerates that may have formed essentially on the blades of the mixer. Epoxidized soybean oil (ESO, Edenol® D82) could optionally have been added to the above compounds before mixing. The resulting composition of the mixture was then used to produce films according to the procedure described below.

Example 1 (not according to the invention) The composition resulting from the mixture did not contain epoxidized soybean oil or filler material.

Example 2 (not according to the invention) The composition resulting from the mixture only contained epoxidized soybean oil.

Example 3 (according to the invention) The resin was mixed with epoxidized soybean oil and a filler material that contained precipitated calcium carbonate having a specific surface area of about 80 m2 / g and 12% by weight (against PCC) of stearin as a coating agent.

Example 4 (according to the invention) The resin was mixed with epoxidized soybean oil and filler material which contained precipitated calcium carbonate having a specific surface area of about 20 m2 / g and containing 3% by weight (against PCC) of stearin as a coating agent.

Example 5 (according to the invention) The resin was mixed with epoxidized soybean oil and a filler material that contained precipitated calcium carbonate having a specific surface area of about 66 m2 / g and contained 9.9% by weight (against PCC) of sodium dodecylbenzenesulfonate as a surfactant.

Example 6 (according to the invention) The resin was mixed with a filler material that contained precipitated calcium carbonate having a specific surface area of about 66 m2 / g and containing 3.3% by weight (against PCC) of sodium dodecylbenzenesulfonate. as a coating agent.

Example 7 (according to the invention) The resin was mixed with a filler material that contained precipitated calcium carbonate having a specific surface area of about 20 m2 / g and containing 12% by weight (against PCC) of stearin as a coating agent.

Table 1 provides the concentrations of different components of the mixtures (in% by weight) as well as the properties of the resulting compositions of the mixtures and the films obtained starting from these compositions.

Table 1 Appearance of the film: (a) normal, (b) translucent, (c) wavy.

Second variant of the invention In each example, an aqueous emulsion of polyvinylidene chloride in demineralised water was prepared by the emulsion polymerization technique according to the procedure detailed above. The obtained emulsion contained 200 g of resin (weight of dry matter) per liter. At the same time, a calcium carbonate suspension comprising 100 g of calcium carbonate (within dry matter) per liter was prepared according to the procedure detailed above. Then 0.2 g of an aluminum salt was added (coagulating agent) to the emulsion and if the amount of the suspension was adjusted in such a way that the emulsion contained an amount of calcium carbonate practically equal to 2.5% by weight of dry matter. The mixture was maintained at a temperature of 13 ° C for a time necessary to obtain complete coagulation of the latex. The composition collected after coagulation was then subjected to heat treatment for 90 min at 70 ° C. The composition was then washed with demineralized water and then dried by fluidization in ambient air at 60 ° C. The composition obtained was then analyzed for the following parameters: incorporation efficiency (IE) porosity DOP - free flux density (abbreviated as FFD) - particle size distribution of the composition - thermal stability (TS) of the composition. The composition was also subjected to a blown film extrusion test in order to measure its oxygen permeability. Prior to extrusion, the following was added to the composition with 70 ° mixing: - 4% by weight of dibutyl sebacate; - 1.2% epoxidized soybean oil.

Example 8 (not according to the invention) In this example, the resin coagulated in the absence of calcium carbonate.

Example 9 (according to the invention) Calcium carbonate having an ultrafine morphology, a median diameter of 15 nm and a specific surface area in the order of 80 m / g was used, and sodium dodecylbenzenesulfonate was introduced into the suspension aqueous as a surfactant.

Example 10 (according to the invention) The same calcium carbonate was used as in Example 1 but sodium lauryl sulfate was introduced into the aqueous suspension as a surfactant.

Example 11 (according to the invention) Calcium carbonate, structured at the nanoscale, was used, obtained according to the method described in the application WO 03/004414 which had a specific surface area of 25 m2 / g, which contained dodecylbenzenesulfonate of sodium previously introduced into the aqueous suspension.

Example 12 (according to the invention) Calcium carbonate was used, structured at the nanoscale, which had a microspheroidal structure which contained sodium dodecylbenzenesulfonate previously introduced into the aqueous suspension. The results of the tests are given in the following Table 2.

Table 2

Claims (20)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, the content of the following CLAIMS is claimed as property: 1. A composition characterized in that it contains: (a) at least one synthetic resin selected from homopolymers and copolymers of ethylene, propylene, styrene, vinyl chloride, vinylidene chloride, acrylic acid, alkyl acrylates, methacrylic acid, alkyl methacrylates, acrylonitrile, vinyl acetate, vinyl alcohol, isoprene, chloroprene, vinyl fluoride, fluoride of vinylidene, tetrafluoroethylene, copolymers of ethylene and alpha-olefins, copolymers of propylene and alpha-olefins other than propylene, copolymers of vinylidene chloride and vinyl chloride, copolymers of vinylidene chloride and alkyl acrylates, copolymers of vinylidene chloride and alkyl methacrylates, copolymers of styrene, butadiene and rubber, copolymers of acrylonitrile and butadiene, coke styrene and acrylonitrile copolymers, copolymers of acrylonitrile, butadiene and styrene, copolymers of vinylidene fluoride and hexafluoropropylene, polyesters, polyamides, polyurethanes, polycarbonates, polyphenylene ethers, polyimides, polyamideimides, polybenzimidazoles, polyalkylene oxides, polyether ether ketones, polyether sulfones, polyisocyanates, polyphenylene sulfides, and (b) at least one filler material containing (bl) at least one inorganic substance having a specific surface area greater than or equal to 15 m2 / g and (b2) at least one surfactant and / or at least one coating agent. The composition according to claim 1, characterized in that the synthetic resin is a copolymer of vinylidene chloride and vinyl chloride containing at least 40% by weight of vinylidene chloride. 3. The composition according to claim 1, characterized in that the synthetic resin is a copolymer of vinylidene chloride and methyl acrylate containing at least 60% by weight of vinylidene chloride. 4. The composition according to any of claims 1 to 3, characterized in that the inorganic substance is in the state of particles with a median diameter of less than 1 μm. The composition according to any of claims 1 to 4, characterized in that the composition of the filler material in the composition is greater than or equal to 0.5% by weight and is less than or equal to 10% by weight. 6. The composition according to any of claims 1 to 5, characterized in that the inorganic substance is calcium carbonate precipitated by the carbonation of the lime milk. The composition according to any of claims 1 to 6, characterized in that the surfactant is selected from alkyl sulfates, aryl sulfonates, alkyl sulfosuccinates and mixtures of at least two thereof. The composition according to any of claims 1 to 6, characterized in that the coating agent is selected. of fatty acids having a number of carbon atoms greater than or equal to 6 and less than or equal to 26, and mixtures of at least two thereof. A method for producing a composition according to any of claims 1 to 8, according to which a synthetic resin is prepared and at least one filler material is added thereto, the filler material characterized in that it contains (a) at least one inorganic substance having a specific surface area greater than or equal to 15 m2 / g and (b) at least one surfactant and / or at least one coating agent. The method according to claim 9, according to which the synthetic resin is prepared by an aqueous emulsion polymerization method or by an aqueous suspension polymerization method. 11. The method according to any of claims 9 and 10, according to which, after the polymerization, an aqueous emulsion of the resin or an aqueous suspension of the resin is collected or the resin is isolated in the form of a solid. 12. The method according to any of claims 9 to 11, characterized in that the filling material is added in the form of a solid, a wet cake or an aqueous suspension. The method according to any of claims 11 and 12, characterized in that the resin is isolated in the form of a solid and the filler material is added thereto in the form of a solid, practically in the absence of liquids. The method according to any of claims 11 and 12, characterized in that an aqueous emulsion is collected from the resin, the filler material is added thereto in the form of an aqueous suspension and the emulsion is coagulated. 15. The method according to claim 14, characterized in that the emulsion is coagulated by adding a coagulating agent. 16. The method according to claim 15, characterized in that the coagulating agent is selected from metal salts. 17. The method according to claim 16, characterized in that the coagulating agent is selected from aluminum salts. 18. The use of a composition according to any of claims 1 to 8 for the production of films. 19. The use according to claim 18, for the production of films by extrusion of film by blowing. 20. The films produced starting from a composition according to any of claims 1 to 8.